Document Detail

Dynamics of the ventilatory response to step changes in end-tidal PCO2 in older humans.
MedLine Citation:
PMID:  9263620     Owner:  NLM     Status:  MEDLINE    
The purpose of this study was to examine the ventilatory response to carbon dioxide (CO2) in young and older men. Six square-wave steps of end-tidal CO2 (PETCO2) were administered in euoxia (PETO2 = 100 torr), hyperoxia (PETO2 = 500 torr), and mild hypoxia (PETO2 = 60 torr). The peripheral and central chemoreflex loops were described by three parameters including a gain (gp and gc), time constant of the response (tau p, tau c), and a time delay (Tp, Tc), respectively. The young and older men showed similar characteristics for Tp and Tc, with Tp being 3 to 5 s shorter than Tc. In hypoxia, the ventilatory responses of the old group were characterised by a significantly smaller gc and a smaller gp. In hypoxia, tau c was significantly shortened from its euoxic value in the young group, but not in the old group. Thus, this study demonstrated that in older men, the ventilatory responses to CO2 in euoxia and hyperoxia are similar to younger men, while in hypoxia the ventilatory responses are characterised by smaller gain terms.
M J Poulin; D A Cunningham; D H Paterson
Publication Detail:
Type:  Comparative Study; Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Canadian journal of applied physiology = Revue canadienne de physiologie appliquée     Volume:  22     ISSN:  1066-7814     ISO Abbreviation:  Can J Appl Physiol     Publication Date:  1997 Aug 
Date Detail:
Created Date:  1997-10-06     Completed Date:  1997-10-06     Revised Date:  2008-11-21    
Medline Journal Info:
Nlm Unique ID:  9306274     Medline TA:  Can J Appl Physiol     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  368-83     Citation Subset:  IM; S    
University Laboratory of Physiology, Oxford, United Kingdom.
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MeSH Terms
Aged, 80 and over
Aging / physiology*
Chemoreceptor Cells / physiology
Exercise Test
Hypercapnia / physiopathology
Respiratory Function Tests
Respiratory Mechanics*

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