Study on the mechanism of atrophy, hypertrophy and regeneration of the skeletal muscle

肌肉萎缩的原因：踝关节石膏固定导致大鼠腓肠肌、比目鱼肌和足底肌萎缩。固定后1周和2周肌肉湿重分别减少22%和23%（1周22%，2周23%）。当关节在足底屈曲时固定时，这些肌肉的萎缩加剧，而在背屈时则减轻。肌腱切断术导致肌肉萎缩（1周时9%，2周时20%）。去神经支配导致进行性和服务性肌肉萎缩（1周为31%，2周为49%）。肌肉恢复：切除石膏或神经移植后萎缩的肌肉开始恢复。每天一次30分钟的游泳，持续2周，可以显著促进肌肉恢复。通过肌肉刺激来预防肌肉萎缩和促进肌肉肥大。肌肉收缩30分钟，而不是15分钟，通过持续的神经刺激产生肌肉损伤。结论：骨骼肌在固定、肌腱切断和去神经后迅速萎缩。当肌肉承受压力时，肌肉萎缩可以减少到最低程度。尽早开始康复是有效的。然而，剧烈运动可能会导致肌肉损伤。

CAUSES OF MUSCLE ATROPHY : Cast immobilization of the ankle joint resulted in the atrophy of the gastrocnemius, soleus and plantaris muscles of the rat. The decrease of muscle wet weight was 22% at 1 week and 23% at 2 weeks (22% at 1 week ; 23% at 2 weeks) after immobilization, respectively. Atrophy of these muscles was enhanced when the joint was immobilized at plantar flexion, whereas alleviated at dorsal flexion. Tenotomy produced muscle atrophy (9% at 1 week ; 20% at 2 weeks). Denervation resulted in progressive and serve muscle atrophy (31% at 1 week ; 49% at 2 weeks).MUSCLE RECOVERY : The atrophied muscles began to reverse after cast removal or reinnervation. Thirty min of swimming once a day for 2 weeks significantly promoted muscle recovery. Prevention of muscle atrophy and promotion of hypertrophy was attempted by muscle stimulation. Muscle contraction for 30 min, but not 15 min, by continuous nerve stimulation produced muscle injury.CONCLUSIONS : Skeletal muscles rapidly atrophied after immobilization, tenotomy and denervation. Muscle atrophy can be minimized when muscles are loaded with tension. An early start of rehabilitation is effective. However, strong exercise may lead to muscle injury.