Detoxification Enzyme Activities in the Frog Rana ridibunda as a Tool for Evaluating the Pollution of a Freshwater Ecosystem of Northern Greece with High Concentrations of Zinc and Copper

The accumulation of two metals (copper and zinc) and the specific activities of two enzyme systems glutathione S-transferases (GSTs) and cytochrome P450-dependent monooxygenases (P450-MO) were measured in four tissues (liver, kidney, small and large intestine) of the frog Rana ridibunda, collected from a wetland near the town of Lagadas, Northern Greece. Very high concentrations of the two metals were found in all studied tissues. The specific activities of both enzyme systems showed a significant decrease in frogs collected from the Lagada area compared to the controls. In the liver, both activities were reduced by about 88–90%. GST activity decreased by about 73% and 87% in the kidneys and small intestine, respectively, whereas the reduction in P450-MO activity was somewhat lower (about 59% in the kidney and 40% in the small intestine). Total protein correlated negatively with GST in the liver and kidney. Negative correlation was also found between copper and GST activity in the kidney. It is concluded ...