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The aim of this study was to evaluate the effects of chronic exposure to cadmium (Cd) on the renal cytochrome P450-dependent monooxygenase system. For this purpose, male Wistar rats were intoxicated with Cd administered in drinking water at a concentration of 5 or 50 mg Cd/l for 6, 12 and 24 weeks. Concentrations of cytochrome P450 and cytochrome b(5) as well as activities of NADPH-cytochrome P450 reductase and NADH-cytochrome b(5) reductase were determined in the kidney microsomal fraction. Protein content of CYP1A1, CYP2E1 and CYP3A1 cytochrome P450 isoforms was evaluated as well. In the rats exposed to 5 mg Cd/l, the concentration of cytochrome P450 decreased (by 41%) after 24 weeks of the experiment. The activity of NADPH-cytochrome P450 reductase decreased (by 24%) after 6 and 12 weeks, whereas after 24 weeks it remained unchanged, compared with the control group. Moreover, a decrease in the concentration of cytochrome b(5) (by 25, 15 and 26% at 6, 12 and 24 weeks, respectively) and the activity of its NADH reductase (by 26 and 31% at 6 and 24 weeks, respectively) was noted in these animals. At the exposure to 50 mg Cd/l, the concentrations of cytochrome P450 and cytochrome b(5) and the activities of their corresponding reductases were decreased at each time-point. Western blot analysis revealed that all isoforms of cytochrome P450 studied were affected by Cd and the effect was dependent on the level and the duration of exposure. The results of this study indicate that chronic exposure to Cd in a dose- and time-dependent manner affects the kidney cytochrome P450-dependent monooxygenase system by decreasing the concentrations of cytochrome P450 and cytochrome b(5) and inhibiting the activities of their corresponding reductases. The effect of Cd on the cytochrome P450 content is associated with its ability to stimulate or inhibit of various P450 isoforms. A very important finding of this study is that Cd affects the kidney cytochrome P450-dependent monooxygenase system at relatively low exposure and low kidney Cd accumulation (2.40+/-0.15 microg/g). As the experimental model used reflects human exposure to Cd, we conclude that Cd can affect the kidney cytochrome P450-dependent monooxygenase system in environmentally exposed humans. Previously we have reported disorders in the system in the liver of rats at the same levels of exposure as in this study. Thus, we hypothesize that the metabolism and detoxification of many substances, including xenobiotics, may be seriously affected in Cd-exposed subjects.

The distribution of tissue kallikrein (TK) and its plasma inhibitor, kallistatin in plasma and intestinal tissue, was studied in patients with active ulcerative colitis (UC) and Crohn's disease (CD). TK was localized to goblet cells and kallistatin to epithelial cells of normal human intestine. Both proteins are visualized in macrophages inside granulomas in CD as well as in plasmocytes in both CD and UC. Intestinal tissue kallikrein (ITK) and kallistatin are significantly decreased in inflamed intestine compared to noninflammatory controls. TK mRNA is significantly decreased in intestinal biopsy samples from active UC patients compared with inactive patients or controls. Immunoreactive TK is present in plasma in very low concentrations in patients and did not differ in normal subjects. Plasma kallistatin was significantly decreased in patients with active disease compared to normal controls. Our data suggest that release of TK during inflammation plays a role in inflammatory bowel disease.

This study was undertaken to investigate the effects of age and some inducers (BNF-40 mg/kg/day, DEX − 20 mg/kg/day for 3 days each) on hepatic mixed function oxidase. Wistar male rats of very young (0.5 and 1 months), older (2, 4, 8,12 months) and very old (20 and 28 months) ages were used. The cytochrome P-450 content and the activity of NADH-cytochrome b5 reductase were highest in one-month-old animals, while the cytochrome b5 content was highest in the youngest but NADPH-cytochrome P-450 activity in the oldest rats. β-Naphthoflavone (BNF) treatment resulted in an enhanced content of cytochrome P-450 in all age groups but the activity NADPH-cytochrome P-450 reductase was increased only in the oldest rats. Dexamethasone (DEX) treatment led to a decrease in the activity of NADPH-cytochrome P-450 reductase in the oldest animals only. The cytochrome P-450 content was decreased in young animals (0.5-, 1-, 2-month-old), too. BNF and DEX decreased the cytochrome b 5 content and the activity of NADH-cytochrome b5 in all age groups.