[Hydrogen sulfide induce negative inotropic effect in isolated hearts via KATP channel and mitochondria membrane KATP channel]

Hydrogen sulfide (H(2)S) dilates blood vessels in vivo and in vitro probably by opening vascular smooth muscle K(+)-ATP channels. The study was designed to observe the role of mitochondria membrane K(ATP) channel blocker (5-HD) in the regulation of cardiac function isolated perfused heart of rat with H(2)S.The isolated rat heart was perfused in a Langendorff apparatus. After 20 minutes of stabilization, physiological concentration of NaHS (H(2)S donor, 100 micromol/L) was continuously perfused for 20 min in group A (n = 6), isolated hearts in group B (n = 6) and C (n = 7) were pretreated with nonspecific K(ATP) channel blocker glibenclamide (100 micromol/L) or 5-HD (100 micromol/L) for 5 minutes then perfused with NaHS (100 micromol/L) for 10 minutes. Heart rate (HR), left ventricular developed pressure (DeltaLVP), dp/dt(max) and dp/dt(min) and coronary perfusion flow (CPF) were measured.Post continuous perfusion of NaHS at physiological concentration for 20 minutes, DeltaLVP, dp/dt(max) and dp/dt(min) all significantly decreased while HR and CPF remained unchanged compared to baseline levels (all P0.05). The negative inotropic effect of H(2)S could partly be blocked by nonspecific K(ATP) channel blocker glibenclamide and mitochondria membrane K(ATP) channel blocker 5-HD.Present findings suggested that H(2)S at physiological concentration could produce negative inotropic effect in isolated hearts and this effect was mediated by K(ATP) channel and mitochondria membrane K(ATP) channel.