Updated on 2025/09/10

写真a

 
IWAMOTO Erika
 
Organization
School of Health Science Department of Physical Therapy Second Division of Physical Therapy Associate Professor
Title
Associate Professor
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Degree

  • 博士(医学) ( 名古屋大学 )

Research Interests

  • Hypoxia

  • 食後高血糖

  • Cerebral artery

  • Atherosclerosis

  • 機能的交感神経遮断

  • Flow mediated dilation

  • Exercise program

  • 内部障害リハビリテーション

  • endothelial function

  • locomotor-respiratory coordination

  • Blood flow

Research Areas

  • Life Science / Rehabilitation science

  • Life Science / Sports sciences

Education

  • Nagoya University

    2010.4 - 2013.9

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  • Hiroshima University

    2008.4 - 2010.3

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Research History

  • 札幌医科大学 保健医療学部 理学療法学科   准教授

    2024.4

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  • Sapporo Medical University   School of Health Sciences   Lecturer

    2020.4 - 2024.3

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  • University of Iowa, Human Integrative and Cardiovascular Physiology Laboratory

    2019.10 - 2019.12

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  • University of Iowa   Human Integrative and Cardiovascular Physiology Laboratory

    2016.9 - 2017.9

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  • Sapporo Medical University   Assistant Professor

    2013.4 - 2020.3

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  • Sapporo Medical University   Research Assistant

    2012.4 - 2013.3

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Professional Memberships

  • American College of Sports Medicine

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  • American Physiological Society

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  • JAPANESE PHYSICAL THERAPY ASSOCIATION

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  • THE JAPANESE SOCIETY OF PHYSICAL FITNESS AND SPORTS MEDICINE

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  • 日本基礎理学療法学会

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Papers

  • Effects of inspiratory muscle metaboreflex on cerebral circulation at rest and during light-intensity exercise in healthy males. International journal

    Kohei Sato, Tatsuki Kamoda, Rintaro Sakamoto, Keisho Katayama, Toru Neki, Masaki Katayose, Erika Iwamoto

    Respiratory physiology & neurobiology   336   104422 - 104422   2025.3

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    Authorship:Last author, Corresponding author   Language:English   Publishing type:Research paper (scientific journal)  

    PURPOSE: This study aimed to clarify the effects of inspiratory muscle metaboreflex on cerebral circulation at rest and during exercise. METHODS: Twelve young males randomly completed two trials (rest and exercise [leg cycling at 40% peak oxygen uptake] trials) on separate days. In each trial, the internal carotid artery (ICA), an index of cerebral circulation, was measured using Doppler ultrasound 2min after inspiratory loading breathing (IL condition) or non-loading breathing (control condition). During ICA assessments, participants engaged in 3min of spontaneous breathing (SB), followed by 3min of isocapnic hyperventilation (IHV). RESULTS: ICA conductance was lower in the IL condition than in the control condition in both rest and exercise trials. Inspiratory mucle metaboreflex did not reduce ICA blood flow during SB but decreased it during IHV in both trials. CONCLUSION: Our findings suggest that inspiratory muscle metaboreflex could decrease cerebrovascular conductance from rest to light-intensity exercise and attenuates cerebral blood flow with increased respiratory muscle work.

    DOI: 10.1016/j.resp.2025.104422

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  • Dilatory responsiveness of the internal carotid artery to shear stimulus is constant under different levels of transient hypercapnia. International journal

    Rintaro Sakamoto, Tatsuki Kamoda, Shigehiko Ogoh, Kohei Sato, Masaki Katayose, Toru Neki, Erika Iwamoto

    Journal of applied physiology (Bethesda, Md. : 1985)   138 ( 2 )   397 - 403   2025.2

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    Peripheral endothelial function, which accounts for the variability in shear stimulus, can be assessed using shear-mediated dilation normalized to the increased shear stimulus. Similarly, shear-mediated dilation of the internal carotid artery (ICA), an index of cerebrovascular endothelial function, should be normalized to increased shear stimulus. However, this approach has not yet been validated. Thus, the shear-mediated dilation of the ICA was assessed in 14 young adults during three levels of transient hypercapnia, induced by elevating the partial pressure of end-tidal carbon dioxide for 30 s by 6, 9, and 12 mmHg. The ICA shear rate (SR) was calculated using the ICA diameter and velocity, both measured by Doppler ultrasound. The total vasodilator stimulus was quantified as the SR area under the curve from the onset of hypercapnia to peak dilation, including and excluding baseline values [(SRAUC) and delta SRAUC (DSRAUC), respectively]. Shear-mediated dilation was calculated as the percent increase in diameter from baselines. ICA dilation was positively associated with DSRAUC [r(rm) = 0.47, P < 0.01] but not with SRAUC [r(rm) = 0.32, P = 0.09]. Consequently, ICA dilation normalized to DSRAUC did not differ among trials (main effect of rial, P = 0.77). Contrarily, the difference in ICA dilation among trials remained significant when normalized to SRAUC (main effect of trial, P = 0.02). Therefore, normalized shear-mediated dilation using DSRAUC can reduce variability associated with increased shear stimulus during ICA dilation assessment, thereby enhancing the validity of evaluating cerebrovascular endothelial function.NEW & NOTEWORTHY This study demonstrated that shear-mediated dilation of the internal carotid artery (ICA), an index of cerebrovascular endothelial function, increased with the increase of shear stimulus induced by different degrees of transient hypercapnia. However, when ICA dilation was normalized to the total increased shear stimulus above baseline, the vasodilation became comparable across different hypercapnia levels. Thus, normalizing ICA dilation to the total shear stimulus increased from baseline may enhance the validity of assessing cerebrovascular endothelial function.

    DOI: 10.1152/japplphysiol.00774.2024

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  • Prolonged sitting is not associated with altered shear-mediated dilation of the internal carotid artery, despite impairing lower limb endothelial function. International journal

    Shotaro Saito, Kento Dora, Marino Karaki, Narumi Kunimatsu, Hayato Tsukamoto, Jun Sugawara, Erika Iwamoto, Shigehiko Ogoh

    Physiological reports   13 ( 3 )   e70097   2025.2

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    The present study aims to examine the effect of 4 h of continuous sitting on cerebral endothelial function, which is a crucial component of cerebral blood flow regulation. We hypothesized that 4 h of sitting may impair cerebral endothelial function similarly to how it affects lower limb vasculature. Thirteen young, healthy participants were instructed to remain seated for 4 h without moving their lower limbs. The blood flow and shear rate (SR) in the popliteal and internal carotid artery (ICA) were measured using duplex Doppler ultrasound. During the 4-h sitting, peripheral (popliteal artery) and cerebral (ICA) endothelial function were assessed every hour. We induced peripheral and cerebral flow-mediated dilation (pFMD and ICA FMD) using hyperemia (5 min of cuff inflation on lower limb, then deflation) or hypercapnia (30s of hypercapnia, end-tidal partial pressure of CO2 + 9 mmHg), respectively. We then calculated each relative peak dilation from the baseline diameter to identify both pFMD and ICA FMD. We observed a significant decrease in pFMD starting at 2 h from the onset of sitting, and this reduction persisted throughout the 4-h sitting [Base (6.8 ± 4.2%) vs. 2-h (3.9 ± 2.0%), p = 0.044; vs. 3-h (3.2 ± 1.8%), p = 0.016; vs. 4-h (3.2 ± 1.9%), p = 0.005]. In contrast, during the 4-h sitting, ICA blood flow, SR, and ICA FMD remained unchanged (p = 0.062, p = 0.068, and p = 0.203, respectively). Unlike peripheral endothelial function, cerebral endothelial function remained stable during 4-h sitting. This suggests that the acute effect of prolonged sitting on cerebral vasculature differs from that of lower limb vasculature.

    DOI: 10.14814/phy2.70097

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  • Vasoconstrictor responsiveness in resting and contracting skeletal muscle following an acute bout of exercise: Impact of aging Reviewed

    DongNyeuck Seo, Jack Shelley, Erika Iwamoto, Darren P. Casey

    Journal of Applied Physiology   In press   2025

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  • Cerebral Perfusion Mismatch: Challenging the Validity of Cerebral Vascular Resistance index in Orthostatic Stress Reviewed

    Shigehiko Ogoh, Hayato Tsukamoto, Erika Iwamoto, Narumi Kunimatsu, Jun Sugawara, Takeshi Hashimoto, Hironori Watanabe

    American Journal of Physiology-Regulatory, Integrative and Comparative Physiology   In press   2025

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  • inhibition of sympathetic vasomotor outflow during low-intensity leg cycling is attenuated in heathy older females International journal

    Katayama K., Shiozawa K., Ishida K., Banno R., Kinoshita A., Iwamoto E., Ogoh S.

    J. Appl. Physiol.   138 ( 5 )   1133 - In press   2025

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    The purpose of the present study was to elucidate the impact of age on muscle sympathetic nerve activity (MSNA) during dynamic leg exercise in females. Nine older females (71 ± 2 yr, means ± SD) and ten younger females (21 ± 2 yr) completed the study. The participants performed two 4-min leg cycling at 10% of their heart rate reserve using a cycle ergometer in a semirecumbent position [MSNA and estimated central venous pressure (eCVP) trials]. MSNA was recorded via microneurography of the left radial nerve. The CVP was estimated based on peripheral venous pressure, which was monitored using a cannula in the right antecubital vein. The magnitude of the change in mean arterial blood pressure during exercise was larger (P < 0.001) in older females (+11.6 ± 4.7 mmHg) compared with younger females (+4.1 ± 3.2 mmHg). MSNA burst frequency (BF) was decreased during cycling in both groups, but the magnitude of the decrease in MSNA BF was smaller (P = 0.004) in older females (-5.6 ± 1.8 bursts/min) than in younger females (-9.1 ± 2.5 bursts/min). The eCVP increased during exercise in both groups, and there was no difference in the changes in eCVP between the two groups (older, +0.80 ± 0.27 vs. younger, +1.02 ± 0.51 mmHg, P = 0.462). From these results, it is possible that the cardiopulmonary baroreflex-mediated inhibition of sympathetic vasomotor outflow, elicited by the muscle pump, may be attenuated with advancing age in females.NEW & NOTEWORTHY Aging does not affect the sympathoinhibitory effect of the cardiopulmonary baroreflex during low-intensity dynamic exercise in males; however, its impact on females remains unknown. The reduction in muscle sympathetic nerve activity burst frequency during low-intensity leg cycling was smaller in older females than in younger females, even with similar changes in estimated central venous pressure. In females, muscle pump-induced inhibition of sympathetic vasomotor outflow during leg cycling may be attenuated with advancing age.

