Chapter 3a Surfactant Treatment before Reperfusion Improves the Immediate Function of Lung Transplants in Rats

An impaired function of alveolar surfactant can cause lung transplant dysfunction early after reperfusion. In this study it was investigated whether treatment with surfactant before reperfusion improves the immediate function of lung transplants and whether an improved transplant function was associated with an increase in alveolar surfactant components. Left lungs with 6-hour (n=8) or prolonged 20-hour ischemia (n=10) were transplanted syngeneically in rats. In both ischemia groups half of the lung transplants were treated with surfactant just before reperfusion. Lung function was measured during reperfusion for 1 hour. Thereafter, the rats were killed and bronchoalveolar lavage was performed to measure alveolar surfactant components. We found that surfactant treatment improved the immediate function of lung transplants in parallel with a higher amount of total surfactant phospholipids, a higher percentage of the heavy subtype of surfactant, a normalized percentage of phosphatidylcholine, and a higher amount of endogenous surfactant protein-A. We conclude that surfactant treatment before reperfusion does improve the immediate lung transplant function in rats in association with an increase in alveolar surfactant com-ponents. More particularly, the amount of (endogenous) SP-A is thought to be crucial for the efficacy of surfactant treatment after lung transplantation. In normal lungs, surfactant reduces the surface tension at the air-fluid interface and thereby preventing an alveolar collapse at end-expiration. To fulfill this function, surfactant is composed of a complex mixture consisting of mainly phospholipids and at least three surfactant proteins (SP), SP-A, SP-B, and SP