Elevter M. Russanov

Studies on lipid peroxidation in rat liver by copper deficiency

Abstract 1. 1. Copper deficiency in rats results in a 2-fold increase in the level of lipid hydroperoxides in liver mitochondria and microsomes. 2. 2. The specific activity of cupro-zinc Superoxide dismutase decreases up to 30% while that of the mangano-enzyme is not changed. 3. 3. Glutathione peroxidase activity as well as catalase activity are suppressed in both cytosol and mitochondrial fractions from copper-deficient rat liver.

Lipid peroxidation and antioxidant enzymes in vanadate-treated rats.

Male Wistar rats received an aqueous solution of ammonium metavanadate (AMV) of 0.15 mg/V/ml concentration instead of water for 14 days. The erythrocyte count and haemoglobin level in blood were not changed; the haematocrit index was slightly increased. The spontaneous lipid peroxidation in kidney and liver homogenates was increased. The Fe(II)- or ascorbate-induced lipid peroxidation was more pronounced in the kidney than in the liver. No changes in lipid peroxidation were observed in erythrocytes after AMV treatment. The AMV treatment resulted in a decrease in the activity of the antioxidant enzymes, catalase and glutathione peroxidase in the kidney and liver; the cytosolic Cu,Zn-SOD and mitochondrial Mn-SOD were unchanged. The activity of the enzymes in blood was not changed. The results are discussed with a view to the participation of lipid peroxidation in vanadium toxicity.

Lipid peroxidation induced by ultrasonication in Ehrlich ascitic tumor cells

The mechanism of sonodynamic action in tumor cells is poorly investigated. It is known that ultrasound generates free radicals in phosphatidylcholine liposomes used as a membrane model. The participation of lipid peroxidation products in the mechanisms of physiological suppression of cell multiplication has been investigated for some tumor cells. In the present work ultrasound-induced lipid peroxidation in Ehrlich ascitic tumor cells was studied. Ultrasonication increased the level of lipid peroxidation quantified by the TBARS method in homogenates from Ehrlich ascitic tumor cells. Changes in the fatty acid composition of lipids from Ehrlich ascitic tumor cells irradiated by sonication were observed. TBARS production obtained by ultrasound was compared to TBARS production obtained by widely used chemical inductors. The free-radical processes evoked by ultrasound are of interest in antitumor therapy.

Effects of cimetidine and its metal complexes on nitroblue tetrazolium and ferricytochrome c reduction by superoxide radicals

The effects of cimetidine, a potent histamine-H2-receptor antagonist and a good -OH scavenger, on the kinetics of ferricytochrome c and NBT reduction by superoxide anions were studied. The drug dose-dependently inhibited ferricytochrome c and NBT reduction by O2- radicals, generated either in xanthine oxidase system or photochemically or directly by KO2. The inhibitory effect of cimetidine remained unchanged in the presence of catalase or mannitol. Cimetidine and its complexes with Cu(II) and Fe(III) ions inhibited ferricytochrome c and NBT reduction even when metal chelators were added to the reaction medium. The results suggest the reaction of cimetidine with O2-radicals.

Lipid peroxidation and antioxidant enzyme activity in aspirin-treated rats.

1. Malondialdehyde formation and antioxidant enzyme activity after oral or intraperitoneal treatment of rats with various doses of aspirin was studied. 2. Aspirin, orally, had no effect on spontaneous, Fe(II)- or Fe(II)/ascorbate-induced malondialdehyde formation in liver homogenates; orally, ascorbate-induced malondialdehyde production was inhibited but only after 5-day treatment with 500 mg/kg aspirin; after intraperitoneal injection, the drug inhibited ascorbate- and Fe(II)/ascorbate-induced production of malondialdehyde. 3. Aspirin had no effect on malondialdehyde formation in erythrocytes, irrespective of the dose and route of drug administration. 4. Aspirin increased glutathione peroxidase activity in liver after 5-day treatment with an oral dose of 500 mg/kg and decreased enzyme activity in both liver and erythrocytes, 24 hr after a single injection of the same dose. 5. Aspirin, in vivo slightly affected lipid peroxidation and antioxidant enzyme activity.

