Document Detail

In vivo exercise followed by in vitro contraction additively elevates subsequent insulin-stimulated glucose transport by rat skeletal muscle.
MedLine Citation:
PMID:  20179245     Owner:  NLM     Status:  MEDLINE    
The cellular mechanisms whereby prior exercise enhances insulin-stimulated glucose transport (GT) are not well understood. Previous studies suggested that a prolonged increase in phosphorylation of Akt substrate of 160 kDa (AS160) may be important for the postexercise increase in insulin sensitivity. In the current study, the effects of in vivo exercise and in vitro contraction on subsequent insulin-stimulated GT were studied separately and together. Consistent with results from previous studies, prior exercise resulted in an increase in AS160 (642)Thr phosphorylation immediately after exercise in rat epitrochlearis muscles, and this increase remained 3 h postexercise concomitant with enhanced insulin-stimulated GT. For experiments with in vitro contraction, isolated rat epitrochlearis muscles were electrically stimulated to contract in the presence or absence of rat serum. As expected, insulin-stimulated GT measured 3 h after electrical stimulation in serum, but not after electrical stimulation without serum, exceeded resting controls. Immediately after electrical stimulation with or without serum, phosphorylation of both AS160 (detected by phospho-Akt substrate, PAS, antibody, or phospho-(642)Thr antibody) and its paralog TBC1D1 (detected by phospho-(237)Ser antibody) was increased. However, both AS160 and TBC1D1 phosphorylation had reversed to resting values at 3 h poststimulation with or without serum. Increasing the amount of exercise (from 1 to 2 h) or electrical stimulation (from 5 to 10 tetani) did not further elevate insulin-stimulated GT. In contrast, the combination of prior exercise and electrical stimulation had an additive effect on the subsequent increase in insulin-stimulated GT, suggesting that these exercise and electrical stimulation protocols may amplify insulin-stimulated GT through distinct mechanisms, with a persistent increase in AS160 phosphorylation potentially important for increased insulin sensitivity after exercise, but not after in vitro contraction.
Katsuhiko Funai; George G Schweitzer; Carlos M Castorena; Makoto Kanzaki; Gregory D Cartee
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Publication Detail:
Type:  Journal Article; Research Support, N.I.H., Extramural     Date:  2010-02-23
Journal Detail:
Title:  American journal of physiology. Endocrinology and metabolism     Volume:  298     ISSN:  1522-1555     ISO Abbreviation:  Am. J. Physiol. Endocrinol. Metab.     Publication Date:  2010 May 
Date Detail:
Created Date:  2010-04-14     Completed Date:  2010-05-03     Revised Date:  2014-10-11    
Medline Journal Info:
Nlm Unique ID:  100901226     Medline TA:  Am J Physiol Endocrinol Metab     Country:  United States    
Other Details:
Languages:  eng     Pagination:  E999-1010     Citation Subset:  IM    
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MeSH Terms
Analysis of Variance
Biological Transport / physiology
Blotting, Western
Electric Stimulation
GTPase-Activating Proteins / metabolism
Glucose / metabolism*
Glucose Transporter Type 4 / metabolism
Glycogen / analysis
Insulin / administration & dosage*,  metabolism
Muscle Contraction / physiology*
Muscle, Skeletal / chemistry,  drug effects,  metabolism*
Physical Exertion / physiology*
Rats, Wistar
Time Factors
Grant Support
Reg. No./Substance:
0/GTPase-Activating Proteins; 0/Glucose Transporter Type 4; 0/Insulin; 0/LOC686547 protein, rat; 0/Slc2a4 protein, rat; 9005-79-2/Glycogen; IY9XDZ35W2/Glucose

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