The distribution, purification, and pharmacological action of an amphibian neuromedin U.

The distribution, primary structure, and relative biological activity of neuromedin U has been determined from the frog Rana temporaria. Following sequential column chromatography of a gastrointestinal extract, the peptide was sufficiently pure to enable characterization by micro-sequence analysis. The entire sequence was found to be an icosapentapeptide which displays marked sequence similarity to both porcine and rat neuromedin U. The sequence of the biologically active, COOH-terminal region is almost completely conserved across all species. Synthetic, COOH-terminally amidated amphibian neuromedin U, like the porcine and rat peptides, stimulates rat uterine contraction in vitro thereby fulfilling the criterion upon which the nomenclature of this peptide family is based. In addition, the peptide demonstrates parallel pressor effects when infused systemically into rats. The high degree of amino acid sequence conservation is indicative of strong evolutionary pressure acting to retain the presence of this possibly physiologically important peptide across the vertebrate subphylum.