Document Detail

Ventilatory acclimatization in response to very small changes in PO2 in humans.
MedLine Citation:
PMID:  15591290     Owner:  NLM     Status:  MEDLINE    
Ventilatory acclimatization to hypoxia (VAH) consists of a progressive increase in ventilation and decrease in end-tidal Pco(2) (Pet(CO(2))). Underlying VAH, there are also increases in the acute ventilatory sensitivities to hypoxia and hypercapnia. To investigate whether these changes could be induced with very mild alterations in end-tidal Po(2) (Pet(O(2))), two 5-day exposures were compared: 1) mild hypoxia, with Pet(O(2)) held at 10 Torr below the subject's normal value; and 2) mild hyperoxia, with Pet(O(2)) held at 10 Torr above the subject's normal value. During both exposures, Pet(CO(2)) was uncontrolled. For each exposure, the entire protocol required measurements on 13 consecutive mornings: 3 mornings before the hypoxic or hyperoxic exposure, 5 mornings during the exposure, and 5 mornings postexposure. After the subjects breathed room air for at least 30 min, measurements were made of Pet(CO(2)), Pet(O(2)), and the acute ventilatory sensitivities to hypoxia and hypercapnia. Ten subjects completed both protocols. There was a significant increase in the acute ventilatory sensitivity to hypoxia (Gp) after exposure to mild hypoxia, and a significant decrease in Gp after exposure to mild hyperoxia (P < 0.05, repeated-measures ANOVA). No other variables were affected by mild hypoxia or hyperoxia. The results, when combined with those from other studies, suggest that Gp varies linearly with Pet(O(2)), with a sensitivity of 3.5%/Torr (SE 1.0). This sensitivity is sufficient to suggest that Gp is continuously varying in response to normal physiological fluctuations in Pet(O(2)). We conclude that at least some of the mechanisms underlying VAH may have a physiological role at sea level.
Simon Donoghue; Marzieh Fatemian; George M Balanos; Alexi Crosby; Chun Liu; David O'Connor; Nick P Talbot; Peter A Robbins
Publication Detail:
Type:  Comparative Study; Journal Article; Research Support, Non-U.S. Gov't     Date:  2004-12-10
Journal Detail:
Title:  Journal of applied physiology (Bethesda, Md. : 1985)     Volume:  98     ISSN:  8750-7587     ISO Abbreviation:  J. Appl. Physiol.     Publication Date:  2005 May 
Date Detail:
Created Date:  2005-04-14     Completed Date:  2005-08-18     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:  1587-91     Citation Subset:  IM    
University Laboratory of Physiology, Parks Rd., Oxford OX1 3PT, UK.
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MeSH Terms
Acclimatization / physiology*
Blood Gas Analysis
Carbon Dioxide / administration & dosage,  metabolism
Oxygen / administration & dosage,  metabolism*
Oxygen Consumption
Pulmonary Ventilation / drug effects,  physiology*
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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