Local (Hill) analysis of Monte Carlo–simulated ionic currents for Scheme 4. W_H[g], shown as dots (f_s = 5 kHz and f_c = 1 kHz, post-filtered to 0.1 kHz), was plotted for [Ca²⁺]_i = 10⁻³ and 10³ µM. The data were taken from a single voltage-ramp experiment and, for purposes of clarity, was decimated fivefold. The dashed curves are the true, numerically derived curves, with three of the four asymptotic lines shown (dotted lines). The vertical axis measures pore opening probability P_O = G/G_max.