CHARACTERIZATION AND LOCALIZATION OF (—‐)[125I]‐CYANOPINDOLOL BINDING TO NON‐β‐ADRENOCEPTOR SITES IN DOG KIDNEY

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Abstract

1. (—)[125I]‐Cyanopindolol (CYP) binding to non‐β‐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= 4). 3. In competition studies, compounds selective for α‐ and β‐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 μmol/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 μmol/l) for (—)[125I]‐CYP binding. 5. In autoradiographic studies, (—) [125I]‐CYP binding to non‐β‐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.

Original languageEnglish
Pages (from-to)711-723
Number of pages13
JournalClinical and Experimental Pharmacology and Physiology
Volume14
Issue number9
DOIs
Publication statusPublished - 1 Jan 1987

Keywords

  • autoradiography, (—)[I]‐cyanopindolol
  • dog kidney
  • radioligand binding.

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