title: Increased palmitoyl-myristoyl-phosphatidylcholine in neonatal rat surfactant is lung specific and correlates with oral myristic acid supply.
abstract: Surfactant predominantly comprises phosphatidylcholine (PC) species, together with phosphatidylglycerols, phosphatidylinositols, neutral lipids, and surfactant proteins-A to -D. Together, dipalmitoyl-PC (PC16:0/16:0), palmitoyl-myristoyl-PC (PC16:0/14:0), and palmitoyl-palmitoleoyl-PC (PC16:0/16:1) make up 75-80% of mammalian surfactant PC, the proportions of which vary during development and in chronic lung diseases. PC16:0/14:0, which exerts specific effects on macrophage differentiation in vitro, increases in surfactant during alveolarization (at the expense of PC16:0/16:0), a prenatal event in humans but postnatal in rats. The mechanisms responsible and the significance of this reversible increase are, however, not understood. We hypothesized that, in rats, myristic acid (C14:0) enriched milk is key to lung-specific PC16:0/14:0 increases in surfactant. We found that surfactant PC16:0/14:0 in suckling rats correlates with C14:0 concentration in plasma chylomicrons and lung tissue triglycerides, and that PC16:0/14:0 fractions reflect exogenous C14:0 supply. Significantly, C14:0 was increased neither in plasma PC, nor in liver triglycerides, free fatty acids, or PC. Lauric acid was also abundant in triglycerides, but was not incorporated into surfactant PC. Comparing a C14:0-rich milk diet with a C14:0-poor carbohydrate diet revealed increased C14:0 and decreased C16:0 in plasma and lung triglycerides, respectively. PC16:0/14:0 enrichment at the expense of PC16:0/16:0 did not impair surfactant surface tension function. However, the PC profile of the alveolar macrophages from the milk-fed animals changed from PC16:0/16:0 rich to PC16:0/14:0 rich. This was accompanied by reduced reactive oxygen species production. We propose that nutritional supply with C14:0 and its lung-specific enrichment may contribute to decreased reactive oxygen species production during alveolarization.
authors.affiliation: Department of Neonatology, Faculty of Medicine, Eberhard-Karls-University, Calwer Strasse 7, D-72076 Tübingen, FRG. wolfgang.bernhard@med.uni-tuebingen.de
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Bernhard
authors.forename: Marco
authors.initials: M
authors.lastname: Raith
authors.forename: Christopher J
authors.initials: CJ
authors.lastname: Pynn
authors.forename: Christian
authors.initials: C
authors.lastname: Gille
authors.forename: Guido
authors.initials: G
authors.lastname: Stichtenoth
authors.forename: Dieter
authors.initials: D
authors.lastname: Stoll
authors.forename: Erwin
authors.initials: E
authors.lastname: Schleicher
authors.forename: Christian F
authors.initials: CF
authors.lastname: Poets
mesh_terms: D000818:Animals; D000831:Animals, Newborn; D004032:Diet; D005230:Fatty Acids, Nonesterified / Q000378:metabolism; D005766:Gastrointestinal Contents / Q000737:chemistry; D050356:Lipid Metabolism / Q000502:physiology; D008074:Lipoproteins / Q000097:blood / Q000378:metabolism; D008099:Liver / Q000378:metabolism; D008168:Lung / Q000502:physiology*; D008892:Milk; D019814:Myristic Acid / Q000378:metabolism* / Q000494:pharmacology; D010713:Phosphatidylcholines / Q000032:analysis / Q000097:blood / Q000378:metabolism*; D011650:Pulmonary Alveoli / Q000378:metabolism; D011663:Pulmonary Surfactants / Q000737:chemistry*; D051381:Rats; D017207:Rats, Sprague-Dawley; D017382:Reactive Oxygen Species / Q000378:metabolism; D014280:Triglycerides / Q000097:blood
chemical_list: D005230:Fatty Acids, Nonesterified; D008074:Lipoproteins; D010713:Phosphatidylcholines; D011663:Pulmonary Surfactants; D017382:Reactive Oxygen Species; D014280:Triglycerides; D019814:Myristic Acid; C086029:1-myristoyl-2-palmitoyl-sn-glycero-3-phosphocholine