不同模式低氧暴露与运动对大鼠骨骼肌纤维百分率的影响

The effects of different modes of hypoxia exposure and exercises on types of skeletal muscle fibers in rats

目的:建立不同低氧暴露与运动模型,观察大鼠骨骼肌纤维类型的变化,为低氧训练提供更科学的训练依据。方法:9周龄大鼠模拟6周不同海拔高度(0m、2200m、2200m^3500m、3500m)低氧暴露与运动两种模型,共8组(n=80)。实验期间,低氧暴露组连续6周单纯低氧刺激,低氧运动组每日按(20~22)m/min的速度跑台运动90min,每周5次;实验结束后用ATP酶染色法测Ⅰ、Ⅱ型肌纤维类型,显微镜采集图像后分析软件计算大鼠比目鱼肌和趾长伸肌SO、FOG、FG肌纤维百分率。结果:(1)比目鱼肌中FOG肌纤维百分率在海拔2200m时运动组较暴露组高6%、在海拔2200m^3500m时运动组较暴露组高9%(p<0.05),SO肌纤维百分率在海拔2200m^3500m时运动组较暴露组高0.8%;(2)趾长伸肌中,4个海拔高度FOG肌纤维百分率运动组均高于暴露组,分别高0.4%、3%、7%、6.7%,SO肌纤维百分率在海拔0m时运动组较安静组增加4.5%;FG肌纤维百分率在4个海拔高度下变化不明显。结论:(1)6周不同海拔低氧暴露与运动双重刺激后,大鼠骨骼肌组织产生适应性变化,比目鱼肌和趾长伸肌FOG肌纤维百分率增加,有利于提高大鼠运动能力;(2)大鼠比目鱼肌SO、FOG肌纤维百分率在海拔2200m^3500m运动后高于暴露组,提示在2200m^3500m低氧复合运动模式下运动,有助于提高大鼠肌肉有氧代谢能力;(3)6周不同海拔高度单纯低氧暴露及中强度低氧运动不会引起骨骼肌纤维类型的改变。

Objective： To observe the changes in the types of skeletal muscle fibers in rats by establishing different models of hypoxia exposure and exercises, providing more scientific basis for hypoxic training. Methods： Nineweek-old rats were divided into the hypoxia exposure model and the hypoxia exercise model in 8 groups at different simulated sea levels for 6 weeks （0m, 2200m, 2200m-3500m, and 3500m） （n=80）. During the experiment, rats in the hypoxia exposure group were subjected to pure stimulation of hypoxia for 6 weeks, while rats in the hypoxic exercise group were given treadmill exercises at 20 to 22m/min for 90min 5 times a week. After the end of the experiment, type I and II fibers were detected by ATPase staining. After the microscopic image acquisition, analytic software was adopted to calculate the percentages of SO, FOG and FG muscle fibers in soleus muscle and extensor digitorum longus in rats. Results： （1） The percentage of muscle fibers in soleus muscle was 6% and 9% higher in the exercise group than in the exposure group at an altitude of 2200m （P〈0.05） and 2200m～3500m（P〈0.05）, respectively. And the percentage of SO muscle fibers was 0.8% higher in the exercise group than in the exposure group at an altitude of 2200m～3500m; （2） The percentages of FOG muscle fibers in the extensor digitorum longus muscle in the exercise group at 4 altitudes were higher than in the exposure group （P〈0.05） by 0.4%, 3%, 7% and 6.7%, respectively. The percentage of SO muscle fibers at the altitude of 0m was increased by 4.5% compared to the exposure group, while the percentages of FG muscle fibers at 4 altitudes were not significantly changed. Conclusions： （1） After 6 weeks of dual stimulation of hypoxia exposure and exercises at different altitudes, the skeletal muscle tissues in rats developed adaptive changes, and the percentages of FOG muscle fibers in the soleus muscle and the extensor digitorum elongus were increased, which was conducive to the improvement in the exercise capacity of rats. （2） The percentages of SO and FOG muscle fibers in the soleus muscle of rats in the exercise group were higher than those in the exposure group at 2200m～3500m, suggesting that exercises under the hypoxic combined exercise mode at 2200m～3500m could improve the ability of aerobic metabolism of muscles in rats. （3） Pure hypoxic exposure and moderate- to high-intensity hypoxic exercises at different altitudes for 6 weeks did not cause changes in types of skeletal muscle fibers.