    DOI: 10.1152/japplphysiol.01008.2024

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  • Acute aerobic exercise enhances cerebrovascular shear-mediated dilation in young adults: the role of cerebral shear. International journal

    Rintaro Sakamoto, Tatsuki Kamoda, Kohei Sato, Shigehiko Ogoh, Masaki Katayose, Toru Neki, Erika Iwamoto

    Journal of applied physiology (Bethesda, Md. : 1985)   136 ( 3 )   535 - 548   2024.3

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    Exercise-induced increases in shear rate (SR) acutely improve peripheral endothelial function, but the presence of this mechanism in cerebral arteries remains unclear. Thus, we evaluated shear-mediated dilation of the internal carotid artery (ICA), which is an index of cerebrovascular endothelial function, before and after exercise. Shear-mediated dilation was measured with 30 s of hypercapnia in 16 young adults before and 10 min after 30 min of sitting rest (CON) or three cycling exercises on four separate days. The target exercise intensity was 80% of oxygen uptake at the ventilatory threshold. To manipulate the ICA SR during exercise, participants breathed spontaneously (ExSB, SR increase) or hyperventilated without (ExHV, no increase in SR) or with ([Formula: see text], restoration of SR increase) addition of CO2 to inspiratory air. Shear-mediated dilation was calculated as a percent increase in diameter from baseline. Doppler ultrasound measures ICA velocity and diameter. The CON trial revealed that 30 min of sitting did not alter shear-mediated dilation (4.34 ± 1.37% to 3.44 ± 1.23%, P = 0.052). ICA dilation after exercise compared with preexercise levels increased in the ExSB trial (3.32 ± 1.37% to 4.74 ± 1.84%, P < 0.01), remained unchanged in the ExHV trial (4.07 ± 1.55% to 3.21 ± 1.48%, P = 0.07), but was elevated in the [Formula: see text] trial (3.35 ± 1.15% to 4.33 ± 2.12%, P = 0.04). Our results indicate that exercise-induced increases in cerebral shear may play a crucial role in improving cerebrovascular endothelial function after acute exercise in young adults.NEW & NOTEWORTHY We found that 30-min cycling (target intensity was 80% of the ventilatory threshold) with increasing shear of the internal carotid artery (ICA) enhanced transient hypercapnia-induced shear-mediated dilation of the ICA, reflecting improved cerebrovascular endothelial function. This enhancement of ICA dilation was diminished by suppressing the exercise-induced increase in ICA shear via hyperventilation. Our results indicate that increases in cerebral shear may be a key stimulus for improving cerebrovascular endothelial function after exercise in young adults.

    DOI: 10.1152/japplphysiol.00543.2023

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  • Handgrip exercise does not alter CO<sub>2</sub>‐mediated cerebrovascular flow‐mediated dilation International journal

    Shotaro Saito, Hironori Watanabe, Erika Iwamoto, Shigehiko Ogoh

    Experimental Physiology   108 ( 10 )   1337 - 1346   2023.8

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    Language:English   Publishing type:Research paper (scientific journal)   Publisher:Wiley  

    Abstract

    Handgrip exercise (HG), a small muscle exercise, improves cognitive function and is expected to provide a useful exercise mode to maintain cerebral health. However, the effect of HG on cerebral blood flow regulation is not fully understood. The present study aimed to examine the effect of acute HG on cerebral endothelial function as one of the essential cerebral blood flow regulatory functions. Thirteen healthy young participants performed interval HG, consisting of 4 sets of 2 min HG at 25% of maximum voluntary contraction with 3 min recovery between each set. Cognitive performance was evaluated before and at 5 and 60 min after interval HG using the Go/No‐Go task (reaction time and accuracy). The diameter and blood velocity of the internal carotid artery (ICA) were measured using a duplex Doppler ultrasound system. To assess cerebral endothelial function, hypercapnia (30 s of hypercapnia stimulation, end‐tidal partial pressure of CO<sub>2</sub>: +9 mmHg)‐induced cerebrovascular flow‐mediated dilatation (cFMD) was induced, calculated as relative peak dilatation from baseline diameter. The shear rate (SR) was calculated using the diameter and blood velocity of the ICA. As a result, cognitive performance improved only at 5 min after interval HG (reaction time, P = 0.008; accuracy, P = 0.186), whereas ICA SR during interval HG and cFMD after interval HG were unchanged (P = 0.313 and P = 0.440, respectively). These results suggest that enhancement in cerebral endothelial function is not an essential mechanism responsible for acute HG‐induced cognitive improvement.

    New Findings

    What is the central question of this study?

    Does handgrip exercise, a small muscle exercise, improve cerebral endothelial function?

    What is the main finding and its importance?

    Acute interval isometric handgrip exercise (2 min of exercise at 25% maximum voluntary contraction, followed by 3 min of recovery, repeated for a total of 4 sets) did not improve cerebral endothelial function. Since the cerebrovascular shear rate did not change during exercise, it is possible that acute handgrip exercise is not sufficient stimulation to improve cerebral endothelial function.

    DOI: 10.1113/ep091125

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  • Skipping breakfast does not accelerate the hyperglycemia-induced endothelial dysfunction but reduces blood flow of the brachial artery in young men. Reviewed International journal

    Tatsuki Kamoda, Rintaro Sakamoto, Masaki Katayose, Saki Yamamoto, Toru Neki, Kohei Sato, Erika Iwamoto

    European journal of applied physiology   124 ( 1 )   295 - 308   2023.7

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    PURPOSE: Postprandial hyperglycemia is assumed to have a negative impact on flow-mediated dilation (FMD), an index of endothelial function, and blood flow of the peripheral conduit arteries. This study aimed to determine whether the enhancement of postprandial hyperglycemia by skipping breakfast accelerates endothelial dysfunction and reduces the blood flow in the brachial artery in young men. METHODS: Using a randomized cross-over design, ten healthy men completed two trials: with and without breakfast (Eating and Fasting trials, respectively). Venous blood sampling and brachial FMD tests were conducted before, 30, 60, 90, and 120 min after a 75-g oral glucose tolerance test (OGTT). RESULTS: Skipping breakfast boosted post-OGTT glucose levels than having breakfast (P = 0.01). The magnitude of the decrease in FMD via OGTT did not vary between trials (main effect of trial P = 0.55). Although brachial blood flow tended to decrease after OGTT in both trials (interaction and main effect of time P = 0.61 and P = 0.054, respectively), the decrease in blood flow following OGTT was greater in the Fasting trial than in the Eating trial (main effect of trial, mean difference =  - 15.8 mL/min [95%CI =  - 25.6 to - 6.0 mL/min], P < 0.01). CONCLUSION: Skipping breakfast did not enhance the magnitude of the decrease in FMD following glucose loading, but did accelerate hyperglycemia-induced reduction in brachial blood flow. Current findings suggest that even missing one breakfast has negative impacts on the blood flow regulation of the peripheral conduit arteries in young men who habitually eat breakfast.

    DOI: 10.1007/s00421-023-05273-6

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  • 呼気終末二酸化炭素分圧の低下が内頸動脈の血流依存性血管拡張反応に与える影響

    坂本 琳太郎, 鴨田 樹, 佐藤 晃平, 片寄 正樹, 根木 亨, 岩本 えりか

    基礎理学療法学   25 ( Suppl.1 )   89 - 89   2023.1

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  • Can alterations in cerebrovascular CO2 reactivity be identified using transfer function analysis without the requirement for carbon dioxide inhalation? International journal

    Shigehiko Ogoh, Hironori Watanabe, Shotaro Saito, James Fisher, Erika Iwamoto

    Journal of Clinical Medicine   12 ( 6 )   2441 - 2441   2023

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    Authorship:Last author   Language:English   Publishing type:Research paper (scientific journal)   Publisher:MDPI AG  

    The present study aimed to examine the validity of a novel method to assess cerebrovascular carbon dioxide (CO2) reactivity (CVR) that does not require a CO2 inhalation challenge, e.g., for use in patients with respiratory disease or the elderly, etc. In twenty-one healthy participants, CVR responses to orthostatic stress (50° head-up tilt, HUT) were assessed using two methods: (1) the traditional CO2 inhalation method, and (2) transfer function analysis (TFA) between middle cerebral artery blood velocity (MCA V) and predicted arterial partial pressure of CO2 (PaCO2) during spontaneous respiration. During HUT, MCA V steady-state (i.e., magnitude) and MCA V onset (i.e., time constant) responses to CO2 inhalation were decreased (p &lt; 0.001) and increased (p = 0.001), respectively, indicative of attenuated CVR. In contrast, TFA gain in the very low-frequency range (VLF, 0.005–0.024 Hz) was unchanged, while the TFA phase in the VLF approached zero during HUT (−0.38 ± 0.59 vs. 0.31 ± 0.78 radians, supine vs. HUT; p = 0.003), indicative of a shorter time (i.e., improved) response of CVR. These findings indicate that CVR metrics determined by TFA without a CO2 inhalation do not track HUT-evoked reductions in CVR identified using CO2 inhalation, suggesting that enhanced cerebral blood flow response to a change in CO2 using CO2 inhalation is necessary to assess CVR adequately.

