title: Interfacial organizations of gel phospholipid and cholesterol in bovine lung surfactant films.
abstract: Pulmonary surfactants stabilize the lung by way of reducing surface tension at the air-lung interface of the alveolus. 31P NMR, thin-layer chromatography, and electrospray ionization mass spectroscopy of bovine lipid extract surfactant (BLES) confirmed dipalmitoylphosphatidylcholine (DPPC) to be the major phospholipid species, with significant amounts of palmitoyl-oleoylphosphatidylcholine, palmitoyl-myristoylphosphatidylcholine, and palmitoyl-oleoylphosphatidylglycerol. BLES and DPPC spread at the air-water interface were studied through surface pressure area, fluorescence, and Brewster angle microscopy measurements. Langmuir-Blodgett films of monomolecular films, deposited on mica, were characterized by atomic force microscopy. BLES films displayed shape, size, and vertical height profiles distinct from those of DPPC alone. Calcium ions in the subphase altered BLES film domain structure. The addition of cholesterol (4 mol %) resulted in the destabilization of compressed BLES films at higher surface pressures (>40 mN m-1) and the formation of multilayered structures, apparently consisting of stacked monolayers. The studies suggested potential roles for individual surfactant lipid components in supramolecular arrangements, which could be the contributing factors in pulmonary surfactant to attain low surface tension at the air-water interface.
authors.affiliation: Department of Biochemistry, Memorial University of Newfoundland, St. Johns, Newfoundland - A1B 3X9, Canada.
authors.forename: Kaushik
authors.initials: K
authors.lastname: Nag
authors.forename: Mauricia
authors.initials: M
authors.lastname: Fritzen-Garcia
authors.forename: Ravi
authors.initials: R
authors.lastname: Devraj
authors.forename: Amiya Kumar
authors.initials: AK
authors.lastname: Panda
mesh_terms: D015060:1,2-Dipalmitoylphosphatidylcholine / Q000737:chemistry; D000818:Animals; D001703:Biophysics / Q000379:methods*; D002417:Cattle; D002855:Chromatography, Thin Layer; D005782:Gels / Q000737:chemistry*; D008055:Lipids / Q000737:chemistry; D008168:Lung / Q000378:metabolism*; D009682:Magnetic Resonance Spectroscopy; D018625:Microscopy, Atomic Force; D010743:Phospholipids / Q000737:chemistry*; D011663:Pulmonary Surfactants / Q000737:chemistry*; D021241:Spectrometry, Mass, Electrospray Ionization / Q000379:methods; D013499:Surface Properties; D014867:Water / Q000737:chemistry
chemical_list: D005782:Gels; D008055:Lipids; D010743:Phospholipids; D011663:Pulmonary Surfactants; D014867:Water; D015060:1,2-Dipalmitoylphosphatidylcholine