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At least 19 recordsLinked to original sources
PubMed1991

Hematin- and peroxide-catalyzed peroxidation of phospholipid liposomes.

The effect of hydroperoxides on hematin-catalyzed initiation and propagation of lipid peroxidation was examined utilizing soybean phosphatidylcholine liposomes as model membranes. Polarographic and spectrophotometric methods revealed a bimodal pseudocatalytic activity for hematin. A slow initiation phase of peroxidation was observed in the presence of low peroxide concentrations, whereas a fast propagative phase was observed at higher peroxide levels. Peroxide levels were manipulated enzymatically by the combination of phospholipase A2 and lipoxidase or by the direct addition of linoleic acid hydroperoxide, cumene hydroperoxide, or hydrogen peroxide. In addition, the effect of two different techniques for liposome preparation, i.e., sonication and extrusion, were compared on the basis of peroxidation kinetics. High pressure liquid chromatography analysis showed that sonicated liposomes contained higher levels of endogenous peroxides than the extruded ones. These sonicated liposomes also exhibited more rapid peroxidation following hematin addition. Extruded liposomes were more resistant to hematin-catalyzed peroxidation but became better substrates when exogenous hydroperoxides were added. All three peroxides reacted with hematin during which decomposition of peroxide and irreversible oxidation of hematin took place. Spectral analysis of hematin indicated that a higher oxidation state of hematin iron may be transiently formed during reaction with hydroperoxides and accounts for the propagation of lipid peroxidation when reactions proceed in the presence of soybean phosphatidylcholine liposomes. Of the three peroxides studied, linoleic acid hydroperoxide was most efficient in supporting hematin-catalyzed lipid peroxidation. The relevance of our findings is discussed in terms of the concentration dependence for lipid peroxides in determining the rate and extent of radical propagation chain reactions catalyzed by heme-iron catalysts such as hematin. Variation of hematin and linoleic hydroperoxide concentrations may provide an efficient and reproducible method for inducing and manipulating the rates and extent of lipid peroxidation through facilitation of the propagative phase of lipid peroxidation. In addition, we address a problem inherent to in vitro studies of heme-catalyzed lipid peroxidation where preparations of peroxide-free membranes should be of concern.

Benzene Derivatives↗
PubMed1990

Malondialdehyde and thiobarbituric acid-reactivity as diagnostic indices of lipid peroxidation and peroxidative tissue injury.

Increasing appreciation of the causative role of oxidative injury in many disease states places great importance on the reliable assessment of lipid peroxidation. Malondialdehyde (MDA) is one of several low-molecular-weight end products formed via the decomposition of certain primary and secondary lipid peroxidation products. At low pH and elevated temperature, MDA readily participates in nucleophilic addition reaction with 2-thiobarbituric acid (TBA), generating a red, fluorescent 1:2 MDA:TBA adduct. These facts, along with the availability of facile and sensitive methods to quantify MDA (as the free aldehyde or its TBA derivative), have led to the routine use of MDA determination and, particularly, the "TBA test" to detect and quantify lipid peroxidation in a wide array of sample types. However, MDA itself participates in reactions with molecules other than TBA and is a catabolic substrate. Only certain lipid peroxidation products generate MDA (invariably with low yields), and MDA is neither the sole end product of fatty peroxide formation and decomposition nor a substance generated exclusively through lipid peroxidation. Many factors (e.g., stimulus for and conditions of peroxidation) modulate MDA formation from lipid. Additional factors (e.g., TBA-test reagents and constituents) have profound effects on test response to fatty peroxide-derived MDA. The TBA test is intrinsically nonspecific for MDA; nonlipid-related materials as well as fatty peroxide-derived decomposition products other than MDA are TBA positive. These and other considerations from the extensive literature on MDA. TBA reactivity, and oxidative lipid degradation support the conclusion that MDA determination and the TBA test can offer, at best, a narrow and somewhat empirical window on the complex process of lipid peroxidation. The MDA content and/or TBA reactivity of a system provides no information on the precise structures of the "MDA precursor(s)," their molecular origins, or the amount of each formed. Consequently, neither MDA determination nor TBA-test response can generally be regarded as a diagnostic index of the occurrence/extent of lipid peroxidation, fatty hydroperoxide formation, or oxidative injury to tissue lipid without independent chemical evidence of the analyte being measured and its source. In some cases, MDA/TBA reactivity is an indicator of lipid peroxidation; in other situations, no qualitative or quantitative relationship exists among sample MDA content, TBA reactivity, and fatty peroxide tone. Utilization of MDA analysis and/or the TBA test and interpretation of sample MDA content and TBA test response in studies of lipid peroxidation require caution, discretion, and (especially in biological systems) correlative data from other indices of fatty peroxide formation and decomposition.

