Abstract: Adrenomedullin which is a novel peptide having a hypotensive effect; proadrenomedullin N-terminal 20 peptide (proAM-N20) corresponding to an amino acid sequence of an N-terminus of proadrenomedullin, having a catecholamine secretion inhibitory effect; proadrenomedullin N-terminal 10-20 peptide (proAM-N(10-20)) having a Na channel inhibitory effect, and a gene encoding these peptides are provided. In addition, according to the present invention, these peptides in a sample containing adrenomdullin or proAM-N20 in an unknown amount can be quantified by using an antibody against adrenomedullin, proAM-N20, or its fragment.

Abstract: The present invention relates to a sandwich immunoassay for rapidly and readily measuring N-peptide using two kinds of monoclonal antibodies recognizing different portions of the N-peptide. The method for measuring N-peptide or a precursor thereof includes the steps of: incubating a mixture containing a sample and a first monoclonal antibody recognizing a portion of N-peptide; adding a labelled second monoclonal antibody recognizing a portion of N-peptide to the mixture, followed by further incubation; and detecting the resulting antigen-antibody complex in the mixture. Alternatively, the method includes the steps of: incubating a mixture containing a sample, a first monoclonal antibody recognizing a portion of N-peptide, and a labelled second monoclonal antibody recognizing another portion of N-peptide; and detecting the resulting antigen-antibody complex.