Modulation of flavocoenzyme levels in rat tissues by N-nitrosodiethylamine.

The hepatocarcinogen N-nitrosodiethylamine (NDEA) was administered continuously in drinking water (200 mg/l) to male Wistar rats, and at intervals tissues were examined for flavocoenzyme levels. Flavin adenine dinucleotide (FAD) and non-FAD riboflavin were determined fluorimetrically. Results revealed significant depletion in hepatic levels of these compounds at the end of 60 days, a period of exposure considered adequate for the development of hepatoma. Considerable reduction was also noticed after 15 days, and also when lower dose of NDEA was administered (50 mg/l). The flavin compounds in liver after short exposure to NDEA remained at depleted levels even after withdrawal of the carcinogen. Changes in the kidney were found to be less significant. The selective depletion of flavin compounds in the target tissue following NDEA exposure is of significance, and may be related to biochemical mechanisms involved in malignant transformation.