Background Previous reports have confirmed that edaravone has protective effects against ischemia-reperfusion(IR) injury of many organs.In this study,we investigated the effect of edaravone on preventing IR injury of the lung in a canine lung transplantation model. Methods Twelve weight-matched pairs of random-bred dogs were randomized into two groups.Within each pair,one dog served as donor and the other as recipient.In the study group,prostaglandin EI(PGEl)(8 μg/kg)was injected into the donor pulmonary artery(PA)before occlusion and the donor lungs were flushed with 1.0L of LPD solution containing edaravone(10mg/kg)and stored in the same LPD solution at a temperature of 1.C for 8 hours.The left single lung transplantation was then performed and recipients received intravenous injection with edaravone l 1 0 mg/kg)at the onset of reperfusion.In the control group,edaravone was substituted by the same volume of sterile saline solution.Another six dogs were obtained as normal control group in which left lungs were dissected after thoracotomy without an IR injury.One hour after repeffusion.or after dissection of the left lung,the right lung was excluded from peffusion and ventilation after which,cardiopulmonary parameters were measured.Wet/dry ratios,malondiaIdehyde(MDA)and myeloperoxidase (MPO)levels were assessed and histological analysis of lung tissue performed at the same time.Results All animals survived until the end of the experiment.The study group showed significantly decreased wet/dry ratios(treated:(74.1±4.2)%vs control:(86.8±5.2)%,P<0.01),MDA levels(treated:0.50±0.08 vs control:0.88±0.15,P <0.01)and MPO activity(treated:0.23±0.05 vs control:0.43±0.07,P