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Early alterations in soleus GLUT-4, glucose transport, and glycogen in voluntary running rats.
- Source :
-
Journal of applied physiology (Bethesda, Md. : 1985) [J Appl Physiol (1985)] 1994 May; Vol. 76 (5), pp. 1862-7. - Publication Year :
- 1994
-
Abstract
- Voluntary 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 < 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.
- Subjects :
- Animals
Body Weight physiology
Female
Glucose Transporter Type 4
Hexokinase metabolism
Insulin pharmacology
Muscle Proteins metabolism
Muscles drug effects
Muscles enzymology
Organ Size physiology
Rats
Rats, Sprague-Dawley
Glucose metabolism
Glycogen metabolism
Monosaccharide Transport Proteins metabolism
Muscles metabolism
Physical Exertion physiology
Subjects
Details
- Language :
- English
- ISSN :
- 8750-7587
- Volume :
- 76
- Issue :
- 5
- Database :
- MEDLINE
- Journal :
- Journal of applied physiology (Bethesda, Md. : 1985)
- Publication Type :
- Academic Journal
- Accession number :
- 8063642
- Full Text :
- https://doi.org/10.1152/jappl.1994.76.5.1862