“CHEMICAL PRECONDITIONING” BY 3-NITROPROPIONATE REDUCES ISCHEMIA-REPERFUSION INJURY IN CARDIAC-ARRESTED RAT LUNGS1

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Abstract
Chemical preconditioning was defined as the induction of resistance to massive disruption of energy metabolism through prior chemical suppression of oxidative phosphorylation, by which phenomena similar to those resulting from increased ischemic tolerance as a result of ischemic preconditioning can be induced. It could be induced by the inhibitor of either mitochondrial complex I or II. We investigated whether or not chemical preconditioning by 3-nitropropionate (an inhibitor of the mitochondrial complex II) can suppress ischemia-reperfusion injury in cardiac-arrested lungs, which will be the major problem in lung transplants donated from non-heart-beating cadavers. In an isolated rat lung perfusion model with fresh rat blood as perfusate, administration of 3-nitropropionate (20 mg/kg) immediately before the induction of cardiac arrest attenuated pulmonary dysfunction during reperfusion after 1 hr postmortem warm ischemia and 1 hr cold preservation. 3-Nitropropionate administration reduced the mitochondrial respiratory functions (state 3 and state 4 respiration, and the respiratory control ratio) before cardiac arrest and kept them at a lower level of activity than when decreased by ischemia alone. 3-Nitropropionate administration also reduced the ATP levels immediately after drug administration. However, 3-nitropropionate did not significantly reduce lipid peroxidation in the lung tissue and mitochondria. These results demonstrated that chemical preconditioning by 3-nitropropionate administration immediately before cardiac arrest suppressed succinate-related oxidation during postmortem warm ischemia and reduced ischemia-reperfusion injury in cardiac arrested rat lungs.