Novel transitions in MHC isoforms: separate and combined effects of thyroid hormone and mechanical unloading
Novel transitions in MHC isoforms: separate and combined effects of thyroid hormone and mechanical unloading
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DOI：
10.1152/jappl.1998.85.6.2237
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发表时间：
1998-12-01
影响因子：
3.3
通讯作者：
Baldwin, KM
中科院分区：
文献类型：
--
作者：
Caiozzo, VJ;Baker, MJ;Baldwin, KM
采用单纤维（n = 3,818根纤维）电泳分析，描述了甲状腺机能亢进（T-3）和后肢悬吊（HS）对大鼠比目鱼肌肌球蛋白重链（MHC）亚型组成（1、2和4周时间点）的单独和联合影响。本研究的主要发现如下：首先，T-3和HS都在单纤维水平上改变了MHC亚型的分布；然而，这两种干预产生的纤维种群明显不同。其次，T-3 + HS迅速将比目鱼肌转化为快速肌，使快速型IIx和IIb MHC亚型的相对含量大幅增加，这些亚型主要表达于几种杂交纤维群体中（如I/IIa/IIx、I/IIx/IIb、I/IIa/lIx/IIb）。最后，T-3 + HS产生了独特的混杂纤维群体，不遵循MHC塑性的IIIaIIxIIb顺序方案。综上所述，本研究结果表明，T-3 + HS的干预是调控和研究慢骨骼肌MHC异构体可塑性的有力模型。
Single fiber (n = 3,818 fibers) electrophoretic analyses were used to delineate the separate and combined effects of hyperthyroidism (T-3) and hindlimb suspension (HS) on the myosin heavy chain (MHC) isoform composition (1-, 2-, and 4-wk time points) of the rat soleus muscle. The key findings of this study are as follows. First, T-3 and HS both altered the distribution of MHC isoforms at the single-fiber level; however, the populations of fibers produced by these two interventions were clearly different from one another. Second, T-3 + HS rapidly converted the soleus into a fast muscle, producing large increases in the relative contents of the fast type IIx and IIb MHC isoforms which were primarily expressed in several populations of hybrid fibers (e.g., types I/IIa/IIx, I/IIx/IIb, I/IIa/lIx/IIb). Finally, T-3 + HS produced unique populations of hybrid fibers that did not adhere to the IIIaIIxIIb sequential scheme of MHC plasticity. Collectively, the findings of this study demonstrate that the intervention of T-3 + HS is a powerful model for manipulating and studying MHC isoform plasticity in slow skeletal muscle.