    DOI: 10.3390/jcm12062441

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  • Hypoxia Offsets the Decline in Brachial Artery Flow-mediated Dilation Following Acute Inactivity. International journal

    Brady E Hanson, Erika Iwamoto, Bryan L Mouser, Kayla A Miller, Darren P Casey

    American journal of physiology. Regulatory, integrative and comparative physiology   323 ( 5 )   R787-R796   2022.9

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    Intermittent- (IH), as opposed to continuous hypoxia (CH), is thought to have beneficial effects on cardiovascular function and health. In the present study we examined the acute effects of IH and CH (~80% pulse oxygen saturation via 10% oxygen tank) on peripheral vascular function. Brachial artery flow-mediated dilation (FMD) was used to assess vascular function in 12 young adults (23±5 yr; 8M/4F) before and after 50 minutes of IH [5 cycles; 4 min normoxia/6 min hypoxia per cycle], CH [20 min normoxia followed by 30 min hypoxia], or time control [50 min normoxia] interventions. Brachial artery diameter and velocity were measured using Doppler ultrasound to assess blood flow and shear rate. The total change in shear rate was greater during IH (634±1073·s-1, P<0.05) and CH (321±833·s-1, P=0.05) compared to time control (-412±789·s-1). %FMD was reduced following time control (7.4±1.2% to 5.9±1.1%, P<0.05) but was maintained following both hypoxia trials (IH: 7.2±1.5% to 7.5±1.5%, P=0.52; CH: 6.9±1.6% to 6.8±1.4%, P=0.73). Normalized %FMD for shear rate area under the curve (%FMDSRAUC) was reduced following the time control trial (4.2±1.4% to 3.7±0.9%, P<0.05) with no change observed with CH (4.0±1.5% to 3.9±1.4%, P=0.71). However, %FMDSRAUC increased with IH (3.8±1.1% to 4.5±1.5%, P<0.05). Our data suggest that acute exposure to hypoxia (both intermittently and continuously) offset the decline in vascular function following brief inactivity. The potential beneficial effect of hypoxia on peripheral vascular function observed in the current study may be associated with enhanced brachial artery shear in response to the hypoxic challenge.

    DOI: 10.1152/ajpregu.00161.2022

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  • Dynamic resistance exercise-induced pressor response does not alter hypercapnia-induced cerebral vasodilation in young adults Reviewed International journal

    Rintaro Sakamoto, Kohei Sato, Shigehiko Ogoh, Tatsuki Kamoda, Toru Neki, Masaki Katayose, and, Erika Iwamoto

    European Journal of Applied Physiology   123 ( 4 )   781 - 796   2022

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    Excessive arterial pressure elevation induced by resistance exercise (RE) attenuates peripheral vasodilatory function, but its effect on cerebrovascular function is unknown. We aimed to evaluate the effect of different pressor responses to RE on hypercapnia-induced vasodilation of the internal carotid artery (ICA), an index of cerebrovascular function. To manipulate pressor responses to RE, 15 healthy young adults (11M/4F) performed two RE: high intensity with low repetitions (HL) and low intensity with high repetitions (LH) dynamic knee extension. ICA dilation, induced by 3 min of hypercapnia, was measured before and 10 min after RE using Doppler ultrasound. HL exercise elicited a greater pressor response than LH exercise. In relaxation phases of RE, ICA blood velocity increased in both HL and LH trials. However, ICA shear rate did not significantly increase in either trial (P = 0.06). Consequently, neither exercise altered post-exercise hypercapnia-induced ICA dilation (HL, 3.9 ± 1.9% to 5.1 ± 1.7%; LH, 4.6 ± 1.4% to 4.8 ± 1.8%; P > 0.05 for all). When viewed individually, the changes in ICA shear rate were positively correlated with changes in end-tidal partial pressure of carbon dioxide (PETCO2) (r = 0.46, P < 0.01) than with mean arterial pressure (r = 0.32, P = 0.02). These findings suggest that the effects of RE-induced pressor response on cerebrovascular function may be different from peripheral arteries. An increase in PETCO2 during the relaxation phase may play a more crucial role than elevated pressure in increasing cerebral shear during dynamic RE.

    DOI: 10.1007/s00421-022-05096-x

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  • Correction to: High-but not moderate-intensity exercise acutely attenuates hypercapnia-induced vasodilation of the internal carotid artery in young men. Reviewed International journal

    Rintaro Sakamoto, Masaki Katayose, Yutaka Yamada, Toru Neki, Tatsuki Kamoda, Katsuyuki Tamai, Kotomi Yamazaki, Erika Iwamoto

    European journal of applied physiology   121 ( 11 )   3259 - 3259   2021.11

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    DOI: 10.1007/s00421-021-04785-3

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  • 異なる強度の単回のレジスタンス運動が運動中の脳血流,内頸動脈の血流依存性血管拡張反応に与える影響

    坂本 琳太郎, 岩本 えりか, 佐藤 晃平, 鴨田 樹, 根木 亨, 片寄 正樹

    日本基礎理学療法学会学術大会プログラム・抄録集   26回   1G15 - 01   2021.10

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  • 血中エストロゲン濃度が内頸動脈の血流依存性血管拡張反応に与える影響

    岩本 えりか, 山崎 琴己, 坂本 琳太郎, 鴨田 樹, 佐藤 晃平, 根木 亨, 片寄 正樹

    日本基礎理学療法学会学術大会プログラム・抄録集   26回   2P4 - 01   2021.10

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  • High-but not moderate-intensity exercise acutely attenuates hypercapnia-induced vasodilation of the internal carotid artery in young men. Reviewed International journal

    Rintaro Sakamoto, Masaki Katayose, Yutaka Yamada, Toru Neki, Tatsuki Kamoda, Katsuyuki Tamai, Kotomi Yamazaki, Erika Iwamoto

    European journal of applied physiology   121 ( 9 )   2471 - 2485   2021.9

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    PURPOSE: Exercise-induced increases in shear rate (SR) across different exercise intensities may differentially affect hypercapnia-induced vasodilation of the internal carotid artery (ICA), a potential index of cerebrovascular function. We aimed to elucidate the effects of exercise intensity on ICA SR during exercise and post-exercise hypercapnia-induced vasodilation of the ICA in young men. METHODS: Twelve healthy men completed 30 min of cycling at moderate [MIE; 65 ± 5% of age-predicted maximal heart rate (HRmax)] and high (HIE; 85 ± 5% HRmax) intensities. Hypercapnia-induced vasodilation was induced by 3 min of hypercapnia (target end-tidal partial pressure of CO2 + 10 mmHg) and was assessed at pre-exercise, 5 min and 60 min after exercise. Doppler ultrasound was used to measure ICA diameter and blood velocity during exercise and hypercapnia tests. RESULTS: SR was not altered during either exercise (interaction and main effects of time; both P > 0.05). ICA conductance decreased during HIE from resting values (5.1 ± 1.3 to 3.2 ± 1.0 mL·min-1·mmHg-1; P < 0.01) but not during MIE (5.0 ± 1.3 to 4.0 ± 0.8 mL·min-1·mmHg-1; P = 0.11). Consequently, hypercapnia-induced vasodilation declined immediately after HIE (6.9 ± 1.7% to 4.0 ± 1.4%; P < 0.01), but not after MIE (7.2 ± 2.1% to 7.3 ± 1.8%; P > 0.05). Sixty minutes after exercise, hypercapnia-induced vasodilation returned to baseline values in both trials (MIE 8.0 ± 3.1%; HIE 6.4 ± 2.9%; both P > 0.05). CONCLUSION: The present study showed blunted hypercapnia-induced vasodilation of the ICA immediately after high-intensity exercise, but not a moderate-intensity exercise in young men. Given that the acute response is partly linked to the adaptive response in the peripheral endothelial function, the effects of aerobic training on cerebrovascular health may vary depending on exercise intensity.

    DOI: 10.1007/s00421-021-04721-5

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  • Effects of menstrual cycle and menopause on internal carotid artery shear-mediated dilation in women. Reviewed International journal

    Erika Iwamoto, Rintaro Sakamoto, Wakako Tsuchida, Kotomi Yamazaki, Tatsuki Kamoda, Toru Neki, Masaki Katayose, Darren P Casey

    American journal of physiology. Heart and circulatory physiology   320 ( 2 )   H679-H689   2021.2

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    This study aimed to elucidate the effects of change in estrogen during the menstrual cycle and menopause on shear-mediated dilation of the internal carotid artery (ICA), a potential index of cerebrovascular endothelial function. Shear-mediated dilation of the ICA and serum estradiol were measured in 11 premenopausal (Pre-M, 21 ± 1 yr), 13 perimenopausal (Peri-M, 49 ± 2 yr), and 10 postmenopausal (Post-M, 65 ± 7 yr) women. Measurements were made twice within the Pre-M group at their early follicular (EF, lower estradiol) and late follicular (LF, higher estradiol) phases. Shear-mediated dilation was induced by 3 min of hypercapnia (target PETCO2 + 10 mmHg from individual baseline) and was calculated as the percent rise in peak diameter relative to baseline diameter. ICA diameter and blood velocity were simultaneously measured by Doppler ultrasound. In Pre-M, shear-mediated dilation was higher during the LF phase than during the EF phase (P < 0.01). Comparing all groups, shear-mediated dilation was reduced across the menopausal transition (P < 0.01), and Pre-M during the LF phase showed the highest value (8.9 ± 1.4%) compared with other groups (Pre-M in EF, 6.4 ± 1.1%; Peri-M, 5.5 ± 1.3%; Post-M, 5.2 ± 1.9%, P < 0.05 for all). Shear-mediated dilation was positively correlated with serum estradiol even after adjustment of age (P < 0.01, r = 0.55, age-adjusted; P = 0.02, r = 0.35). Collectively, these data indicate that controlling the menstrual cycle phase is necessary for the cross-sectional assessments of shear-mediated dilation of the ICA in premenopausal women. Moreover, current findings suggest that a decline in cerebrovascular endothelial function may be partly related to the reduced circulating estrogen levels in peri- and postmenopausal women.NEW & NOTEWORTHY The present study evaluated the effects of the menstrual cycle and menopause stages on the shear-mediated dilation of the ICA, a potential index of cerebrovascular endothelial function, in pre-, peri-, and postmenopausal women. Shear-mediated dilation of the ICA was increased from the low- to high-estradiol phases in naturally cycling premenopausal women and was reduced with advancing menopause stages. Furthermore, lower estradiol was associated with reduced shear-mediated dilation of the ICA, independent of age.

