Document Detail

Evidence of separate pathways for lactate uptake and release by the perfused rat heart.
MedLine Citation:
PMID:  11551857     Owner:  NLM     Status:  MEDLINE    
The simultaneous release and uptake of lactate by the heart has been observed both in vivo and ex vivo; however, the pathways underlying these observations have not been satisfactorily explained. Consequently, the purpose of this study was to test the hypothesis that hearts release lactate from glycolysis while simultaneously taking up exogenous lactate. Therefore, we determined the effects of fatty acids and diabetes on the regulation of lactate uptake and release. Hearts from control and 1-wk diabetic animals were perfused with 5 mM glucose, 0.5 mM [3-(13)C]lactate, and 0, 0.1, 0.32, or 1.0 mM palmitate. Parameters measured include perfusate lactate concentrations, fractional enrichment, and coronary flow rates, which enabled the simultaneous, but independent, measurements of the rates of 1) uptake of exogenous [(13)C]lactate and 2) efflux of unlabeled lactate from metabolism of glucose. Although the rates of lactate uptake and efflux were both similarly inhibited by the addition of palmitate, (i.e., the ratio of lactate uptake to efflux remained constant), the ratio of lactate uptake to efflux was significantly higher in the controls compared with the diabetic group (1.00 +/- 0.14 vs. 0.50 +/- 0.07, P < 0.002). These data, combined with heterogeneous (13)C enrichment of tissue lactate, pyruvate, and alanine, suggest that glycolytically derived lactate production and oxidation of exogenous lactate operate as functionally separate metabolic pathways. These results are consistent with the concept of an intracellular lactate shuttle.
J C Chatham; C Des Rosiers; J R Forder
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't; Research Support, U.S. Gov't, P.H.S.    
Journal Detail:
Title:  American journal of physiology. Endocrinology and metabolism     Volume:  281     ISSN:  0193-1849     ISO Abbreviation:  Am. J. Physiol. Endocrinol. Metab.     Publication Date:  2001 Oct 
Date Detail:
Created Date:  2001-09-11     Completed Date:  2001-10-18     Revised Date:  2007-11-14    
Medline Journal Info:
Nlm Unique ID:  100901226     Medline TA:  Am J Physiol Endocrinol Metab     Country:  United States    
Other Details:
Languages:  eng     Pagination:  E794-802     Citation Subset:  IM    
Division of Magnetic Resonance Research, Department of Radiology, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205, USA.
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MeSH Terms
Alanine / metabolism
Carbon Isotopes
Diabetes Mellitus, Experimental / metabolism*,  physiopathology
Glucose / metabolism
Heart / physiology*,  physiopathology
Lactates / metabolism*
Magnetic Resonance Spectroscopy
Models, Biological
Myocardial Contraction
Myocardium / metabolism*
Palmitic Acid / metabolism
Pyruvates / metabolism
Rats, Sprague-Dawley
Reference Values
Grant Support
Reg. No./Substance:
0/Carbon Isotopes; 0/Lactates; 0/Pyruvates; 50-99-7/Glucose; 56-41-7/Alanine; 57-10-3/Palmitic Acid

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