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在离体家兔房室结(AVN)区标本上,用微电极技术研究了Ⅲ类抗心律失常新药UK-68,798对AN、N、NH、H 4种细胞的电生理效应。浓度为5×10~(-9)至5×10~(-6)mol的UK-68,798对上述4种细胞的APA、RP皆无影响,对AVN的自搏频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~(-6)mol的剂量范围,UK-68,798使APD_50和APD_(90)发生剂量依赖性延长.4种细胞中以N细胞的APD_(50)和APD_(90)延长百分率最高。各类细胞APD_(90)延长百分率依大小排列,其次序为N>AN>H>NH.例如当浓度为5×10~(-6)mol时4类细胞APD_(90)的延长百分率分别为95±26％(N)、75±22％(AN)、63±26％(H)、46±
Electrophysiological effects of a class III antiarrhythmic new drug UK-68,798 on AN, N, NH, H 4 cells were studied using microelectrode technique in a rabbit atrioventricular node (AVN) region. UK-68,798 at a concentration of 5 × 10 -9 to 5 × 10 -6 mol had no effect on the APA and RP of the above four cells, and slowed down the spontaneous firing rate of AVN in a dose-dependent manner But did not change the conduction time of AH.During the dose range of 5 × 10 -8 to 5 × 10 -6 mol, UK-68,798 prolonged APD_50 and APD_90 in a dose-dependent manner The percentages of APD_ (50) and APD_ (90) in N-cell were the highest. The percentages of APD_ (90) in different types of cells were arranged in order of size, with the order of N> AN> H> NH. For example, the percentage elongation of APD_ (90) 95 ± 26% (N), 75 ± 22% (AN), 63 ± 26% (H), 46 ±