DISTRIBUTION AND CHARACTERIZATION OF IMMUNOREACTIVE RAT ADRENOMEDULLIN IN TISSUE AND PLASMA

Adrenomedullin is a new bioactive peptide recently isolated from pheoc hromocytoma. We report on the rat adrenomedullin distribution and mole cular forms in various tissues and plasma. Using a sensitive radioimmu noassay system for rat adrenomedullin, high concentrations of immunore active rat adrenomedullin were detected in adrenal gland, lung and car diac atrium. In lung and atrium, the immunoreactivity concentration in rat was about 6-10 times higher than that in human. The mean plasma c oncentration of immunoreactive rat adrenomedullin was 3.60 +/- 0.34 fm ol/ml (mean +/- S.D.). Analysis in adrenal gland, lung and atrium with reverse-phase and gel-filtration high-performance liquid chromatograp hy showed that most immunoreactive rat adrenomedullin emerged as a sin gle peak at a position exactly identical to that of the authentic rat adrenomedullin peptide, synthesized according to the sequence predicte d from the cDNA.