Comparison of molecular structure of glycerolipids in rat lung

The major individual molecular species of glycerolipids such as phosphatidylcholine, phosphatidylethanolamine, phosphatidylglycerol, phosphatidylinositol and diacylglycerol of rat lung were determined quantitatively as diacylglycerol acetates. 1. In three glycerolipids such as phosphatidylcholine, phosphatidylglycerol and diacylglycerol, the main molecular species was dipalmitoyl. The species was not detectable in phosphatidylethanolamine and was not of quantitative importance in phosphatidylinositol. 2. The oligoenoic molecular species in phosphatidylethanolamine and phosphatidylinositol contained palmitoyl and stearoyl species in almost equal amounts, while those of phosphatidylcholine, phosphatidylglycerol and diacylglycerol were principally of the palmitoyl types. 3. Tetraenoic species of phosphatidylinositol and diacyl types of phosphatidylethanolamine were predominantly of stearoyl types. Tetraenoic diacylglycerol also contained significant amounts of stearoyl-arachidonyl species. The value was about 3-fold that of palmitoyl-arachidonyl species. However, palmitoyl types were rather higher in phosphatidylcholine and phosphatidylglycerol. 4. The alkenyl-acyl types of lung phosphatidylethanolamine consisted predominantly of polyenoic species, namely, tetraenoic, pentaenoic and hexaenoic species. The pentaenoic and hexaenoic species of all glycerolipids examined consisted mainly of palmitoyl types.