Abstract
Studies of humans at high altitude show increases in cardiac output, heart rate, and plasma noradrenaline levels (2,4), suggesting an increase in sympathetic activity. Ventilation (V̇e) as well as heart rate progressively increase during the first few hours of a hypoxic exposure, and both responses have a component that is not rapidly reversible (1,7). We investigated the hypothesis that changing sympathetic activity may be the common factor underlying those slow responses, and studied ventilatory responses during a prolonged hypoxic exposure in the presence of ß-blockade as compared with control. Subjects were studied under isocapnic conditions to eliminate the confounding effect of hypocapnia developing as V̇e increases during the exposure.
This is a preview of subscription content, log in via an institution to check access.
Access this chapter
Tax calculation will be finalised at checkout
Purchases are for personal use only
References
Ciar, C., M.E.F. Pedersen, M.J. Poulin, J.G. Tansley, and P.A. Robbins. Effects of 8 h of eucapnic and poikilocapnic hypoxia on middle cerebral artery velocity and heart rate in humans. Experimental Physiology 82: 791–802, 1997.
Cunningham, W.L., E.J. Becker, and F. Kreuzer. Catecholamines in plasma and urine at high altitude. Journal of Applied Physiology 20: 607–610, 1965.
Folgering, H., J. Ponte, and T. Sadig. Adrenergic mechanisms and chemoreception in the carotid body of the cat and rabbit. Journal of Physiology325: 1–22, 1982.
Grover, R.F., J.T. Reeves, J.T. Maher, R.E. McCullough, J.C. Cruz, J.C. Denniston, and A. Cymerman. Maintained stroke volume but impaired arterial oxygenation in man at high altitude with supplemental CO2. Circulation Research 38(5): 391–396, 1976.
Milsom, W.K., and T. Sadig. Interaction between norepinephrine and hypoxia in carotid body chemoreception in rabbits. Journal of Applied Physiology 55: 1893–1898, 1983.
O’Regan, R.G. Responses of carotid body chemosensory activity and blood flow to stimulation of sympathetic nerves in the cat. Journal of Physiology 315: 81–98, 1981.
Tansley, J.G., C. Ciar, M.E.F. Pedersen, and P.A. Robbins. Human ventilatory response to acute hyperoxia during and after 8 h of both isocapnic and poikilocapnic hypoxia. Journal of Applied Physiology 82: 513–519, 1997.
Author information
Authors and Affiliations
Editor information
Editors and Affiliations
Rights and permissions
Copyright information
© 1998 Springer Science+Business Media New York
About this chapter
Cite this chapter
Clar, C., Dorrington, K.L., Robbins, P.A. (1998). Ventilatory Effects of 8 Hours of Isocapnic Hypoxia with and Without ß;-Blockade. In: Hughson, R.L., Cunningham, D.A., Duffin, J. (eds) Advances in Modeling and Control of Ventilation. Advances in Experimental Medicine and Biology, vol 450. Springer, Boston, MA. https://doi.org/10.1007/978-1-4757-9077-1_5
Download citation
DOI: https://doi.org/10.1007/978-1-4757-9077-1_5
Publisher Name: Springer, Boston, MA
Print ISBN: 978-1-4757-9079-5
Online ISBN: 978-1-4757-9077-1
eBook Packages: Springer Book Archive