中文摘要：

目的研究维拉帕米对快速心房起搏家兔心房有效不应期（AERP）和单相动作电位（MAP）的影响，探讨其抗心律失常的机制。方法24只家兔分为对照组、快速起搏组和维拉帕米组，每组各8只。经颈内静脉将电极置人右心房。分别测定各组基础状态，以600次／min行快速心房起搏和快速起搏同时给予药物维拉帕米后测定2、4、6、8h的心房有效不应期（AERP200和AERP150）和MAP90.结果快速心房起搏组在不同基础刺激周长作用下的AERP缩短，AERP300-150的频率适应性不良，P8与起搏前P0比较差异有统计学意义（P〈0．05），同时MAP90相应缩短。维拉帕米组AERP基本无改变，AERP200-150频率适应性维持，MAP90无明显改变（P〉0．05）。结论维拉帕米可能因减轻钙超载而抑制快速心房起搏所致电重构，即同时延长AERP和MAP，发挥其抗心律失常作用。

英文摘要：

Objective To investigate the effects of Verapamil on atrial effective refraction period （AERP） and monophasic action potential （MAP） by rapid atrial pacing in rabbits and to explore the mechanism of antiarrhythmia effects of Verapamil. Methods Twenty-four rabbits were randomly divided into control group （ n = 8 ）, rapid pacing group （ n = 8） and Verapamil group （n = 8 ）. AERP and MAP duration （MAPD） were determined by programmed electrical stimulation before and 2 h, 4 h, 6 h, and 8 h after pacing. Results Compared with control group, the AERP and MAPD were shortened and the rate adaptation of AERP was lost in rapid pacing group （ P 〈 0. 05 ）, while in verapamil group the shortening of AERP and MAPD were reversed, the rate adapation was maintained （ P 〉 0. 05 ）. Conclusions Short episodes of rapid atrial pacing may induce atrial electrical remodeling including shortening of AERP and MAPDgo. Verapamil can decrease the extent of atrial electrical remodeling.