This study was designed to test whether use of allopurinol could improve lung preservation after 6 hours of cold storage. Thirty-two rabbits were divided into four groups (n = 8 each group): (1) the control group received no flush or storage, (2) the EC group received Euro-Collins (EC) solution for both flush and storage, (3) the Allo-F group received Euro-Collins solution with allopurinol (1 mmol/L) for both flush and storage, and (4) the Allo-R group received Euro-Collins solution to which allopurinol (1 mmol/L) was added only to the reperfused blood. For groups 2 through 4, the lungs were flushed (40 ml/kg) in situ, excised, and then stored at 4 degrees C. After storage, the lungs were reperfused for 1 hour with an in vitro blood-perfused ventilated model. Lung function was measured during reperfusion with mean pulmonary arterial pressure, end-inspiratory airway pressure, and blood gas data. The lung wet/dry weight ratio was used to measure lung edema. The lungs in the EC group had a significant increase in mean pulmonary arterial pressure, airway pressure, and wet/dry weight ratio when compared with the control group. The mean pulmonary arterial pressure in either of the groups receiving allopurinol was consistently lower than that in the EC group. The airway pressure in the Allo-R group also significantly decreased compared with the EC group.(ABSTRACT TRUNCATED AT 250 WORDS)