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

人类骨骼肌对运动训练的细胞适应的分子机制还知之甚少。为探讨耐力训练对人体骨骼肌信使核糖核酸(MRNA)基因表达的影响，以血管生成因子、抗氧化酶和解偶联蛋白(UCPs)为研究对象，对未经耐力训练的男大学生进行了80~90%V02max的大强度间歇游泳和70%VO2max的30min长距离游泳，每周5次，共3个月。在训练前和最后一次训练后约48小时进行肌肉活组织检查。肌肉标本取自股外侧肌中部，采用带抽吸的经皮针刺活检技术。所有受试者的最大摄氧量都显著增加(P&lt；0.001)，这表明他们的有氧能力有所改善。训练后热休克蛋白70、铜锌超氧化物歧化酶和锰超氧化物歧化酶的mRNAs表达显著降低(P&lt；0.04)，而UCP2的mRNAs表达显著增加(P&lt；0.02)，而血管内皮生长因子、碱性成纤维细胞生长因子、低氧诱导因子-1α、肌红蛋白和UCP3的mRNAs水平无明显变化。训练后HIF1a基因表达的变化与VEGFmRNA表达的变化具有很好的相关性(r=0.875，P&lt；0.01)，提示HIF1a影响训练诱导的人骨骼肌中血管内皮生长因子基因的表达，或在转录水平上协同调节。综上所述，可以预见，在从连续的运动中恢复期间，转录的瞬时变化的累积效应可能代表与耐力训练相关的细胞适应的潜在动力学基础。

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.