BACKGROUND The goal of organ preservation is maintenance of physiologic functions during extended extracorporeal storage. METHODS This study was designed to evaluate the efficacy of using low-potassium (4 mmol/L) dextran (1%) solution on lung function after 30 hours hypothermic (10 degrees C) storage and to compare this with lung function after no storage. With low-potassium dextran solution rabbit lungs were flushed (10 degrees C, 40 ml/kg, 60 cm H2O), excised, inflated (with room air), and either not stored (control; no preservation; n = 9) or stored in low-potassium dextran solution (10 degrees C) 30 hours (experimental group; n = 9). RESULTS During the flush the infusion pressure and pulmonary vascular resistance for the two groups did not differ (17.56 +/- 1.3 versus 16.74 +/- 1.5 mm Hg/ml/sec). After either no preservation or after 30 hours of storage, the lungs were first reperfused with low-potassium dextran solution (37 degrees C) for 4 minutes and then with blood (37 degrees C) for 30 minutes at 100 ml/min. During the reperfusion period the mean pulmonary artery pressure and end-inspiratory airway pressure for the control and experimental groups did not differ. After reperfusion the wet and dry weights of the left lung were determined. The wet/dry ratio for the two groups did not differ (5.32 +/- 2.20 versus 4.70 +/- 2.70, respectively). CONCLUSIONS These data suggest that cold flush, cold storage, and initial warm perfusion with low-potassium dextran solution crystalloid preserve lung function after 30 hours of storage.