抄録
The dependency of Na efflux on intracellular Na concentrationwas examined on sartorius muscles of Rana catesbeiana.In normalRinger, the rate coefficient of 22Na efflux is nearly proportional to theinternal Na concentration, i.e., Hill's coefficient in the dependency of Naefflux on internal Na concentration was around two.As long as insulin is present in the bathing solution, the rate coefficient of 22Na efflux retainsthe stimulated level.Insulin caused a leftward shift of the relationship between Na efflux and the logarithm of internal Na concentration, andconcomitantly decreased Hill's coefficient.A model of the coupling of Na transport and hydrolysis of ATP was proposed.The theoretical relation derived from this model accounted for these findings quitesatisfactorily.According to this model, insulin shifts as a cofactorthe equilibrium between dephosphorylated and phosphorylated states of carriers, whose Na binding sites are not occupied by Na, toward the phosphorylated state.
