Effects of aspirin and indomethacin on ventricular arrhythmias--comparative study.

The effects of aspirin and indomethacin on the ventricular arrhythmias produced by ligation (ischaemia) and unligation (reperfusion) of the circumflex branch of the left coronary vessel were evaluated in fifty male rabbits weighing 1.5-2 kg. Pretreatment of animals with aspirin (50 mg/kg i/v) suppressed all arrhythmias during ischaemia. Low dose of aspirin (12.5 mg/kg i/v) produced no mortality. Indomethacin (2.5 mg/kg) was unable to control ischaemia and reperfusion-induced ventricular arrhythmias. However, higher doses of indomethacin (50 mg/kg) suppressed ischaemia-induced arrhythmias to some extent but the mortality rate was increased (37%). Fragment of ventricular fibrillation was zero during ischaemia after treatment with aspirin and indomethacin but reperfusion-induced ventricular fibrillation was not controlled by any of these drugs. Aspirin (12.5 mg/kg, 50 mg/kg) and indomethacin (2.5 mg/kg) significantly suppressed ischaemia--induced tachyarrhythmias while reperfusion induced tachyarrhythmias were suppressed only by aspirin. There was no significant effect on the mean arterial pressure after these drug treatments.