The dose-related metabolism of L-ethionine in acute experiments with rats.

A method is described for a simple column chromatographic determination of N-acetylethionine, N-acetylethionine sulfoxide, and alpha-keto-gamma-ethiolbutyric acid on AG 1. With this analytical method and with chromatography on AG 50W, the urinary excretion pattern of ethionine, composed of all the aforementioned compounds, ethionine sulfoxide and S-adenosylethionine was studied in acute experiments in female rats as a function of the dose of L-[ethyl-1-14C]ethionine. Whereas N-acetylethionine sulfoxide is the major urinary metabolite at low ethionine doses, at higher doses increased amounts of unchanged ethionine and ethionine sulfoxide are found and account for the major portion of the administered dose at 460-613 mumol (75-100 mg)/100 g body wt. The urinary excretion pattern of S-adenosylethionine shows a close relationship to the concentration pattern of this metabolite in the kidney. The extent of t-RNA ethylation and the amount of carbon dioxide formed from the ethyl group of ethionine peak at doses of 77 (12.5) and 306 mumol (50 mg)/100 g body wt respectively, and do not increase further at higher doses.