Ethionine alters the urinary excretion of N1-methylnicotinamide.
Nicotinamide is methylated via S-adenosylmethionine (AdoMet) and excreted in the urine as N1-methylnicotinamide. Since S-adenosylethionine (AdoEth) inhibits nicotinamide methyltransferase, ethionine (0.75 mg/g body wt) was given to rats and its effect on the urinary excretion of N1-methylnicotinamide was examined. Nicotinamide (0.5 mg/g body wt) gave a 13.6-fold increase in the 24-h urine concentration of N1-methylnicotinamide. However, ethionine given 4 h prior to nicotinamide completely prevented this increase by nicotinamide. It appears at ethionine via AdoEth inhibits nicotinamide methyltransferase in vivo and lowers the urine level of N1-methylnicotinamide.
D000818:Animals; D005001:Ethionine / Q000494:pharmacology*; D008099:Liver / Q000187:drug effects / Q000378:metabolism; D008297:Male; D008745:Methylation; D008780:Methyltransferases / Q000037:antagonists & inhibitors; D009243:NAD / Q000096:biosynthesis; D009536:Niacinamide / Q000008:administration & dosage / Q000652:urine*; D051381:Rats; D013997:Time Factors
D009243:NAD; D009536:Niacinamide; D008780:Methyltransferases; D005001:Ethionine