Molecular Pharmacology, Vol 18, 335-340, Copyright © 1980 by the American Society for Pharmacology and Experimental Therapeutics

Characterization of Dopaminergic Receptors in Dispersed Bovine Parathyroid Cells

¹ Endocrine-Hypertension Unit, Department of Medicine, Peter Bent Brigham Hospital, Boston, Massachusetts 02115
² Metabolic Diseases Branch, NIAMDD, NIH, Bethesda, Maryland 20205
³ Experimental Therapeutics Branch, NINCDS, NIH, Bethesda, Maryland 20205

Several dopaminergic ligands were assessed for their effects on cAMP accumulation, adenylate cyclase activity, and parathyroid hormone (PTH) release from dispersed bovine parathyroid cells. Dopamine, 6,7-dihydroxy-1,2,3,4 tetrahydronaphthalene (ADTN), 2,3,4,5-tetrahydro-7,8-dihydroxy-1-phenyl-1H-3-benzazepine (SKF-38393), and apomorphine increased cAMP content 30-, 25-, 10-, and 2- to 3-fold with K_a’s of 0.6, 0.5, 1, and 1-3 µM, respectively. These same agents also stimulated adenylate cyclase activity up to 4-fold and PTH release 1.3- to 3-fold. With the exception of lisuride (K_i = 15 nM), ergot derivatives were of relatively low potency (K_i’s = 0.4-20 µM) in inhibiting dopamine-stimulated cAMP accumulation. Similar K_i’s were observed for effects on dopamine-stimulated adenylate cyclase activity and PTH release. Interactions of these ligands with the dopamine receptor could be clearly differentiated from effects of -adrenergic or -adrenergic receptors also known to modulate cAMP accumulation and secretion in this cell type. These results demonstrate the presence of a D-1 dopaminergic receptor on bovine parathyroid cells and document further the relationship in this receptor subclass between adenylate cyclase activity, cAMP accumulation, and a biologic response.