[Effect of copper and zinc on the metabolism of N-nitrosamine and the activity of cytochrome P-450 in the liver of rats].
The effect of copper and zinc on the metabolism of N-nitrosamine and activity of cytochrome P-450 in the liver of rats was studied. Copper and zinc enhanced obviously the activity of cytochrome P-450 in the liver. The level of cytochrome P-450 in the liver of control rats was 0.64 nmol/mg protein but that in the liver of rats treated with copper or zinc was 1.31 and 1.17 nmol/mg protein. There was a significant difference between the two groups (P less than 0.01-0.001). The activity of demethylase reflected the metabolic level of N-nitrosamine. In the control group, metabolic level of N-dimethyl-nitrosamine, N-methyl-N-butylacetonylnitrosamine and nitrosopyrrolidine was markedly higher than the copper and zinc groups. It is indicated that copper and zinc inhibit obviously the activity of demethylase, resulting in reduction of the metabolic activation of N-dimethylnitrosamine, N-methyl-N-butylacetonylnitrosamine and nitrosopyrrolidine. The role of copper and zinc in the chemical carcinogenesis is discussed.
Cancer Institute, Chinese Academy of Medical Sciences, Beijing.
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Luo
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Lu
D000818:Animals; D003300:Copper / Q000494:pharmacology*; D003577:Cytochrome P-450 Enzyme System / Q000378:metabolism*; D008297:Male; D008862:Microsomes, Liver / Q000201:enzymology*; D009602:Nitrosamines / Q000378:metabolism; D010088:Oxidoreductases / Q000378:metabolism; D051381:Rats; D011919:Rats, Inbred Strains; D015032:Zinc / Q000494:pharmacology*
D009602:Nitrosamines; D003300:Copper; D003577:Cytochrome P-450 Enzyme System; D010088:Oxidoreductases; D015032:Zinc