Animals↗
PubMed1978

Red cell damage induced by peroxidized microsomes: the relationship between hemolytic activity and peroxide content.

Rat red blood cells will hemolyze if they are present in vitro in mixtures of rat liver microsomes in which lipid peroxidation has been initiated by NADPH. Recent work from this laboratory indicated that a toxic factor not having radical properties could be generated from the lipids of the peroxidizing microsomes. This toxic factor produced prelytic damage in rat red blood cells. In this communication we show that if Ca(++)-aggregated microsomes are first peroxidized and then sedimented by centrifugation, the resuspended peroxidized microsomes are capable of hemolyzing red cells in the absence of any further microsomal lipid peroxidation. This result shows conclusively that the microsomal lipid peroxidation step can be separated from the attack on red cells leading to frank hemolysis. Furthermore, lipids extracted from the peroxidized microsomes with chloroform-methanol account quantitatively for the degree of hemolysis produced. The active hemolytic material could not be detected in resuspended microsomal centrifugates obtained during the first 10 minutes of NADPH-stimulated microsomal lipid peroxidation. It appeared rapidly after 10 minutes. It was maximal at 20 minutes, and fell to a low level of activity by 60 minutes. Peak hemolytic activity correlated with peak generation of lipid soluble peroxides. High, but less than maximal levels of peroxides appearing at 10 minutes did not cause hemolysis, and high, but less than maximal levels remaining at 60 minutes were only weakly hemolytic. The extracted lipoidal material with hemolytic potency is more reactive than hydrogen peroxide in a peroxide assay.

Animals↗
PubMed1989

Thiobarbituric acid-reactive malondialdehyde formation during superoxide-dependent, iron-catalyzed lipid peroxidation: influence of peroxidation conditions.

A systematic study of the influence of biological lipid peroxidation conditions on lipid hydroperoxide decomposition to thiobarbituric acid-reactive malondialdehyde is presented. A superoxide-dependent, iron-catalyzed peroxidation system was employed with xanthine oxidase plus hypoxanthine plus ferric iron-adenosine diphosphate complex as free radical generator. Purified cardiac membrane phospholipid (as liposomes) was the peroxidative target, and 15-hydroperoxy-eicosatetraenoic acid was used as a standard lipid hydroperoxide. Exposure of myocardial phospholipid to free radical generator at physiological pH (7.4) and temperature (37 degrees C) was found to support not only phospholipid peroxidation, but also rapid lipid hydroperoxide breakdown and consequent malondialdehyde formation during peroxidation. Under lipid peroxidation conditions, oxidative injury to the phospholipid polyunsaturated fatty acids required superoxide radical and ferric iron-adenosine diphosphate complex, whereas 37 degrees C temperature and trace iron were sufficient for lipid hydroperoxide decomposition to malondialdehyde. Harsh thiobarbituric acid-test conditions following peroxidation were not mandatory for either lipid hydroperoxide breakdown or thiobarbituric acid-reactive malondialdehyde formation. However, hydroperoxide decomposition that had begun in the peroxidation reaction could be completed during a subsequent thiobarbituric acid test in which no lipid autoxidation took place. Iron was more critical than heat in promoting the observed hydroperoxide decomposition to malondialdehyde during the lipid peroxidation reaction at 37 degrees C and pH 7.4. These data demonstrate that the radical generator, at physiological pH and temperature, serves a dual role as both initiator of membrane phospholipid peroxidation and promotor of lipid peroxide breakdown and thiobarbituric acid-reactive malondialdehyde formation.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1992

Activation of complement in normal serum by hydrogen peroxide and hydrogen peroxide-related oxygen radicals produced by activated neutrophils.

