Combined effects of aspirin and propranolol on the tachyarrhythmias

ABSTRACT

We have observed the effects of aspirin and propranolol on the adrenaline-stimulated activity of the isolated auricles of the rabbit heart as well as on the ischaemia-induced and reperfusion-induced activity of the pentobarbitone-anesthetized rabbit heart. Aspirin [25-100 uM] has suppressant effects on the adrenaline-stimulated tachyarrhythmias of the isolated auricles. Aspirin [12.5 mg/kg] also suppresses ischaemia-induced and reperfusion induced tachycardia. These effects of aspirin are similar to propranolol [5x10[-8] M - 3x10[-6] M for isolated auricles and 0.02 mg/kg for pentobarbitone-anesthetized rabbits]. Aspirin-propranolol combination showed no significant effects on the isolated auricles of the rabbit heart while ischaemia-induced and reperfusion induced tachyarrhythmias are significantly suppressed. Therefore, we conclude that aspirin and propranolol alone have marked suppressant effects on the adrenaline-stimulated activity of isolated auricles while aspirin-propranolol combination has no such effect. On the other hand, low dose of aspirin and propranolol have significant suppressant effects on the ischaemia-induced and reperfusion-induced tachyarrhythmias and the combination of aspirin and propranolol showed potentiation in this type of tachyarrhythmias