Oxidative deamination of noradrenaline in human blood vessels.

Human vascular tissue (saphenous vein and uterine artery) was incubated with tritiated noradrenaline. In both vessels, oxidative deamination predominated over O-methylation. Deamination was due to the action of MAO type A and B, as well as of a semicarbazide-sensitive oxidase. Whereas DOPEG was a good index of intraneuronal deamination, NMN, DOMA and OMDA appeared to be entirely extraneuronal in origin. Extraneuronal deamination plays an important role in human vascular tissue and may contribute to the inactivation of circulating catecholamines.