Toxicity of organic phosphates and chloronaphthalenes Part 1. The effect on mitochondrial oxidative phosphorylation in the rat liver

The effect of organic phosphates and chloronaphthalenes, which are used in new pesticides on mitochondrial oxidative phosphorylation in the rat liver was examined. Chlorpyrifos and phoxim decreased State 3 respiration in a dose-dependent manner, but pyridaphenthion, α-and β-chloronaphthalene had only a slight effect. Degree of their effect in the order of chlorpyrifos > phoxim > β-chloronaphthalene > α-chloronaphthalene > pyridaphenthion. Chlorpyrifos, pyridaphenthion, α-and β-chloronaphthalene affected on the State 4 respiration, but phoxim did not. Consequently, they lowered the respiratory control index and the effect being in the order of chlorpyrifos > β-chloronaphthalene > phoxim > α-chloronaphthalene > pyridaphenthion. All the compounds tested stimulated latent ATPase activities, but DNP - stimulated ATPase activities were not affected by these compounds. Their effect on latent ATPase activities were in the descending order of chlorpyrifos > phoxim, β-chloronaphthalene > α chloronaphthalene > pyridaphenthion. These findings suggest that chlorypyrifos, pyridaphenthion, phoxim, α-chloronaphthalene and β-chloronaphthalene impede mitochondrial oxidative phosphorylation.