Effects of free radical production and scavengers on occlusion-reperfusioninduced arrhythmias

Ventricular arrhythmias were studied in rat isolated hearts subjected to co ronary artery occlusion and reperfusion. Free radicals in the perfusate wer e detected by continuous flow luminol-enhanced chemiluminescence. Administr ation of purine (2.3 mM) and xanthine oxidase (0.12 U ml(-1) min(-1)) did n ot significantly modify the severity of reperfusion-induced arrhythmias but did generate free radicals. No free radical generation was detected during the period of coronary artery occlusion or reperfusion. Superoxide dismuta se (SOD) 20-80 U ml(-1) did not alter the severity of reperfusion arrhythmi as but, in the presence of 80 U ml(-1) SOD, occlusion-induced arrhythmias w ere augmented. SOD did not produce any effect on haemodynamics at the conce ntrations tested. Ventricular arrhythmias and cardiac haemodynamics were al so not significantly changed by the combination of scavengers, SOD (10 U ml (-1)), catalase (100 U ml(-1)) and mannitol (20 mM). These data suggest tha t the superoxide free radical is unlikely to be the primary cause of reperf usion induced arrhythmias in rat isolated hearts subjected to regional isch aemia. (C) 1998 The Italian Pharmacological Society.