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The coronary vascular response to the metaboreflex at low-altitude and during acute and prolonged high-altitude in males

journal contribution
posted on 12.05.2022, 11:13 by Austin J. White, Lindsey M. Boulet, Brooke M. Shafer, Tyler D. Vermeulen, Taylor L. Atwater, Michael StembridgeMichael Stembridge, Philip N. Ainslie, Richard J. Wilson, Trevor A. Day, Glen E. Foster

 Myocardial oxygen delivery is primarily regulated through changes in vascular tone to match increased metabolic demands. In males, activation of the muscle metaboreflex during acute isocapnic hypoxia results in a paradoxical coronary vasoconstriction. Whether coronary blood velocity is reduced by metaboreflex activation following travel and/or adaptation to high-altitude is unknown. This study determined if the response of the coronary vasculature to muscle metaboreflex activation at low-altitude differs from acute (1/2 days) and prolonged (8/9 days) high-altitude. Healthy males (n=16) were recruited and performed isometric handgrip exercise (30 % max) followed by post-exercise circulatory occlusion (PECO) to isolate the muscle metaboreflex at low-altitude and following acute and prolonged high-altitude (3,800 m). Mean left anterior descending coronary artery blood velocity (LADvmean, transthoracic Doppler echocardiography), heart rate, mean arterial pressure (MAP), ventilation, and respired gases were assessed during baseline and PECO at all time-points. Coronary vascular conductance index (CVCi) was calculated as LADVmean/MAP. The change in LADvmean (acute altitude: -1.7 ± 3.9 cm/s, low-altitude: 2.6 ± 3.4 cm/s, P = 0.01) and CVCi (acute altitude: -0.05 ± 0.04 cm/s/mmHg, low-altitude: -0.01 ± 0.03 cm/s/mmHg, P = 0.005) induced by PECO differed significantly between acute high-altitude and low-altitude. The change in LADVmean and CVCi induced by PECO following prolonged high-altitude was not different from low-altitude. Our results suggest that coronary vasoconstriction with metaboreflex activation in males is greatest following acute ascent to high-altitude and restored to low-altitude levels following 8-9 days of acclimatization. 

History

Published in

Journal of Applied Physiology

Publisher

American Physiological Society

Version

AM (Accepted Manuscript)

Citation

White, A.J., Boulet, L.M., Shafer, B.M., Vermeulen, T.D., Atwater, T.L., Stembridge, M., Ainslie, P.N., Wilson, R.J., Day, T.A. and Foster, G.E. (2022) 'The coronary vascular response to the metaboreflex at low-altitude and during acute and prolonged high-altitude in males', Journal of Applied Physiology. doi: 10.1152/japplphysiol.00018.2022

Print ISSN

8750-7587

Electronic ISSN

1522-1601

Cardiff Met Affiliation

  • Cardiff School of Sport and Health Sciences

Cardiff Met Authors

Mike Stembridge Michael Stembridge

Cardiff Met Research Centre/Group

  • Cardiovascular Physiology

Copyright Holder

© The Publisher

Language

en