Interaction in the cerebral metabolism of the biogenic amines: effect of intravenous infusion of L-tryptophan on tryptophan and tyrosine in brain and body fluids.

1. The distribution of the amino-acids tryptophan and tyrosine has been determined in plasma ultrafiltrate, whole plasma, erythrocytes, cerebrospinal fluid (c.s.f.) and various regions of the brain in dogs.2. The effect of tryptophan administration on the distribution of both these amino-acids showed that the alterations produced in tryptophan concentration did not appear to change the concentrations of tyrosine from their normal pattern.3. The implications of these results with regard to amino-acid transport systems in man and dog are discussed.