The metabolism of L-ethionine in rats fed alpha-naphthyl isothiocyanate.

L-[ethyl-2-14C] ethionine was administered in a single dose to rats fed a diet containing 0.10% alpha-naththyl isothiocyanate for a period of time between 6 and 99 days. Ethionine metabolites excreted into urine were investigated as a function of induced pathologic changes in the liver. A short-time exposure (6 and 14 days) to alpha-naththyl isothiocyanate increased the excretion of free ethionine and S-adenosylethionine at the expense of total ethionine sulfoxide. With the extended feeding period the excretion of total ethionine sulfoxide became normalized while the excretion of free ethionine and S-adenosylethionine decreased. The acetylated fraction of ethionine sulfoxide decreased rapidly and reached a minimum in 14 days of feeding. This fraction subsequently started to increase, but did not reach the values obtained in normal rats.