title: Metabolic fate of low density lipoprotein and high density lipoprotein labeled with an ether analogue of cholesteryl ester.
abstract: Low density lipoprotein (LDL) metabolism by human skin fibroblasts was studied using LDL labeled with a nonhydrolyzable cholesteryl ether analogue, 3H-cholesteryl linoleyl ether (CLE). The 3H-CLE-LDL was taken up by the apo-B, E receptor mediated endocytosis similar to 125I-labeled LDL. This was shown by saturation kinetics of uptake with respect to 3H-CLE-LDL concentration and very low uptake of 3H-CLE-LDL by receptor negative cell strains. When injected (CE)-LDL were cleared at equal rates and about 30% of the injected LDL was recovered in the liver. Treatment with ethinyl estradiol resulted in a three-fold increase in 3H-CLE-LDL uptake by the liver. The liver is also the major site of uptake of 3H-CLE-high density lipoprotein (HDL) (40%-45% of the injected dose) but its uptake by the liver increased only by 20% with estradiol treatment. As 3H-CLE-HDL was cleared from the circulation at a somewhat faster rate than 125I-HDL it appeared that some dissociation in the tissue uptake of the protein and CE moieties occurs.
mesh_terms: D000311:Adrenal Glands / Q000378:metabolism; D000818:Animals; D002784:Cholesterol / Q000031:analogs & derivatives* / Q000378:metabolism; D002788:Cholesterol Esters / Q000378:metabolism*; D004705:Endocytosis; D004997:Ethinyl Estradiol / Q000494:pharmacology; D005260:Female; D005347:Fibroblasts / Q000378:metabolism; D006801:Humans; D007421:Intestine, Small / Q000378:metabolism; D008075:Lipoproteins, HDL / Q000378:metabolism*; D008077:Lipoproteins, LDL / Q000378:metabolism*; D008099:Liver / Q000378:metabolism; D008297:Male; D051381:Rats
chemical_list: D002788:Cholesterol Esters; D008075:Lipoproteins, HDL; D008077:Lipoproteins, LDL; D004997:Ethinyl Estradiol; C027575:cholesteryl linoleyl ether; D002784:Cholesterol