Anti-arrhythmic effect of nadolol in experimental arrhythmias: comparison with propranolol and alprenolol

The effects of nadolol on experimental arrhythmias were investigated and compared with those of propranolol and alprenolol. The arrhythmias were induced by either ouabain, holothane plus adrenaline or acute coronary occlusion in anesthetized dogs. All three beta-blocking drugs in a dose range of 10 to 200 micrograms/kg inhibited halothane plus adrenaline-induced arrhythmias. These drugs also attenuated coronary occlusion-induced ventricular arrhythmias as well as other electrical abnormalities such as electrical alternation and conduction delay. Among the three drugs, nadolol was the most potent in suppressing both types of arrhythmias. Contrary to the potent effects on these arrhythmias, nadolol was ineffective against ouabain-induced arrhythmias even in a dose of 3 mg kg, while propranolol and alprenolol were significantly effective in a dose of 100 micrograms/kg. It is probable that the anti-arrhythmic effect of nadolol is exclusively due to its beta-blocking activity.