title: Characterization of specific receptors for atrial natriuretic factor in bovine adrenal zona glomerulosa.
abstract: We have recently shown that synthetic rat atrial natriuretic factor (ANF) directly inhibits mineralocorticoid and glucocorticoid secretion in cultured bovine adrenal cells with a potency of 100 pM. [125I]iodo-ANF was used in the present study to characterize potential receptor sites in bovine zona glomerulosa membranes. ANF binds to a class of high affinity binding sites with a pK of 10.2 and a density of 1.3 pmol/mg protein. Detailed competition curves with ANF document a class of high affinity sites with a pK of 10.2 and also a second class of lower affinity sites with a pK of 8.5. Nonspecific binding amounts to less than 10% of [125I]iodo-ANF binding at concentrations less than 100 pM. High affinity binding of [125I]iodo-ANF is reversible with a half-time of association of 15 minutes at 25 pM and a half-time of dissociation of 140 minutes. Monovalent cations Na, Li and K equipotently enhance [125I]iodo-ANF specific binding. Divalent cations Mg, Ca and Mn also increase [125I]iodo-ANF specific binding, with Mn being the most active cation. No effect of guanine nucleotide could be detected on ANF binding. The binding of [125I]iodo-ANF is very specific and is not inhibited by 1 microM angiotensin II, ACTH, VIP, somatostatin, Leu-enkephalin, dynorphin or by the N-terminal of POMC. The N-terminal fragment ANF-(1-16) is also completely inactive. Reduction of the disulfide bridge of ANF inactivates the peptide. This enabled the development of a highly specific radio-receptor assay for ANF with a minimum detectable dose of 2 femtomoles. The results document the specific receptor involved in the potent inhibitory effect of ANF on adrenal steroidogenesis and indicate that bovine adrenal zonal glomerulosa provide a highly sensitive system for studying the recently discovered atrial natriuretic factor.
mesh_terms: D000311:Adrenal Glands / Q000378:metabolism*; D000818:Animals; D009320:Atrial Natriuretic Factor; D001667:Binding, Competitive; D002413:Cations, Divalent; D002414:Cations, Monovalent; D002417:Cattle; D007700:Kinetics; D009124:Muscle Proteins / Q000138:chemical synthesis / Q000378:metabolism*; D010446:Peptide Fragments / Q000138:chemical synthesis; D017461:Receptors, Atrial Natriuretic Factor; D011956:Receptors, Cell Surface / Q000378:metabolism*
chemical_list: D002413:Cations, Divalent; D002414:Cations, Monovalent; D009124:Muscle Proteins; D010446:Peptide Fragments; D011956:Receptors, Cell Surface; D009320:Atrial Natriuretic Factor; C043924:atrial natriuretic factor (1-16); D017461:Receptors, Atrial Natriuretic Factor