Effects of endogenous N-nitrosodiethylamine and blocking of its synthesis with ascorbic acid on the condition of the liver monooxygenase system.

Comparative investigations were performed to study the effect of endogenous and exogenous N-nitrosodiethylamine on the dynamics of content variations of oxidized cytochrome P-450 and its isoforms in the monooxygenase system of rat liver. The variations of cytochrome P-450 contents in both cases were demonstrated to be of the same character correlating with hepatocarcinogenesis stages. Higher quantities of oxidized cytochrome P-450 and its isoforms with MM 52, 53, and 56 kDa in the rat liver when acted upon by NDEA precursors are seen as the precondition of enhancing the monooxygenase reaction of NDEA bioactivation and, as a result, of the carcinogenic effects. Ascorbic acid is assumed to block the synthesis of NDEA from its precursors giving use to a compound whose metabolism does not influence the activity of the monooxygenase system of liver cells.