Document Detail

Glycogen synthase activation in human skeletal muscle: effects of diet and exercise.
MedLine Citation:
PMID:  109015     Owner:  NLM     Status:  MEDLINE    
We investigated the role of glycogen synthase in supranormal resynthesis (supercompensation) of skeletal muscle glycogen after exhaustive exercise. Six healthy men exercised 60 min by cycling with one leg at 75% VO2max, recovered 3 days on a low-carbohydrate diet, exercised again, and recovered 4 days on high-carbohydrate diet. Glycogen and glycogen synthase activities at several glucose-6-phosphate (G6P) concentrations were measured in biopsy samples of m. vastus lateralis. Dietary alterations alone did not affect glycogen, whereas exercise depleted glycogen stores. After the second exercise bout, glycogen returned to normal within 24 h and reached supercompensated levels by 48 h of recovery. Glycogen synthase activation state strikingly increased after exercise in exercised muscle and remained somewhat elevated for the first 48 h of recovery in both muscles. We suggest that 1) forms of glycogen synthase intermediate to I (G6P-independent) and D (G6P-dependent) forms are present in vivo, and 2) glycogen supercompensation can in part be explained by the formation of intermediate forms of glycogen synthase that exhibit relatively low activity ratios, but an increased sensitivity to activation by G6P.
R G Kochan; D R Lamb; S A Lutz; C V Perrill; E M Reimann; K K Schlender
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Publication Detail:
Type:  Journal Article; Research Support, U.S. Gov't, P.H.S.    
Journal Detail:
Title:  The American journal of physiology     Volume:  236     ISSN:  0002-9513     ISO Abbreviation:  Am. J. Physiol.     Publication Date:  1979 Jun 
Date Detail:
Created Date:  1979-07-28     Completed Date:  1979-07-28     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:  E660-6     Citation Subset:  IM; S    
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MeSH Terms
Glucosephosphates / metabolism
Glycogen / metabolism
Glycogen Synthase / metabolism*
Muscles / enzymology*
Oxygen Consumption
Physical Exertion*
Reg. No./Substance:
0/Glucosephosphates; 9005-79-2/Glycogen; EC Synthase

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

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