MODIFICATIONS IN THE CARCINOGEN-METABOLIZING CAPACITY OF MOUSE-LIVER TREATED WITH N-NITROSO COMPOUNDS

One tenth of the LD,,, as a single dose of various N-nitroso compounds (N-nitrosodimethylamine; NDMA, N-nitrosodiethylamine; NDEA, N-nitroso ethylpropylamine; NEPA, N-nitrosodipropylamine; NDPA, N-nitrosomethyle thylamine; NMEA, N-nitroso-methylbutylamine; NMBA and N-nitrosoethylbu tylamine; NEBA) was administrated into male mice. This dose markedly i ncreased the hepatic contents of cytochrome P450 and cytochrome b(5) a nd activities of NADPH-cytochrome c reductase and aryI hydrocarbon hyd roxylase (AHH). The highest increase in the activity of cytochrome P45 0 (+142% relative to the control value) was shown in animals treated w ith either N-nitrosoethylpropylamine or N-nitrosodiethylamine. On the other hand, the lowest increase in the activity (+16%) was revealed in animals treated with N-nitrosodimethylamine (not significant compared to the control value). Cytochrome b, content was increased by 190% of the control value in mice treated with N-nitrosomethylbutylamine, whi le N-nitrosodibutylamine induced the lowest increase (+20%). The maxim um increase (+182%) in the activity of aryl hydrocarbon hydroxylase wa s shown in animals which received N-nitrosomethylbutylamine, while the lowest increase (+23%) in animals which received N-nitrosodiethylamin e. The activity of hepatic AKH was also increased above the control va lue in animals treated with NDMA, NEBA NDPA, NMEA and NDBA by 138, 98, 90, 89 and 69%, respectively. Identically, NADPH-cytochrome c reducta se activity was increased in animals which received NEPA, NMBA, NDMA, NMEA, NDPA, NEBA and NDEA by 202, 150, 110, 95, 94, 77 and 37%, respec tively.