Molecular Mechanism for H2S-Induced Activation of KATP Channels

Abstract Hydrogen sulfide (H2S) is an endogenous opener of KATP channels in many different types of cells. However, the molecular mechanism for an interaction between H2S and KATP channel proteins remains unclear. The whole-cell patch-clamp technique and mutagenesis approach were used to examine the effects of H2S on different KATP channel subunits, rvKir6.1 and rvSUR1, heterologously expressed in HEK-293 cells. H2S stimulated coexpressed rvKir6.1/rvSUR1 KATP channels, but had no effect on KATP currents generated by rvKir6.1 expression alone. Intracellularly applied sulfhydryl alkylating agent (N-ethylmaleimide, NEM), oxidizing agent (chloramine T, CLT), and a disulfide bond–oxidizing enzyme (protein disulfide isomerase) did not alter H2S effects on this recombinant channels. CLT, but not NEM, inhibited basal rvKir6.1/rvSUR1 currents, and both abolished the stimulatory effects of H2S on KATP currents, when applied extracellularly. After selective cysteine residues (C6S and C26S but not C1051S and C1057S) ...