Structural identification, subcellular localization and secretion of bovine adrenomedullary neuromedin C...

Bombesin-like immunoreactivity (BLI) was purified from acid (HCl) extracts of bovine adrenal medulla. High performance liquid chromatography (HPLC) on a mu-Bondapak C18 column revealed the presence of five molecular forms of BLI, one coeluting with synthetic gastrin releasing peptide (GRP), the mammalian counterpart of amphibian bombesin, one coeluting with neuromedin C, one coeluting with neuromedin B and the two other ones coeluting with the oxidized forms of neuromedins B and C. The material corresponding to neuromedin C was purified to homogeneity and its amino acid composition and sequence corresponded to those expected for neuromedin C. HPLC analysis on an analytical SP-5PW column of subcellular extracts of bovine adrenal medulla indicated that neuromedin C is almost exclusively localized in secretory granules. The neuropeptide function of neuromedin C and/or other BLI peptides at this level was supported by the stimulatory effect of carbamylcholine (500 microM) on the release of BLI (4.5-fold increase over the basal release of 19 fmol/5 min) from perfused bovine adrenal glands.