Effect of lead on Na+, K(+)-ATPase activity in Penaeus indicus postlarvae.

In vivo effect of lead on Na, K(+)-ATPase was studied in plasma membrane/mitochondrial fraction of P. indicus post-larvae (PL), exposed to 30 days to a sublethal concentration (1.44 ppm) of lead. A significant (P < 0.05) decrease in the enzyme activity was observed for exposed PL with respect to their controls at different intervals except 24hr. Further the substrate (ATP) and ion (Na+ and K+)-dependent kinetics of Na+, K(+)-ATPase was studied with the plasma membrane/mitochondrial fractions of control and 30 days exposed PL. The apparent KM and V(max). values were calculated to determine the nature of inhibition. Both the control and exposed PL showed almost the same apparent KM values in the presence of different substrate or ion concentrations indicating that lead interacts with the enzyme at a different binding site.