Enhanced protection of rat hearts during ischemia by phosphoenolpyruvate and ATP in cardioplegia.

The paracorporeal rat heart model was used to investigate the extent of myocardial protection by potassium cardioplegia supplemented with phosphoenolpyruvate (PEP) (14.4 mM) and ATP (0.067 mM) singly or in combination. Rat hearts were subjected to 30 minutes of ischemia at 37 degrees. They were subsequently reperfused for 40 minutes during which time the left ventricular isovolumic work was measured and blood samples were taken for creatine kinase isoenzyme MB (CK-MB) analysis. At the end of each experiment the hearts were freeze-clamped for later analyses of high energy phosphate compounds. Supplementation with PEP and ATP (Group I) and with only ATP (Group II) showed a significantly better left ventricular isovolumic work and a significantly higher adenylate charge potential (ACP). Supplementation with only PEP (Group III) resulted in significantly better left ventricular isovolumic work than the control group but significantly lower than groups I and II. There were no significant differences between the groups in regard to the CK-MB efflux. Supplementation with PEP and ATP in combination did not show any positive effect at 40 minutes of reperfusion over and above that which was achieved with ATP only.