A basic research on muscle fiber restoration in transplanted muscle.

点击翻译按钮获取中文摘要

We created a new rat model of muscle transplantation to the face in order to examine muscles transplanted with microneurovascular anastomoses. Using this model enabled comparison of restoration of transplanted muscles electrophysiologically and histologically with that of denervated and self-innervated muscles. Adult male rats were utilized in this study. At 1, 2, 3, 4, 8, 12 and 16 postoperative weeks muscle reinnervation in 5 rats was examined by EMG, followed by sacrificing the rats to obtain histological specimens. The evoked potential of the reinnervated muscle was recorded simultaneously. Transverse sections of the transplanted muscles stained by H-E and the histochemical method to demonstrate the myosin ATPase activity were examined under the light microscope. Pyrophosphate polyacrylamide gel electrophoresis of myosin crudely extracted from the specimens was performed. Similarly were examined both denervated gracilis muscles and self-innervated muscles.The EMG and histological r … More esults of our study revealed that the difference in restoration between transplanted muscle and self-innervated muscle was remarkable, indicating the prominent effects of several problems as ischemia, tenotomy, surgical invasion. The histochemical results of this experiment cannot fully be explained by the neural regulatory hypothesis, while it can be explained by Hoh et al.'s hypothesis, indicating that the muscle fibers may be intrinsically heterogenous and may be "plastic" within the constraints. The 'undifferentiated' type 2c fiber, observed during fetal and neonatal development or regeneration, is thought to contain EM or NM or both. The 'transitional' type 2c fiber, which is expressed during transformation of muscle fiber type caused by denervation, electrical stimulation, foreign-reinnervation, and so on, was, however, found to contain mixtures of SM and FM.Therefore, two kinds of type 2c fiber may exists, though they are phenotypically identical each other with regard to myosin ATPase activity. The appearance of EM or NM during denervation period may indicate possibility of dediffrentiation of myosin isoforms. Less