Effect of short-term training on GLUT-4 mRNA and protein expression in human skeletal muscle.
Six untrained, male subjects (23 +/- 1 years old, 84 +/- 5 kg, (O(2)peak)= 3.7 +/- 0.8 l min(-1)) exercised for 60 min at 75 +/- 1%(O(2)peak) on 7 consecutive days. Muscle samples were obtained before the start of cycle exercise training and 24 h after the first and seventh exercise sessions and analysed for citrate synthase activity, glycogen and glucose transporter 4 (GLUT-4) mRNA and protein expression. Exercise training increased (P < 0.05) citrate synthase by approximately 20% and muscle glycogen concentration by approximately 40%. GLUT-4 mRNA levels 24 h after the first and seventh exercise sessions were similar to those measured before the start of exercise training. In contrast, GLUT-4 protein expression was increased after 7 days of exercise training (12.4 +/- 1.5 versus 3.4 +/- 1.0 arbitray units (a.u.), P < 0.05) and although it tended to be higher 24 h after the first exercise session (6.0 +/- 3.0 versus 3.4 +/- 1.0 a.u.), this was not significantly different (P= 0.09). These results support the suggestion that the adaptive increase in skeletal muscle GLUT-4 protein expression with short-term exercise training arises from the repeated, transient increases in GLUT-gene transcription following each exercise bout leading to a gradual accumulation of GLUT-4 protein, despite GLUT-4 mRNA returning to basal levels between exercise stimuli.
Kraniou
Giorgos N
GN
Centre for Physical Activity and Nutrition, School of Exercise & Nutrition Sciences, Deakin University, Burwood, 3125, Australia.
Cameron-Smith
David
D
Hargreaves
Mark
M
D000328:Adult; D000704:Analysis of Variance; D005786:Gene Expression Regulation / Q000502:physiology; D051275:Glucose Transporter Type 4; D006801:Humans; D008297:Male; D009004:Monosaccharide Transport Proteins / Q000096:biosynthesis* / Q000235:genetics; D009124:Muscle Proteins / Q000096:biosynthesis* / Q000235:genetics; D018482:Muscle, Skeletal / Q000378:metabolism*; D005082:Physical Exertion / Q000502:physiology*; D012333:RNA, Messenger / Q000096:biosynthesis* / Q000235:genetics; D013997:Time Factors
D051275:Glucose Transporter Type 4; D009004:Monosaccharide Transport Proteins; D009124:Muscle Proteins; D012333:RNA, Messenger; C495692:SLC2A4 protein, human