    DOI: 10.1152/ajpheart.00810.2020

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  • Greater increase in internal carotid artery shear rate during aerobic interval compared to continuous exercise in healthy adult men. Reviewed International journal

    Shigehiko Ogoh, Takuro Washio, Kazuya Suzuki, Motoyuki Iemitsu, Takeshi Hashimoto, Erika Iwamoto, Damian M Bailey

    Physiological reports   9 ( 2 )   e14705   2021.1

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    Interval exercise has been determined to be more effective than continuous exercise for achieving improvement in the cardiovascular function of individuals suffering from cardiovascular disease. However, whether interval exercise improves the cerebrovascular function remains unclear. As per our hypothesis, interval exercise induces a higher cerebrovascular shear rate (SR) than continuous exercise. In this study, 11 adult men randomly performed continuous exercise for 12 min or work-equivalent (57.6 kJ/exercise session) interval exercise of semi-recumbent cycling. The SR in the internal carotid artery (ICA) represents an index of the cerebrovascular SR, which was measured during both the exercises using Doppler ultrasonography. Both the aerobic exercise modes increased the ICA SR. Moreover, the average ICA SR of the interval exercise for the final 4 min of exercise or 2 min of recovery was significantly higher than that for continuous exercise (exercise, 351 ± 75 vs. 330 ± 61/s, p = .038; recovery, 327 ± 86 vs. 290 ± 56/s, p = .014). To our knowledge, this is the first study to show that aerobic interval exercise increased the ICA SR more than equivalent work volume of aerobic continuous exercise. Thus, aerobic interval exercise may be more effective at stimulating the cerebrovasculature, resulting in greater improvements in cerebrovascular function as compared to continuous aerobic exercise in healthy adult men. These findings provide some important information that would help enhance exercise therapy programs for patients with arteriosclerosis, especially in the cerebral circulation.

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  • Fluctuating shear during resistance exercise. Reviewed International journal

    Erika Iwamoto, Shigehiko Ogoh

    Experimental physiology   105 ( 12 )   2004 - 2006   2020.12

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    DOI: 10.1113/EP089174

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  • Effect of Age and Acute Exercise on Circulating Angioregulatory Factors. Reviewed International journal

    Meredith J Luttrell, Benjamin R Mardis, Joshua M Bock, Erika Iwamoto, Satoshi Hanada, Kenichi Ueda, Andrew J Feider, Kenzie Temperly, Darren Casey

    Journal of aging and physical activity   29 ( 3 )   1 - 8   2020.10

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    The balance of angiogenic factors, including vascular endothelial growth factor (VEGF), and angiostatic factors, like thrombospondin-1 (TSP-1) and endostatin, controls striated muscle angiogenic responses to exercise training. The effect of age on circulating levels of these factors following a bout of exercise is unclear. The authors hypothesized that older adults would have lower circulating VEGF but higher TSP-1 and endostatin after exercise compared with young adults. Ten young and nine older participants cycled for 45 min at 60% estimated HRmax. Serum [VEGF], [TSP-1], and [endostatin] obtained before (PREX), immediately after (POSTX0), and 3 hr after (POSTX3) exercise were analyzed. [VEGF] increased in older adults only from PREX to POSTX0 (p < .05). [TSP-1] increased in both age groups (p < .05). There was no effect of age or exercise on [endostatin]. In conclusion, immediately after exercise, both groups had a similar increase in [TSP-1], but [VEGF] increased in older adults only.

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  • Greater α1-adrenergic-mediated vasoconstriction in contracting skeletal muscle of patients with type 2 diabetes. Reviewed International journal

    Joshua M Bock, William E Hughes, Kenichi Ueda, Andrew J Feider, Satoshi Hanada, Nicholas T Kruse, Erika Iwamoto, Darren P Casey

    American journal of physiology. Heart and circulatory physiology   319 ( 4 )   H797-H807   2020.10

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    Patients with type 2 diabetes mellitus (T2DM) exhibit diminished exercise capacity likely attributable to reduced skeletal muscle blood flow (i.e., exercise hyperemia). A potential underlying mechanism of the impaired hyperemic response to exercise could be inadequate blunting of sympathetic-mediated vasoconstriction (i.e., poor functional sympatholysis). Therefore, we studied the hyperemic and vasodilatory responses to handgrip exercise in patients with T2DM as well as vasoconstriction to selective α-agonist infusion. Forearm blood flow (FBF) and vascular conductance (FVC) were examined in patients with T2DM (n = 30) as well as nondiabetic controls (n = 15) with similar age (59 ± 9 vs. 60 ± 9 yr, P = 0.69) and body mass index (31.4 ± 5.2 vs. 29.5 ± 4.6 kg/m2, P = 0.48). Intra-arterial infusion of phenylephrine (α1-agonist) and dexmedetomidine (α2-agonist) were used to induce vasoconstriction: [(FVCwith drug - FVCpredrug)/FVCpredrug × 100%]. Subjects completed rest and dynamic handgrip exercise (20% of maximum) trials per α-agonist. Patients with T2DM had smaller increases (Δ from rest) in FBF (147 ± 71 vs. 199 ± 63 ml/min) and FVC (126 ± 58 vs. 176 ± 50 ml·min-1·100 mmHg-1, P < 0.01 for both) during exercise compared with controls, respectively. During exercise, patients with T2DM had greater α1- (-16.9 ± 5.9 vs. -11.3 ± 3.8%) and α2-mediated vasoconstriction (-23.5 ± 7.1 vs. -19.0 ± 6.5%, P < 0.05 for both) versus controls. The magnitude of sympatholysis (Δ in %vasoconstriction between exercise and rest) for PE was lower (worse) in patients with T2DM versus controls (14.9 ± 12.2 vs. 23.1 ± 8.1%, P < 0.05) whereas groups were similar during DEX trials (24.6 ± 12.3 vs. 27.6 ± 13.4%, P = 0.47). Our data suggest patients with T2DM have attenuated hyperemic and vasodilatory responses to exercise, which could be attributable to greater α1-mediated vasoconstriction in contracting skeletal muscle.NEW & NOTEWORTHY Findings presented in this article are the first to show patients with type 2 diabetes mellitus have blunted hyperemic and vasodilatory responses to dynamic handgrip exercise. Moreover, we illustrate greater α1-adrenergic-mediated vasoconstriction may contribute to our initial observations. Collectively, these data suggest patients with type 2 diabetes may have impaired functional sympatholysis, which can contribute to their reduced exercise capacity.

    DOI: 10.1152/ajpheart.00532.2020

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  • Intermittent hypoxia enhances shear-mediated dilation of the internal carotid artery in young adults. Reviewed International journal

    Erika Iwamoto, Brady E Hanson, Joshua M Bock, Darren P Casey

    Journal of applied physiology (Bethesda, Md. : 1985)   129 ( 3 )   603 - 611   2020.9

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    Cyclic intermittent hypoxia (IH) increases cerebral blood velocity. This enhanced velocity augments the commensurate shear stimulus and may subsequently increase cerebrovascular endothelial function. This study aimed to examine the effects of cyclic IH on hypercapnia-induced shear-mediated dilation of the internal carotid artery (ICA), a potential index of cerebrovascular endothelial function. Shear-mediated dilation was measured in nine adults (22 ± 4 yr) before as well as after 50 min of cyclic IH [5 cycles, 4 min of normoxia, followed by 6 min of hypoxia (target 80% [Formula: see text]) per cycle] and control normoxia (sham, 50 min of continuous normoxia) on separate days (≥72 h apart). ICA diameter and velocity were measured using Doppler ultrasound during cyclic IH and hypercapnia. Shear-mediated dilation was induced by 3 min of hypercapnia (Δ[Formula: see text]; IH: pre 10.1 ± 1.0 mmHg, post 10.8 ± 1.3 mmHg; sham: pre 10.5 ± 1.5 mmHg, post 10.8 ± 1.5 mmHg) and was calculated as the percent rise in peak relative to baseline diameter. Hypoxia increased ICA blood flow and shear rate (SR) during each cycle [blood flow: 322 ± 90 to 406 ± 74 mL/min, P < 0.01; SR: 179 ± 42 to 207 ± 55/s, P = 0.06, baseline to hypoxia (average of last minute of each cycle)], which was normalized during the succeeding normoxic period (blood flow: 322 ± 90 to 329 ± 68 mL/min, P = 0.54, SR: 179 ± 42 to 176 ± 32/s, P = 0.56). As such, shear-mediated dilation increased following cyclic IH (4.6 ± 1.3% to 6.2 ± 2.2%, P < 0.01), but not control normoxia (4.9 ± 1.4% to 4.9 ± 1.4%, P = 0.92). Our data indicate that increased blood flow and SR during cyclic IH enhance shear-mediated dilation of the ICA in young adults. These results suggest that cyclic IH could be used to optimize cerebral vascular health.NEW & NOTEWORTHY We explored the effects of cyclic intermittent hypoxia (IH) on shear-mediated dilation of the internal carotid artery (ICA), a potential index of cerebral endothelial function, in young adults. Cyclic IH increased blood flow and shear rate in the ICA and, as a result, increased shear-mediated dilation of the ICA. These data suggest that cyclic IH could potentially be applied as a nonpharmacological therapy to optimize cerebral vascular health.

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  • Aerobic exercise offsets endothelial dysfunction induced by repetitive consumption of sugar-sweetened beverages in young healthy men. Reviewed International journal

    Joshua M Bock, Erika Iwamoto, Jeffrey G Horak, Andrew J Feider, Satoshi Hanada, Darren P Casey

    American journal of physiology. Regulatory, integrative and comparative physiology   319 ( 1 )   R11-R18   2020.7

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    Consumption of a single, sugar-sweetened beverage (SSB) impairs vascular endothelial function. Regular aerobic exercise improves endothelium-dependent vasodilation; however, it is unknown whether these beneficial effects persist with frequent SSB consumption. Therefore, the purpose of this study was twofold; we studied the effects of repetitive SSB consumption (75 g d-glucose, 3 times/day) for 1 wk (Glu, n = 13, 23 ± 4 yr, 23.5 ± 3.4 kg/m2) on endothelium-dependent vasodilation (FMD). Then, in a separate cohort, we investigated whether 45 min of moderate-intensity aerobic exercise on five separate days offset the hypothesized decrease in FMD during the Glu protocol (Glu+Ex, n = 11, 21 ± 3 yr, 23.8 ± 2.4 kg/m2). Baseline, fasting [glucose] (P = 0.15), [insulin] (P = 0.25), %FMD (P = 0.48), absolute FMD (P = 0.66), and shear rate area under the curve (SRAUC; P = 0.82) were similar between groups. Following the interventions, fasting [glucose] (Glu: 94 ± 6 to 92 ± 6 mg/dL, Glu+Ex: 89 ± 8 to 87 ± 6 mg/dL, P = 0.74) and [insulin] (Glu: 11.3 ± 6.2 to 11.8 ± 8.9 μU/mL, Glu+Ex: 8.7 ± 2.9 to 9.4 ± 3.2 μU/mL, P = 0.89) were unchanged. %FMD was reduced in Glu (6.1 ± 2.2 to 5.1 ± 1.3%) and increased in Glu+Ex (6.6 ± 2.2 to 7.8 ± 2.4%, P < 0.05 for both). SRAUC increased similarly in both Glu [17,715 ± 8,275 to 22,922 ± 4,808 arbitrary units (A.U.)] and Glu+Ex (18,216 ± 4,516 to 21,666 ± 5,392 A.U., main effect of time P < 0.05). When %FMD was adjusted for SRAUC, attenuation was observed in Glu (0.41 ± 0.18 to 0.23 ± 0.08%/s × 103, P < 0.05) but not Glu+Ex (0.38 ± 0.14 to 0.38 ± 0.13%/s × 103, P = 0.88). Despite unchanged fasting [glucose] and [insulin], repeated consumption of SSBs impaired conduit artery vascular endothelial function. Additionally, subjects who engaged in regular moderate-intensity aerobic exercise did not demonstrate the same SSB-induced endothelial dysfunction. Collectively, these data suggest aerobic exercise may offset the deleterious effects of repetitive SSB consumption.

