Argüello A, López-Fernández J L, Rivero J L
Department of Animal Production, Faculty of Veterinary Sciences, University of Las Palmas de Gran Canaria, Gran Canaria, Spain.
Anat Rec. 2001 Nov 1;264(3):284-93. doi: 10.1002/ar.1165.
The primary focus of this study was the accurate classification of limb skeletal muscle fiber types in adult goats (Capra hircus) according to the myosin heavy chain (MHC) isoform they express. Combined methodologies of gel electrophoresis, immunoblotting, immunohistochemistry, myofibrillar ATPase (mATPase), and quantitative metabolic enzyme histochemistry of M. semitendinosus samples were developed. Three MHCs were identified and tentatively designated as types I, IIA, and IIX. Five fiber types were defined immunohistochemically according to their MHC content: I, I+IIA, IIA, IIAX, and IIX. The hybrid fast-twitch fibers (IIAX) totaled 21% of the fiber population analyzed. The three major pure fibers (I, IIA, and IIX) could be objectively separated upon the basis of their mATPase activities after acid and alkaline preincubations. The prominent number of hybrid fibers, however, could not be delineated with these mATPase methods. Metabolic and size properties of muscle fibers varied according to their MHC content, but overlapped the full range of muscle fiber phenotypes. These integrated data demonstrate that type II skeletal muscle fibers of small ruminants have been misclassified in previous studies. The immunohistochemical approach developed in the present study offers new prospects for muscle fiber typing in caprine experimental studies and meat production technologies.
本研究的主要重点是根据成年山羊（Capra hircus）所表达的肌球蛋白重链（MHC）异构体，对其肢体骨骼肌纤维类型进行准确分类。开发了结合凝胶电泳、免疫印迹、免疫组织化学、肌原纤维ATP酶（mATPase）以及半腱肌样本定量代谢酶组织化学的方法。鉴定出三种MHC，并初步命名为I型、IIA型和IIX型。根据其MHC含量，通过免疫组织化学定义了五种纤维类型：I型、I+IIA型、IIA型、IIAX型和IIX型。在所分析的纤维群体中，混合快肌纤维（IIAX）占21%。在进行酸和碱预孵育后，三种主要的纯纤维（I型、IIA型和IIX型）可以根据其mATPase活性客观地分离出来。然而，这些mATPase方法无法区分大量的混合纤维。肌肉纤维的代谢和大小特性根据其MHC含量而有所不同，但涵盖了整个肌肉纤维表型范围。这些综合数据表明，在以往的研究中，小型反刍动物的II型骨骼肌纤维被错误分类。本研究中开发的免疫组织化学方法为山羊实验研究和肉类生产技术中的肌肉纤维分型提供了新的前景。
