Different metabolism of norepinephrine and epinephrine by catechol-O-methyltransferase and monoamine oxidase in rats.

摘要: Normetanephrine (NMN) and metanephrine (MN), are the O-methylated metabolites of norepinephrine (NE) epinephrine (E), whereas dihydroxyphenylglycol (DHPG) is deaminated metabolite both NE E. This study compared production NMN, MN DHPG during tracer high-dose infusions Ne E in rats, with without inhibition catechol-O-methyltransferase (COMT) or A B forms monoamine oxidase (MAO). Animals also received NMN to compare plasma clearances spillovers MAO inhibition. Inhibition COMT increased decreased MN, MN. The increase after reflected blocked deamination by MAO-A, but not MAO-B. form was largely responsible for NE. Infused less efficiently than High doses infused were more NE, similarly. After Increased combined effects a decrease clearance an spillover into plasma, smaller due solely Thus, at extraneuronal sites O-methylation, proportionally as concentration increases. above results support preference over neuronal pathways metabolism, indicate considerably complex differences metabolism O-methylation deamination.