The responses of hepatic monooxygenases of guinea pig to cadmium and nickel |
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Authors: | Mümtaz İşcan Tülay Çoban Benay C Eke Mesude İşcan |
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Institution: | 1. Department of Toxicology, Faculty of Pharmacy, Ankara University, Tandogan, Ankara, Turkey 2. Department of Biology, Middle East Technical University, Ankara, Turkey
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Abstract: | When Cd (3.58 mg CdCl2·H2O/kg, ip) was administered to male guinea pigs 72 h prior to sacrifice, the metal significantly inhibited the aniline 4-hydroxylase
(AH) (16%), ethylmorphoneN-demethylase (EMND) (26%), and aminopyrineN-demethylase (AMND) (18%) activities and cytochrome P-450 (12%) and cytochrome b5 (10%) levels. Cd did not alter the hepatic microsomal heme level. Cd, however, significantly increased the hepatic microsomalp-nitroanisoleO-demethylase (p-NAOD) (53%) activity. When Ni (59.5 mg NiCl2·6H2O/kg, sc) was administered to the guinea pigs 16 h prior to sacrifice, the metal significantly depressed AH (49%),p-NAOD (66%), EMND (47%), and AMND (37%) activities, and cytochrome P-450 (15%), cytochrome b5 (24%), and microsomal heme (28%) levels. For the combined treatment, animals received the single dose of Ni 56 h after the
single dose of Cd and then were killed 16 h later. In these animals, significant inhibitions were noted in AH (51%), EMND
(47%), and AMND (30%) activities, and cytochrome P-450 (15%), cytochrome b5 (26%), and microsomal heme (30%) compared to those of controls. In the case ofp-NAOD activity, the influence was in favor of Ni, i.e, the inhibition was about 61% by the combined treatment. These results
reveal that:
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The response of all substrates of hepatic monooxygenases to Cd are not the same, possibly indicating differential regulation
of cytochrome P-450 isozymes by Cd;
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The inhibitory effect of Ni on hepatic monooxygenases is more profound than that of Cd; and
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The combination of Cd and Ni does not have a synergistic effect of hepatic monooxygenases of the guinea pig.
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Keywords: | Index Entries" target="_blank">Index Entries Cadmium nickel combined treatment hepatic monooxygenases guinea pig |
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