Role of inhaled nitric oxide in ischaemia-reperfusion injury in the perfused rabbit lung

We have tested if inhaled nitric oxide (NO) is beneficial in ischaemia-repe rfusion (IR) lung injury using an isolated perfused rabbit lung model. Isch aemia for 60 min was followed by reperfusion and ventilation with nitric ox ide 40 ppm (n=6) or without nitric oxide ventilation (n=6) for 60 min. In t he control group (n=6), the lungs were perfused continuously for 120 min. P ermeability coefficient (Kfc) and vascular resistance (PVR) were measured s erially for 60 min after reperfusion. We also determined the left lung W/D ratio and measured nitric oxide metabolites (NOx) and cGMP concentrations i n bronchoalveolar lavage (BAL) fluid from the right lung. IR increased Kfc, PVR and W/D followed by decreased cGMP. Ventilation with nitric oxide rest ored these changes by preventing the decrease in cGMP. Differences in NOx c oncentrations in BAL fluid between the control and IR groups were not stati stically significant. Our results indicate that IR impaired pulmonary vascu lar function and resulted in microvascular constriction and leakage. Ventil ation with nitric oxide from the beginning of the reperfusion period improv ed pulmonary dysfunction such as vasoconstriction and capillary leak by res toring cGMP concentrations.