A P-31 NMR-STUDY OF PRECONDITIONED ISOLATED-PERFUSED RAT-HEART EXPOSED TO INTERMITTENT ISCHEMIA

Exposure to a short ischemic period (ischemic preconditioning, IP) wil l protect the heart from damage following a subsequent longer ischemic episode, The aim of the study was to test whether IP is cardioprotect ive in the setting of repeated ischemia-reperfusion cycles. Thus, Lang endorff-perfused hearts, exposed to IP, were subjected to three consec utive ischemia-reperfusion (10/15 min) cycles. Myocardial energetics, manifested by P-31 NMR spectroscopy, was correlated with hemodynamics, ATP recovery was significantly higher for the IP group compared with control (P < 0.02) during reperfusions, However, there was no signific ant difference in ATP recovery during the three ischemic intervals. Th e supernormal recovery of phosphocreatine recorded during reperfusion was lower for the IP group (similar to 120%) compared with control (si milar to 135%, P < 0.065), Better recovery of the left ventricular-dev eloped pressure was noted during reperfusions for the IP group and bec ame significant only during the last reperfusion (86% versus 68%, P < 0.025). In conclusion, the above results support prolonged IP cardiopr otection.