Neutrophils activated by soluble particulate stimuli generate superoxide anion and subsequently form hydrogen peroxide and other oxygen radicals. The effect of hydrogen peroxide on the complement system in normal serum was investigated. Treatment of normal serum with hydrogen peroxide resulted in a diminution of the haemolytic activity of the total and alternative complement pathways and the haemolytic titres of C3 and C5 but not of C2, in normal serum. These decreases in complement activity depended on the concentration of hydrogen peroxide added to the serum. Immunoelectrophoretic analysis of hydrogen peroxide-treated serum showed that C3 and C5 proteins were activated. Complement degradation products C3a and C5a were produced in normal serum treated with hydrogen peroxide, and 20 mM EDTA abolished C3a and C5a production in hydrogen peroxide-treated serum but 20 mM Mg-EGTA did not. Catalase completely abolished and dimethylsulphoxide and D-mannitol, hydroxyl radical scavengers, partially inhibited the hydrogen peroxide-mediated complement activation. Hypochlorite, incubated with normal serum, significantly inhibited serum haemolytic activity, and sodium thiosulphate, a reducing agent, abolished the effect of hypochlorite. Normal serum incubated with activated neutrophils showed neutrophil chemotactic activity and decreased serum haemolytic activity, and the addition of catalase or methionine (5 mM) completely abolished the effects of activated neutrophils. These results suggest that hydrogen peroxide activates complement via an alternative pathway of complement activation and that hydroxyl radicals and other hydrogen peroxide-related species such as hypochlorite are most likely involved in hydrogen peroxide-mediated complement activation. Complement activation by oxygen radicals produced by activated neutrophils may be one of the mechanisms by which complement is activated in human immune complex diseases.

Complement Activation↗
PubMed1991

Site-specific mechanisms of initiation by chelated iron and inhibition by alpha-tocopherol of lipid peroxide-dependent lipid peroxidation in charged micelles.

To obtain information on the role of iron-catalyzed lipid peroxidation in the presence of the small amount of lipid peroxide in deterioration of biological membranes, we examined factors affecting peroxidation of fatty acids in charged micelles. Peroxidation of linoleic acid (LA) was catalyzed by Fe2+ via reductive cleavage of linoleic acid hydroperoxide (LOOH) in negatively charged sodium dodecyl sulfate micelles, but not in positively charged tetradecyltrimethylammonium bromide (TTAB) micelles. However, this Fe2(+)-induced, LOOH-dependent lipid peroxidation could be induced in TTAB micelles in the presence of a negatively charged iron chelator, nitrilotriacetic acid (NTA). The linoleic acid alkoxy radical (LO.) generated by the LOOH-dependent Fenton reaction was also trapped by N-t-butyl-alpha-phenylnitrone at the surface of TTAB micelles in the presence of NTA, but not in its absence. The degradation rates of two spin probes, N-oxyl-4,4'-dimethyloxazolidine derivatives of stearic acid (5-NS and 16-NS), were investigated to determine the site of production of radicals formed during LOOH-dependent lipid peroxidation. The rate of consumption of 16-NS during the LOOH-dependent Fenton-like reaction was higher in TTAB micelles containing LA than in those containing lauric acid (LauA), although the rates of formation of LO. in the two types of fatty acid micelles were similar. The rates of 5-NS consumption in LA and LauA micelles were almost the same and were as low as that of 16-NS consumption in LauA micelles. 16-NS was more inhibitory than 5-NS of LOOH-dependent lipid peroxidation, and this inhibition was associated with its higher consumption of 16-NS than of 5-NS. alpha-Tocopherol inhibited NTA-Fe2(+)-induced LOOH-dependent lipid peroxidation in TTAB micelles, and was oxidized during this inhibition process. The rate and amount of alpha-tocopherol oxidized by the LOOH-dependent Fenton reaction were higher in LA micelles than in LauA micelles. alpha-Tocopherol inhibited the consumption of 16-NS during NTA-Fe2(+)-induced LOOH-dependent lipid peroxidation more effectively than that of 5-NS. The distribution of the chromanol moiety of alpha-tocopherol was studied by the fluorescence quenching method. There was no difference between Stern-Volmer plots of the quenchings of alpha-tocopherol fluorescence by 5-NS and 16-NS. From these results, we discuss the mechanism of induction of LOOH-dependent peroxidation of LA and the mechanism of the antioxidant effects of alpha-tocopherol on it from the viewpoint of site-specific reaction.

