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目的观察双苯氟嗪对豚鼠心室肌细胞膜钠电流的影响。方法用酶解方法分离豚鼠心室肌细胞,全细胞膜片钳技术记录钠电流。结果将细胞钳制在-80mV,给(-80～+50)mV,50ms和步阶10mV的去极化脉冲,记录到的电流被河豚毒素10μmol·L-1完全抑制。在该刺激条件下,该电流最大激活电压在-20mV左右,翻转电压在+30mV左右,提示该电流为钠电流。双苯氟嗪可以浓度依赖性地抑制钠电流。双苯氟嗪对钠电流的抑制作用在冲洗后可部分恢复,表明其对钠通道的抑制作用具有可逆性。双苯氟嗪可使钠电流I-V曲线上移,但对钠电流的电压依赖性特征、最大激活电压和翻转电压无明显影响。在双苯氟嗪40μmol·L-1存在下,最大激活电压下的峰值电流下降约46%;双苯氟嗪可明显使钠电流稳态失活曲线左移,但不影响曲线的斜率因子。双苯氟嗪40μmol·L-1可使钠电流半数失活电压从(-73.0±4.6)mV减少到(-82.8±7.2)mV。但双苯氟嗪对钠电流稳态激活无明显影响,在双苯氟嗪40μmol·L-1存在下,半数激活电压(-33.7±3.6)mV和斜率因子(5.6±2.4)mV与对照组激活电压(-34.9±5.1)mV和斜率因子(6.0±4.8)mV相比无显著性差异。双苯氟嗪可以使钠电流从失活状态下恢复明显减慢,双苯氟嗪40μmo·lL-1可使恢复时间常数延长(79±28)vs(36±11)ms。结论双苯氟嗪可以浓度依赖性、使用依赖性和频率依赖性地抑制心肌钠电流,并且主要作用于钠电流的失活状态。
Objective To observe the effect of dipfluzine on sodium current in guinea pig ventricular myocytes. Methods The guinea pig ventricular myocytes were separated by enzymolysis and the whole-cell patch-clamp technique was used to record the sodium current. Results The cells were clamped at -80 mV and depolarized (-80 ~ +50) mV, 50 ms and 10 mV steps were recorded. The currents recorded were completely inhibited by tetrodotoxin 10 μmol·L -1. Under this stimulus condition, the maximum activation current of this current is around -20mV and the over voltage is around + 30mV, suggesting that this current is sodium current. Dipfluzine inhibited sodium currents in a concentration-dependent manner. The inhibitory effect of dipfluzine on sodium current was partially recovered after rinsing, indicating that its inhibitory effect on sodium channel is reversible. Dipfluzine up-regulated the I-V curve of sodium current, but had no significant effect on the voltage-dependent characteristics of sodium current, the maximum activation voltage and the flip voltage. In the presence of dipfluzine 40μmol·L-1, the peak current decreased by about 46% under the maximum activation voltage. Dipfluzine significantly shifted the steady-state sodium inactivation curve to the left without affecting the slope factor of the curve. Diphenhydramine 40 μmol·L-1 reduced the half-sodium inactivation voltage from (-73.0 ± 4.6) mV to (-82.8 ± 7.2) mV. However, dipfluzine had no significant effect on the steady-state sodium current. The half activation voltage (-33.7 ± 3.6) mV and the slope factor (5.6 ± 2.4) mV in the presence of 40μmol·L- There was no significant difference in activation voltage (-34.9 ± 5.1) mV and slope factor (6.0 ± 4.8) mV. Dipfluzine significantly reduced sodium current recovery from inactivation, and the diphenflurazide prolongation of recovery time constant was (79 ± 28) vs (36 ± 11) ms with 40 μmol·L-1. Conclusion Dipfluzine can inhibit cardiac sodium current in a concentration-dependent and frequency-dependent manner and mainly act on the inactivation of sodium current.