Effect of immobilization on glucose transporter expression in rat hindlimb muscles.
Three days after denervation, the expression of GLUT4 mRNA and protein decreases by approximately 50% in rat hindlimb muscles, while GLUT1 mRNA increases transiently by approximately 500%. Although postreceptor insulin resistance of glucose transport develops before GLUT4 declines, the latter likely contributes to the time-dependent increased severity of the resistance. To determine whether muscle inactivity contributes to changes in glucose transporter expression, one rat hindlimb was immobilized in a plaster cast for 3 days; the unencumbered hindlimb served as control. Muscle GLUT4 mRNA decreased by 32% (P < .02) and GLUT4 protein by 40% (P < .05) after 3 days' immobilization. There was no significant change in GLUT1 mRNA or skeletal muscle alpha-actin mRNA expression or in the total RNA concentration. The data suggest that electromyogenic and/or contractile activity regulates GLUT4 expression in skeletal muscle at a pretranslational step.
Didyk
R B
RB
Department of Medicine, Medical University of South Carolina, Charleston 29425.
Anton
E E
EE
Robinson
K A
KA
Menick
D R
DR
Buse
M G
MG
D000199:Actins / Q000378:metabolism; D000818:Animals; D015152:Blotting, Northern; D003714:Denervation; D051275:Glucose Transporter Type 4; D006614:Hindlimb / Q000294:innervation / Q000378:metabolism / Q000503:physiopathology; D007103:Immobilization; D015151:Immunoblotting; D008297:Male; D009004:Monosaccharide Transport Proteins / Q000378:metabolism*; D009124:Muscle Proteins; D018482:Muscle, Skeletal / Q000294:innervation / Q000378:metabolism* / Q000503:physiopathology; D012333:RNA, Messenger / Q000096:biosynthesis*; D051381:Rats; D017208:Rats, Wistar
D000199:Actins; D051275:Glucose Transporter Type 4; D009004:Monosaccharide Transport Proteins; D009124:Muscle Proteins; D012333:RNA, Messenger; C495694:Slc2a4 protein, rat