Crebanine inhibits voltage-dependent Na⁺ current in guinea-pig ventricular myocytes

AIM:To study the effects of crebanine on voltage-gated Na+ channels in cardiac tissues.METHODS:Single ventricular myocytes were enzymatically dissociated from adult guinea-pig heart.Voltage-dependent Na+ current was recorded using the whole cell voltage-clamp technique.RESULTS:Crebanine reversibly inhibited Na+ current with an IC50 value of 0.283 mmolL-1(95% confidence range:0.248-0.318 mmolL-1).Crebanine at 0.262 mmolL-1 caused a negative shift(about 12 mV) in the voltage-dependence of steady-state inactivation of Na+ current,and retarded its recovery from inactivation,but did not affect its activation curve.CONCLUSION:In addition to blocking other voltage-gated ion channels,crebanine blocked Na+ channels in guinea-pig ventricular myocytes.Crebanine acted as an inactivation stabilizer of Na+ channels in cardiac tissues.