T-butyl hydrogen peroxide increases the activities of the Maxi-K channels of rat brain

In this study, we investigated the effects of tertiary-butyl hydrogen peroxide (tBHP) on the large-conductance Ca2+-activated K+ (Maxi-K) channel of rat brain using lipid bilayer. When tBHP was applied to the cytosolic side, the open probability (Po) of both fast- and slow-gating Maxi-K channels increased within 1 min in dose-dependent manner. tBHP effects did not reverse immediately, suggesting tBHP induces some chemical modification on the channel protein. From kinetic analysis of single channel data, the increase in the Po appears to be mainly due to shortening of closed dwell time in both types of the Maxi-K channels. 50 microM diamide, a sulfhydryl-specific oxidant, irreversibly decreased the Po. However, further addition of 7.3 mM tBHP still increased the Po, suggesting that tBHP does not share the target for oxidation with diamide.