Rubinstein N A, Hoh J F
Department of Cell and Developmental Biology, University of Pennsylvania School of Medicine, Philadelphia 19104, USA.
Invest Ophthalmol Vis Sci. 2000 Oct;41(11):3391-8.
To determine the distribution of myosin heavy chain isoforms in each extraocular muscle (EOM) fiber type.
Serial sections of adult rat EOMs were stained with isoform-specific monoclonal antibodies against an array of myosin heavy chains. Immunofluorescent antibody staining of whole adult rat EOMs, examined by confocal microscopy, demonstrated the longitudinal variations of isoforms along individual fibers.
Each global fiber type reacted predominantly with a single isoform-specific antibody and showed no longitudinal variation. Two major orbital fibers were defined, and both contained multiple myosin heavy chains. Both orbital singly and multiply innervated fibers stained proximal and distal to the neuromuscular junction with antibody to embryonic myosin heavy chain, but this isoform was sharply and completely excluded from the domain of the neuromuscular junction. Orbital singly innervated fibers also contained the EOM-specific isoform at the neuromuscular junction. Orbital multiply innervated fibers did not contain the EOM-specific isoform, but additionally contained a slow isoform along their entire length.
Adult rat EOMs show unique fiber types with arrangements of myosin heavy chain isoforms not seen in other skeletal muscles. Moreover, unique cellular mechanisms must exist to target each isoform to its proper domain along individual orbital fibers.
确定肌球蛋白重链亚型在每条眼外肌（EOM）纤维类型中的分布。
用针对一系列肌球蛋白重链的亚型特异性单克隆抗体对成年大鼠EOM的连续切片进行染色。通过共聚焦显微镜检查成年大鼠EOM整体的免疫荧光抗体染色，显示了亚型沿单个纤维的纵向变化。
每种整体纤维类型主要与一种亚型特异性抗体反应，且未显示纵向变化。定义了两种主要的眼眶纤维，两者均含有多种肌球蛋白重链。眼眶单根和多根神经支配的纤维在神经肌肉接头近端和远端用抗胚胎肌球蛋白重链抗体染色，但该亚型被完全排除在神经肌肉接头区域之外。眼眶单根神经支配的纤维在神经肌肉接头处也含有EOM特异性亚型。眼眶多根神经支配的纤维不含有EOM特异性亚型，但在其全长还含有一种慢肌亚型。
成年大鼠EOM显示出独特的纤维类型，其肌球蛋白重链亚型的排列在其他骨骼肌中未见。此外，必然存在独特的细胞机制将每种亚型靶向至单个眼眶纤维的适当区域。
