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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
Author(s) -
Leitha Thomas,
Staudenherz Anton,
Hermann Marcela,
Hüttinger Manfred,
Gmeiner Bernhard
Publication year - 1995
Publication title -
hepatology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.488
H-Index - 361
eISSN - 1527-3350
pISSN - 0270-9139
DOI - 10.1002/hep.1840220439
Subject(s) - chemistry , scintigraphy , endocrinology , medicine , lipoprotein , perfusion , low density lipoprotein , nuclear medicine , cholesterol , biochemistry
This study quantifies the parenchymal and nonparen‐chymal uptake of technetium‐99m ( 99m Tc)‐ and indium‐III ( 111 In)‐low‐density lipoprotein (LDL) in different states of hepatic LDL‐receptor activity to validate quantitative LDL scintigraphy. Iodine‐125 ( 125 I)‐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 99m Tc‐, 111 In‐, and 125 I‐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 111 In‐LDL in comparison with 99m Tc‐LDL but a comparative degree of increase by EE treatment. Both behave quantitatively comparable as residu‐alizing tracers, yet 99m Tc‐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. (H EPATOLOGY 1995; 22:1289–1295.).