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标题：Lipid compositional analysis of pulmonary surfactant monolayers and monolayer-associated reservoirs
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作者：Shou-Hwa Yu ; Fred Possmayer
期刊名称：JLR Papers In Press
印刷版ISSN：0022-2275
电子版ISSN：1539-7262
出版年度：2003
卷号：44
期号：3
页码：621-629
DOI：10.1194/jlr.M200380-JLR200
语种：English
出版社：American Society for Biochemistry and Molecular Biology
摘要：Pulmonary surfactant is a lipid:protein complex containing dipalmitoyl-phosphatidylcholine (DPPC) as the major component. Recent studies indicate adsorbed surfactant films consist of a surface monolayer and a monolayer-associated reservoir. It has been hypothesized that the monolayer and its functionally contiguous reservoir may be enriched in DPPC relative to bulk phase surfactant. We investigated the compositional relationship between the monolayer and its reservoir using paper-supported wet bridges to transfer films from adsorbing dishes to clean surfaces on spreading dishes. Spreading films appear to form monolayers in the spreading dishes. We employed bovine lipid extract surfactant [BLES(chol)] containing [³H]DPPC and either [¹⁴C]palmitoyl, oleoyl-phosphatidylcholine (POPC), [¹⁴C]dipalmitoyl-phosphatidylglycerol (DPPG), [¹⁴C]palmitoyl, oleoyl-phosphatidylglycerol (POPG), or [14C]cholesterol. Radiolabeled phosphatidylglycerols were prepared using phospholipase D. The studies demonstrated that the [³H]DPPC-[¹⁴C] POPC ratios were the same in the prepared BLES dispersions as in Langmuir-Blodgett films, indicating a lack of DPPC selectivity during film formation. Furthermore, identical ³H-¹⁴C isotopic ratios were observed with DPPC and either ¹⁴C-labeled POPC, DPPG, POPG, or cholesterol in the original dispersions, the bulk phases in adsorption dish D1, and monolayers recovered from spreading dish D2. These relationships remained unperturbed with 2-fold increases in bulk concentrations in D1 and 10-fold variations in D1-D2 surface area. These results indicate adsorbed surfactant monolayers and their associated reservoirs possess similar lipid compositions and argue against selective adsorption of DPPC.