Chander A, Reicherter J, Fisher A B
J Clin Invest. 1987 Apr;79(4):1133-8. doi: 10.1172/JCI112929.
We investigated metabolic utilization of exogenous (modelled after lung surfactant) phospholipids by granular pneumocytes in primary culture. Cells were incubated for 21, 65, and 140 min with [3H-methyl]dipalmitoylphosphatidylcholine (DPPC) containing liposomes prepared from synthetic lipids. Radioactivity in cellular phosphatidylcholine (PC) declined steadily to 50% of the total trypsin-resistant cell-associated radioactivity. The proportion of radioactivity increased with time in cytidine-5'-diphosphate-choline and phosphorylcholine, which suggested reutilization of choline for PC synthesis. Cells incubated with liposomes for 2 h revealed that of the total cell-associated radioactivity, 7% was in lamellar bodies and 10% in the microsomal fraction. The lipid-associated radioactivity was 24% in "soluble," 96% in lamellar bodies, and 92% in the microsomal fraction. Percent of total PC label recovered in disaturated PC of microsomal fractions decreased (slope = -5.27%/h) with time of incubation (r = 0.67). Incubation of cells with liposomes containing ([3H-methyl]choline-[14C]palmitoyl) DPPC led to altered isotope ratios in both lamellar bodies and microsomes. These observations indicate that granular pneumocytes degrade exogenous PC and resynthesize PC from degradation products.
我们研究了原代培养的颗粒性肺细胞对外源性（模拟肺表面活性物质）磷脂的代谢利用情况。将细胞与由合成脂质制备的含[3H-甲基]二棕榈酰磷脂酰胆碱（DPPC）的脂质体一起孵育21、65和140分钟。细胞磷脂酰胆碱（PC）中的放射性稳步下降至与细胞相关的总抗胰蛋白酶放射性的50%。胞苷-5'-二磷酸胆碱和磷酸胆碱中的放射性比例随时间增加，这表明胆碱被重新利用用于PC合成。用脂质体孵育2小时的细胞显示，与细胞相关的总放射性中，7%存在于板层小体中，10%存在于微粒体部分。脂质相关放射性在“可溶性”部分为24%，在板层小体中为96%，在微粒体部分为92%。微粒体部分的二饱和PC中回收的总PC标记百分比随孵育时间下降（斜率=-5.27%/小时）（r=0.67）。用含([3H-甲基]胆碱-[14C]棕榈酰)DPPC的脂质体孵育细胞导致板层小体和微粒体中的同位素比率发生变化。这些观察结果表明，颗粒性肺细胞降解外源性PC并从降解产物中重新合成PC。
