Association Of Pre-Ischaemic Disturbances In Energy Metabolism With Postischaemic Dysfunction Of The Rat Isolated Working Heart

1, Metabolic and functional effects of two protocols of preconditioning mew compared in rat isolated hearts subjected to 20 min global ischaemia (37 degrees C) and reperfusion (30 min Langendorff + 15 mill working). Prior to the ischaemic period, hearts were perfused according to Langendorff (control group) or were preconditioned by three 5 min cycles or two 10 min cycles of ischaemia and reperfusion (PC-I and PC-II groups, respectively),2, There was no difference in time contractile function between the two preconditioned groups at the onset of sustained ischaemia, although the PC-II group showed enhanced release of adenosine (Ado), inosine, hypoxanthine and xanthine into the interstitium accompanied by losses of tissue adenine nucleotides (Sigma AN = ATP + ADP + AMP), total creatine (Sigma Cr = phosphocreatine + creatine) and activation of glycolysis following the preconditioning period, During reperfusion, the PC-I group shamed enhanced functional recovery, higher contents of Sigma AN and Sigma Cr, and the smallest lactate dehydrogenase release compared with these indices in the control and PC-II groups, Postischaemic myocardial dysfunction was similar in the control and PC-II groups,3. Functional recovery of heath in both preconditioned groups was positively correlated with myocardial contents of ATP, Sigma AN and Sigma Cr at the end of reperfusion, but not Nil-ln preischaemic Ado release into the interstitium. The results suggest that pre-ischaemic disturbances of energy metabolism, rather than activation of Ado receptors or stunning, map contribute to efficacy of multiple preconditioning in the rat isolated heart.