Equilibrium binding studies in rabbit inner medullary collecting duct cells revealed a single class of high-affinity ANP receptors (Kd = 66.2 pM) with 3,000 sites/cell and a molecular mass of 130 kDa.
The final urinary Na+ concentration is determined in the inner medullary collecting duct (IMCD) and is under hormonal control. In suspensions of IMCD cells we have previously shown that atrial natriuretic peptide (ANP) inhibits Na+ transport-dependent O2 consumption and causes an increase in cellular guanosine 3',5'-cyclic monophosphate (cGMP) content. In this study we sought to identify and characterize the receptor for ANP in these cells. Equilibrium binding studies revealed a single class of cell surface ANP receptors of high affinity (Kd = 66.2 pM) with a total number of 3,000 sites/cell. Specificity of these receptors was shown by the rank order of binding affinities for ANP analogues: ANP-(1-28) = ANP-(4-28) greater than ANP-(5-28) much greater than ANP-(5-25). We have further defined this receptor in a solubilized cell preparation and found it to be of molecular mass 130 kDa by affinity cross linking and sodium dodecyl sulfate-polyacrylamide gel electrophoresis analysis. This is the first characterization of an epithelial cell receptor for ANP; as in other systems this receptor appears to be linked to transport processes via the production of cGMP.
Gunning et al. (Mon,) reported a other. Atrial natriuretic peptide (ANP) was evaluated on ANP receptor characterization (affinity, number of sites, molecular mass). Equilibrium binding studies in rabbit inner medullary collecting duct cells revealed a single class of high-affinity ANP receptors (Kd = 66.2 pM) with 3,000 sites/cell and a molecular mass of 130 kDa.