Differential effects of superoxide dismutase on high energy phosphates, creatine kinase release, and arrhythmias during post-ischaemic reperfusion in isolated rat hearts.

In isolated rat hearts, 25 min of global ischaemia led to significant decreases in the ATP, creatine phosphate (CP), and glycogen contents and increased glucose-6-phosphate (G-6-P) and lactate in the myocardium. During a subsequent reperfusion for 15 min only the CP level, but not ATP and glycogen were restored. G-6-P and lactate were reduced, but remained still elevated in comparison with non-ischaemic hearts. The post-ischaemic coronary flow volume and creatine kinase (CK) release increased significantly compared with preischaemic values. Arrhythmias such as extrasystoles, ventricular tachycardia, flutter and fibrillation, occurred, especially during the first few minutes of reperfusion. Application of the oxygen radical scavenger, superoxide dismutase (SOD), enhanced the myocardial creatine phosphate content during reperfusion. In fibrillating hearts, SOD also increased the ATP content in comparison with non-treated hearts. Superoxide dismutase was effective only during reperfusion and not during the preceding ischaemia. Neither the CK release nor reperfusion arrhythmias were decreased by the radical scavenger. The results suggest that the superoxide radical is involved in the reduction of high energy phosphates during post-ischaemic reperfusion and that this effect can be antagonised by the superoxide anion scavenger superoxide dismutase.