Document Detail

Alveolar PCO2 oscillations and ventilation at sea level and at high altitude.
MedLine Citation:
PMID:  17962582     Owner:  NLM     Status:  MEDLINE    
This study examines the potential for a ventilatory drive, independent of mean PCO2, but depending instead on changes in PCO2 that occur during the respiratory cycle. This responsiveness is referred to here as "dynamic ventilatory sensitivity." The normal, spontaneous, respiratory oscillations in alveolar PCO2 have been modified with inspiratory pulses approximating alveolar PCO2 concentrations, both at sea level and at high altitude (5,000 m, 16,400 ft.). All tests were conducted with subjects exercising on a cycle ergometer at 60 W. The pulses last about half the inspiratory duration and are timed to arrive in the alveoli during early or late inspiration. Differences in ventilation, which then occur in the face of similar end-tidal PCO2 values, are taken to result from dynamic ventilatory sensitivity. Highly significant ventilatory responses (early pulse response greater than late) occurred in hypoxia and normoxia at sea level and after more than 4 days at 5,000 m. The response at high altitude was eliminated by normalizing PO2 and was reduced or eliminated with acetazolamide. No response was present soon after arrival (<4 days) at base camp, 5,000 m, on either of two high-altitude expeditions (BMEME, 1994, and Kanchenjunga, 1998). The largest responses at 5,000 m were obtained in subjects returning from very high altitude (7,100-8,848 m). The present study confirms and extends previous investigations that suggest that alveolar PCO2 oscillations provide a feedback signal for respiratory control, independent of changes in mean PCO2, suggesting that natural PCO2 oscillations drive breathing in exercise.
D J Collier; A H Nickol; J S Milledge; H J A van Ruiten; C J Collier; E R Swenson; Avijit Datta; C B Wolff
Publication Detail:
Type:  Clinical Trial; Journal Article; Research Support, Non-U.S. Gov't     Date:  2007-10-25
Journal Detail:
Title:  Journal of applied physiology (Bethesda, Md. : 1985)     Volume:  104     ISSN:  8750-7587     ISO Abbreviation:  J. Appl. Physiol.     Publication Date:  2008 Feb 
Date Detail:
Created Date:  2008-02-11     Completed Date:  2008-04-04     Revised Date:  2013-09-26    
Medline Journal Info:
Nlm Unique ID:  8502536     Medline TA:  J Appl Physiol (1985)     Country:  United States    
Other Details:
Languages:  eng     Pagination:  404-15     Citation Subset:  IM    
Centre for Clinical Pharmacology, William Harvey Research Institute, Barts & The London Queen Mary School of Medicine & Dentistry, Charterhouse Square, London EC1M 6BQ, UK.
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MeSH Terms
Acetazolamide / pharmacology
Acute Disease
Administration, Inhalation
Anoxia / metabolism,  physiopathology*
Carbon Dioxide / administration & dosage,  metabolism*
Chemoreceptor Cells / metabolism
Chronic Disease
Hypercapnia / metabolism,  physiopathology*
Oxygen / administration & dosage
Pulmonary Alveoli / drug effects,  metabolism,  physiopathology*
Pulmonary Ventilation* / drug effects
Time Factors
Reg. No./Substance:
124-38-9/Carbon Dioxide; 59-66-5/Acetazolamide; 7782-44-7/Oxygen

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

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