Methods for the study of lung metabolism.

The recognition of the non-respiratory functions of the lung has led to an increased interest in pulmonary metabolism. The practical methods used to study metabolism in other tissues have all been applied to the investigation of lung metabolism. Methods fall into two groups: those used in vivo and those used in vitro after disrupting the organ or isolating it from other tissues and perfusing its circulation. Some of the methods used in vitro disturb the tissue environment in such a way as to introduce experimental artifacts which make the interpretation of results difficult. There are advantages to the use of the isolated perfused organ technique which, although it has been established for many years, has recently been improved. This method lends itself particularly well to studies of the intermediary metabolism and uptake of drugs by lung tissue. These improvements are described and the application to pulmonary drug uptake is illustrated by reference to the drug mexiletine. The relative advantages of the various methods and their applications are discussed.