Document Detail

Pyruvate shuttling during rest and exercise before and after endurance training in men.
MedLine Citation:
PMID:  14990548     Owner:  NLM     Status:  MEDLINE    
We describe the isotopic exchange of lactate and pyruvate after arm vein infusion of [3-(13)C]lactate in men during rest and exercise. We tested the hypothesis that working muscle (limb net lactate and pyruvate exchange) is the source of the elevated systemic lactate-to-pyruvate concentration ratio (L/P) during exercise. We also hypothesized that the isotopic equilibration between lactate and pyruvate would decrease in arterial blood as glycolytic flux, as determined by relative exercise intensity, increased. Nine men were studied at rest and during exercise before and after 9 wk of endurance training. Although during exercise arterial pyruvate concentration decreased to below rest values (P < 0.05), pyruvate net release from working muscle was as large as lactate net release under all exercise conditions. Exogenous (arterial) lactate was the predominant origin of pyruvate released from working muscle. With no significant effect of exercise intensity or training, arterial isotopic equilibration [(IE(pyruvate)/IE(lactate)).100%, where IE is isotopic enrichment] decreased significantly (P < 0.05) from 60 +/- 3.1% at rest to an average value of 12 +/- 2.7% during exercise, and there were no changes in femoral venous isotopic equilibration. These data show that 1). the isotopic equilibration between lactate and pyruvate in arterial blood decreases significantly during exercise; 2). working muscle is not solely responsible for the decreased arterial isotopic equilibration or elevated arterial L/P occurring during exercise; 3). working muscle releases similar amounts of lactate and pyruvate, the predominant source of the latter being arterial lactate; 4). pyruvate clearance from blood occurs extensively outside of working muscle; and 5). working muscle also releases alanine, but alanine release is an order of magnitude smaller than lactate or pyruvate release. These results portray the complexity of metabolic integration among diverse tissue beds in vivo.
Gregory C Henderson; Michael A Horning; Steven L Lehman; Eugene E Wolfel; Bryan C Bergman; George A Brooks
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Publication Detail:
Type:  Clinical Trial; Journal Article; Research Support, Non-U.S. Gov't; Research Support, U.S. Gov't, P.H.S.     Date:  2004-02-27
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:  317-25     Citation Subset:  IM    
Department of Integrative Biology, University of California, Berkeley, CA 94720-3140, USA.
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MeSH Terms
Alanine / blood
Anaerobic Threshold / physiology
Body Composition / physiology
Carbohydrate Metabolism
Exercise / physiology*
Exercise Test
Femoral Artery / metabolism
Femoral Vein / metabolism
Gas Chromatography-Mass Spectrometry
Hemodynamics / physiology
Lactic Acid / metabolism
Muscle, Skeletal / metabolism,  physiology
Physical Endurance / physiology*
Physical Fitness / physiology*
Pyruvic Acid / metabolism*
Rest / physiology*
Grant Support
Reg. No./Substance:
127-17-3/Pyruvic Acid; 50-21-5/Lactic Acid; 56-41-7/Alanine

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