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Electrophysiological effects of antiarrhythmic drug UK-68798 on different AV nodal cells in rabbit heart

Gao Tianli, Beyer T, Brachmann J

Department of Biology, Beijing University. Beijing

Abstract

By means of microelectrode techniques the electrophysiological effects of a new class Ⅲantiarrhythmic agent, UK-68798 (Dofetilide), were investigated on atrionodal (AN), nodal(N), nodal-His(NH)and His (H) cells in the AVN area of rabbit heart. UK-68798(5×10~(-9)to 5×10~(-6)mol/L)had no effect on APA and RP of the 4 kinds of cells but caused a dose-dependent decrease in AVN spontaneous rhythm without changing the A-H conduction time. APD_(50) and APD_(90) were prolonged markedly by the drug in a dose-dependent manner. Among the 4 kinds of cells, N cell had the highest percentage increment in APD, indicating a prominent sensetivity to the drug. The effective refractory periods (ERP) of the 4 kinds of cells were lengthened also in a dose-dependent manner. However, ERP corresponding repolarization membrane potentials(ERP-RMP) of the 4 kinds of cells were not affected by the drug. suggested that though ERP increased in parallel with APD prolongation, the homogeneous △ERP% and unchanged ERP-RMP values of the 4 kinds of cells would prevent the AVN area from becoming a source of reentry arrhythmias under the action of UK-68798.

Key words: UK-68798;Atrioventricular node;Action potential duration;Effective refractory period

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Citing This Article：

Gao Tianli, Beyer T, Brachmann J. Electrophysiological effects of antiarrhythmic drug UK-68798 on different AV nodal cells in rabbit heart. Acta Physiol Sin 1994; 46 (3): (in Chinese with English abstract).