骨骼肌25000蛋白分布于Ⅰ型肌纤维

目的:探讨骨骼肌25 000蛋白分布与肌纤维类型的关系。方法:分别对正常人及重症肌无力患者骨骼肌相邻的连续冰冻切片进行ATPase染色及25 000蛋白的免疫组化染色,阐明25 000蛋白在骨骼肌的分布及与骨骼肌纤维类型的关系。用免疫印迹方法观察以Ⅰ型纤维为主的比目鱼肌和以Ⅱ型纤维为主的肱三头肌中25 000蛋白表达的差异。结果:相邻冰冻切片ATPase染包和25 000蛋白免疫组化的结果表明,无论是正常人还是MG患者的骨骼肌,25 000蛋白均存在于胞质内,并主要分布在Ⅰ型纤维;在相同免疫染色条件下,该蛋白在MG骨骼肌的染色强度明显低于正常人。免疫印迹显示,在相同的骨骼肌总蛋白量中,比目鱼肌的25 000蛋白表达水平明显高于肱三头肌,进一步证实了25 000蛋白主要分布在Ⅰ型纤维。结论:25 000蛋白主要在骨骼肌Ⅰ型纤维中表达,MG患者骨骼肌的易疲劳和收缩无力可能与该蛋白在Ⅰ型纤维中低表达有关。

25 000 Protein of Skeletal Muscle Located at I Type Muscle Fiber

Aim: To explore at which type muscle fiber 25 000 protein of skeletal muscle was located. Methods: The serial frozen sections of skeletal muscles from normal and myasthenia gravis( MG) were applied to demonstrate distribution of 25 000 protein in different types of musdcle fiber by the methods of immuno-histochemistry and ATPase histochemistry, respectively. The expression of 25 000 protein in soles and triceps was detected by Immuno-Western blot. Results: The location of 25 000 protein in both of MG and normal muscles was found to locate at the cytoplasm and the protein was principally confined in the muscle fibers of 1 type through comparing ATPase staining and 25 000 protein immuno-histochemical staining in the serial sections, however, the density of 25 000 protein stained in normal muscle was higher than that in MG muscle. Moreover, the expression of 25 000 protein in the soles predominant with 1 type fiber was much more than that in the triceps predominant with II type fiber,it was further proved that the protein was mainly located at I type fiber. Conclusion: 25 000 protein was mostly exprssed in the 1 type muscle fibers and its low expression in MG muscles may be associated with clinical characteristics of MG.