Figure 4.

Differential BK_Ca channel activity measured by membrane potential in breast cancer cell lines. The BK_Ca channel activity was measured in the presence of its activator NS-004 with and without siRNA for KCNMA1 gene. Pretreatment of breast cancer cell lines with siRNA significantly (*p < 0.046; **p < 0.001) inhibited the BK_Ca channel activity following addition of NS-004. Note: Decreased drop in fluorescence (indicator of BK_Ca channel opening/activity) of siRNA + NS-004- treated cells compared to NS-004 treated cells demonstrates that BK_Ca channel activity was inhibited by addition of siRNA to cells, as fluorescence quenching is an indirect measure of K⁺ ion-mediated hyperpolarization (hyperpolarization is caused by efflux of K⁺ through K⁺ channels), shown in the Y-axis. Bars represent the mean and standard error of the mean obtained from three different experiments in triplicate (n = 9).