DeLamatre J G, Gabaldon D M, Arnold C S, Sarphie T G, Hornick C A
Department of Physiology, Louisiana State University Medical Center, New Orleans 70112, USA.
Liver. 1998 Aug;18(4):264-71. doi: 10.1111/j.1600-0676.1998.tb00164.x.
AIMS/BACKGROUND: The metabolism of rat apo E-free high-density lipoproteins (HDL) was contrasted with oxidatively modified apo E-free high-density lipoproteins (OX-HDL) in the rat hepatoma cell, Fu5AH.
When 10-100 microg/ml [125I]-HDL or [125I]-OX-HDL were incubated with cells for 4 h at 37 degrees C, cellular uptake of oxidized lipoproteins was twice control. In contrast, protein degradation was equal. [125I]-HDL or [125I]-OX-HDL were incubated with the cells for 4 h followed by a 4 h chase with unlabeled HDL and OX-HDL, respectively. In these experiments, 80% of [125I]-HDL was resecreted from the cell within 30 min while 50% of [125I]-OX-HDL was retained by the cell after 2 h. Electron microscopy was used to determine if the OX-HDL was retained in lysosomes. Cells were incubated with gold-labeled OX-HDL, and lysosomes were stained with acid phosphatase. Gold-labeled OX-HDL was abundant in intracellular vesicles that were not reactive to acid phosphatase. However, vesicles with a high content of OX-HDL frequently stained positively for 3,3'-diaminobenzidine, a stain that reacts with catalase and is used to detect peroxisomes.
The present evidence indicates that the cellular metabolism of OX-HDL is different from that of unmodified HDL.
目的/背景：在大鼠肝癌细胞Fu5AH中，对比大鼠无载脂蛋白E的高密度脂蛋白（HDL）与氧化修饰的无载脂蛋白E高密度脂蛋白（OX-HDL）的代谢情况。
当10 - 100微克/毫升的[125I]-HDL或[125I]-OX-HDL在37℃下与细胞孵育4小时时，氧化脂蛋白的细胞摄取量是对照组的两倍。相比之下，蛋白质降解量相同。将[125I]-HDL或[125I]-OX-HDL与细胞孵育4小时，随后分别用未标记的HDL和OX-HDL进行4小时的追踪实验。在这些实验中，80%的[125I]-HDL在30分钟内从细胞中重新分泌出来，而50%的[125I]-OX-HDL在2小时后被细胞保留。使用电子显微镜来确定OX-HDL是否保留在溶酶体中。细胞与金标记的OX-HDL孵育，溶酶体用酸性磷酸酶染色。金标记的OX-HDL在对酸性磷酸酶无反应的细胞内小泡中大量存在。然而，含有高含量OX-HDL的小泡经常对3,3'-二氨基联苯胺呈阳性染色，3,3'-二氨基联苯胺是一种与过氧化氢酶反应并用于检测过氧化物酶体的染色剂。
目前的证据表明，OX-HDL的细胞代谢与未修饰的HDL不同。
