NATRIURETIC HORMONE RECEPTORS AND ACTIONS ON BONE ENDOTHELIAL-CELLS

[I-125]Atrial natriuretic peptide (ANP) was used to identify ANP recep tors on a clonal line of bovine bone endothelial (BBE) cells. Specific binding of [I-125]ANP was saturable and of high affinity. Computer an alysis of the equilibrium binding data indicated that the Scatchard pl ots are best fit by a straight line (K(d) = 69.3 +/- 20.9 pm; binding capacity = 37.9 fmol/10(6) cells). The order of potency for competing with [I-125]ANP binding was human ANP (hANP) > rat atriopeptin-1 (rAP- 1) > porcine brain natriuretic peptide (pBNP) > porcine C-type natriur etic peptide. Affinity cross-linking studies indicated the presence of two major 130- and 70-kilodalton bands that specifically bound to hAN P, rAP-1, pBNP, and porcine C-type natriuretic peptide. The binding of natriuretic peptides to BBE cells resulted in an increase in cGMP pro duction and a significant decrease in Na+/K+/Cl-cotransport, without e ffects on cAMP intracellular accumulation. hANP, rAP-1, and pBNP at 10 0-nm concentrations, significantly inhibited PTH-induced cAMP producti on. Treatment with natriuretic hormones was also associated with an in crease in 6-keto-prostaglandin F1alpha levels in the culture medium of BBE cells and a higher cell growth rate. These studies demonstrate th at bone endothelial cells bear receptors for natriuretic hormones asso ciated with changes in PTH-induced cAMP production, prostaglandin prod uction, and cell proliferation.