Kinetic study on p-tyramine metabolism in humans using stable isotope-labeled tracers.

A sensitive method for the determination of p-tyramine was developed using gas chromatography-chemical ionization mass spectrometry. This method was combined with a stable isotope tracer technique to study p-tyramine metabolism in humans. [2H]5-Phenylalanine was administered orally to men (5 mg/kg) as a tracer and the amounts of [2H]4-p-tyramine excreted into urine were determined at each hour. Excretion of [2H]4-p-tyramine was maximal between 1 and 2 hours following administration, at about 15 ng/kg.h in healthy adult men. Possible application in the study of metabolic disorders in human was demonstrated.