Carvedilol Inhibits Na^＋ Current in Rat Ventricular Myocytes

Objectives The effects of carvedilol on sodium current （INa） were investigated in isolated adult rat ventricular myocytes. Methods Single ventricular myocytes were enzymatically dissociated. INa was recorded by whole-cell patch- clamp recording technique. Results an IC50of （6. 35 - 0.40） mol . L^- 1. Carvedilol reversibly inhibited INa in a concentration-dependent manner, with 2. This inhibition was voltage- and frequency-dependent. 3. Carvedilol decreased the peak of the I-V relationship curve at -35 mV from （17.31± 1.68） pA/pF to （6. 58 ± 1.35） pA/pF, but did not change active potential, peak potential and the reverse potential significantly. 4. The steady-state inactivation curve of INa was shifted to more negative potentials. Conclusions Carvedilol inhibits INa in adult rat ventricular myocytes by mechanisms involving preferential interaction with the inactivated state of sodium channel.