低氧训练对大鼠骨骼肌一氧化氮合酶(NOS)系统的影响

Effect of Hypoxic Training on NOS System of Skeletal Muscle in Rats

目的:探讨不同低氧训练模式对机体骨骼肌一氧化氮合酶(NOS)系统影响的机制。方法:选用6周龄SD雄性大鼠120只,经3周适应性训练和力竭实验筛选出90只,随机分成9组:常氧安静对照组、持续低氧安静组、间歇低氧安静组、低住低练组、高住高练组、高住低练组、低住高练组、高住高练后复氧训练组和高住低练后复氧训练组。采用常压低氧仓以13.6%的氧浓度(相当于海拔3500m的氧浓度)进行低氧训练,根据血乳酸-速度曲线确定大鼠常氧训练的强度为35m/min,低氧训练的强度为30m/min。低氧训练持续时间为6周,每周训练5天。在第4周末进行运动能力测试,第5周末进行力竭测试,在第6周末的最后一次运动后休息48h后处死、取材。采用实时荧光定量PCR、免疫组化、Westernblot等技术测试大鼠骨骼肌一氧化氮合酶(NOS)系统变化,以进一步探讨低氧训练对骨骼肌一氧化氮合酶(NOS)系统的适应机制。结果:高住高练组和常氧安静对照组相比,骨骼肌nNOSmRNA表达升高234%,有非常显著性差异(P<0.01);高住高练组与低住低练组相比,骨骼肌nNOSmRNA表达有非常显著性升高(P<0.01);高住高练后复氧训练1周,大鼠骨骼肌nNOS mRNA表达有非常显著性降低(P<0.01),回到常氧安静对照组水平;高住高练组、高住低练组及低住高练组骨骼肌iNOS mRNA表达分别升高92%、79%和125%,都有显著性差异(P<0.05);高住高练和高住低练后复氧训练1周,大鼠骨骼肌iNOS mRNA表达都有显著性降低(P<0.05),基本回到常氧安静对照组水平甚至还略低。与低住低练组相比,高住高练组骨骼肌eNOS mRNA表达有显著性升高(P<0.05);高住高练后复氧训练1周,大鼠骨骼肌eNOS mRNA有非常显著性下降(P<0.01)。结论:三种低氧训练方式都有助于大鼠骨骼肌毛细血管舒张,但作用机制不同,高住低练主要通过iNOS系统来使血管舒张,而低住高练却是通过HO-1系统来达到血管舒张的目的,高住高练组两种方式都有,因此,其血管舒张的效果也是三种方式中最好的,但复氧训练后此功能迅速降低。各低氧训练组eNOS mRNA水平表达变化不大。

The purpose of this study is to probe into the mechanisms of the effect in different hypoxia training methods around nNOSmRNA of skeleton muscle in order to provide theoretical and applying basis for the application of hypoxia training to sports training. Method ： 90 rats are selected from 120 male SD rats （6 week old） by adaptability training and exhaustive test, and randomly divided into 9 groups ： normoxia quiet control group, continuing hypoxia group, intermittent hypoxia group, normaxia training group, living-high and training-high group （Hi- Hi）, living-high and training-low group （HiLo）, living-low and training-high group （LoHi）, normoxia training group after HiHi, normoxia training group after HiLo. During the 6 weeks of experimental period, we employed the 13.6 % concentration of oxygen （equal to altitude of 3500m） in the hypoxic chamber. The rats of hypoxia training were introduced to treadmill. The speed of training was 30m/min in hypoxia, 35m/min in normoxia. The rats were trained 5d/week and were sacrificed after 6 weeks. Technology of RQ-PCR, immunohistochemistry and Western blot are adopted in order to test the mRNA and protein level changes of HIF-lain rat＇s skeletal muscle to probe further into the mechanisms of the acclimatization in skeletal muscle. Result：The mRNA level of nNOS in skeletal muscle of the HiHi group increased significantly （P〈0.01） comparing with the normoxia quite group and the LoLo group. The mRNA level of nNOS in skeletal muscle of the normoxia training group after HiHi decreased significantly （P%0.01）. The mRNA levels of iNOS in skeletal muscle of the HiHi （92%）, Hi-Lo （79 % ） and LoHi （125% ） group all increased significantly, almost returned to the level of normoxia. The mRNA level of eNOS in skeletal muscle of the HiHi group increased significantly （P〈0.05） comparing with the LoLo group. The mRNA level of eNOS in skeletal muscle of the HiHi group decreased significantly（P〈0.01） in the normoxia training group after HiHi. Conclusion ： 1. the hypoxia training methods of HiHi, HiLo and LoHi contribute to capillary vasodilation of skeletal muscle in different mechanism. HiLo mainly through the iNOS system, LoHi mainly in the manner of HO-1 system, while HiHi in both ways, thus it is the best of these three methods. But this function decreased rapidly after returned to normoxia training 2. the mRNA level of eNOS in all hypoxia training group doesn ＇t changed significantly.