Triphasic relaxations arise from closed-channel block, but do not clearly distinguish among different models of closed-channel block. (A) These traces replot Fig. 8 A to allow comparison to simulated currents. Red traces correspond to +240 mV. (B) Currents were simulated using Scheme 2a with activation rates given in Table I, with the effective [blocker] = 5.71 * K_do, with z_o = z_c = 0.2 e. Top traces correspond to 4 µM Ca²⁺ and the bottom traces to 300 µM. When z_o = z_c = 0.1 e, the triphasic relaxations were not as obvious. (C) Currents were simulated with Scheme 2b with z_c = 0.0. No triphasic relaxations are observed. (D) Currents were simulated with Scheme 2b′ but with a ratio of K_do/K_bc based on fitted values from Fig. 4 F. Again, no triphasic relaxation is observed. (E) Currents were simulated with Scheme 3a with z_o = z_c = 0.1 e. (F) Currents were simulated with Scheme 3b (z_o = 0.1 e and z_c = 0.0 e). (G) Currents were stimulated with values corresponding to the fitted values of Scheme 3b′ from Fig. 4 G.