Snelting-Havinga I, Mommaas M, Van Hinsbergh V W, Daha M R, Daems W T, Vermeer B J
Department of Dermatology, Leiden University, The Netherlands.
Eur J Cell Biol. 1989 Feb;48(1):27-36.
A postembedding labeling technique was employed to visualize human native low density lipoproteins (LDL) during transcytosis in rat arterial endothelium. For this purpose human LDL was perfused through rat vasculature before fixation and processing for immunoelectron microscopy. The LDL particles were located on sections by anti-human apolipoprotein B-100 (LDL) antibodies and secondary antibodies or protein-A conjugated to 10-nm colloidal gold. LDL molecules were seen in plasmalemmal vesicles as well as in the subendothelial space. No colloidal gold was found in the intercellular junctions. Perfusion with reductively methylated LDL, which cannot bind to the LDL receptor, gave a similar labeling pattern, indicating that transcytosis of LDL via plasmalemmal vesicles is most likely receptor independent. Furthermore, the passage of LDL through intact vascular endothelium is a vesicular transport rather than an intercellular diffusion process.
采用包埋后标记技术，在大鼠动脉内皮细胞转胞吞作用过程中观察人天然低密度脂蛋白（LDL）。为此，在固定和处理用于免疫电子显微镜观察之前，将人LDL灌注到大鼠脉管系统中。通过抗人载脂蛋白B-100（LDL）抗体以及与10纳米胶体金偶联的二抗或蛋白A，在切片上定位LDL颗粒。在质膜小泡以及内皮下间隙中可见LDL分子。在细胞间连接处未发现胶体金。用不能与LDL受体结合的还原甲基化LDL进行灌注，得到了类似的标记模式，表明通过质膜小泡进行的LDL转胞吞作用很可能不依赖于受体。此外，LDL通过完整血管内皮的过程是一种囊泡运输，而不是细胞间扩散过程。
