Aim: It has been reported that salusin-b is a regulatory peptide that exerts negative inotropic effect on ventricular muscle,but its electrophysiological effects on ventricular myocytes are still unknown.Methods: Action potential and channel currents such as sodium current (INa),transient outward potassium current (Ito),steady-state potassium current (Isus),sodium–calcium exchange current (INaCa) and inward rectifier potassium current (IK1) were measured in ventricular myocytes isolated from 12 to 16 weeks rats by whole-cell voltage-clamp techniques.Results: Salusin-b dose-dependently shortened the duration of action potential in rat ventricular myocytes.Furthermore,salusin-b significantly inhibited INaCa and increased Ito,but did not affect INa,Isus and IK1.Conclusion: These results suggest that the effect of salusin-b on action potential may be partly attributed to a decrease in inward currents and an increase in outward currents.