在离体家兔ＡＶＮ区标本上，用微电极技术研究了Ⅲ类抗心律失常新药ＵＫ－６８７９８对ＡＮ，Ｎ，ＮＨ，Ｈ４种细胞的电生理效应。浓度５×１０－９至５×１０－６ｍｏｌ／Ｌ的ＵＫ－６８７９８对４种细胞的动作电位幅值（ＡＰＡ）、静息膜电位（ＲＰ）皆无影响。对ＡＶＮ的自搏率有剂量依赖性减慢作用，但不改变Ａ－Ｈ传导时间。在５×１０－８－５×１０－６ｍｏｌ／Ｌ剂量范围，此药使动作电位时程（ＡＰＤ５０）和（ＡＰＤ９０）发生剂量依赖性延长。４种细胞中以Ｎ细胞的ＡＰＤ５０和ＡＰＤ９０延长百分率最高。各种细胞ＡＰＤ９０延长百分率的排列次序为Ｎ＜ＡＮ＜Ｈ＜ＮＨ，当浓度为５×１０－６ｍｏｌ／Ｌ时的延长百分率分别为９５±２６％（Ｎ），７５±２２％（ＡＮ），６３±２６％（Ｈ），４６±２６％（ＮＨ）。在ＵＫ－６８７９８的作用下，４种细胞的有效不应期（ＥＲＰ）也发生剂量依赖性延长，但不存在像ＡＰＤ延长百分率那样的差别。此外，４种细胞ＥＲＰ所相当的复极化膜电位未受药物影响，从而避免了由于兴奋性恢复的不均一性，使ＡＶＮ区成为折返性心律失常的发源地． The electrophysiological effects of class III anti-arrhythmic drug UK-68798 on AN, N, NH, H 4 cells were studied using microelectrode technique in isolated rabbit AVN specimens. The concentration of 5 × 10-9 to 5 × 10-6mol / L of UK-68798 had no effect on the APA and resting membrane potential (RP) of the 4 kinds of cells. There was a dose-dependent slowdown of AVN self-paced rate, but no change in A-H conduction time. In the dose range of 5 × 10-8-5 × 10-6mol / L, the drug prolonged the dose-dependent action potential duration (APD50) and (APD90). Among the four kinds of cells, the percentages of N-cell APD50 and APD90 were the highest. The order of elongation of APD90 in various cells was N