Autoradiographic localization of vascular dopamine receptors.
By using combined in vitro radioreceptor binding and autoradiographic techniques, the pharmacological profile and the anatomical localization of dopamine-1 (DA-1) and dopamine-2 (DA-2) receptors were assessed in rat cerebral, mesenteric and renal arteries. 3H-SCH 23390 (DA-1 ligand) was bound by the medial layer of cerebral, mesenteric and renal arteries without different density in large, medium and small sized arteries. Moreover, 3H-SCH 23390 binding sites were not sensitive to chemical sympathectomy, suggesting postjunctional localization of DA-1 receptors. 3H-Spiroperidol (DA-2 ligand) was bound primarily by the adventitial, the adventitial-medial border as well as by the intimal layer of cerebral, mesenteric and renal arteries. The accumulation of adventitial and adventitial-medial 3H-spiroperidol binding sites was higher in medium and small sized arteries than in large ones and was remarkably reduced after chemical sympathectomy. These results show prejunctional localization of DA-2 receptors and further suggest that some DA-2 binding sites are located in the arterial intima.
Dipartimento di Scienze Neurologiche, Università La Sapienza, Rome, Italy.
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D000818:Animals; D001345:Autoradiography; D001552:Benzazepines / Q000378:metabolism; D001665:Binding Sites; D001667:Binding, Competitive; D001808:Blood Vessels / Q000378:metabolism; D002560:Cerebrovascular Circulation; D018492:Dopamine Antagonists; D008297:Male; D051381:Rats; D011919:Rats, Inbred Strains; D011954:Receptors, Dopamine / Q000378:metabolism*; D012079:Renal Circulation; D013134:Spiperone / Q000378:metabolism; D013152:Splanchnic Circulation; D014018:Tissue Distribution
D001552:Benzazepines; D018492:Dopamine Antagonists; D011954:Receptors, Dopamine; D013134:Spiperone