Biphasic effects of H2O2 on BKCa channels

The inhibitory or activating effect of H2O2 on large conductance calcium and voltage-dependent potassium (BKCa) channels has been reported. However, the mechanism by which this occurs is unclear. In this paper, BKCa channels encoded by mouse S/o were expressed in HEK 293 cells and BKCa channel activity was measured by electrophysiology. The results showed that H2O2 inhibited BKCa channel activity in inside-out patches but enhanced BKCa channel activity in cell-attached patches:The inhibition by H2O2 in inside-out patches may be due to oxidative modification of cysteine residues in BKCa channels or other membrane proteins that regulate BKCa channel function. PI3K/AKT signaling modulates the H2O2-induced BKCa channel activation in cell-attached patches. BKCa channels and PI3K signaling pathway were involved in H2O2-induced vasodilation and H2O2-induced vasodilation by PI3K pathway was mainly due to modulation of BKCa channel activity.