Zinc-induced damage to carp (Cyprinus carpio L.) erythrocytes in vitro

Fish erythrocytes were used to elucidate the effect of zinc ions on the cell antioxidant defence system. It was detected that an increase of the Zn2+ concentration (0.01-1 mM) leads to a marked decrease (p < 0.05) in the catalase and the glutathione peroxidase activities. We observed a loss of 14-39% activity of glutathione peroxidase, and 16-20% diminution for catalase. No significant changes were found in case of the superoxide dismutase. Incubation of red blood cells with zinc brought about a decrease of the erythrocyte thiol group content. Treatment of carp erythrocytes with zinc ions also resulted in enhanced hemolysis and in the induction of significant (p < 0.001) changes in the intracellular glucose level. The increase of glucose concentration in the erythrocytes was correlated with increased concentration of metal in the incubation medium. It was proposed that Zn could affect transport systems across the red blood cells and therefore increased the permeability of the membranes to small molecules (e.g. hexose), and led to hemolysis. Zinc ions could act as a potential cell toxicant, leading to disturbances in functions of the antioxidant defence system and to alterations in the erythrocyte membrane properties.