![Figure 6. A Ca2+ spark activates multiple clusters of BK channels to generate a STOC. (A) Calculated Po of a BK channel at 0 mV (red line) and −40 mV (green line) as a function of distance from the spark. Combining eq. 14 from Bao and Cox (2005) for the Po,ss ([Ca2+],V) and reaction-diffusion simulations of sparks that yield free [Ca2+](d,t) allows the calculation of Po,ss(d) (setting t = 9 ms, the peak of ICa(spark)). (B and C) Probability distribution of the number of BK channel clusters activated by RYR2 (B) and RYR1 (C) puncta. The function in A was applied to the spatial relationship between RYRs and BK channels as shown in Fig. 5 to derive the number of BK channel puncta being activated. Black lines are the count of the number of puncta within 600 nm. Red lines and green lines are the expected numbers of BK clusters activated at 0 mV and −40 mV, respectively, by weighting each nearby BK cluster by its Po. The expected value is Σi(Po,i), where Po,i is the Po of the i-th BK cluster within 600 nm of the RYR. Error bars represent means ± SEM. PDF, probability density function.](https://cdn.rupress.org/rup/content_public/journal/jgp/138/2/10.1085_jgp.201110626/5/jgp_201110626_rgb_fig6.jpeg?Expires=1767688255&Signature=YGUsxDm3Xs0V3a8BYAafIKaU~2cyEIF00WHRuZBZSkysOt4jrKyr0shirnOz8BJf15VZGG~AK7BoMAYcFU~BPciYIKnCrZhE0SxNnV4elueR6L3m81Tx~9MZFEBcDqe1ZKHXUkbcVUMpbsr5DGP6z0PQnRZzXdp4A8H0TblDYTFu79B7EPOy~g0a~7xw~tDWefUvU7-rlc0eoZ1eEqPNLQPmQ~RyD4ijQtAnStAGu-k69QImqY~nQ5fuhJh0cTQ6xmyLER76Y~m28nUP85BWJJ-NmjjomKQzqO1pHlRYvUIA~3rBpbamRqRlD0nDhOXkfO93OD-KuqCQd-uwbLsDwA__&Key-Pair-Id=APKAIE5G5CRDK6RD3PGA)
A Ca2+ spark activates multiple clusters of BK channels to generate a STOC. (A) Calculated Po of a BK channel at 0 mV (red line) and −40 mV (green line) as a function of distance from the spark. Combining eq. 14 from Bao and Cox (2005) for the Po,ss ([Ca2+],V) and reaction-diffusion simulations of sparks that yield free [Ca2+](d,t) allows the calculation of Po,ss(d) (setting t = 9 ms, the peak of ICa(spark)). (B and C) Probability distribution of the number of BK channel clusters activated by RYR2 (B) and RYR1 (C) puncta. The function in A was applied to the spatial relationship between RYRs and BK channels as shown in Fig. 5 to derive the number of BK channel puncta being activated. Black lines are the count of the number of puncta within 600 nm. Red lines and green lines are the expected numbers of BK clusters activated at 0 mV and −40 mV, respectively, by weighting each nearby BK cluster by its Po. The expected value is Σi(Po,i), where Po,i is the Po of the i-th BK cluster within 600 nm of the RYR. Error bars represent means ± SEM. PDF, probability density function.
