골격근 수축기전에 있어서의 Ca++의 역할에 관한 실험적 연구

Abstract

Superprecipitation of actomyosin has been consi dered to be an in vitro model of the muscle contraction, and intimate correlation has been found between superprecipitation and ATPase activity of actomyositL In order to elucidate the precise role of calcium un interaction of actin-myosin, the effect of the EGTA on ATPase activity of Perry myosin B" with or without troponin and/or tropomyosin was stndied in rabbit skeletal muscle. The results are as follows: 1) Superprecipitation of Perry myosin B" with both of troponin and tropomyosin was markedly delayed by EGTA , and stopped by addition of EGTA during the reaction. 2) ATPase activity of Perry myosin B" was not influenced by EGTA. 3) ATPase activity of: Perry myosin B" with only troponin or tropomyosin was also not influenced by EGT A. but both of troponin and tropomyosin added Perry myosin B" revealed depressed ATPase activity by EGTA. 4) In the system Perry myosin B" with both of troponin and tropomyosin, addition of EGTA during the reaction caused depression of ATPase activity. It is concluded that the actin-myosin interaction is controled by the minute change of calcium concent ration only in the presence of both troponin and tropomyosin through association and dissociation process.