Parenchymal and nonparenchymal uptake of technetium-99m, indium-111, and iodine-125 low-density lipoprotein in the normal and estradiol-stimulated rat liver: tracer validation for quantitative low-density lipoprotein scintigraphy. 1995

T Leitha, and A Staudenherz, and M Hermann, and M Hüttinger, and B Gmeiner
University Clinic of Nuclear Medicine, University Vienna, Austria.

This study quantifies the parenchymal and nonparenchymal uptake of technetium-99m (99mTc)- and indium-111 (111In)-low-density lipoprotein (LDL) in different states of hepatic LDL-receptor activity to validate quantitative LDL scintigraphy. Iodine-125 (125I)-LDL was used as reference tracer. Four Sprague-Dawley rats with 17-alpha-ethinyl estradiol (EE)-stimulated LDL-receptor activity and five controls received all three tracers simultaneously 90 minutes before collagenase liver perfusion and metrizamide gradient cell separation. Total liver uptake of 99mTc-, 111In-, and 125I-LDL was 1.8 +/- 1.0, 1.6 +/- 0.8, and 0.2 +/- 0.2% injected dose/g organ weight, respectively. The contribution of nonparenchymal cells to total hepatic tracer uptake was 5.4 +/- 4.7%, 11.6 +/- 10.3%, and 9.6 +/- 7.6% in controls. Estradiol treatment increased total liver uptake to 2.4 +/- 0.5, 2.0 +/- 0.2, and 0.5 +/- 0.3% injected dose/g and reduced nonparenchymal cell contribution to 2.3 +/- 2.6%, 4.2 +/- 4.8%, and 2.6 +/- 2.9%, respectively. Dual-isotope scintigraphy in EE-treated and control rats confirmed these data, with a lower total hepatic uptake of 111In-LDL in comparison with 99mTc-LDL but a comparative degree of increase by EE treatment. Both behave quantitatively comparable as residualizing tracers, yet 99mTc-LDL shows a higher affinity to the LDL receptor pathway of parenchymal cells. However, the nonspecific uptake of both tracers can be neglected for quantitative LDL scintigraphy, and external imaging of hepatic tracer uptake primarily reflects LDL-receptor activity of parenchymal cells.

UI MeSH Term Description Entries
D007205 Indium Radioisotopes Unstable isotopes of indium that decay or disintegrate emitting radiation. In atoms with atomic weights 106-112, 113m, 114, and 116-124 are radioactive indium isotopes. Radioisotopes, Indium
D007457 Iodine Radioisotopes Unstable isotopes of iodine that decay or disintegrate emitting radiation. I atoms with atomic weights 117-139, except I 127, are radioactive iodine isotopes. Radioisotopes, Iodine
D007700 Kinetics The rate dynamics in chemical or physical systems.
D008077 Lipoproteins, LDL A class of lipoproteins of small size (18-25 nm) and light (1.019-1.063 g/ml) particles with a core composed mainly of CHOLESTEROL ESTERS and smaller amounts of TRIGLYCERIDES. The surface monolayer consists mostly of PHOSPHOLIPIDS, a single copy of APOLIPOPROTEIN B-100, and free cholesterol molecules. The main LDL function is to transport cholesterol and cholesterol esters to extrahepatic tissues. Low-Density Lipoprotein,Low-Density Lipoproteins,beta-Lipoprotein,beta-Lipoproteins,LDL(1),LDL(2),LDL-1,LDL-2,LDL1,LDL2,Low-Density Lipoprotein 1,Low-Density Lipoprotein 2,LDL Lipoproteins,Lipoprotein, Low-Density,Lipoproteins, Low-Density,Low Density Lipoprotein,Low Density Lipoprotein 1,Low Density Lipoprotein 2,Low Density Lipoproteins,beta Lipoprotein,beta Lipoproteins
D008099 Liver A large lobed glandular organ in the abdomen of vertebrates that is responsible for detoxification, metabolism, synthesis and storage of various substances. Livers
D011877 Radionuclide Imaging The production of an image obtained by cameras that detect the radioactive emissions of an injected radionuclide as it has distributed differentially throughout tissues in the body. The image obtained from a moving detector is called a scan, while the image obtained from a stationary camera device is called a scintiphotograph. Gamma Camera Imaging,Radioisotope Scanning,Scanning, Radioisotope,Scintigraphy,Scintiphotography,Imaging, Gamma Camera,Imaging, Radionuclide
D011973 Receptors, LDL Receptors on the plasma membrane of nonhepatic cells that specifically bind LDL. The receptors are localized in specialized regions called coated pits. Hypercholesteremia is caused by an allelic genetic defect of three types: 1, receptors do not bind to LDL; 2, there is reduced binding of LDL; and 3, there is normal binding but no internalization of LDL. In consequence, entry of cholesterol esters into the cell is impaired and the intracellular feedback by cholesterol on 3-hydroxy-3-methylglutaryl CoA reductase is lacking. LDL Receptors,Lipoprotein LDL Receptors,Receptors, Low Density Lipoprotein,LDL Receptor,LDL Receptors, Lipoprotein,Low Density Lipoprotein Receptor,Low Density Lipoprotein Receptors,Receptors, Lipoprotein, LDL,Receptor, LDL,Receptors, Lipoprotein LDL
D002469 Cell Separation Techniques for separating distinct populations of cells. Cell Isolation,Cell Segregation,Isolation, Cell,Cell Isolations,Cell Segregations,Cell Separations,Isolations, Cell,Segregation, Cell,Segregations, Cell,Separation, Cell,Separations, Cell
D004997 Ethinyl Estradiol A semisynthetic alkylated ESTRADIOL with a 17-alpha-ethinyl substitution. It has high estrogenic potency when administered orally, and is often used as the estrogenic component in ORAL CONTRACEPTIVES. 19-Norpregna-1,3,5(10)-trien-20-yne-3,17-diol, (17alpha)-,Ethynyl Estradiol,Estinyl,Ethinyl Estradiol Hemihydrate,Ethinyl Estradiol, (8 alpha)-Isomer,Ethinyl Estradiol, (8 alpha,17 alpha)-Isomer,Ethinyl Estradiol, (8 alpha,9 beta,13 alpha,14 beta)-Isomer,Ethinyl Estradiol, (9 beta,17 alpha)-Isomer,Ethinyl-Oestradiol Effik,Ethinylestradiol Jenapharm,Ethinyloestradiol,Lynoral,Microfollin,Microfollin Forte,Progynon C,Estradiol, Ethinyl,Estradiol, Ethynyl,Ethinyl Oestradiol Effik,Hemihydrate, Ethinyl Estradiol,Jenapharm, Ethinylestradiol
D006801 Humans Members of the species Homo sapiens. Homo sapiens,Man (Taxonomy),Human,Man, Modern,Modern Man

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