Reduction of 14C-norepinephrine metabolism in rabbit aorta by vasodilators.
In the present study, both of the major enzymes, monoamine oxidase and catechol-o-methyltransferase, involved in the degradation of norepinephrine were examined indirectly in segments of rabbit aorta by exposure of tissues to 14C-norepinephrine and subsequent isolation of metabolites from homogenates by chromatographic techniques. Segments of aorta were preincubated with vasodilators to examine their influence on accumulation and metabolism of 14C-norepinephrine. The accumulation of labeled norepinephrine by aortae was enhanced after preincubation with hydrochlorothiazide or diazoxide, and reduced after preincubation with sodium nitroprusside or nitroglycerin. However, the fraction of accumulated 14C-norepinephrine which was degraded was significantly reduced after exposure to all four vasodilators. These results suggest that a decrease in degradation of norepinephrine in vascular smooth muscle can be observed (1) in vitro and (2) fairly rapidly after exposure to vasodilators.
D000818:Animals; D001011:Aorta / Q000378:metabolism*; D003864:Depression, Chemical; D003981:Diazoxide / Q000494:pharmacology*; D005292:Ferricyanides / Q000494:pharmacology*; D006852:Hydrochlorothiazide / Q000494:pharmacology*; D009130:Muscle, Smooth / Q000378:metabolism; D005996:Nitroglycerin / Q000494:pharmacology*; D009599:Nitroprusside / Q000494:pharmacology*; D009638:Norepinephrine / Q000378:metabolism*; D011817:Rabbits
D005292:Ferricyanides; D006852:Hydrochlorothiazide; D009599:Nitroprusside; D005996:Nitroglycerin; D003981:Diazoxide; D009638:Norepinephrine