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 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. 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.
