Document Detail


Rapid activation of glycogen synthase and protein phosphatase in human skeletal muscle after isometric contraction requires an intact circulation.
MedLine Citation:
PMID:  9026787     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
The effects of isometric contraction (66% of maximal force) and recovery on glycogen synthase fractional activity (GSF) in human skeletal muscle have been studied. Biopsies were taken from the quadriceps femoris muscle at rest, at fatigue and 5 min postexercise on two occasions: after one of the contractions, the circulation to the thigh was occluded during the 5 min recovery (OCC), and after the other contraction, the circulation was intact (control, CON). During CON, GSF decreased from (mean +/- SE) 0.34 +/- 0.05 at rest to 0.24 +/- 0.02 at fatigue and then increased to 0.74 +/- 0.04 at 5 min postexercise; corresponding values for OCC were 0.37 +/- 0.04, 0.25 +/- 0.04 and 0.48 +/- 0.05 (P < 0.001 vs. CON for 5 min postexercise only). Compared with the value at fatigue, protein phosphatase activity (PP) increased by 79 +/- 16% during CON recovery (P < 0.01), whereas no change was observed during OCC recovery. Uridine diphosphate glucose increased by approximately 2.5-fold at fatigue, remained elevated during OCC recovery, but reverted to the preexercise level during CON recovery (P < 0.001 vs. OCC recovery). Glucose 6-P increased approximately 5-fold at fatigue and was higher at 5 min postexercise in OCC vs. CON recovery (8.6 +/- 1.5 vs. 4.1 +/- 0.9 mmol/kg dry wt; P < 0.01). It is concluded that the rapid increase in GSF after intense exercise with an intact circulation may be at least partly attributed to an increase in the specific activity of PP. The increase in GSF during recovery in OCC may be at least partly attributed to the high glucose 6-P content in vivo, which enhances the substrate suitability of GS for PP. Thus, separate mechanisms exist for the activation of PP and GS during recovery from intense short term exercise.
Authors:
A Katz; I Raz
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Publication Detail:
Type:  Clinical Trial; Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Pflügers Archiv : European journal of physiology     Volume:  431     ISSN:  0031-6768     ISO Abbreviation:  Pflugers Arch.     Publication Date:  1995 Dec 
Date Detail:
Created Date:  1997-02-18     Completed Date:  1997-02-18     Revised Date:  2007-11-15    
Medline Journal Info:
Nlm Unique ID:  0154720     Medline TA:  Pflugers Arch     Country:  GERMANY    
Other Details:
Languages:  eng     Pagination:  259-65     Citation Subset:  IM    
Affiliation:
Division of Clinical Physiology, Karolinska Hospital, Stockholm, Sweden.
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MeSH Terms
Descriptor/Qualifier:
Adult
Enzyme Activation / physiology
Exercise / physiology
Female
Glucosephosphates / metabolism
Glycogen Synthase / metabolism*
Humans
Isometric Contraction / physiology*
Male
Muscle Fatigue / physiology
Muscle, Skeletal / blood supply*,  enzymology*
Phosphoprotein Phosphatases / metabolism*
Regional Blood Flow / physiology
Uridine Diphosphate Glucose / metabolism
Chemical
Reg. No./Substance:
0/Glucosephosphates; 133-89-1/Uridine Diphosphate Glucose; EC 2.4.1.11/Glycogen Synthase; EC 3.1.3.16/Phosphoprotein Phosphatases

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