THE CELLULAR ELECTROPHYSIOLOGICAL EFFECTS OF TEDISAMIL IN HUMAN ATRIAL AND VENTRICULAR FIBERS

The cellular electrophysiological effects of 1 mu M tedisamil (KC 8857 ) were studied in human atrial and ventricular fibers. Conventional mi croelectrode technique was applied to record the transmembrane action potentials at stimulation frequency of 100 per min and 37 degrees C. T edisamil lengthened action potential duration (APD) more in atrial tha n in ventricular muscle fibers; prolongation of APD(90) was 28.9+/-3.3 % (n=6; p<0.05) for atrial and 13.3+/-5.2% (n=6; P<0.05) for ventricul ar tissue. The maximal rate of depolarization was depressed slightly, but significantly by 1 mu M tedisamil only in ventricular fibers (12.9 +/-6.5%, n=6, P<0.05). From these cellular electrophysiological data i t is concluded that the bradycardic/antiischemic agent tedisamil posse sses marked Class III properties not only in cardiac tissues of experi mental animals but also those of man.