Kuo C H, Browning K S, Ivy J L
Department of Kinesiology and Health Education, The University of Texas at Austin, USA.
Acta Physiol Scand. 1999 Feb;165(2):193-201. doi: 10.1046/j.1365-201x.1999.00489.x.
The purpose of this study was to determine the time course of GLUT4 protein accumulation following an exercise-carbohydrate supplementation regimen, and to evaluate the effect of this regimen on GLUT4 mRNA regulation. Rats were exercised by swimming and intubated with 1 mL of a 50% glucose solution immediately post-exercise. Exercise significantly reduced muscle glycogen by 50%. By 1.5 h of recovery, muscle glycogen was normalized, but continued to increase above the control level during the next 16 h. A faster and larger repletion of glycogen occurred in the fast-twitch red compared with the fast-twitch white muscle during the 16 h of recovery. GLUT4 protein concentration in fast-twitch red muscle was significantly increased above control by 1.5 h of recovery, and progressively increased throughout the recovery period. Fast-twitch white muscle demonstrated a similar trend, but the increase in GLUT4 protein did not reach significance until 5 h of recovery. Fast-twitch red muscle GLUT4 mRNA was increased by 53% above control immediately post-exercise, but returned to the control level by 1.5 h of recovery. GLUT4 mRNA associated with polysomes, however, increased significantly during this time and remained elevated for a minimum of 5 h. The results suggest that the increased GLUT4 protein expression following a regimen of exercise-carbohydrate supplementation occurs sufficiently fast to contribute to the resynthesis of muscle glycogen, and is controlled by both pre-translational and translational mechanisms.
本研究的目的是确定运动-碳水化合物补充方案后GLUT4蛋白积累的时间进程，并评估该方案对GLUT4 mRNA调节的影响。大鼠通过游泳进行运动，并在运动后立即经插管给予1 mL 50%的葡萄糖溶液。运动使肌肉糖原显著减少了50%。到恢复1.5小时时，肌肉糖原恢复正常，但在接下来的16小时内持续高于对照水平。在恢复的16小时内，快肌红肌中的糖原补充比快肌白肌更快且更多。快肌红肌中GLUT4蛋白浓度在恢复1.5小时时显著高于对照，并在整个恢复期逐渐增加。快肌白肌呈现类似趋势，但GLUT4蛋白的增加直到恢复5小时才达到显著水平。快肌红肌GLUT4 mRNA在运动后立即比对照增加了53%，但在恢复1.5小时时恢复到对照水平。然而，在此期间与多核糖体相关的GLUT4 mRNA显著增加，并至少持续升高5小时。结果表明，运动-碳水化合物补充方案后GLUT4蛋白表达的增加发生得足够快，有助于肌肉糖原的再合成，并且受转录前和翻译机制的控制。
