论文部分内容阅读
Aim:N,N’-[oxybis(2,1-ethanediyloxy-2,1-ethanediyl)]bis(4-methyl)-benzenesuifonamide (OMBSA) is a hit compound with potent voltage-gated K+ (Kv) channel-blocking activities that was found while searching the MDL Avail-able Chemicals Directory with a virtual screening approach. In the present study, the blocking actions of OMBSA on Kv channels and relevant mechanisms were characterized. Methods:Whole-cell voltage-clamp recording was made in acutely dissociated hippocampal CA 1 pyramidal neurons of newb rats. Results:Superfusion of OMBSA reversibly inhibited both the delayed rectifier (IK) and fast transient K+ currents (IA) with IC50 values of 2.1±1.1 μmol/L and 27.8±1.5 μmol/L, respectively. The inhibition was voltage independent. OMBSA markedly acceler-ated the decay time course of IK, without a significant effect on that oflA. OMBSA did not change the activation, steady-state inactivation of IK, and its recovery from inactivation, but the compound caused a significant hyperpolarizing shift of the voltage dependence of the steady-state inactivation of IA and slowed down its recovery from inactivation. Intracellular dialysis of OMBSA had no effect on both IK and IA. Conclusion:The results demonstrate that OMBSA blocks both IK and IA through binding to the outer mouth of the channel pore, as predicted by the molecular docking model used in the virtual screening. In addition, the compound differentially moderates the inactivation kinetics of the K+ channels through allos-teric mechanisms.