Document Detail

Metabolic regulation in peripheral tissues and transition to increased gluconeogenic mode during prolonged exercise.
MedLine Citation:
PMID:  1514617     Owner:  NLM     Status:  MEDLINE    
To assess the means by which peripheral metabolism facilitates the transition to a gluconeogenic state, dogs were studied during 150 min of moderate treadmill exercise. Metabolism in the working hindlimb was assessed with arteriovenous difference and isotopic techniques (n = 9). In a separate group (n = 6), hepatic metabolism was assessed using arteriovenous differences. Limb glucose uptake (LGU) and oxidation (GOX) rose from 33 +/- 10 and 5 +/- 2 to 101 +/- 20 and 54 +/- 15 mumol/min at 10 min of exercise. LGU continued to rise (151 +/- 21 mumol/min at 150 min), while GOX declined. Nonoxidative glucose metabolism (GNOX) was 28 +/- 10 mumol/min at rest and 47 +/- 24 and 108 +/- 16 mumol/min at 10 and 150 min of exercise. Limb nonglycemic (predominantly glycogen) pyruvate formation rose from 52 +/- 22 to 198 +/- 54 and 242 +/- 74 mumol/min at 10 and 150 min of exercise. The gradual increase in GNOX and the high glycogenolytic rate were paralleled by accelerated lactate, pyruvate, and glutamine releases. Limb glycerol release rose promptly and remained elevated during exercise. Plasma nonesterified fatty acids (NEFAs) rose gradually and paralleled the gradual rise in GNOX (r = 0.93). The resulting rise in hepatic NEFA delivery was highly correlated to hepatic O2 uptake (r = 0.87), hepatic vein lactate-to-pyruvate ratio (r = 0.90), and intrahepatic gluconeogenic efficiency (r = 0.96). In summary, during exercise, 1) the primary fate of the added glucose consumed by the working limb is initially oxidation, but becomes GNOX as exercise duration progresses; 2) glycogenolysis rises promptly, but attains its highest rate at the end of exercise; 3) the late increases in GNOX and glycogenolysis relate to an increased gluconeogenic precursor release from the working limb; 4) although lipolysis increases promptly and is sustained, circulating NEFAs rise only gradually; and 5) the gradual rise in plasma NEFAs is highly correlated to the shift from GOX to GNOX and the adjustments in hepatic metabolism that are necessary for the full gluconeogenic response.
D H Wasserman; D B Lacy; D Bracy; P E Williams
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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:  The American journal of physiology     Volume:  263     ISSN:  0002-9513     ISO Abbreviation:  Am. J. Physiol.     Publication Date:  1992 Aug 
Date Detail:
Created Date:  1992-09-25     Completed Date:  1992-09-25     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:  E345-54     Citation Subset:  IM    
Department of Molecular Physiology, Vanderbilt University School of Medicine, Nashville, Tennessee 37232.
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MeSH Terms
Amino Acids / metabolism
Biological Availability
Blood Glucose / analysis
Carbon Dioxide / metabolism
Fatty Acids, Nonesterified / pharmacokinetics
Glucose / biosynthesis*
Hindlimb / blood supply,  metabolism
Lactates / metabolism
Lactic Acid
Lipid Metabolism
Liver / metabolism
Oxygen / metabolism
Physical Exertion*
Pyruvates / metabolism
Time Factors
Grant Support
Reg. No./Substance:
0/Amino Acids; 0/Blood Glucose; 0/Fatty Acids, Nonesterified; 0/Lactates; 0/Pyruvates; 124-38-9/Carbon Dioxide; 50-21-5/Lactic Acid; 50-99-7/Glucose; 7782-44-7/Oxygen

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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