[Biphasic effects of a combined administration of SOD and CAT on Ca overload and recovery of function and metabolites].

The present study was performed to clarify whether the combination of superoxide dismutase (SOD) and catalase (CAT) can reduce Ca2+ overload and improve recovery of function and metabolites during reperfusion in isolated globally ischemic rat hearts. In non-treated hearts, left ventricular developed pressure (LVDP) recovered to only 30% of the preischemic value with elevation of left ventricular end-diastolic pressure (LVEDP) after 30 min of reperfusion following 30 min of global zero-flow ischemia. ATP and CP fell by 40% and 60%, respectively with 13 fold increase in Ca2+ uptake. A combined administration of SOD and CAT at low concentrations improved recovery of function (LVDP to 60%), reduced Ca2+ uptake (10 fold) without any improvement in high energy phosphates. However a combination of SOD and CAT at higher concentrations did not improve, or even deteriorate functional and metabolic recovery with increased Ca2+ overload (12 to 14 fold). These results indicated that the extracellular free radical scavengers, SOD and CAT, had a biphasic effect on reperfusion injury and could be partially beneficial at low concentrations.