title: Radioiodinated p-iodoclonidine: a high-affinity probe for the alpha 2-adrenergic receptor.
abstract: The chemical synthesis of 2-[(2,6-dichloro-4-iodophenyl)imino]imidazolidine (PIC) and its radioiodinated analogue [125I]PIC is described. PIC was synthesized from 2,6-dichloroaniline in five synthetic steps. This agent displayed a high affinity for the alpha 2-adrenergic receptor (IC50 = 1.5 nM) in competitive binding assays conducted with purified human platelet plasma membrane fractions. For the synthesis of radioiodinated PIC the triazene intermediate 11 was synthesized from 2,6-dichloro-4-nitroaniline in five synthetic steps. Acid-catalyzed decomposition of 11 with no-carrier-added Na125I afforded high specific activity [125I]PIC. In view of its high affinity for the alpha 2-adrenergic receptor, [125I]PIC is a potentially useful probe for studies in adrenergic pharmacology.
mesh_terms: D000345:Affinity Labels / Q000138:chemical synthesis* / Q000378:metabolism; D003000:Clonidine / Q000031:analogs & derivatives* / Q000138:chemical synthesis / Q000378:metabolism; D006801:Humans; D007457:Iodine Radioisotopes; D011942:Receptors, Adrenergic, alpha / Q000378:metabolism*
chemical_list: D000345:Affinity Labels; D007457:Iodine Radioisotopes; D011942:Receptors, Adrenergic, alpha; C053113:4-iodoclonidine; D003000:Clonidine