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KMID : 1161520000040010063
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Animal Cells and Systems
2000 Volume.4 No. 1 p.63 ~ p.70
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Receptor subtypes for endothelin in the kidney of the freshwater turtle (amyda japonica)
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Kim Sung-Zoo
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Abstract
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The distribution of receptor subtypes for endothelin (ET) in the kidney of the freshwater turtle, Amyda japonica, was examined by quantitative in vitro receptor autoradiography using iodinated mammalian type ET?1 (125I?ET?1) as a radiolabeled ligand. Specific 125I?ET?1 bindings were localized to renal tubules, renal arteries and ureter with binding densities of 111.21 ± 19.14, 182.13 ± 10.57 and 219.46 ± 12.83 amol/mm2, respectively. Binding dissociation constants in renal tubules, renal arteries and ureter were 1.05 ± 0.63, 2.03±0.56 and 1.70±0.47nM, respectively. Receptor subtypes for ET in the kidney were characterized by competition with BQ 123 and BQ 788 as specific antagonists for ET receptors, type A (ETA), and type B (ETB) subtypes, respectively. Specific 125I?ET?1 bindings in renal arteries and ureter were potently inhibited by BQ 123 in a dose?dependent manner, whereas BQ 788 was not in competing for specific 125I?ET?1 bindings in this structure. However, specific 125I?ET?1 bindings in renal tubules were inhibited more potently by BQ 788. Therefore, these results indicate that specific ET receptors are localized in renal tubules, renal arteries and the ureter of the freshwater turtle. Results also suggest that the predominant ET receptor subtypes are like the ETA receptor in renal arteries and ureter, and like the ETB receptor in the renal tubule.
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KEYWORD
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Endothelin, Receptor subtype, Quantitative in vitroautoradiography, Kidney, Freshwater turtle, Amyda japonica
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