Abstract
The urinary excretion of radioactive metabolites has been qualitatively and quantitatively investigated in rabbits after the intraperitoneal administration of tyramine-C14. The major urinary metabolite found was p-hydroxy-phenylacetic acid, which accounted for approximately 85% of the urinary radioactivity. Three other metabolites, 3-methoxy-4-hydroxymandelic acid (VMA), homovanillic acid (HVA) and p-hydroxymandelic acid (p-HMA), which have not previously been found in urine after tyramine administration, have been identified. In addition, p-hydroxyphenylethyl alcohol and two unidentified metabolites were found. The presence of radioactive catecholamine metabolites (i.e., HVA and VMA) indicates that tyramine can be converted in vivo to catecholamines. The finding of p-HMA provides further evidence for the in vivo conversion of tyramine to octopamine. The significance and implications of these metabolic pathways are discussed.
Footnotes
- Accepted March 1, 1966.
- The Williams & Wilkins Comapny
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