Document Detail

Regulation of GLUT4 protein and glycogen synthase during muscle glycogen synthesis after exercise.
MedLine Citation:
PMID:  9578375     Owner:  NLM     Status:  MEDLINE    
The pattern of muscle glycogen synthesis following its depletion by exercise is biphasic. Initially, there is a rapid, insulin independent increase in the muscle glycogen stores. This is then followed by a slower insulin dependent rate of synthesis. Contributing to the rapid phase of glycogen synthesis is an increase in muscle cell membrane permeability to glucose, which serves to increase the intracellular concentration of glucose-6-phosphate (G6P) and activate glycogen synthase. Stimulation of glucose transport by muscle contraction as well as insulin is largely mediated by translocation of the glucose transporter isoform GLUT4 from intracellular sites to the plasma membrane. Thus, the increase in membrane permeability to glucose following exercise most likely reflects an increase in GLUT4 protein associated with the plasma membrane. This insulin-like effect on muscle glucose transport induced by muscle contraction, however, reverses rapidly after exercise is stopped. As this direct effect on transport is lost, it is replaced by a marked increase in the sensitivity of muscle glucose transport and glycogen synthesis to insulin. Thus, the second phase of glycogen synthesis appears to be related to an increased muscle insulin sensitivity. Although the cellular modifications responsible for the increase in insulin sensitivity are unknown, it apparently helps maintain an increased number of GLUT4 transporters associated with the plasma membrane once the contraction-stimulated effect on translocation has reversed. It is also possible that an increase in GLUT4 protein expression plays a role during the insulin dependent phase.
J L Ivy; C H Kuo
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't; Review    
Journal Detail:
Title:  Acta physiologica Scandinavica     Volume:  162     ISSN:  0001-6772     ISO Abbreviation:  Acta Physiol. Scand.     Publication Date:  1998 Mar 
Date Detail:
Created Date:  1998-06-15     Completed Date:  1998-06-15     Revised Date:  2008-11-21    
Medline Journal Info:
Nlm Unique ID:  0370362     Medline TA:  Acta Physiol Scand     Country:  ENGLAND    
Other Details:
Languages:  eng     Pagination:  295-304     Citation Subset:  IM; S    
Department of Kinesiology, The University of Texas at Austin, 78712, USA.
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MeSH Terms
Glucose Transporter Type 4
Glycogen / biosynthesis*
Glycogen Synthase / metabolism*
Monosaccharide Transport Proteins / metabolism*
Muscle Proteins*
Muscle, Skeletal / chemistry,  enzymology*
Physical Exertion / physiology*
Reg. No./Substance:
0/Glucose Transporter Type 4; 0/Monosaccharide Transport Proteins; 0/Muscle Proteins; 0/SLC2A4 protein, human; 9005-79-2/Glycogen; EC Synthase

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