Copper increases superoxide dismutase activity in rat liver

Superoxide dismutase (SOD) activity in rat liver cytosol and submitochondrial fractions was characterized as enzymatic and nonenzymatic (due to the SOD-like activity of copper) by four approaches: (i) aerobic NBT2+ (nitroblue tetrazolium) photoreduction in the absence of EDTA; (ii) aerobic NBT2+ photoreduction in the presence of 10(-4)M EDTA; (iii) anaerobic NBT2+ photoreduction; and (iv) o-dianisidine photooxidation. Under normal conditions nonenzymatic SOD activity has been observed only in the intermembrane space. The single subcutaneous injection of rats with CuSO4 solution (5 mg Cu/kg body wt) led to (i) an elevation of the copper level in all submitochondrial fractions; (ii) an increase in enzymatic SOD activity in only cytosol and intermembrane spaces; (iii) the appearance of a new electrophoretic SOD activity band in the intermembrane space preparations; and (iv) the appearance of nonenzymatic SOD-like activity in the outer and inner mitochondrial membranes, and a twofold increase in lipid hydroperoxides. This suggests that the increased nonenzymatic copper in vivo has a prooxidant effect, and does not catalyze the dismutation of O2- as it has been shown in in vitro experiments [E. M. Russanov, S. G. Ljutakova, and S. I. Leutcher (1982) Arch. Biochem. Biophys. 215, 220-229]. The peculiarities of the SOD activity in the intermembrane space are explained by the lysosomal localization of the granular CuZnSOD.

Aconitase activity in rat liver

This paper presents data about the subcellular distribution of aconitases in rat liver and some properties of the aconitase activity in cytosol, mitochondria and soluble mitochondrial protein (SMP). The cytosolic and mitochondrial aconitase activity was 64.8% or 61.0% and 20.1% or 19.4% of the total rat liver aconitase activity when cis-aconitate or isocitrate was used as substrate. Aconitase activity of stored SMP and mitochondria with phosphate buffer (pH 7.4) and 0.25 M sucrose (pH 7.4) as isolation medium respectively, was reduced to an equal extent upon exposure to air. Fresh SMP preparations immediately and three hr after isolation had the same aconitase activity. It is concluded that phosphate has no role in the oxidative degradation of mitochondrial aconitase and does not inhibit it. Complete restoration of the decreased mitochondrial aconitase activity to the initial level was achieved with thiomalate and Fe2+ under anaerobic conditions or 60-70% was restored during the long period (60 min) of incubation with exogenous substrate. The aconitase activity of cytosol and mitochondria increased upon exposure to air for 7 1/2 hr. This finding is interpreted to suggest the existence of putative aconitase activity.

Vanadyl-and Vanadate-Induced Lipid Peroxidation in Mitochondria and in Phosphatidylcholine Suspensions

Vanadyl (V(IV] was found to induce rapidly developing lipid peroxidation in intact and sonicated mitochondria as well as in phosphatidylcholine suspension. The ability of vanadate (V(V] to induce lipid peroxidation was much less pronounced compared to that of vanadyl. The peroxidative action of vanadate on phosphatidylcholine much increased in the presence of NADH and ascorbate. Preincubation of vanadate with glucose had the same effect. Vanadyl-induced lipid peroxidation was not essentially influenced by SOD, catalase and ethanol but was completely inhibited by butylated hydroxytoluene. All these effects of vanadyl and vanadate are thought to participate in the insulin-like and other biological actions of vanadium.

Enzymes of oxygen metabolism and lipid peroxidation in erythrocytes from copper-deficient rats

1. Copper deficiency in the rat results in a high decrease of erythrocyte superoxide dismutase activity (by 70%), an increase of glutathione peroxidase activity (by 17%) and glucose 6-phosphate dehydrogenase activity (by 40%) and no change in catalase activity. 2. Ascorbate (30 nM) and copper (10 and 50 nmol/mg protein) enhance about 2-fold the lipid peroxidation of erythrocyte membranes from copper-deficient rats. 3. The osmotic stability of copper-deficient rat erythrocytes is higher compared with that of the controls.

Effect of cuprizone on copper exchange and superoxide dismutase activity in rat liver.

Abstract 1. 1. Cuprizone decreased the liver copper by 32% and inhibited both cytosolic and mitochondrial superoxide dismutase activity by 61 and 18% respectively. 2. 2. The single injection of copper sulfate increased the copper content in microsomes, cytosol and particularly in mitochondria at the 48th hr as copper was removed almost completely till the 96th hr. 3. 3. Cuprizone decreased and/or delayed copper loading and copper removal in the liver and especially in mitochondria. 4. 4. Copper injection caused a high increase in the activity of cytosolic and mitochondrial superoxide dismutase in the liver of both control and cuprizone-pretreated rats. 5. 5. These findings suggest cuprizone reaction with cellular copper.