Determination of the response of ATPases in freshwater fish Oreochromis niloticus exposed to cadmium, zinc and cadmium+zinc

The aquatic environments receive several metal mixtures at the same moment and organisms are exposed to this combination of metals. Enzymes such as ATPases have a key role between fishes and their environments and also are molecules with a great sensitivity to environmental pollution. Therefore, in this study the responses of ATPases (Na+/K+-ATPase, Mg+2-ATPase, Ca+2-ATPase) in different tissues of a freshwater fish Oreochromis niloticus to 1 µg/ml concentration of Cd+2 and Zn+2 at different periods (0, 7, 14, 21, 28 days) were investigated. At the end of experimental periods, the activities Na+/K+-ATPase and Mg+2-ATPase in gill tissues and Ca+2-ATPase activity in muscle tissues were measured. While living under the experimental conditions, fish did not have any observable health problem. There were some significant alterations in ATPase activities in gill and muscle tissues of fish exposed to metals as single or combination. According to the results, there were general declining trends in Na+/K+-ATPase and Ca+2-ATPase activities in regard to metal type, single or combined exposures, period of exposures, and tissues, though there was no significant alteration in Mg+2-ATPase activity. There was also no considerable change in tissue total protein levels of fish.