Actions of the Decarboxylase Inhibitor, α-Methyl-3,4-dihydroxyphenylalanine, in the Dog

Abstract

Alpha-methyl-3,4-dihydroxy-DL-pheny]alanme was shown by Sourkes¹to be a potent inhibitor of the decarboxylation of 3,4-dihydroxyphenylalanine in vitro. This action was confirmed by animal studies in which the pharmacological actions of 3,4-dihydroxyphenylalanine and 5-hydroxytryptophan were decreased by administration of this compound^2,3. Further evidence of the activity of α-methyl-3,4-dihydroxy-DL-phenylalanine in vivo was obtained by Smith⁴, who reported that levels of serotonin in the brains of mice were decreased after parenteral administration of this compound. More recently, Oates et al. ⁵, in this Laboratory, observed a decrease in the formation of serotonin, tryptamine and tyramine from the precursor amino-acids when 1.0–6.0 gm./day of α-methyl-3,4-dihydroxy-DL-phenylalanine were administered to hypertensive patients. Associated with this decrease in amine production was the development of transient sedation and a lowering of the blood pressure.