RECEPTORS FOR ATRIAL-NATRIURETIC-PEPTIDE IN ADRENAL CHROMAFFIN CELLS

Receptors for atrial natriuretic peptide (ANP) in isolated bovine adre nal chromaffin cells were characterized. I-125-ANP specifically bound to the cells with a K-d of 103 PM and a B-max of 5.6 fmol/10(6) cells (16.4 fmol/mg of cell protein). C-ANF, a highly selective ligand for A NP-C receptors of natriuretic peptides, did not compete for I-125-ANP binding at concentrations up to 10 nM. Chemical cross-linking of I-125 -ANP to the cells showed a single molecular size of the 120 kDa bindin g site on SDS gel electrophoresis under reducing conditions. CNP, a sp ecific peptide for the ANP-B receptor, was much less potent than ANP i n inhibiting I-125-ANP binding and in displacing I-125-ANP from the 12 0 kDa band. These results suggest that ANP specifically binds to the A NP-A receptor of 120 kDa and that there is no ANP-C receptor in bovine adrenal chromaffin cells.