Liu Jing-Xia, Eriksson Per-Olof, Thornell Lars-Eric, Pedrosa-Domellöf Fatima
Department of Integrative Medical Biology, Section of Anatomy, Umeå, Sweden.
J Histochem Cytochem. 2002 Feb;50(2):171-83. doi: 10.1177/002215540205000205.
Data on the myosin heavy chain (MyHC) composition of human muscle spindles are scarce in spite of the well-known correlation between MyHC composition and functional properties of skeletal muscle fibers. The MyHC composition of intrafusal fibers from 36 spindles of human biceps brachii muscle was studied in detail by immunocytochemistry with a large battery of antibodies. The MyHC content of isolated muscle spindles was assessed with SDS-PAGE and immunoblots. Four major MyHC isoforms (MyHCI, IIa, embryonic, and intrafusal) were detected with SDS-PAGE. Immunocytochemistry revealed very complex staining patterns for each intrafusal fiber type. The bag(1) fibers contained slow tonic MyHC along their entire fiber length and MyHCI, alpha-cardiac, embryonic, and fetal isoforms along a variable part of their length. The bag(2) fibers contained MyHC slow tonic, I, alpha-cardiac, embryonic, and fetal isoforms with regional variations. Chain fibers contained MyHCIIa, embryonic, and fetal isoforms throughout the fiber, and MyHCIIx at least in the juxtaequatorial region. Virtually each muscle spindle had a different allotment of numbers of bag(1), bag(2) and chain fibers. Taken together, the complexity in intrafusal fiber content and MyHC composition observed indicate that each muscle spindle in the human biceps has a unique identity.
尽管肌球蛋白重链（MyHC）组成与骨骼肌纤维功能特性之间存在着众所周知的相关性，但关于人类肌梭的MyHC组成的数据却很稀少。我们使用大量抗体，通过免疫细胞化学方法，对来自36个肱二头肌肌梭的梭内纤维的MyHC组成进行了详细研究。通过SDS - PAGE和免疫印迹法评估了分离出的肌梭的MyHC含量。SDS - PAGE检测到四种主要的MyHC亚型（MyHCI、IIa、胚胎型和梭内型）。免疫细胞化学显示，每种梭内纤维类型都有非常复杂的染色模式。袋（1）纤维在其整个纤维长度上含有慢张力型MyHC，在其长度的可变部分含有MyHCI、α - 心肌型、胚胎型和胎儿型亚型。袋（2）纤维含有慢张力型MyHC、I型、α - 心肌型、胚胎型和胎儿型亚型，存在区域差异。链纤维在整个纤维中含有MyHCIIa、胚胎型和胎儿型亚型，至少在近赤道区域含有MyHCIIx。实际上，每个肌梭的袋（1）、袋（2）和链纤维数量分配都不同。综上所述，观察到的梭内纤维含量和MyHC组成的复杂性表明，人类肱二头肌中的每个肌梭都具有独特的特征。
