Studies on Phenylalanine Metabolism by Use of Tracer Techniques. II. Measurement of Distribution of L- and D-Phenylalanine with Their Deuterated Species

Abstract

The technique of mass fragmentography was applied to the determination of deuterated L- and D-phenylalanine loaded in animals. Method I : L-Phe-d₅ or D-Phe-d₅ is injected into the rat intravenously and the labeled compound in the plasma is measured at appropriate intervals with L-Phe-d₈ as an internal standard. Method II : Equimolar mixture of L-Phe-d₈ and D-Phe-d₅ is injected into the rat intravenously and the isomers in the plasma are measured simultaneously by the double dilution method. The values obtained by the two different methods agreed well. In the distribution, however, a large difference between L- and D-forms was recognized.