THE FUNCTION OF SURFACTANT IS IMPAIRED DURING THE REIMPLANTATION RESPONSE IN RAT LUNG TRANSPLANTS

In this study we investigated the surfactant function in rat lung tran splants at the peak of the reimplantation response in experimental gro ups with increasing warm ischemic times of the lung transplant. The le ft and right lungs in five groups of rats were assessed 24 hours after left lung transplantation: rats receiving transplants with lung graft ischemic times of 60 (n = 4), 90 (n = 5), and 120 (n = 5) minutes, do nor rats with 120 minutes lung ischemia (n = 5) and normal (nonoperate d) rats (n = 6). The reimplantation response was assessed by the venti lation score on chest roentgenograms, measurement of the static lung c ompliance, and the (serum) protein concentration in the bronchoalveola r lavage fluid. Surfactant in the bronchoalveolar lavage fluid was ass essed by measuring the amount and the composition of surfactant phosph olipids and the in vitro surfactant function in a pulsating bubble sur factometer. We found that longer ischemic times caused a more severe r eimplantation response in the left lung grafts. Although the ventilati on scores were equally low in the 60-, 90-, and 120-minute ischemia gr oups, the lung compliances decreased and the (serum) protein concentra tions increased stepwise in correlation with longer ischemic times. Th e amount of surfactant phospholipids during the reimplantation respons e was not changed, but the percentage phosphatidyl choline decreased p rogressively in parallel with the severity of the reimplantation respo nse. Finally, the in vitro function of surfactant from the lung transp lants decreased in parallel with the prolongation of the ischemic time , whereas the function of surfactant from donor lungs with 120 minutes of ischemia and from native right lungs was not changed. We conclude that the surfactant function is impaired during the reimplantation res ponse as a result of a high concentration of inhibiting serum proteins and a low percentage of phosphatidyl choline.