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  • 脳の血管機能およびメンタルヘルスの改善を引き起こす有酸素性運動の運動強度の検討

    岩本 えりか, 坂本 琳太郎, 根木 亨, 片寄 正樹

    若手研究者のための健康科学研究助成成果報告書   ( 35 )   12 - 17   2020.4

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  • Habitual cigarette smoking attenuates shear-mediated dilation in the brachial artery but not in the carotid artery in young adults. Reviewed International journal

    Kazuya Suzuki, Takuro Washio, Shingo Tsukamoto, Kazunori Kato, Erika Iwamoto, Shigehiko Ogoh

    Physiological reports   8 ( 3 )   e14369   2020.2

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    In the present study, we hypothesized that habitual cigarette smoking attenuates endothelial function in the cerebral circulation as well as that of the peripheral circulation in young adults. To test this hypothesis, we measured cerebrovascular and peripheral flow-mediated dilation (FMD) in young smokers and nonsmokers in the present study. Ten healthy nonsmokers and 10 smokers participated in the study. We measured blood velocity and diameter in the brachial artery and internal carotid artery (ICA) using Doppler ultrasound. We identified shear-mediated dilation in the brachial artery and ICA by the percentage change in peak diameter during hyperemia stimulation (reactive hyperemia and hypercapnia). We measured the baseline diameter and the shear rate area under the curve from the onset of hyperemia to peak dilation in the brachial artery and ICA, finding the measurements of the smokers and those of the nonsmokers did not differ (p > .05). In contrast to brachial FMD (5.07 ± 1.79% vs. 7.92 ± 3.01%; smokers vs. nonsmokers, p = .019), FMD in the ICA was not attenuated in the smokers compared with that of the nonsmokers (5.46 ± 2.32% vs. 4.57 ± 2.70%; p = .442). These findings indicate that in young healthy smokers, cerebral endothelial function was preserved, and the response of cerebral endothelial function to smoking was different from that of peripheral vasculature.

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  • Acute hypotension attenuates brachial flow-mediated dilation in young healthy men. Reviewed International journal

    Erika Iwamoto, Yutaka Yamada, Masaki Katayose, Rintaro Sakamoto, Toru Neki, Jun Sugawara, Shigehiko Ogoh

    European journal of applied physiology   120 ( 1 )   161 - 169   2020.1

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    PURPOSE: This study aimed to test our hypothesis that acute hypotension attenuates brachial flow-mediated dilation (FMD) as an index of endothelial function in healthy humans. METHODS: Twelve healthy men (21.8 ± 1.6 years, body mass index; 22.2 ± 1.6 kg/m2) participated in this study. Brachial FMD was measured in three trials: standardized FMD protocol (control trial), abrupt decrease in blood pressure (BP) via thigh cuff inflation-deflation (hypotension trial) and decrease in shear rate (SR) via a shortened forearm occlusion time (SR reduction trial). Brachial diameter and blood velocity were measured using Duplex ultrasound. RESULTS: Mean arterial pressure during reactive hyperaemia showed a marked decrease in the hypotension trial (- 23.7 ± 6.0 mmHg), but not in the control and SR reduction trials. SR area under the curve was attenuated in the SR reduction trial (P < 0.001), but not in the control and hypotension trials (P = 0.316). Consequently, FMD was attenuated in the hypotension and SR reduction trials compared with that in the control trial (P = 0.003 and P = 0.043, respectively), and was attenuated to a greater extent in the hypotension trial compared with the SR reduction trial (P = 0.006; control, 6.9 ± 3.5%; hypotension, 3.5 ± 1.7%; SR reduction, 5.0 ± 2.2%). After adjusting FMD using SR, FMD remained attenuated in the hypotension trial (P = 0.014), but not in the SR reduction trial. CONCLUSION: Our findings indicate that arterial pressure as well as sympathetic nervous system activation could be an important determinant of FMD. Blunted FMD of peripheral arteries may be a rational response to restore BP and/or prevent further reduction of BP following acute hypotension in healthy humans.

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  • 全身性の血圧低下が上腕動脈の血流依存性血管拡張反応に与える影響

    山田 悠, 岩本 えりか, 坂本 琳太郎, 根木 亨, 片寄 正樹

    日本基礎理学療法学雑誌   22 ( 1 )   54 - 62   2019.12

  • Effects of Respiratory Muscle Endurance Training in Hypoxia on Running Performance. Reviewed International journal

    Keisho Katayama, Kazushige Goto, Toshiyuki Ohya, Erika Iwamoto, Kenji Takao, Nobukazu Kasai, Daichi Sumi, Hisashi Mori, Koji Ishida, Kaori Shimizu, Kana Shiozawa, Yasuhiro Suzuki

    Medicine and science in sports and exercise   51 ( 7 )   1477 - 1486   2019.7

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    PURPOSE: We hypothesized that respiratory muscle endurance training (RMET) in hypoxia induces greater improvements in respiratory muscle endurance with attenuated respiratory muscle metaboreflex and consequent whole-body performance. We evaluated respiratory muscle endurance and cardiovascular response during hyperpnoea and whole-body running performance before and after RMET in normoxia and hypoxia. METHODS: Twenty-one collegiate endurance runners were assigned to control (n = 7), normoxic (n = 7), and hypoxic (n = 7) groups. Before and after the 6 wk of RMET, incremental respiratory endurance test and constant exercise tests were performed. The constant exercise test was performed on a treadmill at 95% of the individual's peak oxygen uptake (V˙O2peak). The RMET was isocapnic hyperpnoea under normoxic and hypoxic conditions (30 min·d). The initial target of minute ventilation during RMET was set to 50% of the individual maximal voluntary ventilation, and the target increased progressively during the 6 wk. Target arterial oxygen saturation in the hypoxic group was set to 90% in the first 2 wk, and thereafter it was set to 80%. RESULTS: Respiratory muscle endurance was increased after RMET in the normoxic and hypoxic groups. The time to exhaustion at 95% V˙O2peak exercise also increased after RMET in the normoxic (10.2 ± 2.4 to 11.2 ± 2.6 min) and hypoxic (11.5 ± 2.6 to 12.6 ± 3.0 min) groups, but not in the control group (9.6 ± 3.2 to 9.4 ± 4.0 min). The magnitude of these changes did not differ between the normoxic and the hypoxic groups (P = 0.84). CONCLUSION: These results suggest that the improvement of respiratory muscle endurance and blunted respiratory muscle metaboreflex could, in part, contribute to improved endurance performance in endurance-trained athletes. However, it is also suggested that there are no additional effects when the RMET is performed in hypoxia.

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  • Neuromuscular electrical stimulation increases serum brain-derived neurotrophic factor in humans. Reviewed International journal

    Takehide Kimura, Fuminari Kaneko, Erika Iwamoto, Shigeyuki Saitoh, Takashi Yamada

    Experimental brain research   237 ( 1 )   47 - 56   2019.1

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    Brain-derived neurotrophic factor (BDNF) plays several important roles in nervous system function including neuronal growth and plasticity. The purpose of the present study was to clarify whether neuromuscular electrical stimulation (NMES) and voluntary exercise to the same integrated force as by the NMES-induced exercise would enhance serum BDNF. Eleven healthy male subjects completed three interventions (NMES, voluntary exercise, and resting interventions) for 20 min on different days. In the NMES intervention, NMES was applied to the quadriceps femoris muscles. The stimulus intensity of NMES was progressively increased to the highest tolerated intensity during the experiment. In the voluntary exercise intervention, subjects performed an isometric knee-extension task; in this intervention, the target torque was calculated in accordance with the integrated force of knee extension obtained during the NMES intervention. In the resting intervention, subjects relaxed in a sitting posture. We measured serum BDNF, blood lactate, heart rate, oxygen uptake, respiratory ratio, and blood pressure. Serum BDNF was increased in the NMES (p = 0.003) and voluntary exercise interventions (p = 0.004) after each intervention. At the post-timepoint, serum BDNF in the NMES intervention was highest among all interventions (p = 0.038) and significantly higher than in the voluntary exercise (p = 0.036) and resting (p = 0.037) interventions. Our results showed that NMES was more effective for enhancing serum BDNF than voluntary exercise at least when employing the same method and integrated force.

