Inhibition of L-type calcium currents by salusin-β in rat cardiac ventricular myocytes

Salusin-β is a new regulatory peptide relevant to the cardiovascular system and exerts negative inotropic effect on ventricular muscle. The purpose of the present study was to determine whether salusin-β can inhibit cardiac L-type calcium channel current (ICa,L). Using whole-cell voltage-clamp techniques, ICa,L was measured in ventricular myocytes isolated from 12 to 16 weeks rats. Salusin-β dose-dependently and reversibly reduced the magnitude of ICa,L in rat ventricular myocytes. Neither threshold potential nor the peak potential of current–voltage relationship was affected. Salusin-β increased the rate of ICa,L inactivation without altering its gating properties. These results suggest salusin-β inhibited ICa,L by increasing the rate of ICa,L inactivation and the inhibition of L-type Ca2+ channels induced by salusin-β may contribute to its negative inotropic effect on ventricular muscle.