Kinetic parameters of simulated data. (A) Pooled P_o values obtained from analysis of simulated single-channel data from all eight individual channels exhibit a sigmoidal relationship with increasing [Ca²⁺]_cyt when fitted with a log [agonist] versus response curve where the EC₅₀ was 1.75 ± 0.59 µM and the Hill coefficient was 1.52 ± 0.84 (n = 8). Simulated data were obtained from models derived at 0.25, 1, 10, 100, and 200 µM [Ca²⁺]_cyt. (B and C) The relationships of closed (T_c) and open times (T_o), respectively, when activated by [Ca²⁺]_cyt. The data points are color coded according to the single channels used to derive the models (see Fig. S1). For clarity, these data are displayed on the same axes as in Fig. 2.