IMMUNOREACTIVE PROADRENOMEDULLIN N-TERMINAL-20 PEPTIDE IN HUMAN TISSUE, PLASMA AND URINE

Proadrenomedullin N-terminal 20 peptide (PAMP) is a candidate for a no vel biologically active peptide processed from proadrenomedullin. This study clearly demonstrates the existence of PAMP in vivo that had bee n deduced from analysis of cDNA. To identify PAMP in vivo, we establis hed a radioimmunoassay for PAMP and characterized immunoreactivities i n human tissue, plasma and urine. Half maximal inhibition of the assay was observed at 10 fmol/tube. A high concentration of immunoreactive PAMP was found in adrenal medulla (18.4 +/- 8.95 fmol/mg, mean +/- S.D .) and pheochromocytoma tissue (12.3 +/- 9.82 fmol/mg) where the conce ntrations are comparable to that of adrenomedullin. As determined by t hree different kinds of chromatography, most of the immunoreactive pep tide in pheochromocytoma was eluted at a position exactly identical to that of synthetic PAMP. Further, considerable concentration of immuno reactive PAMP was found in human plasma and urine. The present data in dicate that PAMP as well as adrenomedullin is processed from an adreno medullin precursor. (C) 1994 Academic Press, Inc.