(Met)enkephalin and carboxypeptidase processing enzyme are co-released from chromaffin cells by cholinergic stimulation.
A carboxypeptidase B-like enzyme is involved in processing of proenkephalin in adrenal medulla. Nicotine stimulated the co-release of this enzyme with (Met)enkephalin pentapeptide from bovine chromaffin cells in primary culture. The ratio of enzyme activity/immunoreactivity was determined for the released carboxypeptidase to provide an index of the level of enzyme activity per unit number of enzyme molecules. The ratio for the Co++-stimulated carboxypeptidase secreted into the cell culture medium upon nicotinic stimulation was 10.1 +/- 1.02 (pmol Met-enkephalin formed per ng carboxypeptidase immunoreactivity), while the Co++-stimulated carboxypeptidase in the soluble and membrane components of purified chromaffin granules had lower ratios of 5.46 +/- 0.70 and 1.07 +/- 0.13, respectively. Hexamethonium, a nicotinic receptor antagonist, blocked the nicotine-induced release of the carboxypeptidase processing enzyme and (Met)enkephalin. These data suggest that a pool of carboxypeptidase enzyme molecules at a high state of activation are present in functionally mature granules whose contents are released by nicotinic receptor stimulation.
D000818:Animals; D043424:Carboxypeptidase B; D002268:Carboxypeptidases / Q000378:metabolism*; D002417:Cattle; D002837:Chromaffin Granules / Q000378:metabolism*; D002838:Chromaffin System / Q000378:metabolism*; D003035:Cobalt / Q000494:pharmacology; D004744:Enkephalin, Methionine / Q000378:metabolism*; D006584:Hexamethonium Compounds / Q000494:pharmacology; D009538:Nicotine / Q000494:pharmacology*; D011863:Radioimmunoassay
D006584:Hexamethonium Compounds; D003035:Cobalt; D004744:Enkephalin, Methionine; D009538:Nicotine; D002268:Carboxypeptidases; D043424:Carboxypeptidase B