Identification of alpha atrial natriuretic peptide [4-28] and [5-28] in porcine brain.

Although atrial natriuretic peptide (ANP) has recently been verified to function as a neuropeptide in the central nervous system, its definite identification has not been done so far. We have isolated two ANP-related peptides from porcine brain by utilizing alpha-ANP specific radiommunoassay coupled with immunoaffinity chromatography and reverse phase HPLC. By structural analyses, these two peptides were determined to be alpha-ANP [4-28] and alpha-ANP [5-28]. They were found to elicit chick rectum relaxant activity comparable to alpha-ANP. These results indicate that proteolytic processing of ANP precursor in the central nervous system takes place in a manner different from that in heart and plasma, where gamma-ANP and alpha-ANP are known to be the main components of ANP, respectively.