The primary aim of this project is to determine how pulmonary surfactants are metabolized. We will approach the problem experimentally from the point of view of molecular mechanisms in which the biosynthesis, catabolism, transport, storage, secretion, and regulation of both the lipid and protein components of lung surfactants will be investigated. A unique aspect of this study is that pure populations of alveolar type II cells grown in vivo (mouse pulmonary adenomas induced by urethan) and in vitro (rat type II cells in culture) will be used as model systems. We also plan to determine the role that surfactants play, at the molecular level, in pulmonary diseases such as emphysema, black lung disease, and lung carcinoma.