Document Detail

Human muscle sarcoplasmic reticulum function during submaximal exercise in normoxia and hypoxia.
MedLine Citation:
PMID:  15220318     Owner:  NLM     Status:  MEDLINE    
In this study, the response of the sarcoplasmic reticulum (SR) to prolonged exercise, performed in normoxia (inspired O(2) fraction = 0.21) and hypoxia (inspired O(2) fraction = 0.14) was studied in homogenates prepared from the vastus lateralis muscle in 10 untrained men (peak O(2) consumption = 3.09 +/- 0.25 l/min). In normoxia, performed at 48 +/- 2.2% peak O(2) consumption, maximal Ca(2+)-dependent ATPase activity was reduced by approximately 25% at 30 min of exercise compared with rest (168 +/- 10 vs. 126 +/- 8 micromol.g protein(-1) x min(-1)), with no further reductions observed at 90 min (129 +/- 6 micromol x g protein(-1) x min(-1)). No changes were observed in the Hill coefficient or in the Ca(2+) concentration at half-maximal activity. The reduction in maximal Ca(2+)-dependent ATPase activity at 30 min of exercise was accompanied by oxalate-dependent reductions (P < 0.05) in Ca(2+) uptake by approximately 20% (370 +/- 22 vs. 298 +/- 25 micromol x g protein(-1) x min(-1)). Ca(2+) release, induced by 4-chloro-m-cresol and assessed into fast and slow phases, was decreased (P < 0.05) by approximately 16 and approximately 32%, respectively, by 90 min of exercise. No differences were found between normoxia and hypoxia for any of the SR properties examined. It is concluded that the disturbances induced in SR Ca(2+) cycling with prolonged moderate-intensity exercise in human muscle during normoxia are not modified when the exercise is performed in hypoxia.
T A Duhamel; H J Green; J G Perco; S D Sandiford; J Ouyang
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Publication Detail:
Type:  Clinical Trial; Journal Article; Randomized Controlled Trial; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Journal of applied physiology (Bethesda, Md. : 1985)     Volume:  97     ISSN:  8750-7587     ISO Abbreviation:  J. Appl. Physiol.     Publication Date:  2004 Jul 
Date Detail:
Created Date:  2004-06-28     Completed Date:  2004-12-20     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:  180-7     Citation Subset:  IM    
Department of Kinesiology, University of Waterloo, Waterloo, Ontario, Canada N2L 3G1.
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MeSH Terms
Anoxia / physiopathology*
Bicycling / physiology
Calcium / metabolism
Calcium Signaling / physiology
Calcium-Transporting ATPases / metabolism
Cross-Over Studies
Exercise / physiology*
Exercise Test
Muscle, Skeletal / enzymology,  physiology*
Pulmonary Gas Exchange
Sarcoplasmic Reticulum / enzymology,  physiology*
Reg. No./Substance:
7440-70-2/Calcium; EC ATPases

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

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