Electron Spin Resonance Spectroscopy↗
PubMed1991

Hydrogen peroxide-induced oxidative stress to the mammalian heart-muscle cell (cardiomyocyte): lethal peroxidative membrane injury.

Oxidative stress induced by hydrogen peroxide (H2O2) may contribute to the pathogenesis of ischemic-reperfusion injury in the heart. For the purpose of investigating directly the injury potential of H2O2 on heart muscle, a cellular model of H2O2-induced myocardial oxidative stress was developed. This model employed primary monolayer cultures of intact, beating neonatal-rat cardiomyocytes and discrete concentrations of reagent H2O2 in defined, supplement-free culture medium. Cardiomyocytes challenged with H2O2 readily metabolized it such that the culture content of H2O2 diminished over time, but was not depleted. The consequent H2O2-induced oxidative stress caused lethal sarcolemmal disruption (as measured by lactate dehydrogenase release), and cardiomyocyte integrity could be preserved by catalase. During oxidative stress, a spectrum of cellular derangements developed, including membrane phospholipid peroxidation, thiol oxidation, consumption of the major chain-breaking membrane antiperoxidant (alpha-tocopherol), and ATP loss. No net change in the protein or phospholipid contents of cardiomyocyte membranes accompanied H2O2-induced oxidative stress, but an increased turnover of these membrane constituents occurred in response to H2O2. Development of lethal cardiomyocyte injury during H2O2-induced oxidative stress did not require the presence of H2O2 itself; a brief "pulse" exposure of the cardiomyocytes to H2O2 was sufficient to incite the pathogenic mechanism leading to cell disruption. Cardiomyocyte disruption was dependent upon an intracellular source of redox-active iron and the iron-dependent transformation of internalized H2O2 into products (e.g., the hydroxyl radical) capable of initiating lipid peroxidation, since iron chelators and hydroxyl-radical scavengers were cytoprotective. The accelerated turnover of cardiomyocyte-membrane protein and phospholipid was inhibited by antiperoxidants, suggesting that the turnover reflected molecular repair of oxidized membrane constitutents. Likewise, the consumption of alpha-tocopherol and the oxidation of cellular thiols appeared to be epiphenomena of peroxidation. Antiperoxidant interventions coordinately abolished both H2O2-induced lipid peroxidation and sarcolemmal disruption, demonstrating that an intimate pathogenic relationship exists between sarcolemmal peroxidation and lethal compromise of cardiomyocyte integrity in response to H2O2-induced oxidative stress. Although sarcolemmal peroxidation was causally related to cardiomyocyte disruption during H2O2-induced oxidative stress, a nonperoxidative route of H2O2 cytotoxicity was also identified, which was expressed in the complete absence of cardiomyocyte-membrane peroxidation. The latter mode of H2O2-induced cardiomyocyte injury involved ATP loss such that membrane peroxidation and cardiomyocyte disruption on the one hand and cellular de-energization on the other could be completely dissociated.(ABSTRACT TRUNCATED AT 400 WORDS)

Adenosine Triphosphate↗
PubMed1991

Peroxide-dependent and -independent lipid peroxidations catalyzed by chelated iron.

