Document Detail

Tricarboxylic acid cycle intermediates in human muscle at rest and during prolonged cycling.
MedLine Citation:
PMID:  9124329     Owner:  NLM     Status:  MEDLINE    
Previous studies have used the muscle concentration of citrate + malate + fumarate to estimate tricarboxylic acid (TCA) cycle pool size in humans [e.g., Am. J. Physiol. 259 (Cell Physiol. 28): C834-C841, 1990]. Our purpose was to quantify changes in individual TCA cycle intermediates (TCAI) and total pool size by measuring the concentrations of the eight TCAI in human muscle. Eight males cycled to exhaustion (Exh) at approximately 70% of their maximal oxygen uptake, and biopsies were obtained from the vastus lateralis at rest and during exercise. Succinyl-CoA was not consistently detectable, but the sum of the other seven TCAI was 1.23 +/- 0.04 mmol/kg dry wt at rest, 4.80 +/- 0.25 and 4.87 +/- 0.30 mmol/kg after 5 and 15 min of exercise, respectively, and 3.08 +/- 0.15 mmol/kg at Exh. Pool size during exercise was approximately 50% higher than that seen in rodent muscle after intense electrical stimulation (Eur. J. Biochem. 110: 371-377, 1980). Relative changes in individual TCAI were not uniform, and no one intermediate was "representative" of the changes in total pool size. We conclude that changes in specific intermediates or total pool size cannot be used as indicators of cycle flux and that the apparent species differences in total pool size may reflect differences in fiber type composition, recruitment pattern, or relative intensity of contraction.
M J Gibala; M A Tarnopolsky; T E Graham
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  The American journal of physiology     Volume:  272     ISSN:  0002-9513     ISO Abbreviation:  Am. J. Physiol.     Publication Date:  1997 Feb 
Date Detail:
Created Date:  1997-04-24     Completed Date:  1997-04-24     Revised Date:  2008-11-21    
Medline Journal Info:
Nlm Unique ID:  0370511     Medline TA:  Am J Physiol     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  E239-44     Citation Subset:  IM; S    
Department of Human Biology and Nutritional Sciences, University of Guelph, Ontario, Canada.
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MeSH Terms
Blood / metabolism
Citric Acid Cycle*
Heart / physiology
Muscle, Skeletal / metabolism*
Physical Exertion*
Time Factors

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