Biomarkers assessment in juvenile Cyprinus carpio exposed to waterborne cadmium

The impact of long-term exposure to waterborne cadmium (Cd) on Cyprinus carpio was evaluated through changes of selected parameters considered as biomarkers of toxicity. Fish were exposed to 1.6 mg l(-1) Cd for 14 days and then transferred to Cd-free water for 19 days. The measured parameters were gill ATPases, brain acetylcholinesterase (AchE), liver glutamate oxaloacetate (GOT) and glutamate pyruvate (GPT) transaminases, muscle water content, and protein content of liver, gills and brain. Condition factor and liver somatic index were also calculated. Branchial ATPase activities were impaired in a dissimilar way: the (Na(+),K(+))-ATPases were inhibited by approximately 30%, while the Mg(2+)-ATPase was significantly activated by 70%. Brain AchE showed no changes after Cd exposure. Both liver GOT and GPT activities were increased by the metal by 63 and 98%. Water content of the skeletal muscle showed no significant alterations. After the 19-day recovery phase, changes in the Mg(2+)-ATPase and GPT were reversed to values similar to controls, but the Cd exposure resulted in an irreversible alteration in GOT activity. Results indicate that the sublethal Cd concentrations are stressful to carp, particularly with reference to branchial enzymes which may disrupt the osmotic and ionic balance of the animals.