Objective To evaluate the effects of aerosolized prostaglandin E1（PGE1） inhaled to ventilated lung on hemodynamics and oxygenation during one-lung ventilation（OLV）.Methods Eighteen pigs,weighing 1417 kg,were premedicated with diazepam,ketamine and atropine and intubated and mechanically ventilated.A catheter was placed in the right femoral artery for arterial pressure monitoring and blood sampling.Swan-Ganz catheter was inserted just into the main right pulmonary artery via the left femoral vein.Anesthesia was maintained by infusion of ketamine,procaine,and succinylcholine.The lungs were initially ventilated at a rate of 15 bpm.Tidal volume was adjusted between 1215 ml · kg-1 to achieve PaCO2 of 4.9-5.7 kPa.The FiO2 was set to 0.7.After established OLV,the respiratory rate was increased to 20 bpm and minute volume was congruously maintained throughout the experiment.Following the baseline measurement of all parameters,OLV was established by clamping the left bronchia.Eighteen pigs were divided randomly into three groups: the infused PGE1 group（A,n=6）,the inhaled PGE1 group（B,n=6） and the timecourse control group（C,n=6）.After 60 min OLV,PGE1 was infused into the right pulmonary artery in group A via an infusion pump,or inhaled to ventilated lung in group B via an aerosolized inhalant with an initial dose of 0.01 μg·kg-1 ·min-1 which was gradually increased to 0.02 μg·kg-1·min-1,0.04 μg·kg-1·min-1,0.06 μg·kg-1·min-1,0.08 μg·kg-1·min-1,0.1 μg·kg-1·min-1at 20-min intervals.After the PGE1 administration was stopped,all parameters were recorded at 20,40,and 60 min.The group C received the same amount of normal saline infusion into the right pulmonary artery and inhaled into ventilated lung during the whole periods.Hemodynamic variables and respiratory function parameters were measured at each step.Results One-lung ventilation increased MPAP、PVR、SVR、PIP and Qs/Qt,and reduced CO、Cdyn and PaO2 significantly（P<0.05）in all animals.During selective infusion or inhalation of
