Effect of denervation on the expression of two glucose transporter isoforms in rat hindlimb muscle.
Denervation rapidly (within 24 h) induces insulin resistance of several insulin-responsive pathways in skeletal muscle, including glucose transport; resistance is usually maximal by 3 d. We examined the effect of denervation on the expression of two glucose transporter isoforms (GLUT-1 and GLUT-4) in rat hindlimb muscle; GLUT-4 is the predominant species in muscle. 1 d postdenervation, GLUT-1 and GLUT-4 mRNA and protein concentrations were unchanged. 3 and 7 d postdenervation, GLUT-4 mRNA and protein (per microgram DNA) were decreased by 50%. The minor isoform, GLUT-1 mRNA increased by approximately 500 and approximately 100%, respectively, on days 3 and 7 while GLUT-1 protein increased by approximately 60 and approximately 100%. The data suggest that the insulin resistance of glucose transport early after denervation does not reflect a decrease in total glucose transporter number; however, decreased GLUT-4 expression may contribute to its increased severity after 3 d. Parallel decreases in GLUT-4 mRNA and GLUT-4 protein postdenervation are consistent with pretranslational regulation; GLUT-1 expression may be regulated pre- and posttranslationally. The cell type(s) which overexpress GLUT-1 postdenervation need to be identified. Nervous stimuli and/or contractile activity may modulate the expression of GLUT-1 and GLUT-4 in skeletal muscle tissue.
Block
N E
NE
Division of Endocrinology, Metabolism and Nutrition, Gazes Cardiac Research Institute, Medical University of South Carolina, Charleston 29425.
Menick
D R
DR
Robinson
K A
KA
Buse
M G
MG
D000818:Animals; D006614:Hindlimb; D015151:Immunoblotting; D008297:Male; D009004:Monosaccharide Transport Proteins / Q000032:analysis* / Q000235:genetics; D009121:Muscle Denervation; D009132:Muscles / Q000737:chemistry*; D012333:RNA, Messenger / Q000032:analysis; D051381:Rats; D011919:Rats, Inbred Strains
D009004:Monosaccharide Transport Proteins; D012333:RNA, Messenger