title: Binding of a novel dopaminergic agonist radioligand [3H]-fenoldopam (SKF 82526) to D-1 receptors in rat striatum.
abstract: Fenoldopam (SKF 82526), a dopamine agonist which exhibits D-1 receptor subtype selectivity, was evaluated as a radioligand for this receptor subtype. In saturation studies in rat striatal membrane preparations, [3H]-fenoldopam appeared to label a single binding site with a KD of 2.3 +/- 0.1 nM and a Bmax of 590 +/- 40 fmoles/mg protein. In competition binding experiments, binding was shown to be stereoselective, and rank ordering of affinities of dopaminergic and non-dopaminergic compounds closely correlated with potencies of these compounds in stimulating or inhibiting dopamine-sensitive adenylate cyclase (D-1) and in binding to D-1 sites labelled with the antagonist [3H]-cis-flupenthixol. The most potent competitors were the recently identified D-1 selective antagonists, SCH 23390 and SKF R-83566. [3H]-Fenoldopam was also used to assess agonist/D-1 receptor interactions. The results suggest that [3H]-fenoldopam is a useful and selective agonist radioligand for the D-1 receptor.
authors.forename: K E
authors.initials: KE
authors.lastname: Flaim
authors.forename: G W
authors.initials: GW
authors.lastname: Gessner
authors.forename: S T
authors.initials: ST
authors.lastname: Crooke
authors.forename: H M
authors.initials: HM
authors.lastname: Sarau
authors.forename: J
authors.initials: J
authors.lastname: Weinstock
mesh_terms: D000067956:Adenylyl Cyclase Inhibitors; D000818:Animals; D001552:Benzazepines / Q000378:metabolism* / Q000494:pharmacology; D001667:Binding, Competitive; D002421:Caudate Nucleus / Q000378:metabolism*; D018818:Fenoldopam; D005475:Flupenthixol / Q000378:metabolism; D006165:Guanylyl Imidodiphosphate / Q000494:pharmacology; D066298:In Vitro Techniques; D008297:Male; D011699:Putamen / Q000378:metabolism*; D011869:Radioligand Assay; D051381:Rats; D011919:Rats, Inbred Strains; D011954:Receptors, Dopamine / Q000378:metabolism*; D017447:Receptors, Dopamine D1; D012964:Sodium / Q000494:pharmacology; D013134:Spiperone / Q000378:metabolism
chemical_list: D000067956:Adenylyl Cyclase Inhibitors; D001552:Benzazepines; D011954:Receptors, Dopamine; D017447:Receptors, Dopamine D1; D006165:Guanylyl Imidodiphosphate; D013134:Spiperone; D012964:Sodium; D005475:Flupenthixol; D018818:Fenoldopam