中文摘要：

目的在心肌兴奋的绝对不应期给予电刺激，虽然不会引发兴奋，但可通过电一机械偶联机制增强心肌收缩力，改善心脏功能。本文采用心室肌细胞的LR91模型，通过计算机仿真方法，在动作电位绝不应期的不同时间给予不同形式的电刺激，以探讨其与细胞内Ca^2＋浓度的关系，初步研究了绝对不应期电刺激的作用机制。方法在心室肌细胞LR91模型上加脉冲宽度为1．5ms、电流强度为-30μAcm^-2的刺激（S1），引起细胞兴奋，从动作电位0相75ms之后，分别加入复极化刺激、除极化刺激、先复极化后除极化对称双向刺激（S2）。结果在绝对不应期加复极化刺激可明嶷增加Ca^2＋内流。绝对不应期刺激脉冲的幅度、宽度以及与动作电位。相上升支之间的时间间隔对细胞膜内Ca^2＋浓度影响较大。结论在绝对不应期适时加载幅度和脉宽适宜的复极化刺激脉冲可增加细胞膜内Ca^2＋的浓度。绝对不应期的复极化刺激引起Ca^2＋通道的电驱动力增加是Ca^2＋内流加大的主要原因。

英文摘要：

Objective The electrical stimulation during absolute refractory period does not induce excitation, but it can enhance the cardiac contractility and improve the cardiac function. The relationship between [Ca^2＋]; and different forms of electrical stimulation applied during absolute refractory period has been examed in this studg. Methods The excitement was induced by applying a S1 stimulate （current strength was-30μAcm^-2, pulse width was 1.5ms） at the LR91 model of mammalian ventricular cell. The S2 stimulates of repolarization, polarization and symmetric form of first repolarization and then polarization was applied to the cell at 75ms after the upstroke first phase of action potential. Results The inward calcium current was increased by applying repolarization stimulation during absolute refractory period. The [Ca^2＋]; was affected by the amplitude and width of the stimulate that was applied during absolute refractory period, The [Ca^2＋]; was also affected by the interval between the upstroke first phase of action potential and repolarization stimulation. Conclusions The [Ca^2＋]; can be increased by timely applying a repolarization stimulation with suitable amplitude and width during absolute refractory period. That the repolarization stimulation during absolute refractory enhances the electric driving force of calcium channel is the main cause of increasing the inward calcium current.