PURIFICATION AND CHARACTERIZATION OF PAMP-12 (PAMP[9-20]) IN PORCINE ADRENAL-MEDULLA AS A MAJOR ENDOGENOUS BIOLOGICALLY-ACTIVE PEPTIDE

Proadrenomedullin N-terminal 20 peptide (PAMP-20) is a potent hypotens ive peptide processed from the adrenomedullin (AM) precursor, We devel oped a specific radio-immunoassay which recognizes the C-terminal regi on of PAMP-20, Using this radioimmunoassay, the distribution of immuno reactive (ir-) PAMP was determined in porcine tissues, High concentrat ions of ir-PAMP were observed in the adrenal medulla and in the atrium , and these values mere comparable to the corresponding concentrations of ir-AM, The concentration of ir-PAMP was almost the same as that of ir-AM in the kidney, while ir-PAMP was significantly lower than ir-AM in the ventricle, lung, and aorta, Reversed-phase high performance li quid chromatography in each porcine tissue sample revealed that two ma jor peaks of ir-PAMP existed: one emerged at a position identical to t hat of authentic porcine PAMP-20; the other unknown peak was eluted ea rlier, The unknown peptide was purified to homogeneity from porcine ad renal medulla, and its complete amino acid sequence was determined, Th is peptide was found to be PAMP[9-20] with a C-terminal amide structur e, and was named PAMP-12, Intravenous injections of PAMP-12 in anesthe tized rats showed a significant hypotensive effect in a dose-dependent fashion, and the effect mas comparable to that of PAMP-20. These data indicate that PAMP-12, a major component of ir-PAMP, is processed fro m the AM precursor, as is PAMP-20, and may participate in cardiovascul ar control. (C) 1997 Federation of European Biochemical Societies.