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、比目鱼肌和跖肌萎缩。肌肉湿重在制动后1周和2周分别减少22%和23%（1周22%; 2周23%）。跖屈关节制动时，这些肌肉的萎缩增强，而背屈关节制动时，这些肌肉的萎缩减轻。肌腱切开术导致肌肉萎缩（1周时9%; 2周时20%）。失神经支配导致进行性和严重的肌肉萎缩（1周时31%; 2周时49%）。肌肉恢复：在石膏取出或神经再支配后，萎缩的肌肉开始逆转。每天游泳一次，每次30分钟，持续2周，可显著促进肌肉的恢复。尝试通过肌肉刺激预防肌肉萎缩和促进肌肉肥大。肌肉收缩30分钟，但不是15分钟，通过连续的神经刺激产生肌肉injuries.Conclusions：骨骼肌迅速萎缩后制动，肌腱切断和去神经。当肌肉承受张力时，肌肉萎缩可以最小化。早期康复是有效的。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.