Influence of bismuth on the metabolism of endogenous metals in rats

In this study the effect of single and multiple doses of bismuth on the metabolism and excretion of endogenous metals (Cu, Zn) was investigated. Wistar rats were administered bismuth chloride subcutaneously (1 x 3 mg Bi/kg or 7 x 3 mg Bi/kg). Rats were sacrificed at different time periods after bismuth injections. The levels of Cu and Zn were determined in the liver, kidneys and brain, as well as the concentrations of metallothionein (MT) in the liver and kidneys. Cu, Zn and total protein levels in the urine of control and exposed animals were estimated. Additionally, a histopathological examination of the kidneys and brain was carried out. The increase in the renal and hepatic Cu and Zn content was paralleled by an augmentation in the level of MT in these organs following both kinds of exposure to bismuth. Some changes in the ultrastructure of the kidneys were correlated with the dose of bismuth. Zinc content in the brains of exposed rats was lower than in control animals brains, but there was no difference in copper level and no histological changes. The excretion of copper and zinc was higher in the exposed groups than in control groups. The presented results indicate that the disturbances in the metabolism of Zn or Cu in the liver, kidneys and brain and the increase in urinary output of metals may be a much more sensitive index than morphological damage and impaired renal function to the bismuth exposure.