RECIPROCAL GLUT-1 AND GLUT-4 EXPRESSION AND GLUCOSE-TRANSPORT IN DENERVATED MUSCLES

We investigated in S-day-denervated muscles 1) the expression of GLUT- 1 in perineurial sheaths (PNS) and muscle, 2) the muscle fiber-specifi c changes in GLUT-1 and GLUT-4, and 3) changes in basal and insulin-st imulated 3-O-methylglucose transport. GLUT-1 was increased in both the PNS (P < 0.05) and in the muscle membranes (P < 0.05). GLUT-1 and GLU T-4 concentrations were changed reciprocally, in a fiber-dependent fas hion [GLUT-1: red gastrocnemius (RG), +31%; white gastrocnemius (WG), +10%; GLUT-4: RG, -53%; WG, -16%]. Basal glucose transport was increas ed (P < 0.05), and this increase was correlated with the oxidative nat ure of the muscles (r = 0.97). Insulin-stimulated glucose transport wa s decreased in denervated muscles (P < 0.05). This was also related to the oxidative nature of the muscles (r = -0.88). The increase in basa l glucose transport was correlated with the loss of insulin-stimulated transport (r = 0.95). Thus the increase in GLUT-1 compensates for the loss of GLUT-4, resulting in a 56% regain of the reduced insulin-stim ulated glucose transport.