Ventilatory Effects of 8 Hours of Isocapnic Hypoxia with and Without ß;-Blockade

  • Christine Clar
  • Keith L. Dorrington
  • Peter A. Robbins
Part of the Advances in Experimental Medicine and Biology book series (AEMB, volume 450)


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.


Sympathetic Activity Carotid Body Apply Physiology Ventilatory Response Hypoxic Exposure 
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Copyright information

© Springer Science+Business Media New York 1998

Authors and Affiliations

  • Christine Clar
    • 1
  • Keith L. Dorrington
    • 1
  • Peter A. Robbins
    • 1
  1. 1.University Laboratory of PhysiologyUniversity of OxfordOxfordUK

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