ALTERATIONS IN PULMONARY SURFACTANT COMPOSITION AND ACTIVITY AFTER EXPERIMENTAL LUNG TRANSPLANTATION

Pulmonary surfactant facilitates breathing by reducing the surface ten sion at the air/liquid interface. We examined the effect of experiment al lung transplantation on the phospholipid pool sizes of alveolar sur factant large and small aggregates, the composition of the large aggre gates, the surface tension-reducing ability of lipid extract surfactan t, and the leakage of serum proteins into the lung. A double-lung bloc k from the donor animal was stored for 2 or 12 h after perfusion with either Euro-Collins solution or University of Wisconsin solution. The right donor lung was lavaged immediately after the storage period to d etermine the effects of storage on pulmonary surfactant. The left dono r lung was transplanted. The recipient animal, containing its own nati ve right lung and the transplanted left lung, was reperfused for 6 h. After the reperfusion period, the transplanted left lung and the nativ e right lung were lavaged. After an ischemic time of 12 h, impaired ga s exchange was observed in the transplanted lung as well as the native lung during the 6 h of reperfusion. This impaired gas exchange was as sociated with several significant changes in pulmonary surfactant: (1) total serum protein in the lung lavage was increased, (2) the small t o large surfactant aggregate ratio was increased, (3) sphingomyelin co ntent was increased and phosphatidylglycerol content was decreased in large aggregates, and (4) the surfactant-associated protein. A content was decreased in large aggregates. No significant differences were ob served between the results obtained with Euro-Collins and University o f Wisconsin solutions. We conclude that prolonged storage of the donor lung before transplantation results in ischemic damage that produces an increase in potential surfactant inhibitors and can alter the small to large surfactant aggregate ratio after lung transplantation. These alterations in pulmonary surfactant resemble those observed in many a dult respiratory distress syndrome types of injuries. We conclude that surfactant supplementation in lung transplantation should be investig ated.