Effects of adrenergic beta-blockers and a membrane stabilizing agent on ouabain-induced cardiac arrhythmias in anaesthetized guinea pigs.

The antiarrhythmic effects of dl'propranolol, d-propranolol, metoprolol and lidocaine against ouabain-induced cardiac arrhythmias were studied. It was found that contrary to earlier findings in the dog, the effects of the adrenergic beta-blockers against ouabain-arrhythmias in guinea pigs were due to beta-blocking activity and not the membrane-stabilizing activity of the compounds. The cardioselective beta-blocker, metoprolol, was more or equally effective as dl-propranolol against ouabain-induced arrhythmias in guinea pigs.