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.
Original language | English |
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Journal | American Journal of Physiology: Endocrinology and Metabolism |
Volume | 270 |
Issue number | 1 |
Pages (from-to) | E197-E201 |
Number of pages | 5 |
ISSN | 0193-1849 |
Publication status | Published - 1996 |
Keywords
- Adult
- Biological Transport
- Blotting, Western
- Cell Membrane
- Glucose
- Glucose Transporter Type 4
- Humans
- Male
- Membrane Proteins
- Monosaccharide Transport Proteins
- Muscle Proteins
- Muscles
- Physical Exertion
- R-SNARE Proteins
- Sarcolemma