Transient enhancement of GLUT-4 levels in rat epitrochlearis muscle after exercise training.
The purpose of the present study was to examine the effect of detraining on the glucose transport system after short-term swim training (5 days), long-term swim training (5 wk), and treadmill run training (5 wk). Skeletal muscles were isolated from female Wistar rats at 24 or 48 h posttraining. SST produces a 48% increase in GLUT-4 mRNA, a 30% increase in GLUT-4 protein, and a 60% increase in insulin-stimulated glucose transport activity at 24 h posttraining but not at 48 h posttraining. Similar to SST, long-term swim training produces a 60% increase in GLUT-4 mRNA and a 30% increase in GLUT-4 protein content at 24 h posttraining but not at 48 h posttraining. Finally, treadmill run training produces a transient 35% increase in GLUT-4 protein content that is completely reversed at 48 h after the last bout of exercise. These results demonstrate that the increase in GLUT-4 mRNA and GLUT-4 protein occurs during the first week of exercise training and is rapidly lost after training cessation. We believe that the transient enhancement in GLUT-4 protein after exercise training is due to a short GLUT-4 half-life, a process that is primarily regulated by pretranslational mechanisms.
Reynolds
T H
TH
Diabetes Branch, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892, USA. threynol@umich.edu
Brozinick
J T
JT
Larkin
L M
LM
Cushman
S W
SW
D000818:Animals; D001692:Biological Transport; D001835:Body Weight; D002950:Citrate (si)-Synthase / Q000378:metabolism; D005260:Female; D005552:Forelimb; D005947:Glucose / Q000378:metabolism; D051275:Glucose Transporter Type 4; D006003:Glycogen / Q000378:metabolism; D007328:Insulin / Q000494:pharmacology; D009004:Monosaccharide Transport Proteins / Q000235:genetics / Q000378:metabolism*; D009043:Motor Activity / Q000502:physiology; D009124:Muscle Proteins; D018482:Muscle, Skeletal / Q000378:metabolism*; D010805:Physical Conditioning, Animal / Q000502:physiology*; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D013550:Swimming / Q000502:physiology; D013997:Time Factors
D051275:Glucose Transporter Type 4; D007328:Insulin; D009004:Monosaccharide Transport Proteins; D009124:Muscle Proteins; D012333:RNA, Messenger; C495694:Slc2a4 protein, rat; D006003:Glycogen; D002950:Citrate (si)-Synthase; D005947:Glucose