title: Characterization and localization of (-)[125I]-cyanopindolol binding to non-beta-adrenoceptor sites in dog kidney.
abstract: 1. (-)[125I]-Cyanopindolol (CYP) binding to non-beta-adrenoceptor sites in dog kidney was characterized in homogenate preparations and their distribution in sections determined using autoradiography. 2. In homogenate studies, (-)[125I]-CYP bound to a single population of non-interacting sites (Bmax = 5.45, s.e.m. = 1.00 fmol/mg wet weight; nH = 0.99, s.e.m. = 0.01) with high affinity (KD = 3.84, s.e.m. = 0.76 nmol/l, n = 40. 3. In competition studies, compounds selective for alpha- and beta-adrenoceptors, muscarinic cholinoceptors and receptors for 5-HT, histamine and benzodiazepines, calcium channel antagonists, catecholamine uptake inhibitors, MAO inhibitors and adrenergic neurone blockers were ineffective at concentrations of 10 mumol/l. 4. Compounds selective for dopamine D1-receptors (fluphenazine, SCH 23390 and SK & F 82526) and D2-receptors (pimozide, domperidone, spiperone, haloperidol, sulpiride, cis- and trans-flupenthixol) competed with similar affinities (5-25 mumol/l) for (-)[125I]-CYP binding. 5. In autoradiographic studies, (-)[125I]-CYP binding to non-beta-adrenoceptor sites was localized over glomeruli, juxtaglomerular apparatus, distal tubules, blood vessels and medullary rays and tubules. 6. It is concluded that in dog kidney, (-)[125I]-CYP binds to a site closely associated with dopamine receptors.
mesh_terms: D000319:Adrenergic beta-Antagonists / Q000378:metabolism*; D000818:Animals; D001345:Autoradiography / Q000379:methods; D001667:Binding, Competitive; D004285:Dogs; D005260:Female; D066298:In Vitro Techniques; D007457:Iodine Radioisotopes; D007668:Kidney / Q000033:anatomy & histology / Q000378:metabolism*; D007700:Kinetics; D008297:Male; D008566:Membranes / Q000378:metabolism; D010869:Pindolol / Q000031:analogs & derivatives* / Q000378:metabolism; D011869:Radioligand Assay
chemical_list: D000319:Adrenergic beta-Antagonists; D007457:Iodine Radioisotopes; C047975:cyanopindolol; D010869:Pindolol