Rooney S A, Page-Roberts B A, Motoyama E K
J Lipid Res. 1975 Nov;16(6):418-25.
Lamellar inclusion bodies in the type II alveolar epithelial cell are believed to be involved in pulmonary surfactant production. However, it is not clear whether their role is that of synthesis, storage, or secretion. We have examined the phospholipid composition and fatty acid content of rabbit lung wash, lamellar bodies, mitochondria, and microsomes. Phosphatidylcholine and phosphatidylglycerol, the surface-active components of pulmonary surfactant, accounted for over 80% of the total phospholipid in lung wash and lamellar bodies but for only about 50% in mitochondria and microsomes. Phosphatidylethanolamine, phosphatidylinositol, phosphatidylserine, and sphingomyelin accounted for over 40% of the total in mitochondria and microsomes but for only 6% in lung wash and 15% in lamellar bodies. The fatty acid composition of lamellar body phosphatidylcholine was similar to that of lung wash, but different from that of mitochondria and microsomes, in containing palmitic acid as a major component with little stearic acid and few fatty acids of chain length greater than 18 carbon atoms. The biosynthesis of phosphatidylcholine and phosphatidylglycerol was examined in the mitochondrial, microsomal, and lamellar body fractions from rat lung. Cholinephosphotransferase was largely microsomal. The activity in the lamellar body fraction could be attributed to microsomal contamination. The activity of glycerolphosphate phosphatidyltransferase, however, was high in the lamellar body fraction, although it was highest in the mitochondria and was also active in the microsomes. These data suggest that the lamellar bodies are involved both in the storage of the lipid components of surfactant and in the synthesis of at least one of those components, phosphatidylglycerol.
II型肺泡上皮细胞中的板层小体被认为与肺表面活性物质的产生有关。然而，其作用是合成、储存还是分泌尚不清楚。我们检测了兔肺灌洗液、板层小体、线粒体和微粒体的磷脂组成和脂肪酸含量。肺表面活性物质的表面活性成分磷脂酰胆碱和磷脂酰甘油，在肺灌洗液和板层小体中占总磷脂的80%以上，但在线粒体和微粒体中仅约占50%。磷脂酰乙醇胺、磷脂酰肌醇、磷脂酰丝氨酸和鞘磷脂在线粒体和微粒体中占总量的40%以上，但在肺灌洗液中仅占6%，在板层小体中占15%。板层体磷脂酰胆碱的脂肪酸组成与肺灌洗液相似，但与线粒体和微粒体不同，其主要成分是棕榈酸，硬脂酸含量很少，链长大于18个碳原子的脂肪酸也很少。我们在大鼠肺的线粒体、微粒体和板层体组分中检测了磷脂酰胆碱和磷脂酰甘油的生物合成。胆碱磷酸转移酶主要存在于微粒体中。板层体组分中的活性可归因于微粒体污染。然而，甘油磷酸磷脂转移酶的活性在板层体组分中较高，尽管它在线粒体中最高，在微粒体中也有活性。这些数据表明，板层小体既参与表面活性物质脂质成分的储存，也参与至少一种成分磷脂酰甘油的合成。
