AJP - Endocrinology and Metabolism, Vol 264, Issue 6 E882-E889, Copyright © 1993 by American Physiological Society

ARTICLES

Exercise training increases GLUT-4 protein in rat adipose cells

M. F. Hirshman, L. J. Goodyear, E. D. Horton, L. J. Wardzala and E. S. Horton
Department of Medicine, University of Vermont College of Medicine, Burlington 05405.

The relative abundance and subcellular distribution of the GLUT-1 and GLUT-4 glucose transporter isoforms were determined in basal and insulin-stimulated adipose cells from wheel cage exercise-trained rats and compared with both age-matched sedentary controls and young cell size-matched sedentary controls. Exercise training increased total estimated GLUT-4 by 67 and 54% compared with age-matched and young controls, respectively. Total estimated GLUT-1 per cell was not significantly different among the three groups. Expressed per cell, plasma membrane GLUT-4 protein in basal adipose cells from exercise-trained and age-matched control rats was 2.5-fold greater than in young controls (P < 0.05) and was associated with higher basal rates of glucose transport in these cells (P < 0.02). In insulin-stimulated cells, plasma membrane GLUT-4 was 67% greater in the exercise-trained animals than young controls (P < 0.01), and 31% greater than in age-matched controls. Rates of glucose transport were correspondingly higher. In basal cells, low-density microsomal GLUT-4 from exercise-trained rats was approximately twofold greater than from age-matched controls and young controls. With insulin stimulation, GLUT-4 in low-density microsomes decreased to similar levels in all groups. We conclude that the total amount of GLUT-4 protein, but not GLUT-1, is increased in adipose cells by exercise training and that this increase in GLUT-4 is due primarily to an increase in intracellular GLUT-4.(ABSTRACT TRUNCATED AT 250 WORDS)

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