Phosphoenolpyruvate administration protects ischemia–reperfusion injury in isolated rabbit lungs

Phosphoenolpyruvate (PEP) is an intermediate metabolite of the glycolytic pathway and an in vivo high-energy phosphate compound. We have examined the protective effects of PEP on ischemia–reperfusion lung injury in isolated rabbits lungs perfused with a physiological salt solution. The lungs were divided into three treatment groups: (1) ischemia–reperfusion (IR), (2) ischemia–reperfusion with PEP treatment (PEP-IR), in which 1 mM PEP was pre-administered into the perfusate during the stable period, and (3) ventilation–perfusion continued without interruption (Cont). In the IR and PEP-IR groups, ventilation–perfusion was discontinued for about 60 min after a 30-min stable period and then restarted. The capillary filtration coefficients ( K fc ) and pyruvate concentration in the perfusate were determined immediately before ischemia and 30 and 60 min after reperfusion. The left lungs were dried at the end of the experiment to calculate the tissue wet-to-dry weight ratio (W/D). The K fc values after reperfusion were significantly higher in the IR group than in the other two groups. Pyruvate concentrations were significantly higher at three time-points in the PEP-IR group than in the other two groups. The W/D was significantly higher in the IR group than in the other two groups. Based on these results, we conclude that the administration of PEP prior to lung ischemia alleviates lung ischemia–reperfusion injury.