| Summary: | 碩士 === 輔仁大學 === 食品營養學系 === 94 === Glucose transporter subtype 4 (GLUT4) is an important factor for glycogen resynthesis in muscle. The mRNA and protein level of GLUT4 can be regulated with exercise or carbohydrate supplementation in rat and human skeletal muscle. The purpose of this study is to investigate the effect of different glycemic index (GI) carbohydrate supplementation after exercise on GLUT4 protein expression in human skeletal muscle. Eighteen untrained subjects(age 21.3±1.46 yr, height 173.1±5.33cm, weight 70.21±7.34 kg, VO2 peak 43.65±10.58 ml/kg/min) were asked to take a single bout of cycle ergometer at 75% peak oxygen consumption for 60 minutes. Subjects were randomly assigned to one of three treatment groups after exercise: fasting, high GI carbohydrate (HGI) supplement or low GI (LGI) carbohydrate supplement. Biopsies were performed on the deep portion of the vastus lateralis muscle of all subjects immediately after exercise and 3 hours after the carbohydrate ingestion. Protein expressions of GLUT4 are showed quantitatively with Western Blotting technique. Blood samples are collected immediately after the exercise and every 30 minutes thereafter, up to 3 hours. Blood samples were collected for glucose and insulin analysis. The blood area under curve (AUC) is not different between HGI and LGI groups. Concentrations of blood glucose and insulin are significant different from three groups (p<0.05). Insulin AUC is significant higher in HGI group than in LGI and fasting groups. GLUT4 protein content in HGI group is significant increase above LGI and fasting trails. The results of this study suggest that HGI carbohydrate supplement after exercise can enhance GLUT4 protein expression and increase insulin secretion during recovery period. We propose that the insulin may play a role of mediator than stimulator for GLUT4 protein.
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