[The effect of isoniazid and lipovitan on the components of the microsomal electron-transport chains in the rat liver].

The early influence of isoniazide, used by a stomach-tube single or in combination with lipovitane, was studied on some components of electron-transporting chains in the microsomal fraction from livers of male and female rats. In comparatively unchanged amount of cytochrom P450, anilinhydroxylasic activity was increased many times in all experimental groups. This could be explained by induction of the specific isoenzyme of cytochrom P450 by isoniazide. The combination of isoniazide with lipovitane in male rats did not change the additional activity of the enzyme, but it was altered in the female rats in various directions. Isoniazide alone or with lipovitane did not change significantly N-demethylation of aminopyrine. The amount of cytochrom b5 was the same after action with isoniazide. Its combination with lipovitane in male rats reduced significantly the amount of cytochrom b5. Similar tendency in female animals was observed after usage of isoniazide during a longer interval. The reduction of cytochrom b5 was explained by a lowered inclination to lipid peroxidation due to synthesis of phosphatidylcholin, induced by lipotropic components of lipovitane. The applied doses of isoniazide were not hepatotoxic, because triacylglycerols in the serum and liver homogenate as well as nonesterified fatty acids, bilirubin and transaminase activity in serum were unchanged.