Abstract

The liver is the organ in the body where most toxic substances are metabolized. The histochemical methods of determining enzyme acitivity have provided new interesting information on the metabolism of hepatocytes in Cd, Se and Cd-Se intoxication. The activites of the following enzymes were assayed in the mouse hepatocyte: succinate dehydrogenase(SDH), Mg2+-adenosine triphosphate (Mg2+-ATP-ase), alkaline phosphatase (AP) and acid phosphatase (AcP). Qualitative methods were used in the study. Moreover,ultrastructure of mouse hepatocytes under the experimental conditions was studied.Three-month long experiments were conducted on 24 male white Balby mice. The animals were divided into four groups. The control group I (C) was fed a standard Murigran diet. Group II (Cd.) received 50 ppm Cd as cadmium acetate in drinking water. Group III (Se) was fed a diet supplemented with 5.0 mg Se/kg DM/24 h. as acid sodium selenate. Mice in group IV /Cd+Se/ received a diet supplemented with Cd and Se in the same amounts as Groups II and III. During the experimental period mice were intoxicated with 0.2. mg Se/kg b.w./24h and 16.8 mg Cd/ kg b.w./24h. Our experiments indicated that prolonged Cd intoxication singnificantly lowered the activity of SDH and Mg2+-ATP-ase, which are involved in oxidative phosphorylation and active membrane transport. Accordingly, it seems that energetic processes were deranged. Selenium did not affect enzymatic activities. Se in interaction with Cd suppressed the toxic effects on the level of SDH and Mg2+-ATP-ase activities. Mouse hepatocytes after Cd, Se and Cd-Se-interaction treatment demonstrated ultrastructure changes which appeared to correlate with the enzymatic activities noted and with the previously described incorporation of the protein synthesis precursor. We concluded that prolonged Cd intoxication significantly decreased the activity of enzymes involved in oxidative phosphoralation and active transport. Se in interaction with Cd suppressed toxic effects on SDH and Mg2+-ATP-ase activity.

Keywords: Cadmium, hepatocyte ultrastructure, enzymatic activity, Selenium, Liver