カエル骨格筋におけるカリウム拘縮の Spontaneous Relaxation と Deactivation Relaxation の機序について

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The properties of spontaneous relaxation of potassium contracture and the deactivation relaxation in single twitch muscle fibers of the frog were studied at room temperature (24℃) and at a low temperature of 4℃ and the following results were obtained. 1. At 24℃, the maximum rate of spontaneous relaxation of contracture induced with 190 mM K+ was 281.9±22.4 mg/sec (mean±S.E.) and the maximum rate of the deactivation relaxation induced by washing with 2.5 mM K-Ringer solution at the peak of 190 mM K contracture was 647.6±52.9 mg/sec. 2. At 4℃, the maximum rates of spontaneous relaxation and deactivation relaxation were ll.9±1.2 and 170.3±14.1 mg/sec, respectively. 3. The values of Q10 of the spontaneous relaxation rate and the deactivation relaxation rate were 4.87 and 1.95, respectively. 4. At 4℃, the peak tension of the contracture induced by 190 mM K+, after the interruption of the initial contracture in an early period during the plateau phase, was almost equal to the plateau tension shown immediately prior to the deactivation relaxation. On the basis of these results, the mechanisms of the spontaneous relaxation and the deactivation relaxation of the potassium contracture were discussed.
1981-10-01