不同运动强度对大鼠骨骼肌中低氧诱导因子-1αmRNA表达的影响

Effects of exercise intensities on expression of hypoxia inducible factor-1α mRNA in the skeletal muscle of rats

目的探讨不同运动强度和持续时间对大鼠腓肠肌中低氧诱导因子-1α(HIF-1α)mRNA表达的影响。方法80只大鼠随机分为对照组、低强度运动组、中强度运动组和高强度运动组,各组又按时间(1、3、7、14d)分为四个亚组,运用透射电镜观察大鼠骨骼肌细胞和RT-PCR法测定大鼠腓肠肌中HIF-1αmR-NA的表达。结果对照组HIF-1αmRNA存在基础性表达。与对照组HIF-1αmRNA的表达相比:低强度运动组第7天差异有显著性意义(P<0.05);中强度运动组和高强度运用组与对照组比较第3天和第7天差异均有显著性意义(P<0.05);但在第3天和第7天各不同强度运动组之间差异无显著性意义(P>0.05);各组第14天后HIF-1αmRNA表达与对照组相比差异均无显著性意义(P>0.05)。电镜结果提示:高强度运动组肌丝排列紊乱,线粒体肿胀明显,部分空泡化。结论运动会在一定时间内造成大鼠骨骼肌HIF-1αmRNA表达增加,是其适应机制之一;但不同运动强度诱导HIF-1αmRNA表达无显著性差异;长时间高强度运动会对骨骼肌细胞造成损害。

Objective To study effects of exercise intensities and durations on expression of hypoxia inducible factor-let mRNA in the skeletal muscle of rats. Methods Eighty rats were randomized into control group, low-intensity exercise group, moderate-intensity exercise group and high-intensity exercise group. Each group was further divided into four sub-groups in which rats were trained on the treadmill for one day, three days, seven days and 14 days respectively. Then cells of the skeletal muscle were observed under a transmission electron microscope and the expression of HIF-1α mRNA was detected by RT-PCR. Results HIF-1α mRNA could be basically expressed in control group during the 14 days. By contrast, there was a significant increase of HIF-1α mRNA in low-intensity exercise group at day 7 （ P 〈 0. 05）. The expression of HIF-1α mRNA in moderate-intensity exercise group increased significantly at both day 3 and day 7 （ P 〈 0.05）. The same results were observed in high-intensity exercise group, but had no significant difference compared with those in moderate-intensity exercise group（ P 〉 0.05）. At day 14, however, there was little significant difference in the result among all the groups （ P 〉 0.05）. The observation by electron microscope revealed disordered skeletal muscle myofilaments, obvious swelling and partial vacuolization of mitochondria in high-intensity exercise group at day 14. Conclusions Appropriate exercise with appropriate duration can improve expression of HIF-1α mRNA in the skeletal muscle of rats which might be a positive mechanism to adjust to the exercise. Although different exercise intensities have little effect on the expression of HIF-1α mRNA, constant high-intensity exercise may damage skeletal muscles in rats.