| Pyruvate shuttling during rest and exercise before and after endurance training in men. | |
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MedLine Citation:
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PMID: 14990548 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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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. |
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Authors:
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Gregory C Henderson; Michael A Horning; Steven L Lehman; Eugene E Wolfel; Bryan C Bergman; George A Brooks |
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Publication Detail:
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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:
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Title: Journal of applied physiology (Bethesda, Md. : 1985) Volume: 97 ISSN: 8750-7587 ISO Abbreviation: J. Appl. Physiol. Publication Date: 2004 Jul |
Date Detail:
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Created Date: 2004-06-28 Completed Date: 2004-12-20 Revised Date: 2007-11-15 |
Medline Journal Info:
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Nlm Unique ID: 8502536 Medline TA: J Appl Physiol Country: United States |
Other Details:
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Languages: eng Pagination: 317-25 Citation Subset: IM |
Affiliation:
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Department of Integrative Biology, University of California, Berkeley, CA 94720-3140, USA. |
Export Citation:
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APA/MLA Format Download EndNote Download BibTex |
| MeSH Terms | |
Descriptor/Qualifier:
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Adult Alanine / blood Anaerobic Threshold / physiology Body Composition / physiology Carbohydrate Metabolism Exercise / physiology* Exercise Test Femoral Artery / metabolism Femoral Vein / metabolism Gas Chromatography-Mass Spectrometry Glycolysis Hemodynamics / physiology Humans Lactic Acid / metabolism Male Muscle, Skeletal / metabolism, physiology Physical Endurance / physiology* Physical Fitness / physiology* Pyruvic Acid / metabolism* Rest / physiology* |
| Grant Support | |
ID/Acronym/Agency:
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AR-42906/AR/NIAMS NIH HHS |
| Chemical | |
Reg. No./Substance:
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127-17-3/Pyruvic Acid; 50-21-5/Lactic Acid; 56-41-7/Alanine |
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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