[Histochemical studies on skeletal muscle atrophy, with reference to the relationship between atrophy and muscle tension, and to the effect of electrical stimulation].

To clarify the significance of muscle tension and the effect of electrical stimulation on the immobilized muscle, two experiments were performed. First, the ankle joint of rat was fixed by a Kirschner-wire in two ways. After fixation at a strained position for one to twelve weeks, wet weight of soleus had decreased less than after fixation at a relaxed position. Histochemical investigation revealed the fiber type transformation of soleus from type 1 to type 2 at relaxed position, which was not observed at a strained position. The result confirmed the importance of muscle tension not only in the nutrition but also in the differentiation of the muscle. Secondly, electrical stimulation was given to the immobilized soleus for two weeks. Under the experimental procedure, the electrical stimulation prevented the transformation of muscle fiber type, but not muscle atrophy. This result suggested that the nutrition and the differentiation of muscle could be regulated independently.