title: Exercise-induced increase in glucose transport, GLUT-4, and VAMP-2 in plasma membrane from human muscle.
abstract: A major effect of muscle contractions is an increase in sarcolemmal glucose transport. We have used a recently developed technique to produce sarcolemmal giant vesicles from human muscle biopsy samples obtained before and after exercise. Six men exercised for 10 min at 50% maximal O2 uptake (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.microgram-1.min-1 at rest to 6.6 +/- 1.0 pmol.microgram-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 GLUT-4 protein content. Glucose transport normalized to GLUT-4 protein content also increased with exercise, suggesting increased intrinsic activity of GLUT-4. Furthermore, exercise resulted in a 1.4-fold increase in sarcolemmal vesicle-associated membrane protein (VAMP-2) content, suggesting that muscle contractions may induce trafficking of GLUT-4-containing vesicles via a mechanism similar to neurotransmitter release. Our results demonstrate for the first time exercise-induced translocation of GLUT-4 and VAMP-2 to the plasma membrane of human muscle and increased sarcolemmal glucose transport.
authors.affiliation: Copenhagen Muscle Research Centre, August Krogh Institute, University of Copenhagen, Denmark.
authors.forename: S
authors.initials: S
authors.lastname: Kristiansen
authors.forename: M
authors.initials: M
authors.lastname: Hargreaves
authors.forename: E A
authors.initials: EA
authors.lastname: Richter
mesh_terms: D000328:Adult; D001692:Biological Transport; D015153:Blotting, Western; D002462:Cell Membrane / Q000378:metabolism; D005947:Glucose / Q000378:metabolism*; D051275:Glucose Transporter Type 4; D006801:Humans; D008297:Male; D008565:Membrane Proteins / Q000378:metabolism*; D009004:Monosaccharide Transport Proteins / Q000378:metabolism*; D009124:Muscle Proteins; D009132:Muscles / Q000378:metabolism*; D005082:Physical Exertion; D050683:R-SNARE Proteins; D012508:Sarcolemma / Q000378:metabolism
chemical_list: D051275:Glucose Transporter Type 4; D008565:Membrane Proteins; D009004:Monosaccharide Transport Proteins; D009124:Muscle Proteins; D050683:R-SNARE Proteins; C495692:SLC2A4 protein, human; D005947:Glucose