Determination of the atpase responses in tissues of freshwater fish (Oreochromis niloticus) exposed to CD+2 in water with different CA+2 levels

Freshwater fish (Oreochromis niloticus) was individually exposed to Ca2+, Cd2+ and Ca2++Cd2+ in three different concentrations Ca2+ for acute (48 h , 20 ?M Cd2+) and chronic (14 days, 10 ?M Cd2+) exposure periods. At the end of exposure periods, Na+/K+-ATPase and Mg2+-ATPase activities in the gills and intestine and Ca2+-ATPase activity in the muscle were measured. Results showed that enzyme activities depend on Cd2+ and Ca2+ concentration, exposure duration and tissue type. As long as Ca2+ concentration increase ATPase activities of control fishes inreased, also. Generally, ATPase activities increased in fish exposed to only Ca2+ concentration, while they showed both increases and decreases after exposure to Ca2++Cd2+. While gill Na+/K+-ATPase activity showed opposite reactions, Mg2+-ATPase and Ca2+-ATPase showed similar trend in acute and chronic periods. The aim of this study was to investigate the effects of Ca2+ on metal toxicity.