Phospholipid metabolism in the lung of fat-fed rats.

Phospholipid metabolism in the lung was studied because the lung was the first organ at which the ingested lipids arrived. It was revealed in this study that the lung contained phosphatidyl cho-line, ethanolamine, phosphoinositol, sphingomyelin and lysolecithin, that the amount of phosphatidyl serine were very small in the lung, and that a phosphatidic acid was discovered in the lung after the administration of fats. Furthermore, an unknown phospholipid subfraction was revealed in the lung. Fatty acid composition of phospolipid subfractions was investigated one and six hours after the administration of trilinolein. The elongation of fatty acids occured also in the lung. Phosphatidyl ethanolamine and an unknown subfraction were active in the elongation but phosphatidyl choline was stable. It was resulted by ligation of the thoracic duct that appearance of a phosphatidic acid was delayed, and that saturated fatty acid increased, unsaturated decreased. These findngs suggest that the lung has an ability of lipid synthesis, and that phosphatidyl ethanolamine and an unknown subfraction were active in lipid metabolism although phosphatidyl choline was stable.