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  • Hypercapnia-induced shear-mediated dilation in the internal carotid artery is blunted in healthy older adults. Reviewed International journal

    Erika Iwamoto, Joshua M Bock, Darren P Casey

    American journal of physiology. Heart and circulatory physiology   315 ( 5 )   H1279-H1286 - H1286   2018.11

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    This study aimed to elucidate the effect of aging on shear-mediated dilation of the common and internal carotid arteries (CCA and ICA, respectively). Hypercapnia-induced shear-mediated dilation in the CCA and ICA were assessed in 10 young (5 women and 5 men, 23 ± 1 yr) and 10 older (6 women/4 men, 68 ± 1 yr) healthy adults. Shear-mediated dilation was induced by two levels of hypercapnia (target end-tidal Pco2, +5 and +10 mmHg from individual baseline values) and was calculated as the percent rise in peak diameter from baseline diameter. There were no differences in shear-mediated dilation between young and older adults in either artery under lower levels of hypercapnia (CCA: 2.8 ± 0.6 vs. 2.0 ± 0.3%, P = 0.35; ICA: 4.6 ± 0.8 vs 3.6 ± 0.4%, P = 0.37). However, shear-mediated dilation in response to higher levels of hypercapnia was attenuated in older compared with young adults in the ICA (4.5 ± 0.5 vs. 7.9 ± 1.2%, P < 0.01) but not in the CCA (3.7 ± 0.6 vs. 4.5 ± 0.8%, P = 0.35). Shear-mediated dilation was significantly correlated to the percent change in shear rate in the ICA (young: r = 0.55, P = 0.01; older: r = 0.49, P = 0.03) but not in the CCA in either young or older adults (young: r = -0.30, P = 0.90; older: r = 0.16, P = 0.50). These data indicate that aging attenuates shear-mediated dilation of the ICA in response to higher levels of hypercapnia, and shear rate is an important stimulus for hypercapnic vasodilation of the ICA in both young and older adults. The present results may provide insights into age-related changes in the regulation of cerebral circulation in healthy adults. NEW & NOTEWORTHY We explored the effect of aging on shear-mediated dilation in the common and internal carotid arteries (CCA and ICA, respectively) in healthy adults. Our findings suggest that 1) aging attenuates shear-mediated dilation of the ICA but not the CCA and 2) shear rate is an important stimulus for hypercapnic vasodilation of the ICA in young and older adults. These findings may provide insights into the age-related changes in cerebrovascular regulation of healthy adults.

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  • Impaired modulation of postjunctional α1 - but not α2 -adrenergic vasoconstriction in contracting forearm muscle of postmenopausal women. Reviewed International journal

    Nicholas T Kruse, William E Hughes, Kenichi Ueda, Satoshi Hanada, Andrew J Feider, Erika Iwamoto, Joshua M Bock, Darren P Casey

    The Journal of physiology   596 ( 13 )   2507 - 2519   2018.7

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    KEY POINTS: Contraction-mediated blunting of postjunctional α-adrenergic vasoconstriction (functional sympatholysis) is attenuated in skeletal muscle of ageing males, brought on by altered postjunctional α1 - and α2 -adrenergic receptor sensitivity. The extent to which postjunctional α-adrenergic vasoconstriction occurs in the forearms at rest and during exercise in postmenopausal women remains unknown. The novel findings indicate that contraction-mediated blunting of α1 - (via intra-arterial infusion of phenylephrine) but not α2 -adrenergic (via intra-arterial infusion of dexmedetomidine) vasoconstriction was attenuated in postmenopausal women compared to young women. Additional important findings revealed that postjunctional α-adrenergic vasoconstrictor responsiveness at rest does not appear to be affected by age in women. Collectively, these results contribute to our understanding of local neurovascular control at rest and during exercise with age in women. ABSTRACT: Contraction-mediated blunting of postjunctional α-adrenergic vasoconstriction (functional sympatholysis) is attenuated in older males; however, direct confirmation of this effect remains unknown in postmenopausal women (PMW). The present study examined whether PMW exhibit augmented postjunctional α-adrenergic receptor vasoconstriction at rest and during forearm exercise compared to young women (YW). Eight YW (24 ± 1 years) and eight PMW (65 ± 1 years) completed a series of randomized experimental trials: (1) at rest, (2) under high flow (adenosine infusion) conditions and (3) during 6 min of forearm exercise at relative (20% of maximum) and absolute (7 kg) intensities. Phenylephrine (α1 -agonist) or dexmedetomidine (α2 -agonist) was administered during the last 3 min of each trial to elicit α-adrenergic vasoconstriction. Forearm vascular conductance (FVC) was calculated from blood flow and blood pressure. Vasoconstrictor responsiveness was identified as the change in FVC (%) during α-adrenergic agonist infusions from baseline (resting trial) or from steady-state conditions (high flow and exercise trials). During resting and high flow trials, the %FVC during α1 - and α2 -agonist stimulation was similar between YW and PMW. During exercise, α1 -mediated vasoconstriction was blunted in YW vs. PMW at relative (-6 ± 2% vs. -15 ± 3%) and absolute (-4 ± 2% vs. -14 ± 5%) workloads, such that blood flow and FVC were lower in PMW (P < 0.05 for all). Conversely, α2 -mediated vasoconstriction was similar between YW and PMW at relative (-22 ± 3% vs. -22 ± 4%; P > 0.05) and absolute (-19 ± 3% vs. -18 ± 4%; P > 0.05) workloads. Collectively, these findings demonstrate that despite similar α-adrenergic vasoconstrictor responsiveness at rest, PMW have a decreased ability to attenuate α1 -adrenergic vasoconstriction in contracting skeletal muscle.

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  • Blunted shear-mediated dilation of the internal but not common carotid artery in response to lower body negative pressure. Reviewed International journal

    Erika Iwamoto, Joshua M Bock, Darren P Casey

    Journal of applied physiology (Bethesda, Md. : 1985)   124 ( 5 )   1326 - 1332   2018.5

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  • Evidence of a greater functional sympatholysis in habitually aerobic trained postmenopausal women. Reviewed International journal

    Nicholas T Kruse, William E Hughes, Satoshi Hanada, Kenichi Ueda, Joshua M Bock, Erika Iwamoto, Darren P Casey

    Journal of applied physiology (Bethesda, Md. : 1985)   124 ( 3 )   583 - 591   2018.3

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    Habitual aerobic exercise attenuates elevated vasoconstriction during acute exercise (functional sympatholysis) in older men; however, this effect remains unknown in postmenopausal women (PMW). This study tested the hypothesis that PMW who participate in habitual aerobic exercise demonstrate a greater functional sympatholysis compared with their untrained counterparts. Nineteen PMW (untrained n = 9 vs. trained n = 10) performed 5 min of steady-state (SS) forearm exercise at relative [10% and 20% of maximum voluntary contraction (MVC)] and absolute (5 kg) contraction intensities. Lower-body negative pressure (LBNP) was used to increase sympathetic vasoconstriction during rest and forearm exercise. Brachial artery diameter and blood velocities (via Doppler ultrasound) determined forearm blood flow (FBF; ml/min). Forearm muscle oxygen consumption ([Formula: see text]; ml/min) and arteriovenous oxygen difference (a-vO2diff) were estimated during SS-exercise and SS-exercise with LBNP. Forearm vascular conductance (FVC; ml·min-1·100 mmHg-1) was calculated from FBF and mean arterial pressure (MAP; mmHg). Vasoconstrictor responsiveness was determined as the %change in FVC during LBNP. The reduction in FVC (% change FVC) during LBNP was lower in trained compared with untrained PMW at 10% MVC (-7.3 ± 1.2% vs. -13.0 ± 1.1%; P < 0.05), 20% MVC (-4.4 ± 0.8% vs. -8.6 ± 1.4%; P < 0.05), and 5 kg (-5.3 ± 0.8% vs. -8.9 ± 1.4%; P < 0.05) conditions, whereas there were no differences at rest (-32.7 ± 4.4% vs. -33.7 ± 4.0%). Peripheral (FVC, FBF, and [Formula: see text]) and the magnitude change in systemic hemodynamics (heart rate and MAP) did not differ between groups during exercise. Collectively, the findings present the first evidence suggesting that PMW who participate in aerobic exercise demonstrate a greater functional sympatholysis compared with untrained PMW during mild to moderate forearm exercise. NEW & NOTEWORTHY Habitual aerobic exercise attenuates the elevated sympathetic nervous system-induced vasoconstriction during an acute bout of exercise (improved functional sympatholysis) in aging men; however, this effect remains unknown in postmenopausal women (PMW). The novel findings of this study suggest that habitual aerobic exercise results in an enhanced functional sympatholysis in PMW. Conversely, habitual aerobic exercise does not alter blood flow and oxygen utilization during acute forearm exercise compared with PMW who do not habitually exercise.

    DOI: 10.1152/japplphysiol.00411.2017

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  • High-Intensity Exercise Enhances Conduit Artery Vascular Function in Older Adults. Reviewed International journal

    Erika Iwamoto, Joshua M Bock, Darren P Casey

    Medicine and science in sports and exercise   50 ( 1 )   124 - 130   2018.1

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    DOI: 10.1249/MSS.0000000000001405

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  • 急性の電気刺激が血流依存性の血管調節機能に与える影響

    大岩 正太郎, 岩本 えりか, 長岡 凌平, 伊藤 翔太, 高見 次郎, 根木 亨, 片寄 正樹

    理学療法科学   32 ( 2 )   249 - 254   2017.4

  • Acute vascular effects of carbonated warm water lower leg immersion in healthy young adults. Reviewed International journal

    Shigehiko Ogoh, Ryohei Nagaoka, Takamasa Mizuno, Shohei Kimura, Yasuhiro Shidahara, Tomomi Ishii, Michinari Kudoh, Erika Iwamoto

    Physiological reports   4 ( 23 )   2016.12

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    DOI: 10.14814/phy2.13046

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  • Blunted blood pressure response during hyperpnoea in endurance runners. Reviewed International journal

    Yuka Itoh, Keisho Katayama, Erika Iwamoto, Kazushige Goto, Yasuhiro Suzuki, Toshiyuki Ohya, Kenji Takao, Koji Ishida

    Respiratory physiology & neurobiology   230   22 - 8   2016.8

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    DOI: 10.1016/j.resp.2016.04.010

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  • ERK Plays a Role in Chromosome Alignment and Participates in M-Phase Progression. International journal

    Erika Iwamoto, Natsumi Ueta, Yuki Matsui, Keiju Kamijo, Takahisa Kuga, Youhei Saito, Naoto Yamaguchi, Yuji Nakayama

    Journal of cellular biochemistry   117 ( 6 )   1340 - 51   2016.6

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    Cell division, a prerequisite for cell proliferation, is a process in which each daughter cell inherits one complete set of chromosomes. The mitotic spindle is a dedicated apparatus for the alignment and segregation of chromosomes. Extracellular signal-regulated kinase (ERK) 1/2 plays crucial roles in cell cycle progression, particularly during M-phase. Although, association with the mitotic spindle has been reported, the precise roles played by ERK in the dynamics of the mitotic spindle and in M-phase progression remain to be elucidated. In this study, we used MEK inhibitors U0126 and GSK1120212 to dissect the roles of ERK in M-phase progression and chromosome alignment. Fluorescence microscopy revealed that ERK is localized to the spindle microtubules in a manner independent of Src kinase, which is one of the kinases upstream of ERK at mitotic entry. ERK inhibition induces an increase in the number of prophase cells and a decrease in the number of anaphase cells. Time-lapse imaging revealed that ERK inhibition perturbs chromosome alignment, thereby preventing cells from entering anaphase. These results suggest that ERK plays a role in M-phase progression by regulating chromosome alignment and demonstrate one of the mechanisms by which the aberration of ERK signaling may produce cancer cells.

