Identification of an atrial natriuretic peptide specific receptor in human kidney

A specific receptor for human atrial natriuretic peptide (h-ANP) was identified in the human kidney using the radioligand binding assay. Samples were prepared from non-malignant renal tissues obtained at nephrectomy of patients with renal carcinoma. Binding studies using [125I]hANP were performed at 0 degree C for 20 minutes and terminated by a rapid filtration technique. Scatchard plot analysis revealed [125I]hANP bound to a single class of binding site (Kd = 0.4 +/- 0.2 nM) with a density of 16 +/- 4 fmol/mg protein in the renal cortex (n = 7). The binding was rapid and maximal binding was obtained within 20 minutes after the start of incubation. Radioligand displacement was observed in a dose dependent fashion when cold hANP was entered into the reaction mixture. However, unrelated agents, such as angiotensin II or 1-epinephrine, did not affect the binding. This is the first time characterization of the hANP receptor in the human kidney has been conducted using a Scatchard plot analysis.