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

AimTo study the effects of crebanine on voltage-gated Na+ channels in cardiac tissues.MethodsSingle ventricular myocytes were enzymatically dissociated from adult guinea-pig heart. Voltage-dependent Na+ current was recorded using the whole cell voltage-clamp technique.ResultsCrebanine reversibly inhibited Na+ current with an IC50 value of 0.283 mmol·L−1 (95% confidence range: 0.248–0.318 mmol·L−1). Crebanine at 0.262 mmol·L−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.ConclusionIn 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.