Distribution and metabolism of dl-3,4-dihydroxy[2-14C]-phenylalanine in rat tissues

Although this amino acid is widely used in pharmacological experiments, its distribution and metabolism in tissues have not been investigated systematically.It has been reported that, after the injection of L-or DL-dopa, the concentration of the amino acid (as well as that of 3-hydroxytyramine) increases in the brain, lungs, kidney, heart and spleen (Goldstein, Musacchio & Gerber, 1963; Sourkes, 1961; Wegmann, Kako & Chrysohou, 1961).Further, 24 hr.after the injection of DL- [2-14C]dopa, only negligible amounts of radio- activity were found in the liver, kidney, heart and spleen, but more than 80 % was recovered from the urine and 2 % from the expiratory air (Pellerin & D'Iorio, 1955, 1956/57).Recent radioautographic studies at various time-intervals after the intravenous injection of DL-[2-14C]dopa showed a high overall radioactivity in the adrenal medulla, pan- creas, kidney, intestinal mucosa, salivary glands, bone marrow and liver (Rosell, Sedvall & Ullberg, 1963).The present paper deals with the tissue distribution of DL-[2-14C]dopa and of its metabolites in the albino rat.Extracts of organs were fractionated into phenolic amino acids, amines and metabolic end products (e.g.phenolcarbonic acids, phenol alcohols etc., briefly designated as phenolcarbonic acids).