RELATIONSHIP BETWEEN FLUSHING PRESSURE AND NITRIC-OXIDE PRODUCTION INPRESERVED LUNGS

Background. Nitric oxide (NO) is considered to be one of the endogenou s inhibitory factors of ischemic reperfusion injury, In this study, th e NO-producing ability of the preserved lung, flushed at various pulmo nary artery pressures (flushing pressure), was studied during reperfus ion using an ex vivo rabbit lung perfusion model. Methods. The lungs w ere flushed with 200 mi of preservation solution with flushing pressur es adjusted to 15, 15, 20, and 25 mmHg for groups 1, 2, 3, and 4, resp ectively (n=5 in each group), In the control group (group 1), the hear t-lung block was harvested after flushing and the lungs were assessed without preservation, In the other groups, the harvested blocks were p reserved at 8 degrees C for 24 hr and reperfused with homologous blood for pulmonary functional assessment, Pulmonary function was assessed by measuring mean airway pressure, mean pulmonary arterial pressure, p artial oxygen tension of pulmonary venous effluent blood, and pulmonar y wet-dry weight ratio, The sequential changes in the concentration of NO-related substances (NO-RS) in the serum of reperfused blood were a lso measured by chemiluminescence. Results. During reperfusion, biphas ic increases in NO-RS were observed in all groups, In groups 3 and 4, the increases in NO-RS were significantly lower than those of groups 1 and 2, and pulmonary function deteriorated. Conclusion. These data su ggest that in order to maintain the endogenous NO-producing ability of preserved lung, the flushing pressure must be less than 20 mmHg.