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Early alterations in soleus GLUT-4, glucose transport, and glycogen in voluntary running ratsVoluntary wheel running (WR) by juvenile female rats was used as a noninterventional model of soleus muscle functional overload to study the regulation of insulin-stimulated glucose transport activity by the glucose transporter (GLUT-4 isoform) protein level and glycogen concentration. Soleus total protein content was significantly greater (+18%;P greater than 0.05) than in age-matched controls after 1 wk of WR, and this hypertrophic response continued in weeks 2-4 (+24-32%). GLUT-4 protein was 39% greater than in controls in 1-wk WR soleus, and this adaptation was accompanied by a similar increase in in vitro insulin-stimulated glucose transport activity(+29%). After 2 and 4 wk of WR, however, insulin-stimulated glucose transport activity had returned to control levels, despite a continued elevation (+25-28%) of GLUT-4 protein. At these two time points, glycogen concentration was significantly enhanced in WR soleus (+21-42%), which coincided with significant reductions in glycogen synthase activity ratios (-23 to-41%). These results indicate that, in this model of soleus muscle functional overload, the GLUT-4 protein level may initially regulate insulin-stimulated glucose transport activity in the absence of changes in other modifying factors. However,this regulation of glucose transport activity by GLUT-4 protein may be subsequently overridden by elevated glycogen concentration.
Document ID
19950030916
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
Authors
Henriksen, Erik J.
(Univ. of Arizona, Tucson, AZ United States)
Halseth, Amy E.
(Univ. of Arizona, Tucson, AZ United States)
Date Acquired
August 16, 2013
Publication Date
May 1, 1994
Publication Information
Publication: Journal of Applied Physiology
Volume: 76
Issue: 5
ISSN: 8750-7587
Subject Category
Aerospace Medicine
Accession Number
95A62515
Funding Number(s)
CONTRACT_GRANT: NAG2-782
Distribution Limits
Public
Copyright
Other

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