EFFECT OF ARRESTED REOXYGENATION ON MYOCARDIAL HIGH-ENERGY PHOSPHATE RECOVERY IN A RAT MODEL OF STUNNED MYOCARDIUM

The effect of temporary cardiac arrest during reoxygenation on the pos t-anoxic recovery of myocardial high energy phosphates and cardiac fun ction was studied in an isolated perfused rat heart model of stunned m yocardium. The hearts were subjected to 20 min of anoxia followed by 6 0 min of reoxygenation. Cardiac arrest was maintained for the initial 30 min of reoxygenation either by membrane depolarization with a high K+ perfusate (high K+ group) or by excitation-contraction uncoupling w ith 2,3-butanedione monoxime (BDM group). These groups were compared w ith a group of hearts subjected to unmodified reoxygenation (control g roup). Myocardial high energy phosphates were continuously measured by P-31-NMR spectroscopy. Although creatine phosphate increased to a sup ranormal level during early reoxygenation in all three groups, it retu rned faster to the preanoxic level in the high K+ and BDM groups compa red with the control group. Both myocardial oxygen consumption and car diac function (as assessed by the rate pressure product) were signific antly better in the high K+ and BDM groups compared with the control g roup at the end of reoxygenation. These results suggest that temporary cardiac arrest during initial reoxygenation may ameliorate the distur bance of myocardial energy metabolism and improve cardiac function aft er anoxia.