Effects of Notoginsenoside Fc on Sodium Ion Channel Currents in Ventricular Myocytes of SD Rats

OBJECTIVE To explore the effects of notoginsenoside Fc(N-Fc) on sodium ion channel currents of ventricular myocytes in SD rats. METHODS Ventricular myocardial cells were enzymatically isolated from SD rats by Langendorff with constant pressure and temperature, the whole-cell patch clamp techniques were used to observe and record the effects of I_Na and its kinetics in ventricular mgocytes of SD rats treated with different concentrations of N-Fc. RESULTS There was no significant effect on I_Na when the concentration of N-Fc was 5 µmol·L^–1, with the increase of drug concentration, the peak sodium current was decreased from (–87.49±3.40)pA/pF to (–62.91±2.37), (–49.30±1.27), (–34.68±3.21)pA/pF(P<0.01) under the effects of 10, 20 and 50 µmol·L^–1 N-Fc. I-V curve of I_Na were shifted upward, but the morphological trajectories, activation potential and peak potential did not change. The activation curve of I_Na were shifted to the depolarization direction, and the half in activation voltage was changed from (–52.37 ±1.32)mV to (–42.74 ±0.37), (–38.92 ±2.77), (–33.78 ±0.96)mV(P<0.05). The inactivation curve shifted significantly to the left, the half inactivation voltage changed from (–55.95±4.88)mV to (–64.29±1.77), (–69.57±3.47), (–73.32±3.79)mV(P<0.05). In addition, N-Fc significantly prolonged the recovery time after I_Na inactivation, and the time constant τ(before administration, after treated with 10, 20, 50 µmol·L ^-1N-Fc) were (12.50±1.17), (21.36±2.23), (25.35±1.25), (34.35±1.24)ms(P<0.05). CONCLUSION N-Fc can inhibit I_Na of SD rats ventricular myocytes in a concentration-dependent manner and it has an significant effect on the kinetics characteristics of activation, inactivation and recovery.