ADRENAL RECEPTORS FOR NATRIURETIC PEPTIDES AND INHIBITION OF ALDOSTERONE SECRETION IN CALF ZONA GLOMERULOSA CELLS IN CULTURE

Atrial and brain natriuretic peptides specifically bind to primary cultures of calf adrenal glomerulosa cells. Binding of both natriuretic peptides to the same receptor has been proved by: a Dixon plot showing competitive effects for the binding of I-125-labeled brain natriuretic peptide in the presence of increasing concentrations of unlabeled atrial natriuretic peptide; a Scatchard plot showing a lower dissociation constant (K(d)) for atrial natriuretic peptide than for brain natriuretic peptide binding, but the maximum binding (B(max)) values were the same; autoradiography of sodium dodecyl sulfate polyacrylamide gels after cross-linking of I-125-labeled atrial natriuretic peptide and I-125-labeled brain natriuretic peptide, showing the same molecular weights for both peptide receptors-a single 66-kD band in whole cells and a main band at 125 kD in membranes. C-Type atrial natriuretic peptide only slightly displaced atrial natriuretic peptide binding. Angiotensin II- and potassium-mediated stimulation of aldosterone production were inhibited strongly and to the same degree by atrial and brain natriuretic peptide but only slightly by C-type atrial natriuretic peptide. Stimulation of aldosterone production mediated by adrenocorticotropin was only partially inhibited by atrial and brain natriuretic peptide, while baseline aldosterone was not affected. These results suggest that atrial and brain natriuretic peptide bind to the same receptors and provoke the same effects on aldosterone production. The weak effects found with C-type atrial natriuretic peptide suggest that the primary culture of calf adrenal glomerulosa cells contain the guanylate cyclase A receptor.