Oxidation of linoleic acid (LA) in tetradecyltrimethylammonium bromide micelles was induced by ferrous- and ferric-chelates in the presence of linoleic acid hydroperoxide (LOOH). Ferrous-chelates also induced lipid peroxidation in the presence of H2O2, but ferric-chelates did not, thought they could generate OH-radicals in the presence of H2O2, resulting in deoxyribose degradation. Of the chelators tested, nitrilotriacetic acid (NTA) chelated with iron showed the highest activity for induction of H2O2- and LOOH-dependent lipid peroxidations and H2O2-dependent deoxyribose degradation. NTA with ferrous ion, but not with ferric ion, also initiated oxidation of LA after a short lag period in the absence of peroxides such as H2O2 and LOOH, but other chelators with ferrous ion did not. The peroxide-independent lipid peroxidation and associated oxidation of ferrous-NTA to ferric-NTA progressed in two steps: an induction step in a lag period and then a propagation step. Ferrous ion complexed with NTA was autoxidized pH-dependently and synchronously with oxygen uptake. The rates of both reactions increased with increase of pH, but were not related to the length of the lag period, which was also dependent on pH, and was shortest at pH 4.2. The EPR spectrum of the ferric-NTA complex prepared directly from ferric salt was different from that of the complex prepared from ferrous salt, confirming that some ferric-type active oxygen participated in induction of peroxide-independent lipid peroxidation. From these results, we propose a possible mechanism of lipid peroxidation induced by ferrous-NTA without peroxides. The finding that iron-NTA had the highest activity for induction of the oxidations of LA and deoxyribose is discussed in relation to the carcinogenic and nephrotoxic effects of this chelating agent.

Catalysis↗
PubMed1989

Damage to protein synthesis concurrent with lipid peroxidation in rat liver slices: effect of halogenated compounds, peroxides, and vitamin E1.

Protein synthesis and lipid peroxidation were evaluated in rat liver slices incubated in the presence of oxidants and protein synthesis inhibitors. Protein synthesis by rat liver slices was evaluated by [3H]leucine incorporation into the trichloroacetic acid (TCA)-insoluble material, and lipid peroxidation was evaluated by thiobarbituric acid-reactive substances (TBARS) released into the incubation medium. Protein synthesis inhibition by bromotrichloromethane (BrCCl3) or t-butyl hydroperoxide (t-BOOH) depended on the incubation time and oxidant concentration. [3H]Leucine incorporation was decreased to 20 and 47% of control values and TBARS were enhanced from the control value of 16.9 to 45.3 and 62.5 nmol/g of liver by incubation for 1 h with 1 mM BrCCl3 and t-BOOH, respectively. Following incubation, both protein synthesis damage and lipid peroxidation were decreased in control and oxidant-treated slices prepared from rats injected with 200 mg of DL-alpha-tocopherol/kg of body wt. Release of lactate dehydrogenase was not enhanced by oxidant treatment. Protein synthesis inhibitors reversibly decreased [3H]leucine incorporation, but the effect of oxidants on protein synthesis was irreversible. Cumene hydroperoxide and methyl ethyl ketone peroxide, but not hydrogen peroxide, damaged protein synthesis and induced lipid peroxidation. The ability of carbon tetrabromide, benzyl chloride, bromoform, bromobenzene, carbon tetrachloride, chloroform, dichloromethane, and bromochloromethane to inhibit protein synthesis was correlated with their ability to induce lipid peroxidation, and with their LD50. The results suggest that oxidant-induced lipid peroxidation and protein synthesis damage occurred concurrently, and that protein synthesis inhibition may be involved in cell injury or death mediated by free radicals.

Animals↗
PubMed1991

Plasma lipoprotein peroxidation potential: a test to evaluate individual susceptibility to peroxidation.

Peroxidation of lipids is believed to play a key role in various degenerative diseases. However, few simple tests are able to detect individual susceptibility or resistance to peroxidation. Measurement of the basal concentrations of lipid peroxides in plasma is not satisfactory because they are so low. Therefore, we developed a test to determine susceptibility of whole plasma to metal/H2O2-catalyzed peroxidation. Incubation of 300-500 microL of plasma with H2O2/cupric acetate resulted in the formation of products from fatty acids (malonaldehyde, measured by thiobarbituric acid assay) and cholesterol (predominantly cholest-3,5-dien-7-one, measured by gas-liquid chromatography). In the presence of Cu2+, formation of malonaldehyde and cholest-3,5-dien-7-one increased at least 10-fold over basal values. Lipid peroxide (malonaldehyde) and cholesterol oxide concentrations after peroxidation were significantly higher (P less than 0.01) in diabetic plasma than in normal plasma. Because susceptibility to plasma peroxidation represents a balance between pro-oxidant factors and antioxidant protection, this test may be useful in determining individual susceptibility to peroxidation as influenced by nutritional and clinical status.

