A MONOCLONAL-ANTIBODY TO C-TYPE NATRIURETIC PEPTIDE - PREPARATION ANDAPPLICATION TO RADIOIMMUNOASSAY AND NEUTRALIZATION EXPERIMENT

C-type natriuretic peptide (CNP), the third member of natriuretic pept ides, has recently been discovered from the porcine brain. Using a pol yclonal antiserum to CNP, we demonstrated that CNP-like immunoreactivi ty (CNP-LI) is present mainly in the central nervous system. Recently, however, we have discovered the production and secretion of CNP in va scular endothelial cells. These observations suggested that CNP may ac t not only as a neuropeptide but also as a local regulator of vascular tone or growth. In order to further clarify the pathophysiological si gnificance of CNP, we aimed at the preparation of a monoclonal antibod y to CNP. A monoclonal antibody to CNP, KY-CNP-I, has been produced. T his monoclonal antibody belongs to the immunogloblin G, subclass and h as high affinity for CNP. Using this monoclonal antibody, we establish ed a specific radioimmunoassay (RIA) for CNP. The RIA detected CNP-LI in rat brain extracts and culture media conditioned with bovine endoth elial cells. In addition, the pretreatment of cultured aortic smooth m uscle cells with KY-CNP-I attenuated cyclic GMP production induced by CNP in vitro. The preadministration of KY-CNP-I to rats also attenuate d plasma cyclic GMP increase after intravenous injection of CNP in viv o. These results indicate that this monoclonal antibody is a useful to ol to clarify the pathophysiological role of CNP as a neuropeptide and as a local vascular regulator.