In vitro dose-response study of the effect of cadmium on eel (Anguilla anguilla) gill Na+/K(+)-ATPase activities.

The effect of cadmium exposure was studied in vitro on the ATPase activities of gill membrane microsomes from seawater- and freshwater-adapted eel (Anguilla anguilla) using a microassay technique. The basal activity (Mg(2+)-ATPase) was decreased by 40 and 25%, respectively, in seawater and freshwater preparations for the highest concentrations tested (respectively, 4 and 2 microM). The Na+/K(+)-ATPase activity was estimated either by potassium stimulation or by ouabain inhibition. This enzyme activity was inhibited by cadmium in a dose-dependent manner with a I50 of 146 +/- 9.3 nM. Neither the technique used to measure the enzyme nor the adaptative environment significantly changed the I50. The results are compared to results obtained in other groups and to the effects of cadmium on metal ion exchanges in fish.