Study on effects and mechanism to oxidative capacity in skeletal muscle by physical training

人体骨骼肌细胞适应运动训练的分子机制尚不清楚。为了研究耐力训练对人体骨骼肌信使RNA （mRNA）水平上各种基因表达的影响，重点研究了血管生成因子、抗氧化酶和解偶联蛋白（UCPs），未经训练的男学生进行了80-90% vo2max的高强度间歇游泳和30分钟70%VO2max的长距离游泳，每周5次，持续3个月。在训练前和最后一次训练后约48小时进行肌肉活检。采用抽吸法经皮穿刺活检法从股外侧肌中段取肌样本。所有受试者在使用Monark自行车运动器训练后，其最大摄氧量水平均显著提高（P < 0.001），表明有氧能力有所提高。训练后，热休克蛋白70、Cu、zn -超氧化物歧化酶（Cu、Zn-SOD）和Mn-SOD mRNA表达显著（P < 0.04）降低，UCP2 mRNA表达显著（P < 0.02）升高，而血管内皮生长因子（VEGF）、碱性成纤维细胞生长因子、缺氧诱导因子-la （HIF1a）、肌红蛋白或UCP3 mRNA表达水平无明显变化。训练后HIF1a mRNA的表达变化与VEGF mRNA的表达变化具有良好的相关性（r=0.875, P < 0.01），表明HIF1a影响了训练诱导的VEGF基因表达，或者在人骨骼肌中，VEGF和HIE1a的表达在转录水平上受到协同调节。综上所述，我们可以设想，在连续几次运动后恢复过程中，转录的短暂变化的累积效应可能代表了与耐力训练相关的细胞适应性的潜在动力学基础。

The molecular mechanisms mediating the cellular adaptations to exercise training in human skeletal muscle are very poorly understood. The current study was undertaken to investigate the effect of endurance training on the expression of various genes at the messenger RNA (mRNA) levels in human skeletal muscle, focusing on angiogeneic factors, antioxidant enzymes, and uncoupling proteins (UCPs), untrained male students underwent an intensive interval swimming at 80-90%V02max and 30-min long distance swimming at 70%VO2max, five times a week for 3 months. Muscle biopsies were taken before training and about 48 h after the last session. Muscle sample were obtained from the middle portion of the vastus lateralis muscle by use of the percutaneous needle biopsy technique with suction. All the subjects markedly increased their maximal oxygen uptake levels due to training (P < 0.001) using a Monark bicycle ergomater, indicating an improvement in aerobic capacity. After training there were significant (P < 0.04) decreases in the expression of mRNAs for heat shock protein 70, Cu, Zn-superoxide dismutase (Cu, Zn-SOD), and Mn-SOD but a significant (P < 0.02) increase in UCP2 mRNA expression, whereas no definite changes were observed in the levels of mRNAs for vascular endothelial growth factor (VEGF), basic fibroblast growth factor, hypoxia-inducible factor-la (HIF1a), myoglobin, or UCP3. The changes in HIF1a mRNA expression correlated well with those in VEGF mRNA expression after training (r=0.875, P < 0.01), suggesting that HIF1a influences the training-induced VEGF gene expression or alternatively that VEGF and HIE1a expressions are coregulated at the transcriptional level in human skeletal muscle. Taken together, it is envisioned that cumulative effects of transient changes in transcription during recovery from successive bouts of exercise may represent the underlying kinetic basis for the cellular adaptations associated with endurance training.