Document Detail

Evidence in man for a fast neural mechanism during the early phase of exercise hyperpnea.
MedLine Citation:
PMID:  6810429     Owner:  NLM     Status:  MEDLINE    
Recently, the rapid increase in ventilation at the onset of exercise has been attributed to reflexes stimulated by the concomitant increase in cardiac output. To evaluate these 'fast-humoral' hypotheses in supine man, the heart rate, ventilation, and end-tidal PCO2 and PO2 were observed during four procedures: the onset of mild dynamic exercise by the lower legs (1) with and (2) without inflation of occluding cuffs around the upper thighs, (3) rapid induction of circulatory occlusion at the level of the upper thighs, and (4) abrupt release of circulatory occlusion after 2.5 min of ischemia. Exercise resulted in abrupt hyperpnea, alveolar hyperventilation, and tachycardia whether or not there was circulatory occlusion. Circulatory occlusion engendered abrupt bradycardia and transient, hyperventilatory hyperpnea. Release of circulatory occlusion resulted in relatively large tachycardia and, after a delay, small hyperpnea and alveolar hypoventilation. The results demonstrate that the early response to exercise is not inherently isocapnic hyperpnea and that, contrary to the prediction of the fast-humoral hypotheses, the presumed increase in cardiac output following cuff release does not produce a ventilatory response similar to that of exercise. These findings support the existence of a neurally mediated factor during the early stages of exercise hyperpnea.
W E Fordyce; F M Bennett; S K Edelman; F S Grodins
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Publication Detail:
Type:  Journal Article; Research Support, U.S. Gov't, P.H.S.    
Journal Detail:
Title:  Respiration physiology     Volume:  48     ISSN:  0034-5687     ISO Abbreviation:  Respir Physiol     Publication Date:  1982 Apr 
Date Detail:
Created Date:  1982-10-12     Completed Date:  1982-10-12     Revised Date:  2009-11-11    
Medline Journal Info:
Nlm Unique ID:  0047142     Medline TA:  Respir Physiol     Country:  NETHERLANDS    
Other Details:
Languages:  eng     Pagination:  27-43     Citation Subset:  IM; S    
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MeSH Terms
Carbon Dioxide
Heart Rate
Nervous System Physiological Phenomena*
Partial Pressure
Physical Exertion*
Thigh / blood supply
Time Factors
Grant Support
Reg. No./Substance:
124-38-9/Carbon Dioxide; 7782-44-7/Oxygen

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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