Adult↗
PubMed1990

Intestinal motility disorder induced by peroxides: possible role of lipid peroxidation.

The effect of oxidative stress on the rat small intestine was investigated by pretreatment of isolated segments from the jejunum with hydrogen peroxide or cumene hydroperoxide. Both peroxides induced responses in the small intestine, viz. a contraction followed by a slow relaxation. The contraction could be blocked by the cyclooxygenase inhibitor indomethacin and the phospholipase A2 inhibitor quinacrine, suggesting a role for prostaglandins in the response. Pretreatment of intestinal segments with the peroxides diminished the muscarinic cholinergic response to methacholine. The lipoxygenase inhibitor nordihydroguaiaretic acid (NDGA) and the antioxidant butylated hydroxytoluene (BHT) both protected against the damage induced by cumene hydroperoxide, but did not influence the effect of hydrogen peroxide on the muscarinic response. In contrast to hydrogen peroxide, cumene hydroperoxide induced lipid peroxidation in intestinal membranes, which could also be blocked by NDGA or BHT. We conclude that cumene hydroperoxide alters the muscarinic response in the rat jejunum by the induction of lipid peroxidation, whereas the damage by hydrogen peroxide is probably induced intracellularly.

Animals↗
PubMed1991

Cytochrome c-catalyzed membrane lipid peroxidation by hydrogen peroxide.

Cytochrome c(3+)-catalyzed peroxidation of phosphatidylcholine liposomes by hydrogen peroxide (H2O2) was indicated by the production of thiobarbituric acid reactive substances, oxygen consumption, and emission of spontaneous chemiluminescence. The iron chelator diethylenetriaminepentaacetic acid (DTPA) only partially inhibited peroxidation when H2O2 concentrations were 200 microM or greater. In contrast, iron compounds such as ferric chloride, potassium ferricyanide, and hemin induced H2O2-dependent lipid peroxidation which was totally inhibitable by DTPA. Cyanide and urate, which react at or near the cytochrome-heme, completely prevented lipid peroxidation, while hydroxyl radical scavengers and superoxide dismutase had very little or no inhibitory effect. Changes in liposome surface charge did not influence cytochrome c3+ plus H2O2-dependent peroxidation, but a net negative charge was critical in favoring cytochrome c(3+)-dependent, H2O2-independent lipid auto-oxidative processes. These results show that reaction of cytochrome c with H2O2 promotes membrane oxidation by more than one chemical mechanism, including formation of high oxidation states of iron at the cytochrome-heme and also by heme iron release at higher H2O2 concentrations. Cytochrome c3+ could react with mitochondrial H2O2 to yield "site-specific" mitochondrial membrane lipid peroxidation during tissue oxidant stress.

Cytochrome c Group↗
PubMed1988

Influence of lipid peroxidation and hydrogen peroxide on muscarinic cholinergic receptors and ATP level in rat myocytes and lymphocytes.

Isolated rat neonatal cardiac myocytes and rat lymph-node lymphocytes were treated with Fe2+ cumene hydroperoxide or hydrogen peroxide. The intensity of lipid peroxidation was estimated by measuring production of malondialdehyde (MDA). The level of muscarinic cholinergic receptors was determined by [3H]-QNB binding. Cumene hydroperoxide treatment was found to induce lipid peroxidation in both myocytes and lymphocytes, the process being more pronounced in myocytes. An important decrease of muscarinic cholinergic receptor level and a significant drop of intracellular ATP level in these cells were simultaneously observed. In both cell types, hydrogen peroxide treatment decreased the ATP level while lipid peroxidation and muscarinic cholinergic receptors were unaffected. The different effect of hydrogen peroxide on lipid peroxidation and the level of muscarinic cholinergic receptors on the one hand and the ATP level on the other suggests that this substance acts mainly in the intracellular space.

Adenosine Triphosphate↗
PubMed1988

Lipid peroxidation and cell viability in isolated hepatocytes in a redesigned oxystat system: evaluation of the hypothesis that lipid peroxidation, preferentially induced at low oxygen partial pressures, is decisive for CCl4 liver cell injury.

