[Induction of cytochrome P-450 forms by prolonged administration of nifedipine]. / Induktsiia form tsitokhroma P-450 pri dlitel'nom vvedenii nifedipina.

In experiments on male Wistar rats it has been found that nifedipine applied in a dose of 10 mg/kg body weight i.p. daily for 20 days did not significantly increase the total amount of cytochrome P-450 but markedly increased the 7 alpha-, 16 beta- and 6 beta-hydroxylation of androstenedione in liver microsomes, suggesting the induction of cytochromes P-450a, P-450b and P-450p respectively. The induction of cytochrome P-450b was also confirmed immunochemically with polyclonal antibodies against cytochrome P-450b/e.

[Protective action of fat- and water-soluble antioxidants on the cytochrome P-450 system during lipid peroxidation in liver microsomes]. / Zashchitnoe deistvie lipo- i vodorastvorimykh antioksidantov na sistemu tsitokhroma P-450 pri perekisnom okislenii lipidov v mikrosomakh pecheni.

The protective effects of alpha-tocopherol, carnosine and their mixture on monooxygenase system during lipid peroxidation in liver microsome membranes were studied. It was shown that for optimal protection effect of cytochrome P-450 system the mixture of water and liposoluble antioxidants is required.

[Effectiveness of lipid peroxidation inhibition in biomembranes by antioxidants with and without hydrocarbon chains]. / Effektivnost' ingibirovaniia perekisnogo okisleniia lipidov v biomembranakh antioksidantami, soderzhashchimi i ne soderzhashchimi uglevodorodnye tsepi.

The efficacy of lipid peroxidation inhibition by the natural antioxidant alpha-tocopherol and 2,2,5,7,8-pentamethyl-6-hydroxy-chromane (PMC), a derivative without hydrocarbon tail, as well as by the synthetic antioxidant 4-methyl-2,6-diterbutyl phenol (BHT) and its phospholipid derivative was studied in the membranes of rat liver microsomes and mitochondria. The presence of hydrocarbon tail in the antioxidant molecule determines the decrease of antioxidant efficiency in biomembranes. PMC and BHT exert a destructive effect on biomembranes, leading to an increase in their permeability to ions. This evidence suggests that the presence of hydrocarbon tail in the molecules of natural antioxidants provides not only for a relatively high antioxidant efficiency but also for a structural stability of biomembranes.

[Effect of thiol compounds on aniline toxicity and aniline metabolism]. / Vliianie na niakoi tiolovi suedineniia vurkhu anilinovata toksichnost i anilinoviia metabolizum.

The authors examined systematically the influence of some thiol compounds on the drug metabolism, investigating the effect of potassium ethylxanthogenate, diethyldithiocarbamata, inithiol and penicilamine on the aniline toxicity, methemoglobin formation and aniline-hydroxylase activity. They found that the examined compounds increased aniline toxicity in white male rats. These compounds inhibited aniline-hydroxilase activity. The connection between the increase of the toxicity of aniline under the influence of the examined compounds and their inhibiting action on the metabolism of aniline was discussed.

[Mechanisms of hexobarbital anesthesia potentiation by hydrocortisone]. / Vurkhu mekhanizmite na potentsrane na kheksobarbitalovata narkoza ot khidrokortizona.

The authors carried out studies on white rats of Wistar strain and investigated some of the mechanisms, metabolic and central, by means of which hydrocortisone affected hexobartital sleep. They established that hydrocortisone in dose of 25 and 50 mg, administered singly, together with hexobarbital or after a 30-minute interval, potentiated hexobarbital sleep significantly. The concentrations of hexobarbital in blood serum and in brain on the 30th minute after its administration were higher in the experimental animals, treated with hexobarbital in comparison with the controls of both sexes. The experiments with determination of the activity of liver microsomal hexobarbital enzymic system showed convincingly a considerable inhibition of enzymic activity (with 53%) of hydrocortisone after 20 minutes after its application in vivo. Subthreshold sreep dose of hexobarbital, determined by the method of Lewy, was lowered than that of the experimental group and higher in the control rats. Hexobarbital concentrations in blood serum and in brain at the moment of waking were lower in experimental animals, treated with hydrocortisone, and higher in the control animals. The obtained results gave foundations to the authors to assume that metabolic and central nervous mechanisms participated in potentiation of hexobarbital sleep.