Pressures in the pulmonary artery, left atrium, airway, and lung weight were continuously registered by using pressure transducers as well as a force transducer connected to a data acquisition system (Power Lab, AD Instrument, Australia). All lungs included in the study exhibited no signs of hemostasis, edema, or atelectasis, maintained constant mean pulmonary artery and peak airway pressures, and were isogravimetric during the first 30 min of the steady state period. Because flow-rate of the perfusate was constant, changes in PAP were proportional to pulmonary vascular resistance. Composition of Ventilatory Gas and Perfusate We used two different gas mixtures for

lung ventilation: normoxia plus normocapnia Inhibitors,research,lifescience,medical (21.0% O2 and 5.5% CO2 balanced with N2) and hypoxia plus normocapnia (1.0% O2 and 5.5% Inhibitors,research,lifescience,medical CO2 balanced with N2). The perfusate used for this study contained 120.0 mM NaCl, 1.1 mM K2HPO4, 1.3 mM MgCl2, 4.3 mM KCl, 2.4 mM CaCl2, 13.3 mM glucose, and 1 g dextran/100

ml (mw 70000). In all experiments the pH was corrected to normal values by the addition of NaHCO3-. Study Protocol At 30 min after surgical preparation (the first 15 min for increasing the flow and temperature, and the second 15 min for stabilizing the preparation), we performed hypoxic ventilation for 10 min to determine the lung’s response to alveolar hypoxic-normocapnia in order to ensure Inhibitors,research,lifescience,medical a normal vasoreactive response by the pulmonary Lumacaftor vessels. Subsequently, Inhibitors,research,lifescience,medical hypoxic-normocapnic ventilation was changed to normoxic-normocapnic ventilation for 15 min. Thereafter, we randomly divided the lungs into five experimental groups that included normoxic-normocapnia (NOX, n=7), hypoxic-normocapnia (HOX, n=7), PHE pre- (PHE-HOX, n=5) or post-treated hypoxic-normocapnia (HOX-PHE, n=5) and PHE pre-treated normoxic-normocapnia (PHE-NOX, n=6) in which the lungs were ventilated with normoxic-normocapnic or hypoxic-normocapnic gas for 60 min. In the PHE treated groups, we added PHE (30 µM) to the perfusate 3 min prior or 3 min after the onset of gas ventilation. Statistical Analysis Data Inhibitors,research,lifescience,medical are given as mean±SEM. Analysis of variance (ANOVA) with the Student-Newman-Keuls (SNK) post hoc test was used

for comparison of more than two groups. For comparison until of the values during the time course of one group we used the repeated measurement of one-way ANOVA with SNK post hoc. Student’s t test was used for the comparison of two groups. Significance was assumed when P<0.05. Results We used a gas analyzer (Easy Blood Gas, USA) to measure PO2, PCO2 and pH of the perfusate for all groups. Table 1 shows these values and the values for osmolarity of the perfusate at 10 min after starting each experiment. These values remained stable during 60 min of experiments. Table 1 PO2, PCO2, pH, HCO3- and osmolarity in the perfusate during the experimental conditions Baseline values in the NOX group (n=7) were 10.28±1.27 for PAP, 2.47±0.17 for LAP, and 4.46±0.