Limited donor supply is the major factor restricting the application of lung transplantation. A uniformly reliable method of lung preservation would improve donor organ availability. At present, Euro-Collins’ solution, an intracellular fluid-type solution, is most widely used in organ preservation. However, we have previously shown that initial pulmonary flush with an extracellular-type solution (low-potassium dextran solution [LPD]) provided better pulmonary preservation than Euro-C. In the present study, we used an in vitro— ventilated, blood-perfused rabbit lung model to examine whether the mechanism for this improvement was related to the effect of LPD during pulmonary flush or its effect during storage. Rabbit lungs were harvested and stored after pulmonary flush with different solutions (group 1: 400 ml of LPD; group 2: 400 ml of Euro-C; group 4: 300 ml of Euro-C followed by 100 ml of LPD; n=5 in each group). The lungs were then preserved at 10°C for 18 hr and reperfused with fresh venous blood. After 10 min of reperfusion, lungs in group 1 showed the highest P02 (group 1: 124.4±7.7 mmHg; group 2: 46.2±9.4 mmHg P<0.01). Lungs in both group 3 and group 4 showed better lung function and lower wet/dry weight ratio than those in group 2. We conclude that LPD provides better lung preservation by its effects both on pulmonary flush and on storage.