Myosin heavy chain composition in normal and atrophic equine laryngeal muscle
Myosin heavy chain composition in normal and atrophic equine laryngeal muscle
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DOI：
10.1354/vp.43-6-881
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发表时间：
2006-11-01
影响因子：
2.4
通讯作者：
Parente, E. J.
中科院分区：
文献类型：
--
作者：
Adreani, C. M.;Li, Z. B.;Parente, E. J.
肌肉的肌球蛋白重链（MHC）组成决定了肌肉的收缩特性，从而决定了肌肉的纤维类型分布。喉肌中MHC异构体的表达受神经输入和功能的调节，它代表了骨骼肌去神经支配和再神经支配发生的细胞水平变化。本研究的目的是评估喉肌中MHC异构体的表达模式，这些喉肌取材于正常尸体和自然发生的左喉偏瘫，继发于复发性喉神经病变。左侧喉内肌萎缩的7匹马和2匹正常马分别获得左、右甲状腺腱肌（TA）和背环腱肌（CAD）。冷冻切片进行组织学评估萎缩程度和纤维类型组成。采用肌肉蛋白十二烷基硫酸钠-聚丙烯酰胺凝胶电泳（SDS-PAGE）检测MHC异构体的表达。3匹马的所有萎缩肌和部分右侧肌肉以及1匹正常马的左侧TA均出现组织学萎缩。除1匹病马外，其余病马的左侧喉部肌肉中均有纤维类型分组或I型肌纤维丢失，2匹病马的右侧肌肉和1匹正常马的左侧喉部肌肉中也有纤维类型分组或I型肌纤维丢失。SDS-PAGE在2匹正常马的CAD和TA中发现了2个与I型和IIB型肌球蛋白亚型相对应的条带。受影响的马在萎缩肌肉中表现出IIB型异构体表达增加和I型异构体表达减少的趋势。本研究证实在大体正常的马喉肌中存在组织学异常，并证实在受影响的肌肉中IIB型MHC表达增加，同时I型MHC表达减少。在去神经和再神经条件下，在细胞水平上评估肌纤维的变化可能有助于评估萎缩性喉肌再神经移植或再生的未来策略。
The myosin heavy chain (MHC) composition of a given muscle determines the contractile properties and, therefore, the fiber type distribution of the muscle. MHC isoform expression in the laryngeal muscle is modulated by neural Input and function, and it represents the cellular level changes that occur with denervation and reinnervation of skeletal muscle. The objective of this study was to evaluate the pattern of MHC isoform expression in laryngeal muscle harvested from normal cadavers and cadavers with naturally occurring left laryngeal hemiplegia secondary to recurrent laryngeal neuropathy. Left and right thyroarytenoideus (TA) and cricoarytenoideus dorsalis (CAD) were obtained from 7 horses affected with left-sided intrinsic laryngeal muscle atrophy and from 2 normal horses. Frozen sections were evaluated histologically for degree of atrophy and fiber type composition. MHC isoform expression was determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) of muscle protein. Histologic atrophy was seen in all atrophic muscles and some right-sided muscles of 3 affected horses, as well as the left TA of I normal horse. Fiber type grouping or loss of type I muscle fibers was observed in the left-sided laryngeal muscles in all but I affected horse, as well as in the right muscles of 2 affected horses, and the left TA of I normal horse. SDS-PAGE showed 2 bands corresponding to the type I and type IIB myosin isoforms in the CAD and TA of the 2 normal horses. Affected horses demonstrated a trend toward increased expression of the type IIB isoform and decreased expression of the type I isoform in atrophic muscles. This study confirmed the presence of histologic abnormalities in grossly normal equine laryngeal muscle, and it demonstrated an increased expression of type IIB MHC with a concurrent decreased expression of type I MHC in affected muscles. Evaluation of muscle fiber changes at the cellular level under denervated and reinnervated conditions may aid in assessing future strategies for reinnervation or regeneration of atrophic laryngeal muscle.