Yang B F, Zong X G, Wang G, Yao W X, Jiang M X
Department of Pharmacology, Tongji Medical University, Hankou.
Yao Xue Xue Bao. 1990;25(7):481-4.
The mechanism of antiarrhythmic action and the electrophysiologic effects of 7-bromoethoxybenzene-tetrahydroptamine (EBP) have been studied using conventional microelectrode technique. The effect of EBP on the membrane ISi and I(X) currents were investigated in the canine cardiac purkinje fibres using the double microelectrode voltage clamp methods. EBP was shown to increase the duration of action potential at 20 and 90% of repolarization of isolated guinea pig papillary muscles. However, the amplitude of action potential, the resting potential and the overshoot and maximum rate of 0 phase depolarization (Vmax) remained unchanged. The membrane potential was held at 40 mV and command potential at -15 mV, 0.3 Hz 500 ms. After 10 min of perfusion of EBP 30 mumol/L, the slow inward current (ISi) was reduced markedly. When the holding potential was held at -20 mV, and the command potential at +10 mV, EBP (10-100 mumol/L) exerted a depressed effect on the delayed (outward) rectifier current (I(X)) in a dose-dependent manner. It may be concluded that the antiarrhythmic effects of EBP is mainly related to decrease the automaticity and prolong the duration of action potential at 20-90% of repolarization of isolated guinea pig papillary muscles.
采用传统微电极技术研究了7-溴乙氧基苯四氢普胺（EBP）的抗心律失常作用机制和电生理效应。使用双微电极电压钳方法，在犬心脏浦肯野纤维中研究了EBP对膜内向电流（ISi）和外向电流（I(X)）的影响。结果显示，EBP可增加离体豚鼠乳头肌复极化20%和90%时动作电位的持续时间。然而，动作电位幅度、静息电位、超射值和0期去极化最大速率（Vmax）均保持不变。将膜电位钳制在40mV，指令电位为-15mV，频率0.3Hz，波宽500ms。用30μmol/L的EBP灌注10分钟后，慢内向电流（ISi）显著降低。当钳制电位为-20mV，指令电位为+10mV时，EBP（10 - 100μmol/L）对延迟（外向）整流电流（I(X)）产生剂量依赖性抑制作用。可以得出结论，EBP的抗心律失常作用主要与降低离体豚鼠乳头肌复极化20% - 90%时的自律性和延长动作电位持续时间有关。
