Document Detail

Role of the carotid bodies in the respiratory compensation for the metabolic acidosis of exercise in humans.
MedLine Citation:
PMID:  1822563     Owner:  NLM     Status:  MEDLINE    
1. In response to an acute exercise-induced metabolic acidosis, the fall of arterial pH is constrained by the magnitude of the compensatory hyperventilation. To determine the role of the carotid bodies in this regulatory process, subjects performed prolonged (24 min) square-wave cycle ergometry from a background of unloaded cycling at inspired oxygen fractions (FI,O2) of 0.12 O2 (high carotid body gain), 0.21 O2 (normal carotid body gain) and 0.80 O2 (low carotid body gain). The work rates were selected to provide the same exercise intensity, despite the different inspirates; i.e. resulting in a constant increase in arterial blood [lactate] (delta [L-] approximately 4 mequiv l-1. 2. Ventilatory and pulmonary gas exchange variables were computed breath-by-breath and arterial blood was sampled at intervals throughout the tests and analysed subsequently for [lactate], [pyruvate], arterial partial pressures of oxygen and carbon dioxide (PO2, PCO2), pH, [bicarbonate] and [potassium]. 3. Hypoxia markedly reduced, and hyperoxia magnified, the transient decrease in arterial pH following exercise onset. However, there was a slow acid-base compensatory component, even when carotid chemosensitivity was suppressed by hyperoxia. We therefore conclude that, in humans, carotid body chemosensitivity plays a dominant role in constraining variations of arterial pH in response to the acute metabolic acidosis of heavy exercise, but that secondary-presumably central chemosensory-mechanisms subserve a slower compensatory role.
S M Rausch; B J Whipp; K Wasserman; A Huszczuk
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Publication Detail:
Type:  Journal Article; Research Support, U.S. Gov't, P.H.S.    
Journal Detail:
Title:  The Journal of physiology     Volume:  444     ISSN:  0022-3751     ISO Abbreviation:  J. Physiol. (Lond.)     Publication Date:  1991 Dec 
Date Detail:
Created Date:  1992-08-31     Completed Date:  1992-08-31     Revised Date:  2009-11-18    
Medline Journal Info:
Nlm Unique ID:  0266262     Medline TA:  J Physiol     Country:  ENGLAND    
Other Details:
Languages:  eng     Pagination:  567-78     Citation Subset:  IM; S    
Division of Respiratory and Critical Care Physiology and Medicine, Harbor-UCLA Medical Center, Torrance 90509.
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MeSH Terms
Acidosis / blood,  physiopathology*
Bicarbonates / blood
Carbon Dioxide / blood
Carotid Body / physiopathology*
Exercise / physiology*
Hydrogen-Ion Concentration
Hyperventilation / blood,  physiopathology
Lactates / blood
Pulmonary Gas Exchange
Respiration / physiology*
Grant Support
Reg. No./Substance:
0/Bicarbonates; 0/Lactates; 124-38-9/Carbon Dioxide

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

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