    DOI: 10.1002/jcb.25424

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  • Flow-mediated dilation in the inactive limb following acute hypoxic exercise Reviewed International journal

    Keisho Katayama, Shin Yamashita, Erika Iwamoto, Koji Ishida

    CLINICAL PHYSIOLOGY AND FUNCTIONAL IMAGING   36 ( 1 )   60 - 69   2016.1

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    DOI: 10.1111/cpf.12194

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  • Exercise intensity modulates brachial artery retrograde blood flow and shear rate during leg cycling in hypoxia. Reviewed International journal

    Erika Iwamoto, Keisho Katayama, Koji Ishida

    Physiological reports   3 ( 6 )   2015.6

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    DOI: 10.14814/phy2.12423

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  • Retrograde blood flow in the inactive limb is enhanced during constant-load leg cycling in hypoxia Reviewed International journal

    Erika Iwamoto, Keisho Katayama, Shin Yamashita, Yoshiharu Oshida, Koji Ishida

    EUROPEAN JOURNAL OF APPLIED PHYSIOLOGY   113 ( 10 )   2565 - 2575   2013.10

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    DOI: 10.1007/s00421-013-2694-8

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  • Hypoxic effects on sympathetic vasomotor outflow and blood pressure during exercise with inspiratory resistance Reviewed International journal

    Keisho Katayama, Shin Yamashita, Koji Ishida, Erika Iwamoto, Teruhiko Koike, Mitsuru Saito

    AMERICAN JOURNAL OF PHYSIOLOGY-REGULATORY INTEGRATIVE AND COMPARATIVE PHYSIOLOGY   304 ( 5 )   R374 - R382   2013.3

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    DOI: 10.1152/ajpregu.00489.2012

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  • The effect of acute exercise in hypoxia on flow-mediated vasodilation. Reviewed International journal

    Keisho Katayama, Osamu Fujita, Motoyuki Iemitsu, Hiroshi Kawano, Erika Iwamoto, Mitsuru Saito, Koji Ishida

    European journal of applied physiology   113 ( 2 )   349 - 57   2013.2

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    The purpose of this study was to clarify the effect of acute exercise in hypoxia on flow-mediated vasodilation (FMD). Eight males participated in this study. Two maximal exercise tests were performed using arm cycle ergometry to estimate peak oxygen uptake [Formula: see text] while breathing normoxic [inspired O(2) fraction (FIO(2)) = 0.21] or hypoxic (FIO(2) = 0.12) gas mixtures. Next, subjects performed submaximal exercise at the same relative exercise intensity [Formula: see text] in normoxia or hypoxia for 30 min. Before (Pre) and after exercise (Post 5, 30, and 60 min), brachial artery FMD was measured during reactive hyperemia by ultrasound under normoxic conditions. FMD was estimated as the percent (%) rise in the peak diameter from the baseline value at prior occlusion at each FMD measurement (%FMD). The area under the curve for the shear rate stimulus (SR(AUC)) was calculated in each measurement, and each %FMD value was normalized to SR(AUC) (normalized FMD). %FMD and normalized FMD decreased significantly (P < 0.05) immediately after exercise in both condition (mean ± SE, FMD, normoxic trial, Pre: 8.85 ± 0.58 %, Post 5: -0.01 ± 1.30 %, hypoxic trial, Pre: 8.84 ± 0.63 %, Post 5: 2.56 ± 0.83 %). At Post 30 and 60, %FMD and normalized FMD returned gradually to pre-exercise levels in both trials (FMD, normoxic trial, Post 30: 1.51 ± 0.68 %, Post 60: 2.99 ± 0.79 %; hypoxic trial, Post 30: 4.57 ± 0.78 %, Post 60: 6.15 ± 1.20 %). %FMD and normalized FMD following hypoxic exercise (at Post 5, 30, and 60) were significantly (P < 0.05) higher than after normoxic exercise. These results suggest that aerobic exercise in hypoxia has a significant impact on endothelial-mediated vasodilation.

    DOI: 10.1007/s00421-012-2442-5

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  • The effect of acute exercise in hypoxia on flow-mediated vasodilation.

    Katayama K, Fujita O, Iemitsu M, Kawano H, Iwamoto E, Saito M, Ishida K

    Eur J Appl Physiol   9   47   2012.6

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  • Hypoxia Augments Oscillatory Blood Flow in Brachial Artery during Leg Cycling Reviewed International journal

    Erika Iwamoto, Keisho Katayama, Yoshiharu Oshida, Koji Ishida

    MEDICINE AND SCIENCE IN SPORTS AND EXERCISE   44 ( 6 )   1035 - 1042   2012.6

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    DOI: 10.1249/MSS.0b013e31824294f9

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  • Inspiratory muscle fatigue increases sympathetic vasomotor outflow and blood pressure during submaximal exercise Reviewed International journal

    Keisho Katayama, Erika Iwamoto, Koji Ishida, Teruhiko Koike, Mitsuru Saito

    AMERICAN JOURNAL OF PHYSIOLOGY-REGULATORY INTEGRATIVE AND COMPARATIVE PHYSIOLOGY   302 ( 10 )   R1167 - R1175   2012.5

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    DOI: 10.1152/ajpregu.00006.2012

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  • Hypoxia augments muscle sympathetic neural response to leg cycling Reviewed International journal

    Keisho Katayama, Koji Ishida, Erika Iwamoto, Motoyuki Iemitsu, Teruhiko Koike, Mitsuru Saito

    AMERICAN JOURNAL OF PHYSIOLOGY-REGULATORY INTEGRATIVE AND COMPARATIVE PHYSIOLOGY   301 ( 2 )   R456 - R464   2011.8

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    DOI: 10.1152/ajpregu.00119.2011

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  • The neural influence on the occurrence of locomotor-respiratory coordination Reviewed International journal

    Erika Iwamoto, Shunsuke Taito, Toshihiro Kawae, Kiyokazu Sekikawa, Makoto Takahashi, Tsutomu Inamizu

    RESPIRATORY PHYSIOLOGY & NEUROBIOLOGY   173 ( 1 )   23 - 28   2010.8

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    DOI: 10.1016/j.resp.2010.06.002

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MISC

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Awards

  • 第28回 日本基礎理学療法学会優秀賞, 日本基礎理学療法学会

    2024.10  

    鴨田樹 (指導教員:岩本えりか)

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  • ベストルーキーアワード, 日本糖尿病理学療法学会

    2024.9  

    鴨田樹 (指導教員: 岩本えりか)

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  • 最優秀若手演題賞

    2022.11   日本血管血流学会  

    坂本琳太郎 (指導教員 岩本えりか)

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  • John F. Perkins, Jr. Memorial Award for International Physiologists

    2019.6   American Physiological Society  

    IWAMOTO Erika

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  • International Early Career Physiologist Travel Award

    2018.4   American Physiological Society  

    IWAMOTO Erika

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  • 最優秀演題賞

    2015.11   日本血管血流学会  

    岩本えりか

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Research Projects

  • Autonomic Regulation to Promote Brain Waste Clearance and Prevent Dementia

    Grant number:25K21803  2025.6 - 2029.3

    Japan Society for the Promotion of Science  Grants-in-Aid for Scientific Research  Grant-in-Aid for Challenging Research (Pioneering)

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    Grant amount:\25610000 ( Direct Cost: \19700000 、 Indirect Cost:\5910000 )

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  • 加齢に伴う血管収縮力増加に対抗し脳血流を維持するための新規メカニズムの解明

    Grant number:25K03021  2025.4 - 2029.3

    日本学術振興会  科学研究費助成事業  基盤研究(B)

    岩本 えりか

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    Grant amount:\18460000 ( Direct Cost: \14200000 、 Indirect Cost:\4260000 )

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  • 糖尿病患者におけるレジスタンス運動中の眼圧上昇を防ぐ新規介入方策の開発

    Grant number:24K22253  2024.6 - 2027.3

    日本学術振興会  科学研究費助成事業  挑戦的研究(萌芽)

    岩本 えりか, 片山 敬章, 小河 繁彦

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    Grant amount:\6370000 ( Direct Cost: \4900000 、 Indirect Cost:\1470000 )

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  • 心不全の治療経過に着目したサルコペニアの発症・進行因子の解明

    Grant number:24K14251  2024.4 - 2027.3

    日本学術振興会  科学研究費助成事業  基盤研究(C)

    山田 悠, 角谷 尚哉, 岩本 えりか, 片寄 正樹

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    Grant amount:\4680000 ( Direct Cost: \3600000 、 Indirect Cost:\1080000 )

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  • Comparative Analysis of Cerebral and Peripheral Circulatory Function, Exercise Pressor Response, and Brain Anatomical Characteristics Between Japanese and Caucasian Americans

    Grant number:23KK0179  2023.9 - 2029.3

    Japan Society for the Promotion of Science  Grants-in-Aid for Scientific Research  Fund for the Promotion of Joint International Research (International Collaborative Research)

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    Grant amount:\21060000 ( Direct Cost: \16200000 、 Indirect Cost:\4860000 )

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  • Effect of the response of shear rate in the cerebral artery to exercise on cerebral endothelial function and cognitive function

    Grant number:22H03470  2022.4 - 2026.3

    Japan Society for the Promotion of Science  Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (B)  Grant-in-Aid for Scientific Research (B)

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    Grant amount:\17420000 ( Direct Cost: \13400000 、 Indirect Cost:\4020000 )

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  • Cardiopulmonary baroreflex control of arterial blood pressure during exercise in the elderly

    Grant number:22H03479  2022.4 - 2025.3

    Japan Society for the Promotion of Science  Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (B)  Grant-in-Aid for Scientific Research (B)

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    Grant amount:\17680000 ( Direct Cost: \13600000 、 Indirect Cost:\4080000 )

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  • Role of the cardiopulmonary baroreflex in exaggerated arterial blood presure response during exercise in elderly

