ラットの赤筋ならびに白筋線維に対する除神経の影響に関する組織化学的研究 I. Succinic Dehydrogenase 活性について

In order to clarify or otherwise elucidate problems related to white, red and intermediate fibers of mammalian skeletal muscle, and to determine which fibers are more markedly influenced by denervation and whether this denervation effect differs between proximal nerve cutting and distal cutting, histochemical studies were carried out on the succinic dehydrogenase (SDH) activity of the three types of fibers of rat leg muscles. And the following results were obtained. 1) In a histochemical study on SDH activity, it was confirmed that normal tibialis anterior and gastrocnemius medialis muscles are composed of three types of fibers; white, red and intermediate fibers, while normal soleus muscle is composed of two types of fibers; namely red and intermediate fibers. 2) One to two weeks following denervation, the SDH activity of the individual fibers contained in tibialis anterior and soleus decreased with the lapse of time, although a difference between the extent of the decrease of SDH activity of the three types of fibers was present. This decrease of SDH activity was markedly observed at the periphery of all types of fibers. The change was more marked in the red fibers. Three to four weeks following denervation, the SDH activity further decreased and the activity corresponding to the surface membrane of both white and red fibers (subsarcolemmal activity) disappeared, although there was a difference in the inhibition of the SDH activity between red and white fibers. The outline of adjacent fibers became obscure and the number of diformazan particles decreased. 3) The diameter of the individual fibers decreased with the lapse of time following denervation. One week after denervation, no difference between the rate of decrease of the diameter of white and red fibers was observed. Three and four weeks after denervation, this change was marked in white fibers. 4) The shape and interfibrillar structure of the individual fibers changed with time after denervation. The degree of the destruction differed depending on the type of fibers and was marked in white fibers. This change was prominent three to four weeks after denervation. 5) Following denervation the wet and dry weights of muscle decreased. The rate of this decrease was independent of the length of time after denervation and the type of muscle. 6) The changes induced by denervation on the SDH activity, on the shape and internal structure of the individual fibers, and of the wet and dry weights of the muscles were not influenced by the site of nerve cutting. On the basis of these results, several problems regarding the changes of SDH activity, shape and internal structure of the individual fibers induced by denervation, together with the difference of denervation effect on the white and red fibers, including the relation of metabolism to the maintenance of structure, and in relation to the site of nerve cutting to the denervation effect were discussed.