低氧训练对大鼠骨骼肌VEGF mRNA表达及毛细血管密度的影响

Effect of Hypoxic Training on the Expression of VEGF mRNA and the Capillary Density in Skeletal Muscle of Rats

目的:探讨低氧训练对大鼠骨骼肌血管内皮细胞生长因子(VEGF) mRNA水平表达及毛细血管密度的影响。方法:选用6周龄雄性SD大鼠120只,经3周适应性训练和力竭实验筛选出90只,随机分为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、高住低练后复氧训练组。采用常压低氧舱以13.6%的氧浓度(相当于海拔3500m的氧浓度)作为低氧环境,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6周末的最后一次运动后休息48小时后处死大鼠并取材。采用实时荧光定量PCR技术、免疫组化染色法检测大鼠骨骼肌VEGF mRNA表达及毛细血管密度。结果:与常氧安静对照组相比,高住高练组骨骼肌VEGF mRNA表达明显提高(P<0.01),而高住低练组和低住高练组变化不明显;高住高练后复氧训练1周,大鼠骨骼肌VEGF mRNA表达有非常显著性下降(P<0.01),回到常氧安静组水平。与常氧安静对照组相比,高住高练组和低住高练组骨骼肌毛细血管密度增加,有非常显著性差异(P<0.01)。结论:(1)高住高练比高住低练和低住高练更能显著提高骨骼肌VEGFmRNA表达水平。(2)低氧-常氧的反复刺激更有利于血管生成。低氧下训练比常氧下训练更有利于提高骨骼肌毛细血管密度。低住高练和高住高练对血管生成的效果好于高住低练。

Objective The purpose of this study was to probe into the effect of hypoxic training on the expression of VEGF mRNA and the capillary density of skeletal muscle in rats. Methods Ninety from 120 male SD rats （6 week old） were selected in accordance to their adaptability to the training and the results of exhaustive test, and then randomly divided into 9 groups： normoxic untrained group, persistent hypoxic untrained group, intermittent hypoxic untrained group, normoxic training group, living at high altitude and training at high altitude group （HiHi）, living at high altitude and training at low altitude group （HiLo）, living at low altitude and training at high altitude group （Lo-Hi）, normoxic training after HiHi group, normoxic training after HiLo group. A hypoxic chamber （containing 13.6% of oxygen） was employed to simulate 3500m of altitude. Treadmill running was carried out for 6 weeks with 35m/min for normoxic training and 30m/min for hypoxic training. Rats were sacrificed after 6 weeks. RQ-PCR, immunohisto-chemistry and Western blot were adopted in this study. Results The mRNA of VEGF in skeletal muscle increased sig- nificantly in HiHi group （P〈0.01） while remained unchanged in HiLo group and LoHi group. The mRNA level of VEGF declined significantly in normoxic training after HiHi group （P〈0.01）. Skeletal muscle capillary density of Hi-Hi group and LoHi group increased significantly. Conclusion （1） HiHi was more beneficial to improve the rnRNA level of VEGF in skeletal muscle as comparing with HiLo and LoHi. （2） Repeated stimulation of hypoxia-nommoxia was more useful to develop capillary. LoHi and HiHi revealed a better effect on the development of capillary than Hi-Lo.