Inhibition of choline synthesis in young rats by 2-amino-2-methyl-propanol-1.

2-Amino-2-methylpropanol-1 and LY ,a-dimethyltriethylcholine have been found to be competitive inhibitors of choline utilization in 40 to 50 gm. male albino rats (1). The former substance apparently only antagonized the utilization of choline in the kidney’ while the latter was an antimetabelite both in the liver and kidney. The quantitative relationships between these inhibitors and choline in such animals were also reported. 2-Amino-2-methylpropanol-1 was found to be a strict competitive inhibitor of choline over the range of concentrations studied. The concentrations of choline chloride required to be present in the diet in order to prevent the occurrence of hemorrhagic kidney degeneration when the diet also contained 0.33, 0.67, or 1.0 per cent of the inhibitor were 100, 150, or 200 mg. per cent, respectively. In this paper we wish to present the results of further studies with 2-amino-2-methylpropanol1. In these experiments the abilities of DLmethionine, betaine, and &dimethylpropiothetin to replace choline in the presence of the inhibitor have been determined. Normally 1 mg. of choline chloride is replaced in the diet by 4 mg. of nn-methionine or betaine hydrochloride (2) and theoretically by about 4 mg. of fl-dimethylpropiothetin hydrochloride. In the presence of the inhibitor several times these amounts of the metabolites were required to replace 1 mg. of choline. These results are interpreted as indicating that in young rats 2-amino-2-methylpropanol-1 inhibits not only the utilization of choline but also its synthesis.