Document Detail

Short-term modulation of the exercise ventilatory response in young men.
MedLine Citation:
PMID:  17991790     Owner:  NLM     Status:  MEDLINE    
Arterial isocapnia is a hallmark of moderate exercise in humans and is maintained even when resting arterial Pco(2) (Pa(CO(2))) is raised or lowered from its normal level, e.g., with chronic acid-base changes or acute increases in respiratory dead space. When resting ventilation and/or Pa(CO(2)) are altered, maintenance of isocapnia requires active adjustments of the exercise ventilatory response [slope of the ventilation (Ve)-CO(2) production (Vco(2)) relationship, DeltaVe/DeltaVco(2)]. On the basis of animal studies, it has been proposed that a central neural mechanism links the exercise ventilatory response to the resting ventilatory drive without need for changes in chemoreceptor feedback from rest to exercise, a mechanism referred to as short-term modulation (STM). We tested the hypothesis that STM is elicited by increased resting ventilatory drive associated with added external dead space (DS) in humans. Twelve young men were studied in control conditions and with added DS (200, 400, and 600 ml; randomized) at rest and during mild-to-moderate cycle exercise. DeltaVe/DeltaVco(2) increased progressively as DS volume increased (P < 0.0001). While resting end-tidal Pco(2) (Pet(CO(2))) increased with DS, the change in Pet(CO(2)) from rest to exercise was not increased, indicating that increased chemoreceptor feedback from rest to exercise cannot account for the greater exercise ventilatory response. We conclude that STM of the exercise ventilatory response is induced in young men when resting ventilatory drive is increased with external DS, confirming the existence of STM in humans.
Helen E Wood; Gordon S Mitchell; Tony G Babb
Publication Detail:
Type:  Journal Article; Randomized Controlled Trial; Research Support, Non-U.S. Gov't     Date:  2007-11-08
Journal Detail:
Title:  Journal of applied physiology (Bethesda, Md. : 1985)     Volume:  104     ISSN:  8750-7587     ISO Abbreviation:  J. Appl. Physiol.     Publication Date:  2008 Jan 
Date Detail:
Created Date:  2008-01-16     Completed Date:  2008-02-28     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:  244-52     Citation Subset:  IM    
Institute for Exercise and Environmental Medicine, Presbyterian Hospital of Dallas, and University of Texas Southwestern Medical Center-Dallas, Dallas, Texas 75231, USA.
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MeSH Terms
Adaptation, Physiological
Age Factors
Carbon Dioxide / blood
Hypercapnia / blood,  physiopathology*
Partial Pressure
Pulmonary Ventilation*
Research Design
Respiratory Dead Space*
Respiratory Mechanics
Time Factors
Reg. No./Substance:
124-38-9/Carbon Dioxide
Comment In:
J Appl Physiol (1985). 2008 Jul;105(1):390; author reply 391   [PMID:  18641232 ]

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