Cadmium induced changes in ion levels and ATPase activities in the muscle of the fry and fingerlings of the freshwater fish,

Levels of sodium, potassium and calcium ions and the activities of Na+---K+, Mg2+ and Ca2+ ATPases were estimated in the muscle of the fry and fingerlings of an economically important edible freshwater fish, , at 1,2,3 and 4 days on exposure to the lethal, 4.3 mg/L and 17.1 mg/L respectively for the fry and fingerlings,and 1,7,15 and 30 days on exposure to sublethal, 0.86 mg/L and 3.42 mg/L, concentrations of cadmium. All the ion levels and ATPase activities progressively decreased over time of exposure, in the order day 1 < 2 < 3 < 4, in the muscle of both fry and fingerlings on exposure to lethal concentrations; the magnitude of decrease was higher in the fry than the fingerlings. In sublethal concentrations, an initial decrease in these parameters of the fry was noticed at day 1, but on further exposure they increased over control, however, the order was day 7 > 15 > 30 in sodium ions and Na+---K+ and Mg2+ ATPase activities and 7 < 15 > 30 in potassium and calcium ions and Ca2+ ATPase activity. In fingerlings, all the parameters decreased at days 1 and 7 (day 1 < 7) but increased at days 15 and 30 (day 15 < 30). All these changes in iono-regulatory pattern of the fish were discussed in the light of available literature.