Elimination of mercury from amalgam in rats.

The aim of this study was to measure the urinary mercury excretion in rats exposed to amalgam over a two months period. Animals were either exposed to mercury from 4 dental amalgams or fed the diet containing powdered amalgams. The results showed significantly higher mercury amount in urine of both exposed groups than in control. Even two months after the amalgam had been placed in rats teeth, the amount of mercury in the urine remained 4-5 times higher than in control, and 4 times higher than in rats exposed to diet containing powdered amalgam. The elevated urinary Hg amount was accompanied by an increased level of total protein in urine. In the same exposure period the excretion of total protein in urine of rats with amalgam fillings was 2 times higher than in control and 1.5 times higher than in rats exposed to amalgam through diet. Concentrations of mercury in the sera of all groups were below the detection limit of the method. The results show that amount of mercury and protein in the urine of rats were related to the mercury release from dental malgam.

Effects of oxprenolol treatment on pseudocholinesterase and lipids in rats.

The effect of chronic treatment with the non-selective beta-blocker oxprenolol (CAS 6452-71-7) administered orally in two different doses (15 or 30 mg/kg/day for 6, 10 and 12 weeks) on plasma cholinesterase (PChE) activity and on the plasma level of triglyceride and total cholesterol were studied in normal rats. In all treated groups a significant increase (approximately 27-51%) of PChE activity was obtained (p < 0.05 vs. control group). The plasma concentration of total cholesterol was significantly increased as well (21-48%, p < 0.05 vs. control) but oxprenolol exerted no significant effect on plasma triglyceride levels. The increase of enzyme activity and total cholesterol were not time- or dose-dependent. According to these results which showed a direct relationship between PChE activity and total cholesterol it is supposed that the increase of enzyme activity is initially due to the action of oxprenolol on total cholesterol metabolism but that it does not have a direct effect on the enzyme. The results contribute to the hypothesis that PChE plays a role in lipoprotein metabolism although this has not yet been proven.

Dental amalgam mercury exposure in rats.

The aim of this study was to measure the distribution of mercury, in tissues of rats exposed to amalgam over a two months period. Possible interaction of mercury with copper and zinc in organs was also evaluated. Rats were either exposed to mercury from 4 dental amalgams, or fed the diet containing powdered amalgam during two months. Mercury was measured in the kidney, liver and brain, copper in kidney and brain and zinc in kidney. The results showed significantly higher concentrations of mercury in the kidneys and the brains of rats in both exposed groups compared to control. Even after two months of exposure to mercury brain mercury concentration in rats with amalgam fillings was 8 times higher than in the control and 2 times higher than in rats exposed to amalgam supplemented diet. The highest mercury concentration in the latter group was found in the kidneys and it was 5 times higher than in the control group. We found no significant differences between mercury levels in exposed and control rat's liver. Exposure to mercury from dental amalgams did not alter the concentrations of copper and zinc in the tissues. Histopathological analyses of rats tissues did not show any pathological changes. These results support previously proposed nose-brain transport of mercury released from dental amalgam fillings.