Document Detail

Effect of plasma carbonic anhydrase on ventilation in exercising dogs.
MedLine Citation:
PMID:  6777349     Owner:  NLM     Status:  MEDLINE    
Recent studies suggest pH sampled by arterial chemoreceptors may not equal that sampled by external pH electrodes, because the uncatalyzed hydration of CO2 in plasma is a slow reaction (t 1/2 approximately 9 S). The importance of this reaction rate to ventilatory control (particularly during exercise) is not known. We studied the effect of catalyzing the CO2-pH reaction in three awake exercising dogs with chronic tracheostomies and carotid loops; the dogs were trained to run on a treadmill. Respiration frequency, tidal volume, total ventilation, and end-tidal partial pressure of CO2 (PCO2) were continuously monitored. Periodically, carotid artery blood was drawn and analyzed for partial pressure of O2 (PO2), PCO2, pH, and plasma carbonic anhydrase (CA) activity. Measurements were made during steady-state exercise (3 mph and 10% grade), during a control period, after injection of a 5 ml bolus of saline, and after injection of 5 mg/kg of bovine CA dissolved in 5 ml of saline. This dose of CA increased the reaction rate by more than 80-fold. Neither the control nor the CA injections significantly altered the ventilatory parameters. Saline and CA date differed by less than 5% in ventilation, 1 Torr in arterial PCO2, 0.01 in pH units, and 1.5 Torr in end-tidal PCO2. Thus the of CO2 hydration in plasma is not a significant factor in ventilatory control.
S M Lewis; E P Hill
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Publication Detail:
Type:  Journal Article; Research Support, U.S. Gov't, P.H.S.    
Journal Detail:
Title:  Journal of applied physiology: respiratory, environmental and exercise physiology     Volume:  49     ISSN:  0161-7567     ISO Abbreviation:  J Appl Physiol Respir Environ Exerc Physiol     Publication Date:  1980 Oct 
Date Detail:
Created Date:  1981-02-24     Completed Date:  1981-02-24     Revised Date:  2013-09-26    
Medline Journal Info:
Nlm Unique ID:  7801242     Medline TA:  J Appl Physiol Respir Environ Exerc Physiol     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  708-14     Citation Subset:  IM; S    
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MeSH Terms
Carbon Dioxide / blood
Carbonic Anhydrases / blood,  pharmacology*
Dose-Response Relationship, Drug
Lung / physiology
Oxygen / blood
Physical Exertion*
Respiration / drug effects*
Grant Support
Reg. No./Substance:
124-38-9/Carbon Dioxide; 7782-44-7/Oxygen; EC Anhydrases

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

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