PHYSICAL-TRAINING INCREASES MUSCLE GLUT4 PROTEIN AND MESSENGER-RNA INPATIENTS WITH NIDDM

Patients with non-insulin-dependent diabetes mellitus (NIDDM) exhibit insulin resistance and decreased glucose transport in skeletal muscle. Total content of muscle GLUT4 protein is not affected by NIDDM, where as GLUT4 mRNA content is reported, variously, to be unaffected or incr eased. Physical training is recommended in the treatment of NIDDM, but the effect of training on muscle GLUT4 protein and mRNA content is un known. To clarify the effect of training in NIDDM, seven men with NIDD M (58 +/- 2 years of age [mean +/- SE]) and eight healthy men (59 +/- 1 years of age) (control group) performed one-legged ergometer bicycle training for 9 weeks, 6 days/ week, 30 min/day. Biopsies were obtaine d from the vastus lateralis leg muscle before and after training. GLUT 4 protein analyses was performed along with analyses of muscle biopsie s from five young (23 +/- 1 years of age) (young group), healthy subje cts who participated in a previously published identical study. in res ponse to training, maximal oxygen uptake increased (Delta 3.3 +/- 1.8 in NIDDM subjects and 4.5 +/- 1.2 ml . min(-1) . kg(-1) in control sub jects [both P < 0.05]). Before training, GLUT4 protein content was sim ilar in NIDDM, control, and young subjects (0.35 +/- 0.02, 0.34 +/- 0. 03, and 0.41 +/- 0.03 arbitrary units, respectively), and it increased (P < 0.05) in all groups during training (to 0.43 +/- 0.03, 0.40 +/- 0.03, and 0.57 +/- 0.08 arbitrary units, respectively). GLUT4 mRNA con tent was always lower in NIDDM compared with control subjects (P < 0.0 5) and increased in both groups (P < 0.05) during training (94 +/- 6 t o 122 +/- 8 and 151 +/- 5 to 170 +/- 4 arbitrary units/10 mu g total R NA, respectively). me conclude that muscle GLUT4 protein and mRNA incr ease in both NIDDM and control subjects in response to training. GLUT4 mRNA content is lower in NIDDM subjects compared with control subject s. GLUT4 protein content does not change with age.