Skeletal muscle GLUT-4 and postexercise muscle glycogen storage in humans.
The purpose of this study was to examine the relationship between skeletal muscle GLUT-4 protein and postexercise glycogen storage in human subjects fed adequate carbohydrate. Eleven men completed 2 h of cycling, and a biopsy of the vastus lateralis was performed immediately after exercise cessation for the determination of muscle GLUT-4 protein and glycogen concentrations, glycogen synthase activity, and citrate synthase activity. The subjects ingested meals providing 2.0 g carbohydrate/kg body weight at 0, 2, and 4 h postexercise, and a second biopsy was performed 6 h postexercise. Muscle glycogen concentration increased significantly during the 6-h recovery period (glycogen immediately postexercise, 27.2 +/- 5.4 mmol/kg wet weight; glycogen storage, 52.4 +/- 2.9 mmol x kg wet weight-1 x 6 h-1; P<0.05). Glycogen storage during recovery was directly related to GLUT-4 protein (2.20 +/- 0.33 arbitrary standard units; r = 0.63; P<0.05) and inversely related to glycogen immediately postexercise (r = -0.70; P < 0.05). A direct correlation existed between glycogen storage during recovery and the activity of the I form of glycogen synthase (r = 0.60; P < 0.05). These results suggest that muscle GLUT-4 protein concentration, as well as factors relating to glucose disposal, may affect postexercise glycogen storage in humans fed adequate carbohydrate.
McCoy
M
M
Department of Physiology, Royal Melbourne Hospital, The University of Melbourne, Parkville, Victoria, Australia.
Proietto
J
J
Hargreaves
M
M
D000328:Adult; D001642:Bicycling; D002950:Citrate (si)-Synthase / Q000378:metabolism; D004040:Dietary Carbohydrates / Q000494:pharmacology; D015444:Exercise / Q000502:physiology*; D051275:Glucose Transporter Type 4; D006003:Glycogen / Q000378:metabolism*; D006006:Glycogen Synthase / Q000378:metabolism; D006339:Heart Rate / Q000187:drug effects / Q000502:physiology; D006801:Humans; D008297:Male; D009004:Monosaccharide Transport Proteins / Q000097:blood / Q000378:metabolism*; D009124:Muscle Proteins; D018482:Muscle, Skeletal / Q000201:enzymology / Q000378:metabolism*; D010101:Oxygen Consumption / Q000187:drug effects / Q000502:physiology
D004040:Dietary Carbohydrates; D051275:Glucose Transporter Type 4; D009004:Monosaccharide Transport Proteins; D009124:Muscle Proteins; C495692:SLC2A4 protein, human; D006003:Glycogen; D002950:Citrate (si)-Synthase; D006006:Glycogen Synthase