Document Detail


Anaplerosis of the tricarboxylic acid cycle in human skeletal muscle during exercise. Magnitude, sources, and potential physiological significance.
MedLine Citation:
PMID:  9781333     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
In comparison to cardiac tissue, relatively few data are available regarding the concentrations of tricarboxylic acid cycle intermediates (TCAI) and the potential influence of TCAI pool size on the regulation of cycle flux in mammalian skeletal muscle. However, recent human exercise studies have confirmed the fundamental observation made in electrically-stimulated rodent muscle that moderate to intense contraction results in a net accumulation of TCAI. The increase in TCAI pool size, termed "anaplerosis," appears exponentially related to work intensity, although the relative changes in the individual cycle intermediates differ markedly. While a number of mechanisms could potentially contribute to the increase in TCAI, the reaction catalyzed by alanine aminotransferase appears primarily responsible for anaplerosis at the onset of exercise in humans. The expansion of the TCAI pool has been suggested to be important for aerobic energy provision, and various theories have been proposed which link the total concentration of TCAI with the capacity for TCA cycle flux during exercise. However, despite the recent advances which have been made with regard to the magnitude and potential source of TCAI expansion in humans, our understanding of the physiological significance of anaplerosis is limited. Indeed, it remains speculative whether the increase in TCAI pool size represents an important regulatory signal or is simply a consequence of the huge increase in metabolic flux which occurs during exercise.
Authors:
T E Graham; M J Gibala
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't; Review    
Journal Detail:
Title:  Advances in experimental medicine and biology     Volume:  441     ISSN:  0065-2598     ISO Abbreviation:  Adv. Exp. Med. Biol.     Publication Date:  1998  
Date Detail:
Created Date:  1998-12-01     Completed Date:  1998-12-01     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  0121103     Medline TA:  Adv Exp Med Biol     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  271-86     Citation Subset:  IM    
Affiliation:
Department of Human Biology and Nutritional Sciences, University of Guelph, Ontario, Canada.
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MeSH Terms
Descriptor/Qualifier:
Exercise*
Humans
Muscle, Skeletal / metabolism*
Tricarboxylic Acids / metabolism*
Chemical
Reg. No./Substance:
0/Tricarboxylic Acids

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