Lucas C A, Hoh J F
Department of Physiology, University of Sydney, New South Wales, Australia.
Invest Ophthalmol Vis Sci. 1997 Dec;38(13):2817-25.
To determine whether the levator palpebrae superioris (LPS) and the retractor bulbi (RB) muscles, which share contractile characteristics with extraocular muscles (EOMs), express fast EOM-specific myosin heavy chain (MyHC) in the rabbit and other mammalian species.
Cryostat sections of rabbit eye and limb muscles were stained by indirect peroxidase immunohistochemical procedures using monoclonal antibodies (MAbs), including one (4A6) against EOM-specific fast MyHC. Myosin heavy chain isoforms from these muscles were separated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), and the 4A6-reactive component was identified by immunoblotting.
MAb 4A6 stained muscle fibers in rabbit LPS and RB. SDS-PAGE resolved a rabbit EOM-specific MyHC isoform (band 1) from two other components (bands 2 and 3) that comigrated with limb fast MyHCs. MAb 4A6 reacted only with band 1. Rabbit LPS and RB also displayed corresponding MyHC components with the same mobilities and immunoreactivities as bands 1 to 3 in the EOM. MAb 4A6 also stained muscle fibers in monkey and cat LPS, but it failed to stain muscle fibers in cat RB and rat LPS and RB.
The expression of EOM-specific fast MyHC in EOM, LPS, and RB reflect their common developmental origin and similar contractile characteristics. These properties set them apart from other skeletal muscle groups. Eye muscles may constitute a distinct muscle group or allotype characterized by unique properties, including their propensity or resistance to disease.
确定与眼外肌（EOM）具有共同收缩特性的提上睑肌（LPS）和眼球退缩肌（RB）是否在兔及其他哺乳动物物种中表达快速眼外肌特异性肌球蛋白重链（MyHC）。
兔眼和肢体肌肉的冰冻切片采用间接过氧化物酶免疫组织化学方法，使用单克隆抗体（MAb）进行染色，其中一种（4A6）针对眼外肌特异性快速MyHC。这些肌肉中的肌球蛋白重链异构体通过十二烷基硫酸钠-聚丙烯酰胺凝胶电泳（SDS-PAGE）分离，4A6反应性成分通过免疫印迹鉴定。
单克隆抗体4A6对兔LPS和RB中的肌纤维进行了染色。SDS-PAGE从与肢体快速MyHC共迁移的其他两种成分（条带2和3）中分离出一种兔眼外肌特异性MyHC异构体（条带1）。单克隆抗体4A6仅与条带1反应。兔LPS和RB还显示出与眼外肌中条带1至3具有相同迁移率和免疫反应性的相应MyHC成分。单克隆抗体4A6也对猴和猫LPS中的肌纤维进行了染色，但未对猫RB以及大鼠LPS和RB中的肌纤维进行染色。
眼外肌、LPS和RB中眼外肌特异性快速MyHC的表达反映了它们共同的发育起源和相似的收缩特性。这些特性使它们与其他骨骼肌群区分开来。眼肌可能构成一个独特的肌肉群或异型，其具有独特的特性，包括对疾病的易感性或抵抗力。