    Grant number:23K24736  2022.4 - 2025.3

    Japan Society for the Promotion of Science  Grants-in-Aid for Scientific Research  Grant-in-Aid for Scientific Research (B)

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    Grant amount:\17680000 ( Direct Cost: \13600000 、 Indirect Cost:\4080000 )

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  • 閉塞性睡眠時無呼吸の根治を目指した個別化医療の確立

    Grant number:21K11170  2021.4 - 2024.3

    日本学術振興会  科学研究費助成事業 基盤研究(C)  基盤研究(C)

    宇野 英二, 岩本 えりか, 片寄 正樹, 角谷 尚哉

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    Grant amount:\4160000 ( Direct Cost: \3200000 、 Indirect Cost:\960000 )

    本研究は、医療施設およびそれに附置する医療法42条施設が連携して実施している。研究体制は、医療施設の医師、看護師、臨床検査技師、放射線技師、および医療法42条施設の理学療法士、健康運動指導士、管理栄養士が連携することで、研究組織を構築している。
    初年度は、閉塞性睡眠時無呼吸に対する運動療法導入に向けたメディカルチェックの方法を確立し、その安全性および有効性を検証した。メディカルチェックの実施項目は、①終夜ポリグラム検査、②問診、③体成分分析、④身体機能評価、⑤栄養評価、⑥心肺運動負荷試験とした。医療施設では主に閉塞性睡眠時無呼吸の診断、および併存疾患のコントロール状況を把握することで運動に伴うリスクを判断することを目的に選定した。また医療法42条施設においては、効果的な運動療法を実施するための情報収集を目的に選定した。また、糖尿病に対する運動処方を参考に、閉塞性睡眠時無呼吸に対する運動処方を考案した。運動内容は、コンディショニング、ファンクショナルトレーニング、ウエイトトレーニング、インターバルトレーニングから構成される。行動変容ステージに応じて段階的に運動強度を変更し、コンディショニングやファンクショナルトレーニング中心から、徐々にウエイトトレーニングやインターバルトレーニングを導入することが特徴的である。運動療法導入時には、迷走神経反射によるめまいなどの自覚症状を認めたが、治療を有する有害事象は発生しなかった。
    メディカルチェックおよびその後の運動療法実施時に有害事象は認めず、安全性および有効性が示された。

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  • The impact of the fluctuation in female hormone levels during the menstrual cycle on foot alignment

    Grant number:21K11290  2021.4 - 2024.3

    Japan Society for the Promotion of Science  Grants-in-Aid for Scientific Research  Grant-in-Aid for Scientific Research (C)

    Katayose Masaki

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    Grant amount:\3900000 ( Direct Cost: \3000000 、 Indirect Cost:\900000 )

    Fluctuations in female hormone levels during the menstrual cycle have been discussed as a possible link to the incidence of lower limb disorders in sport. The present study focused on foot alignment, which is a contributing factor to changes in lower limb alignment during jump landing movements. It was shown that changes in the ratio of estrogen to progesterone are important factors affecting foot alignment. Additionally, we examined the effect of sex differences on muscle endurance, which is crucial for maintaining foot alignment during sports activities. The study demonstrated that there were no significant sex differences in blood glucose fluctuations and blood flow regulation during exercise in young adult men and women, even after energy intake before exercise.

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  • 慢性閉塞性肺疾患の認知機能低下における脳血管動脈硬化の役割

    Grant number:20K11186  2020.4 - 2023.3

    日本学術振興会  科学研究費助成事業 基盤研究(C)  基盤研究(C)

    岩本 えりか

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    Grant amount:\4420000 ( Direct Cost: \3400000 、 Indirect Cost:\1020000 )

    本研究は、脳血管の動脈硬化を含めた網羅的な脳循環機能の評価を行い、慢性閉塞性肺疾患(COPD)患者の認知機能低下に関与する脳循環機能の変化を解明すること、また、呼吸筋疲労が脳循環機能の変化を介して認知機能低下に関与するかを明らかにすることを目的としている。本研究実施においては、外来COPD患者を被験者として用いる予定であったが、COPD患者はCOVID-19に対してより重症化のリスクが高い患者であることから、本年度はCOPD患者を用いた実験を行うことはできなかった。そのため、本研究のメインテーマである「呼吸機能が脳血管および認知機能に与える影響」を明らかにするために健康成人を被験者として用いた実験のための倫理審査申請書類の作成・変更および予備実験を実施した。
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    具体的には、健康成人に対して安静時および運動時に段階的な吸気抵抗を負荷し、呼吸筋負荷をかけた際の介入中の脳血流(中大脳動脈の血流速度、内頸動脈の血流速度・血管径)、全身の循環機能(連続指尖血圧、心拍数、心電図)、介入前後の脳血管の内皮機能(内頸動脈の高炭酸を用いた血管拡張反応)にどのような影響を与えるかの予備実験を実施した。また、健康成人に対して、軽度の呼気抵抗と呼吸コントロールを行うことにより、安静時および運動時に動的肺過膨張を引き起こし、脳血流(中大脳動脈の血流速度、内頸動脈の血流速度・血管径)、全身の循環機能(連続指尖血圧、心拍数、心電図)に与える影響を検討した。これらの予備実験結果を活かし、今後は健康成人における本実験を進めていく予定である。

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  • Evaluation of local arteriosclerosis using shear wave elastography

    Grant number:16K16432  2016.4 - 2019.3

    Japan Society for the Promotion of Science  Grants-in-Aid for Scientific Research Grant-in-Aid for Young Scientists (B)  Grant-in-Aid for Young Scientists (B)

    Iwamoto Erika

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    Authorship:Principal investigator  Grant type:Competitive

    The purpose of this study was to verify the evaluation of arteriosclerosis using the shear wave elastography (ultrasound tissue elastic imaging) which is a new imaging that images local arterial stiffness. Specifically, we aimed to clarify 1) whether Young's modulus measured by shear wave elastography more reflects "structural factors" such as the structure of blood vessel walls or "functional factors" such as vascular reactivity and 2) the physiological factors that influence Young's modulus. We found that the changes in estradiol during menstrual cycle in the young women and acute aerobic exercise did not affect Young's modulus. These results suggest that arterial stiffness measured by shear wave elastography may more reflect arterial structural factors compared to the functional factors.

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  • ノーステック財団 研究開発助成事業

    2014.7 - 2015.3

    ノーステック財団 

    岩本えりか

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  • Effect of respiratory muscle training in hypoxia on endurance exercise performance

    Grant number:26560348  2014.4 - 2017.3

    Japan Society for the Promotion of Science  Grants-in-Aid for Scientific Research Grant-in-Aid for Challenging Exploratory Research  Grant-in-Aid for Challenging Exploratory Research

    Katayama Keisho, IWAMOTO Erika, ITOH Yuka, GOTO Kanako, SHIMIZU Kaori, TAKAO Kenji, KASAI Nobukazu, SUMI Daichi, MORI Hisashi

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    Grant amount:\3640000 ( Direct Cost: \2800000 、 Indirect Cost:\840000 )

    The purpose of the present study was to clarity the effect of respiratory muscle endurance training in hypoxia on respiratory muscle-induce metaboreflex. Collegiate male endurance runners assigned to a normoxic or hypoxic group. Before and after 6 weeks of respiratory muscle endurance training, cardiovascular response to an incremental respiratory endurance test was measured. Minute ventilation during the training increased progressively. Target SpO2 in the hypoxic group set at 80%. The change arterial blood pressure during the incremental respiratory endurance test reduced significantly after the training in both groups. No significant difference in arterial blood pressure during hyperpnoea was found after the training between the two groups. These results suggest respiratory muscle-induced metaboreflex is attenuate by respiratory muscle endurance training, but no additional effect appears when the training is performed under hypoxic conditions.

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  • YMFSチャレンジ研究助成

    2013.4 - 2014.3

    岩本えりか

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  • Effect of respiratory system on circulatory regulation during exercise

    Grant number:24300222  2012.4 - 2015.3

    Japan Society for the Promotion of Science  Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (B)  Grant-in-Aid for Scientific Research (B)

    KATAYAMA KEISHO, ISHIDA Koji, SAITO Mitsuru, KOIKE Teruhiko, IWAMOTO Erika

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    Grant amount:\18330000 ( Direct Cost: \14100000 、 Indirect Cost:\4230000 )

    It has been thought that an increase in respiratory muscle activity affects cardiovascular regulation during exercise. We found that an enhancement of inspiratory muscle work causes an increase in sympathetic vasomotor outflow with a corresponding enhancement of arterial blood pressure during exercise. An enhancement of inspiratory muscle activity under hypoxic condition leads to large increases in sympathetic vasomotor outflow and BP. It is possible that this large vasoconstrictor activity reduces blood flow and oxygen transport to the working limb, thereby exacerbating limb fatigue and compromising exercise performance.

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  • 公益財団法人伊藤医薬学術交流財団助成

    2012.3 - 2014.4

    岩本えりか

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    Authorship:Principal investigator  Grant type:Competitive

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  • 日本体力医学会国際交流事業,米国スポーツ医学会参加助成制度

    2011.4 - 2012.3

    岩本えりか

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    Authorship:Principal investigator  Grant type:Competitive

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  • Clarification of the effective way of breathing and its mechanism during aerobic exercise

    Grant number:23500777  2011 - 2013

    Japan Society for the Promotion of Science  Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (C)  Grant-in-Aid for Scientific Research (C)

    ISHIDA Koji, KATAYAMA Keisho, KOIKE Teruhiko, HOTTA Norio, IWAMOTO Erika

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    Grant amount:\5200000 ( Direct Cost: \4000000 、 Indirect Cost:\1200000 )

    This study revealed that (1) repeated and exaggerated ventilation during exercise produced by short term aerobic training combined with chest wall restriction or inhalation of hypoxic gas, reinforced subsequent ventilatory response to normal exercise, indicating that learning should be involved in the respiratory control during exercise, and that (2) high intensity cycle exercise often induced a locomotor-respiratory coupling and resultant easiness during exercise, while during moderate intensity cycle exercise which was often used in aerobic exercise, there was no difference in cardio-respiratory responses between coupling and non-coupling so that the locomotor-respiratory coupling should have no beneficial effect on moderate intensity exercise. These results suggest that during aerobic exercise, we should keep in mind to breathe slowly rather than to synchronize respiration to locomotion, and that appropriate breathing way during exercise could be obtained from repetitive learning.

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