骨格筋ミクロゾームのカルシウム取りこみおよびATPase活性に対するNa⁺およびK⁺の影響

抄録

1. Calcium uptake by rabbit skeletal muscle microsomes was stimulated by the addition of Na⁺ or K⁺ alone or both, but the synergistic action of Na⁺ and K⁺ was not remarkable.
2. The stimulation of calcium uptake was the highest at the concentration of 20 mM of Na⁺ or 40mM of K⁺.
3. The pH optimum of calcium uptake was 6.8. The pH optimum of ATPase activity was about 78 in the case of Mg²⁺ alone or Mg²⁺+Na⁺, and about 7.4 in the case of Mg²⁺+ Na⁺+K⁺
4. ATPase activity was also stimulated by the addition of Na⁺ or K⁺, but the synergistic action of Na⁺ and K⁺ was not observed. Ouabain did not affect the stimulated ATPase activity.
5. ATPase activity was stimulated by a low concentration of Ca²⁺ in the presence of Na⁺ and K⁺ alone or both regardless of the presence of oxalate. In the presence of Mg²⁺ alone the ATPase activity was stimulated slightly by the addition of Ca²⁺, but in the presence of oxalate the ATPase activity with Mg²⁺ alone was not stimulated by the presence of Ca²⁺.
6. The addition of salyrgan depressed the ATPase activity to a certain level. The ATPase which links to Ca²⁺ uptake was considered to be Na⁺-K⁺ stimulated, Ca²⁺ stimulated ouabain insensitive and salyrgan sensitive enzyme.