ATPase and dehydrogenase activities from house flies susceptible and resistant to organochlorine insecticides

Abstract

Comparisons were made on ATPase, glucose-6-phosphate dehydrogenase (G-6-PDH) and 6-phosphogluconate dehydrogenase (6-P-GDH) activities in strains of the house fly, Musca domestica L., susceptible and resistant to organochlorine insecticides. Oligomycin sensitive (OS) Mg 2+-ATPase was more sensitive to inhibition by DDT and aldrin than Na +K +-ATPase. OS-Mg 2+-ATPase was present at similar levels in susceptible and resistant strains of house flies and was equally sensitive to inhibition by the pesticides. Levels of Na +K +-ATPase were 40% lower in the two resistant strains of house flies than in the susceptible strain. In contrast to OS-Mg 2+-ATPase in the resistant strains, the Na +K +-ATPase was about 10 times less sensitive to inhibition by DDT and aldrin than in a susceptible strain. However, in vivo, DDT was a strong inhibitor of OS-Mg 2+-ATPase and a very weak inhibitor of Na +K +-ATPase. Activities of G-6-PDH and 6-P-GDH were 1.2- to 4.6-fold higher in the resistant strain compared to the susceptible strains. Increased dehydrogenase activities were noted in susceptible flies after in vivo exposure to DDT (100 ppm). Variations in levels of activity and in sensitivity to inhibition of the enzymes tested indicate that toxicity and resistance to organochlorine insecticides may be related to different enzymes associated with ATP production and utilization.