Document Detail


Oxygen uptake kinetics at work onset: role of cardiac output and of phosphocreatine breakdown.
MedLine Citation:
PMID:  23043876     Owner:  NLM     Status:  Publisher    
Abstract/OtherAbstract:
The hypothesis that variability in individual's cardiac output response affects the kinetics of pulmonary O(2) uptake ( [Formula: see text] ) was tested by investigating the time constants of cardiac output (Q˙) adjustment (τ(Q)), of PCr splitting (τ(PCr)), and of phase II pulmonary O(2) uptake ( [Formula: see text] ) in eight volunteers. [Formula: see text] , Q˙, and gastrocnemius [PCr] (by (31)P-MRS) were measured at rest and during low intensity two-legged exercise. Steady state [Formula: see text] and Q˙ increased ( [Formula: see text] =182±58 mLmin(-1); ΔQ˙=1.3±0.4 Lmin(-1)), whereas [PCr] decreased significantly (21±8%). [Formula: see text] , τ(PCr) and τ(Q) were significantly different from each other (38.3±4.0, 23.9±2.5, 11.6±4.6 s, respectively; p<0.001). τ(PCr) assumed to be equal to the time constant of [Formula: see text] at the muscle level ( [Formula: see text] ), was not related to τ(Q), whereas [Formula: see text] and τ(Q) were significantly related (p<0.05) as were [Formula: see text] and τ(PCr) (p<0.05). Venous blood O(2) stores changes, as determined from arterio-to-mixed-venous O(2) content, were essentially equal to those estimated as ( [Formula: see text] -τ(PCr)) [Formula: see text] . This suggests that cardiac output responses affect O(2) stores utilization and hence [Formula: see text] : thus [Formula: see text] is not necessarily a good estimate of [Formula: see text] .
Authors:
M P Francescato; V Cettolo; P E di Prampero
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Publication Detail:
Type:  JOURNAL ARTICLE     Date:  2012-10-5
Journal Detail:
Title:  Respiratory physiology & neurobiology     Volume:  -     ISSN:  1878-1519     ISO Abbreviation:  Respir Physiol Neurobiol     Publication Date:  2012 Oct 
Date Detail:
Created Date:  2012-10-9     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  101140022     Medline TA:  Respir Physiol Neurobiol     Country:  -    
Other Details:
Languages:  ENG     Pagination:  -     Citation Subset:  -    
Copyright Information:
Copyright © 2012. Published by Elsevier B.V.
Affiliation:
Department of Medical and Biological Sciences, University of Udine, 33100 - UDINE, ITALY. Electronic address: maria.francescato@uniud.it.
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