Distribution of fast myosin heavy chain-based muscle fibres in the gluteus medius of untrained horses: mismatch between antigenic and ATPase determinants
Distribution of fast myosin heavy chain-based muscle fibres in the gluteus medius of untrained horses: mismatch between antigenic and ATPase determinants
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DOI：
10.1046/j.1469-7580.1999.19430363.x
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发表时间：
1999-04-01
影响因子：
2.4
通讯作者：
Rivero, JLL
中科院分区：
文献类型：
--
作者：
Linnane, L;Serrano, AL;Rivero, JLL
通过将免疫组织化学与特异性抗 MHC 单克隆抗体和标准肌原纤维 ATP 酶 (mATPase) 组织化学相关联，对未训练的成年马臀中肌的肌肉活检中根据不同肌球蛋白重链 (MHC) 亚型含量进行分类的肌纤维分布进行了分析。对 4 匹 4 岁安达卢西亚种马进行 3 个深度（20、40 和 60 毫米）的经皮穿刺活检。从最浅到最深的采样点，“纯”I MHC 纤维的百分比增加，而纯 IIX MHC 纤维的百分比减少。在快速纤维中，IIA 型和 IIAX 型 MHC 分类的纤维在最深采样部位比在肌肉表面区域更丰富。在纤维与纤维之间对大量单纤维 (n = 1375) 的免疫组织化学和组织化学特征进行比较和关联。结果显示，40% 的分析纤维是纯 I 型（仅表达 MHC-I）；他们的抗原决定簇和 mATP 酶决定簇之间显示出正确的匹配。相反，在快速纤维中，发现相当大比例的纤维显示出其免疫组织化学和 mATP 酶谱之间的不匹配。最常见的不匹配纤维表型包括通过免疫细胞化学分析时显示两种快速 MHC 共表达的纤维，但显示出与典型 IIX 纤维相似的 mATP 酶谱（在 pH 4.4 预孵育后中等 mATP 酶反应）。综合考虑，失配纤维总数仅占肌肉浅层区域快纤维总数的 4.2%，但在臀中肌中部和深层区域，其比例分别增至 15.6% 和 38.4%。结论是，未经训练的马的臀中肌中存在相当数量的混合快速 MHC IIAX 纤维，这表明马 II 型纤维可能在许多先前仅使用组织化学的出版物中被错误分类。这对于充分研究马的快速纤维类型的生理特性具有重要意义。
The distribution of muscle fibres classified on the basis of their content of different myosin heavy chain (MHC) isoforms was analysed in muscle biopsies from the gluteus medius of adult untrained horses by correlating immunohistochemistry with specific anti-MHC monoclonal antibodies and standard myofibrillar ATPase (mATPase) histochemistry. Percutaneous needle biopsies were taken at 3 depths (20, 40 and 60 mm) from 4 4-y-old Andalusian stallions. The percentage of 'pure' I MHC fibres increased whereas that for pure IIX MHC fibres decreased from the most superficial to the deepest sampling site. Within the fast fibres, types IIA and IIAX MHC-classified fibres were proportionately more abundant in the deepest sampling site than in the superficial region of the muscle. The immunohistochemical and histochemical characterisation of a large number of single fibres (n = 1375) was compared and correlated on a fibre-to-fibre basis. The results showed that 40 % of the fibres analysed were pure type I (expressing only MHC-I); they showed correct matching between their antigenic and mATPase determinants. In contrast, within the fast fibres, a considerable proportion of fibres were found showing a mismatch between their immunohistochemical and mATPase profiles. The most common mismatched fibre phenotypes comprised fibres displaying coexpression of both fast MHCs when analysed by immunocytochemistry, but showing an mATPase profile similar to typical IIX fibres (moderate mATPase reaction after preincubation at pH 4.4). Considered altogether, the total mismatched fibres represented only 4.2 % of the whole fast fibre population in the superficial region of the muscle, but their proportion increased to 15.6 % and 38.4 % in the middle and deep regions, respectively, of gluteus medius. It is concluded that a considerable number of hybrid fast MHC IIAX fibres are present in the gluteus medius of untrained horses, suggesting that equine type II fibres have probably been misclassified in numerous previous publications based on the use of histochemistry alone. This has important implications in attempts to study the physiological properties of fast fibre types adequately in horses.