Does prevention of free radical reactions influence digoxin-arrhythmias

In the present study, the possible role of oxygen-derived free radicals (OF R) on digoxin- (0.6 mg/kg(-1) IV bolus) induced arrhythmias of anesthetized guinea-pigs has been investigated. Guinea-pigs (300-400 g) of either sex w ere anesthetized with urethane (1.5 g/kg(-1), IF), and their trachea for re spiration,left common carotid artery for blood pressure monitoring, and rig ht jugular vein for drug administration were cannulated. ECG and haemodynam ics were recorded throughout the experiments. None of the agents used [N-ac etyl-L-cysteine (20 mg/kg(-1) IV bolus), or SOD (30,000 IU/kg(-1) IV bolus) + catalase (15,000 IU/kg-1 IV bolus)] significantly inhibited the arrhythm ias except desferrioxamine which reduced the incidence of ventricular fibri llation and arrhythmia score. Desferrioxamine, by acting intracellularly un like other agents used, might prevent the reduction of Fe+3 by ascorbate an d superoxide anion thus inhibiting the formation of cytotoxic hydroxyl radi cal in this experimental setting. (C) 1999 Elsevier Science Inc. All rights reserved.