Temperature dependency of the rate and equilibrium constants to open channels in Hi-Na ⁺ and in Hi-K ⁺ (cyan and pink symbols, respectively). (A) The K_D at 0 mV. K_D were calculated from Eq. 3 with the determination of ss at different voltages and fit to Eq. 4 (Fig. 2, D and D′). The continuous lines are drawn assuming ΔG° = 22.6 kJ/mol for Hi-K⁺ and −1.2 kJ/mol for Hi-Na⁺. Vertical error bars are the standard error of the fit. Horizontal error bars are SD. (B) Effective valence of the voltage dependency (zδ) from the above fits to Eq. 4. The solid lines do not have any physical meaning. Vertical error bars are the SE of the fit. (C) Dissociation rate constant measured at +60 mV (see Fig. 2, E and E′). The solid lines were drawn from Eq. 5 with ΔH^≠ = = 9.3 ± 5.9 kJ/mol and 17.2 ± 3.8 kJ/mol for Hi-Na⁺ and Hi-K⁺, respectively (standard error of the fit). Horizontal error bars are SD. (D) Association rate constant measured at +60 mV (see Fig. 2, E and E′). The solid lines were drawn from Eq. 5 with ΔH^≠ = = 19.1 ± 5.4 kJ/mol and 46.9 ± 7.1 kJ/mol for Hi-Na⁺ and Hi-K⁺, respectively. In C and D, data are mean ± SD; asterisks indicate statistical differences between data obtained at similar temperatures (P value <0.05). See also Data S4 for a summary of experimental data in open channels.