Identification of "B" receptor for natriuretic peptide in human kidney

Three distinct receptor types for natriuretic peptides (NP) have been identified in human tissue. "A" and "B" receptors initiate biological actions, whereas the "C" receptor has a clearance function. It has been proposed that the natural ligand for the B receptor is c-type natriuretic peptide (CNP), rather than atrial natriuretic peptide (ANP), and that the B receptor is only found in the central nervous system (CNS) and is responsible for all NP-mediated effects in the CNS. Contrary to this hypothesis, we have identified, by means of the polymerase chain reaction (PCR), the B receptor in human kidney tissue. To detect A and C receptors, the PCR reaction was performed with primers which yielded predicted 600 and 378 base pair (bp) products, respectively. For the B receptor, 3 different primer sets were used, resulting in the expected 785, 453 and 228 bp fragments. Restriction mapping of the latter two products with Rsa I yielded the expected fragment numbers and sizes, indicating the PCR products were from B receptor mRNA. These results indicate that the human kidney has B as well as A and C receptors. Thus CNP may have a renal as well as a CNS site of action.