过度训练对大鼠骨骼肌糖原含量、AMPK活性及肌膜GLUT4的影响

目的:观察过度训练后大鼠骨骼肌糖原含量、AMPK活性和肌膜GLUT4蛋白含量的变化,探讨过度训练与骨骼肌葡萄糖代谢之间的联系。方法:27只SD大鼠随机分为安静对照组(A组),大强度运动组(B组)和过度训练组(C组)。B、C组进行9周大强度耐力训练,其中B组每天训练60分钟,C组每天训练120分钟,每周训练6天。9周后分别测定各组大鼠腓肠肌糖原、AMPK活性和肌膜GLUT4含量。结果:与A组比较,B组肌膜GLUT4升高,AMPK活性显著提高,肌糖原含量有上升趋势;C组肌膜GLUT4明显低于B组,AMPK活性受到抑制,但肌糖原含量正常。结论:过度训练状态下,大鼠肌肉AMPK活性降低,GLUT4蛋白向肌膜转位受抑,可能影响肌膜葡萄糖的转运。本实验结果不支持过度训练的糖原耗竭学说。

Effect of Overtraining on Skeletal Muscle Glycogen, AMPK Activity and Sarcolemma GLUT4 Protein Content in Rats

Objective The purpose of the present study was to observe the muscle glucose metabolism by determining the changes in sarcolemma GLUT4 protein content and muscle AMPK activity in overtraining rats.Methods Twenty-seven SD rats were randomly divided into group A(sedentary),group B(underwent endurance exercise 60 minutes/day)and group C(underwent endurance exercise 120 minutes/day).Both exercise groups trained 6 days/wk for 9 weeks.Muscle glycogen,sarcolemma GLUT4 contents and muscle AMPK activity were determined after the 9-week training.Results Sarcolemma GLUT4 content and muscle AMPK activity increased,muscle glycogen contents tended to rise in group B as compared with that in group A.Sarcolemma GLUT4 content and muscle AMPK activity decreased,but muscle glycogen contents were equivalent in group C as compared with that in group B.Conclusion Muscle AMPK activity deceased,and the translocation of GLUT4 protein was inhibited in the overtraining rats.The results could not support a glycogen depletion hypothesis.