Occurrence of glyceryl ethers in the phosphatidylcholine fraction of surfactant from dog lungs.
The molecular species of ether-linked lipids in the phosphatidylcholine (PC) fraction of the pulmonary surfactant obtained from the lavage fluid of dog were characterized. A combination of base-catalyzed methanolysis, phospholipase C treatment, gas-liquid chromatography, and mass spectrometry procedures were applied. The phospholipid composition of the surfactant, obtained by phosphorus assay of lipids separated by silica gel G thin-layer chromatography (TLC), was: PC (75%), phosphatidylglycerol (10%), phosphatidylethanolamine (7%), plus small amounts of sphingomyelin, phosphatidylinositol, and phosphatidylserine. The major components of the PC were 1,2-diacylPC (95%), and 1-O-alkyl-2-acylPC (5%). No detectable amounts of 1-O-alkyl-1'-enyl-2-acylPC or di-alkyl-1-enylPC were observed. The acyl groups present in the diacylPC were 14:0 (5%), 16:0 (68%), 16:1 (12%), 18:0 (6%), 18:1 (7%) and 18:2 (2%). The predominant alkyl ether chains located at the carbon 1 position of the 1-O-alkyl-2-acylPC were 16:0 (84%), 18:0 (5%) and 18:1 (14%). At the carbon 2 position only a 16:0 fatty acyl residue was detected. In three out of seven animals platelet-activating factor-like activity, as determined by a platelet aggregation assay, was isolated by TLC. This aggregating activity was lost upon base-catalyzed methanolysis, but was restored by functional levels after acetylation.
D000818:Animals; D001681:Biological Assay; D001792:Blood Platelets / Q000187:drug effects; D004285:Dogs; D005227:Fatty Acids / Q000032:analysis; D008168:Lung / Q000032:analysis*; D013058:Mass Spectrometry; D010713:Phosphatidylcholines / Q000032:analysis; D010972:Platelet Activating Factor / Q000032:analysis; D010974:Platelet Aggregation; D011663:Pulmonary Surfactants / Q000032:analysis*; D011817:Rabbits; D012701:Serotonin / Q000378:metabolism
D005227:Fatty Acids; D010713:Phosphatidylcholines; D010972:Platelet Activating Factor; D011663:Pulmonary Surfactants; D012701:Serotonin