Y-1 adrenocortical tumor cells contain atrial natriuretic peptide receptors which regulate cyclic nucleotide metabolism and steroidogenesis.

The effects of atrial natriuretic peptide (ANP) on adrenocortical fasciculata cells were examined in the ACTH-responsive Y-1 mouse adrenocortical tumor cell line. Y-1 cell membranes rapidly bound [125I]ANP, with equilibrium binding (22 C) reached within 45 min. Binding of [125I]ANP was inhibited in a concentration-dependent manner by unlabeled ANP and atriopeptin-I (IC50, approximately 1.2 X 10(-9) and 1.6 X 10(-8) M, respectively), but not by C- or N-terminal-deleted ANP fragments, ACTH, or arginine vasopressin (up to 10(-6) M). Scatchard analysis revealed a single class of high affinity binding sites with a Kd of 1.6 X 10(-10) M and a binding capacity of 560 fmol/mg protein. Photo-affinity labeling demonstrated the specific binding of ANP to two protein entities of 130 and 63 kDa. ANP stimulated both cGMP synthesis and secretion from Y-1 cells (EC50, approximately 3.5 X 10(-9) M). Release of the nucleotide was inhibited by probenecid (IC50, approximately 5 X 10(-5) M). The atrial peptide partially inhibited ACTH-stimulated cAMP formation (IC50, approximately 10(-8) M) and partially antagonized basal and ACTH-stimulated steroidogenesis. The data demonstrate the presence in Y-1 cells of specific and saturable ANP receptors, activation of which leads to changes in cyclic nucleotide metabolism and inhibition of steroidogenesis.