Exercise-induced increase in glucose transport, glut4 and vamp-2 in
plasma membrane from human muscle.
Kristiansen, Soren, Mark Hargreaves, and Erik A. Richter.
Copenhagen Muscle Research Centre, August Krogh Institute,
University of Copenhagen, 13 Universitetsparken, DK-2100, Copenhagen,
Denmark, Department of Physiology, The University of Melbourne,
Parkville, Victoria 3052, Australia
APStracts 2:0211E, 1995.
A major effect of muscle contractions is an increase in sarcolemmal
glucose transport. We have used a recently developed technique to
produce sarcolemmal giant (SG) vesicles from human muscle biopsy
samples obtained before and after exercise. Six men exercised for 10
min at 50% VO2max and then to fatigue at 100% VO2max (5.7 +/- 0.2
min). Vesicle glucose transport at 5 mM increased from 3.3 +/- 0.6
pmol [mu]g-1 min-1 at rest to 6.6 +/- 1.0 pmol [mu]g-1 min-1 at
fatigue (mean +/- SE, n = 6, p < 0.05). This increase in glucose
transport was associated with a 1.6 fold increase in vesicle GLUT4
protein content. Glucose transport normalized to GLUT4 protein
content also increased with exercise, suggesting increased intrinsic
activity of GLUT4. Furthermore, exercise resulted in a 1.4 fold
increase in sarcolemmal VAMP-2 (vesicle associated membrane protein)
content, suggesting that muscle contractions may induce trafficking
of GLUT4 containing vesicles via a mechanism similar to
neurotransmitter release. Our results for the first time demonstrate
exercise-induced translocation of GLUT4 and VAMP-2 to the plasma
membrane of human muscle and increased sarcolemmal glucose transport.
Received 10 July 1995; accepted in final form 12 October 1995.
APS Manuscript Number E323-5.
Article publication pending Am. J. Physiol. (Endocrinol. Metab.).
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on 6 November 95