In vitro Effects of Corticosteroids, DDT, and 4,9-Dichlorodibenzodioxin on Rat Liver Xanthine Oxidase Activity. Interactions between Xanthine Oxidase and Cytochrome P450 in Rat Liver in vivo

V. V. Sumbayev

Department of Biochemistry, Mechnikov Odessa State University, Shampanskii Pereulok 2, Odessa, 270058 Ukraine; E-mail: inna@farlep.net

Received November 16, 1999; Revision received April 18, 2000

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It was established that deoxycorticosterone, cortisol, dexamethasone, DDT, and 4,9-dichlorodibenzodioxin inhibit in vitro binding of xanthine to highly purified rat liver xanthine oxidase. They are suggested to be allosteric inhibitors. The corresponding inhibition and binding constants were estimated. Also established was that cortisol and DDT, in dose 20 mg per kg of weight, inhibit xanthine oxidase and increase microsomal cytochrome P450 level in rat liver. There is an inverse relationship between xanthine oxidase activity and cytochrome P450 level in rat liver.

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KEY WORDS: xanthine oxidase, cytochrome P450, corticosteroids, DDT, 4,9-dichlorodibenzodioxin

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