PROPRANOLOL MJ 1999 AND CIBA 39089 BA IN OUABAIN AND ADRENALINE INDUCED CARDIAC ARRHYTHMIAS

The threshold anti-arrhythmic doses of the (3-receptor antagonists propranolol, MJ 1999' (4-(2-isopropylamin o1-hydroxyethyl)-methanesulphonanilide) and Ciba 39089 Ba (1-isopropylamino-2-hydroxy-3-(0-allyloxyphenoxy)propane) required to prevent or revert arrhythmias induced by adrenaline-methylchloroform and ouabain respectively were determined in chloralose anaesthetised cats. Quinidine-like activity was assessed by determining changes in the effective refractory period of rabbit auricles, local anaesthesia using the rabbit cornea and mouse tail-clip methods and β-receptor blockade in cats was determined against isoprenaline induced tachycardia. Low doses of the three antagonists, which could be expected to produce specific β-receptor blockade, abolished adrenaline-induced arrhythmias, and reverted ouabain-induced arrhythmias in 20% of the experiments performed. Such doses could be correlated with the clinically effective doses required to abolish adrenaline-halothane and digitalis-induced arrhythmic activity. In the remaining experiments the quinidine-like activity of the drugs appeared to be responsible for the reversion of the ouabain arrhythmias, 20 to 50 times the dose required to abolish adrenaline arrhythmias was necessary. © 1968.