Effects of Salusin-β on action potential and ionic currents in ventricular myocytes of rats

Abstract

Salusin-β is a regulatory peptide that exerts negative inotropic effect on ventricular muscle, but its electrophysiological effects on ventricular myocytes are still unknown. Action potential and channel currents such as sodium current (I(N) (a) ), transient outward potassium current (I(to) ), steady-state potassium current (I(sus) ), sodium-calcium exchange current (I(N) (aCa) ) and inward rectifier potassium current (I(K) (1) ) were measured in ventricular myocytes isolated from 12 to 16weeks rats by whole-cell voltage-clamp techniques. Salusin-β dose-dependently shortened the duration of action potential in rat ventricular myocytes. Furthermore, salusin-β significantly inhibited I(N) (aCa) and increased I(to) , but did not affect I(N) (a) , I(sus) and I(K) (1) . These results suggest that the effect of salusin-β on action potential may be partly attributed to a decrease in inward currents and an increase in outward currents.