Effects of isometric training on skeletal myosin heavy chain expression
Effects of isometric training on skeletal myosin heavy chain expression
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DOI：
10.1152/jappl.1998.84.6.2036
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发表时间：
1998-06-01
影响因子：
3.3
通讯作者：
Baldwin, KM
中科院分区：
文献类型：
--
作者：
Haddad, F;Qin, AX;Baldwin, KM
这项研究验证了一种假设，即等长阻力训练计划诱导快速抽动骨骼肌中慢速肌球蛋白重链(MHC)表达上调。因此，我们研究了两种阻力训练方案对啮齿动物腓肠肌内侧肌(MG)的影响，这两种训练方案旨在诱导不同持续时间(8次对5次S)和每次收缩激活频率(100赫兹对60赫兹)的重复等长收缩(10-12次/次；4次/次)在每次训练中(共6次和12次)。结果表明，两种训练模式在训练结束后都能显著增加肌肉重量(接近11-13%)(P<；0.05)。MHC表达发生了显着变化，特别是涉及快型IIb MHC相对表达的降低和伴随的Fast型IIx MHC表达的增加。在MG的“白色”和“红色”区域都观察到了这些适应，它们发生在mRNA和蛋白质水平上。这些适应在仅仅六次训练后就被检测到了。这两种训练方案都没有改变慢型MHC和中快型IIa型MHC的相对表达，后者可以通过慢性功能超负荷上调红色MG的表达。这些发现表明，本研究中使用的等长分析方法不足以诱导啮齿动物骨骼肌中肌球蛋白重链亚型表达的假想变化。
This study tested the hypothesis that an isometric resistance-training program induces upregulation of slow myosin heavy chain (MHC) expression in a fast-twitch skeletal muscle. Thus we studied the effects of two resistance-training programs on rodent medial gastrocnemius (MG) muscle that were designed to elicit repetitive isometric contractions (10-12 per set; 4 sets per session) of different duration (8 vs. 5 s) and activation frequency (100 vs. 60 Hz) per contraction during each training session (total of 6 and 12 sessions). Results showed that both training paradigms produced significant increases in muscle weight (similar to 11-13%) after completion of training (P < 0.05). Significant transformations in MHC expression occurred and involved specifically a decrease in the relative expression of the fast type IIb MHC and concomitant increased expression of the fast type IIx MHC. These adaptations were observed in both the "white" and "red" regions of the MG, and they occurred at both the mRNA and protein levels. These adaptations were detected after only six training sessions. Neither of the training programs produced any change in the relative expression of either the slow type I MHC or the moderately fast type IIa MHC, which can be upregulated in the red MG by chronic functional overload. These findings show that the isometric protocols used in this investigation were not sufficient to induce the hypothesized changes in the myosin heavy chain isoform expression in rodent skeletal muscle.