Comparative activity of gill ATPase in three freshwater teleosts exposed to cadmium.

The comparative activity of gill ATPase was examined in the bluegill sunfish (Lepomis macrochirus), fathead minnow (Pimephales promelas), and golden shiner (Notemigonus crysoleucas). Basal Na/K ATPase activity was highest in bluegill sunfish (1.46 mumol Pi/mg protein/hr) and lowest in golden shiners (1.01 mumol Pi/mg protein/hr). While a stimulation of Na/K ATPase activity was observed at an exposure concentration of 1 micrograms Cd/liter in the bluegill sunfish and fathead minnows, an inhibition of enzymatic activity was observed at higher exposure concentrations (10 and 100 micrograms Cd/liter). Gill Na/K ATPase activity in golden shiners was not significantly influenced by cadmium exposure. The observed insensitivity of Na/K ATPase in golden shiners may, in part, be related to high background concentrations of cadmium in gill tissue. In all three species examined, gill residual ATPase activity was not significantly altered by cadmium exposure.