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 IC 50 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.