Antiarrhythmic property of a new
adrenergic beta-blocking agent, dl-1-(tert.butylamino)-3[(2-propinyloxy) phenoxy]-
2-propanol hydrochloride (Kö 1400-Cl) was studied, using 1)
ouabain-induced
arrhythmia in the guinea pig, 2)
aconitine-induced
arrhythmia in the rat, 3)
arrhythmia induced by two-step
ligation of coronary artery (Harris's method) in the dog and 4)
halothane-
adrenaline arrhythmia in the dog and was compared with those of
propranolol,
oxprenolol,
procainamide and
ajmaline.
Procainamide and
ajmaline produced a marked protective effect against
aconitine-induced
ventricular extrasystole, but were not so effective against
aconitine-induced
ventricular fibrillation, while
oxprenolol and, to a lesser degree,
propranolol were effective against the latter type of
aconitine arrhythmias. Kö 1400-Cl proved to be ineffective. All the compounds tested produced a marked protective action against
ouabain-
arrhythmia. Whereas
procainamide was most effective in abolishing the ventricular
arrhythmia due to coronary-
ligation even on the first postoperative day, Kö 1400-Cl and
propranolol were almost ineffective on the first day. Even on the second postoperative day, the antiarrhythmic effects of these two beta-blockers were not remarkable, effective only in 2/4 animals in the case of Kö 1400-Cl and in 2/3 animals in the case of
propranolol. On the contrary, all the beta-blockers tested produced a protective action against
halothane-
adrenaline arrhythmia at much lower doses than against coronary
ligation arrhythmia. The potency ratio of Kö 1400-Cl and
propranolol was 3 : 1, which paralleled with beta-blocking activity of these compounds.