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Changes in the activity of a NADPH-dependent monooxygenase system of the rat liver are studied under the effect of tetramethylthiuramdisulphide. Under these conditions aniline hydroxylation is shown to be inhibited to a higher extent than amidopyrine demethylation. Besides a decrease in the level of cytochrome P-450, the central component of the microsomal system of hydroxylation, there appears cytochrome P-420--an inactivated form of cytochrome P-450.

The cytochrome oxidase and succinate dehydrogenase activities were studied in the liver supernatant fraction and homogenate of rats whom different amounts of valexon, organophosphoric pesticide with a hepatotoxic effect, were administered to. A significant increase in the enzymic activity in the supernatant fraction and the resulted rise in the value of the ratio of the activity in the supernatant fraction to that in the homogenate were found five days after a single administration of the preparation in a dose of 310 mg per 1 kg of body weight and after its three-month administration in a dose of 31 mg/kg. These changes may be believed to result from disturbances of the structural-functional state of the mitochondria due to penetration of valexon and its accumulation in them.

The free and unprecipitated activity of succindehydrogenase and glucose-6-phosphatase, as well as of that of glucose-6-phosphate-dehydrogenase in the rats liver was determined. The animals received for a long time (1--3 and 6 months) a new organophosphorus pesticide valexon (0.0-diethyl thiophosphoryl-oxyiminophenylnitryle acetate) by mouth in doses of 31 mg/kg and 3.1 mg/kg which corresponds to 1/20 and 1/200 LD50. The earliest changes (after 1 month) include: falling activity of hexokinase and a rise in that of glucose-6-phosphatase and succindehydrogenase, pointing to the damage of microsomes and mitochondria supervenes in 1 and 6 months time after introduction, respectively. The role of an early injury of microsomes and of disturbed first stages of glucose metabolism in the mechanism of the valexon action is suggested.

In rats, which were administered daily during four months polychlorocamphene, the lactate dehydrogenase activity rises in the myocardium independently of the method of the preparation application and in the liver it increases only with a simultaneous peroral and epicutaneous administration. Under the effect of the pesticide administered by all the methods the content of LDG5 decreases and that of LDC1 increases in the liver, in the myocardium the amount of LDG1 lowers and that of LDG3 and LDG4 rises.

The activity of hexokinase, glucose-6-phosphatase and glucose-6-phosphoric dehydrogenase was studied in the liver of rats after one hour, one and five days after a single oral administration of organic phosphorus insecticide valekson. It was determined that administration of the preparation led to an increase of activity in the homogenate and solubilization of glucose-6-phosphatase, activation of glucose-6-phosphoric dehydrogenase and inhibition of hexokinase. The changes were maximum one hour after the administration of the compound. The results show that a decrease of the intensity of glucose-6-phosphate formation and metabolism is one of the pathogenetic factors in the development of valekson-induced intoxication.