An oxystat system is described which is capable of maintaining steady-state oxygen partial pressures (PO2) at levels between 0.1 and 300 mm Hg for hours or even days in incubations of respiring cells. The system was used to study effects of the hepatotoxin carbon tetrachloride (CCl4) on lipid peroxidation and cell viability in isolated hepatocytes from phenobarbital-pretreated rats at various steady-state PO2. At PO2 below 35 mm Hg, with a maximum effect at 7 mm Hg, CCl4 induced an immediate lipid peroxidation, the rate of which slowed down during further incubation. AT PO2 between 35 and 70 mm Hg, CCl4 initially induced only slight lipid peroxidation, while there was a significant increase in lipid peroxidation after approximately 30 min. At PO2 above 100 mm Hg, no lipid peroxidation was induced by CCl4. At PO2 of 70 mm Hg and below, with the maximum effect at 3 mm Hg, CCl4 also induced marked losses of cell viability. Under anaerobic conditions and at PO2 greater than 70 mm Hg, CCl4 was without effect on the viability of the liver cells. Cells isolated from the pericentral area of the liver lobule showed more lipid peroxidation and loss of cell viability than cells from the periportal area of the lobule. These results provide further evidence for the decisive role of lipid peroxidation, preferentially induced at low PO2, in CCl4 liver injury.

Animals↗
PubMed1990

Increased levels of lipid peroxides in aged rat brain as revealed by direct assay of peroxide values.

Lipid peroxide concentrations in brain tissues of young and aged rats were determined by a direct method for measuring peroxide values. Three different brain regions were analyzed for lipid peroxides. The peroxide levels increased in all three regions of aged as compared to those of young rats, while lipid peroxides in plasma appeared to be stable along with age. Lipid peroxides in cerebrum and cerebellum increased 1.6-2.0 times in aged brains compared with young ones, and about 3-fold in the brain stem. Increased levels of lipid peroxides in aged brains seem not merely due to increased pools of precursor polyene fatty acids, but rather due to altered protection systems for lipid peroxidase formation.

Aging↗
PubMed1992

Ferric(III) ions inhibits copper(II)/hydrogen peroxide-catalyzing lipid peroxidation in human erythrocyte membranes.

1. Effect of ferric ions (Fe3+) on the lipid peroxidation catalyzed by copper ions (Cu2+) and hydrogen peroxide (H2O2) was studied in human erythrocyte membranes. 2. The formation of thiobarbituric acid-reactive products elicited by CuCl2/H2O2 was inhibited by FeCl3 in a concentration-dependent manner; 0.25 mM FeCl3 were enough to cause 50% inhibition of the formation of peroxides. 3. The inhibitory effect of FeCl3 is not due to competition against Cu2+. 4. FeCl3 inhibited the initiation, but did not inhibit the propagation of Cu2+/H2O2-catalyzing lipid peroxidation. 5. In the heat- or trypsin-treated erythrocyte membranes, FeCl3 had no inhibitory effect on Cu2+/H2O2-catalyzing lipid peroxidation. 6. Sodium azide, an inhibitor of catalase, had no effect on the inhibitory effect of FeCl3. 7. These results suggest that a protein factor(s), which is not catalase, is involved in the inhibition of Cu2+/H2O2-catalyzing lipid peroxidation by Fe3+.

Copper↗
PubMed1977

Studies on vitamin E and selenium deficiency in young pigs. II. The hydrogen peroxide hemolysis test and the measure of red cell lipid peroxides as indices of vitamin E and selenium status.

The usefulness of the hydrogen peroxide hemolysis test and the measure of red cell lipid peroxides as indices of vitamin E and selenium deficiency in swine has been evaluated. Results indicated that although the hydrogen peroxide hemolysis test may be of some indication of the vitamin E status, it is not a reliable index of vitamin E deficiency in swine, at least on an individual basis. In contrast, the measure of red cell lipid peroxides can be considered a reliable test for vitamin E deficiency in swine. The hydrogen peroxide hemolysis test and the red cell lipid peroxides were not significantly affected by selenium deficiency.

Animals↗