Transport pathways of beta-VLDL by aortic endothelium of normal and hypercholesterolemic rabbits.

The uptake and transport of beta-VLDL by the aortic endothelium was investigated in normal and hyperlipidemic rabbits fed a cholesterol-enriched diet for 1 week to 5 months. Weekly (in the first month) or every other week afterwards, animals were given one of the following probes: (a) [125I]-beta-VLDL injected in vivo and after 24 h the whole aorta or its intima and media were separately collected and examined by spectrometry and autoradiography; (b) [125I]-beta-VLDL coupled to the fluorescent probe 1,1'-dioctadecyl-3,3,3',3'-tetramethylindocarbocyanine perchlorate perfused in situ for 1-2 h and aorta examined by radioassay and fluorescence microscopy; (c) beta-VLDL-gold complex perfused in situ for 10-15 min and aortic fragments examined by electron microscopy. In addition, cryosections of aortic wall were processed for the immunocytochemical detection of apolipoprotein B and apolipoprotein E.

Prelesional events in atherogenesis. Accumulation of extracellular cholesterol-rich liposomes in the arterial intima and cardiac valves of the hyperlipidemic rabbit.

Biochemical, physiologic, and ultrastructural modifications which appear in the aortic intima and atrioventricular valves before monocyte diapedesis and foam cell formation were investigated in rabbits fed a cholesterol-rich diet. In the first 2 weeks of the diet, while plasma beta-VLDL cholesterol was increased up to 15-fold, the intima showed an enhanced uptake and deposition of dietary 3H-cholesterol, 125I-beta-VLDL, and the fluorescent beta-VLDL-1,1'-dioctadecyl-3,3,3',3'-tetramethylindocarbocyanine conjugate. beta-VLDL-gold complex perfused in situ was transcytosed across endothelium by plasmalemmal vesicles.

Visualization of the binding, endocytosis, and transcytosis of low-density lipoprotein in the arterial endothelium in situ.

We investigated the interaction and transport of low-density lipoprotein (LDL) through the arterial endothelium in rat aorta and coronary artery, by perfusing in situ native, untagged human, and rat LDL. The latter was rendered electron-opaque after it interacted with the endothelial cell and was subsequently fixed within tissue. We achieved LDL electron-opacity by an improved fixation procedure using 3,3'-diaminobenzidine, and mordanting with tannic acid.

Immunocytochemical visualization of coated pits and vesicles in human fibroblasts: relation to low density lipoprotein receptor distribution.

The coated pit-coated vesicle system has a key role in the uptake of plasma low density lipoprotein (LDL) and other receptor-bound proteins in human fibroblasts. To study the distribution of coated pits and coated vesicles in fibroblasts by immunochemical techniques at both the light and electron microscopic levels, we immunized rabbits with coat protein extracted from bovine brain-coated vesicles. The resulting anti-coat protein antibody was directed predominantly against clathrin, the 180,ooo dalton protein that constitutes the major component of coat protein.