Simulated STOCs recapitulate the salient feature of STOCs recorded experimentally. (A) The time course of I_BKs (top) generated by each BK channel punctum as marked in Fig. 5 and the underlying [Ca²⁺] (bottom) as a result of a Ca²⁺ spark with an average I_Ca(spark) (see Materials and methods). The middle row shows the corresponding P_o of BK channels in each punctum. E_k is −80 mV, and the holding potential is 0 mV. The three dotted lines mark the onset of I_BK decay. The far right trace in the top row is the STOC created by adding the I_BKs from the three puncta near this RYR2 punctum. (B) The parameters of simulated STOCs (open bars) activated by RYR2s resemble those from measured STOCs (closed bars). Simulated STOCs were obtained based on the spatial relationship between RYR2 and BK channels as shown in Fig. 5, and experimental STOCs were measured at 0 mV (E_k, −80 mV). Data are means ± SEM.