Fig 6. ER Ca²⁺ contribution to SK current.

(A) Application of CPA to empty ER Ca²⁺ stores significantly reduced SK current (orange, n = 6, Wilcoxon signed rank test, p = 0.0313) and further application of 10 μM H89 to inhibit PKA activity further significantly reduced SK current (brown, n = 6, Wilcoxon signed rank test, p = 0.0313), but does not reduce it any further than H89 alone (Mann-Whitney U test, p = 0.1320). Inhibiting ryanodine receptors with 10 μM dantrolene did not change SK current (black, n = 4, Wilcoxon signed rank test, p = 1.00). (B) Left, an example experiment showing the effect of DHPG application on ER Ca²⁺ levels. Right, summary of normalized data showing a small, but not significant change in induced ER Ca²⁺ release after application of H89 (n = 4) compared to control (n = 7) recordings (Mann-Whitney U test, p = 0.2303).