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PubMed1992

Cytosolic calcium increase in coronary endothelial cells after H2O2 exposure and the inhibitory effect of U78517F.

1. Cytosolic calcium concentrations ([Ca2+]i) were determined with fura-2 on both resting (unstimulated) and A23187-stimulated coronary endothelial cells following injury by hydrogen peroxide (H2O2). 2. Treatment of cells with H2O2 (10(-4) M) caused an increase in the resting [Ca2+]i, which reached a maximum of five fold after 3 h. 3. The increase in resting [Ca2+]i was significantly attenuated by treatment with U78517F, a potent inhibitor of lipid peroxidation, at a concentration of 10(-6) M or greater. Catalase (50 u ml-1) also markedly inhibited the H2O2-induced rise in [Ca2+]i. Pretreatment with verapamil (10(-5) M), nifedipine (10(-6) M) or diltiazem (10(-5) M) had no effect on the increase in [Ca2+]i following addition of H2O2. 4. A23187 produced a transient increase in [Ca2+]i followed by a sustained plateau. The initial peak and plateau phase responses to A23187 were augmented by H2O2. This augmentation of [Ca2+]i was suppressed by U78517F or catalase but not by Ca-entry blockers. 5. Thus, it is likely that lipid peroxidation plays a critical role in the sustained increase in [Ca2+]i that occurs following treatment with H2O2 and that this continues in the presence of agonists which stimulate the endothelium. Voltage-gated Ca2+ channels do not seem to be involved in the genesis of cellular damage associated with sustained large increases in [Ca2+]i.

Animals↗
PubMed1991

Does hydrogen peroxide exist "free" in biological systems?

Hydrogen peroxide (H2O2) can diffuse far from the site of production to intracellular locations where biological effects may be greater. The diffusion range is extended by H2O2 carriers formed spontaneously by hydrogen bonding with monomeric and polymeric compounds, including amino and dicarboxylic acids, peptides, proteins, nucleic acid bases, and nucleosides. Hydrogen peroxide adducts (HPAs) are readily synthesized, e.g., crystalline histidine (His)-H2O2 adducts. An equilibrium exists between an adduct-forming compound and H2O2. The detection and relative stabilities of HPAs are measured by the degree of decomposition of H2O2 as influenced by test compounds in buffered solution competing with glucose or fructose for H2O2. The HPAs delay decomposition of H2O2 up to several hundredfold. The overall charge on an HPA, i.e., its ability to penetrate cell membranes, influences the cytotoxic and clastogenic effects of H2O2. Growth inhibition of Salmonella typhimurium LT2 by H2O2 is enhanced by neutral HPAs but decreased by anionic HPAs. Addition of catalase 1, 10, or 30 min after inoculation of S. typhimurium LT2 reduces or nearly eliminates partial growth inhibition by H2O2, but a neutral HPA, especially His-H2O2, transported H2O2 into the cells within 1 min, and in about 10 min completely inhibited growth. The stability of HPAs decreases with increasing pH or increasing temperature, while added Fe(II) in the presence and absence of EDTA accelerates H2O2 and HPA decomposition. Calculations indicate H2O2 hydrogen bonds with nucleic acid-base pairs with no apparent bond strain and energy stabilization comparable to normal hydrogen bonding.

Adenine↗
PubMed1991

Role of antioxidants and scavengers on argemone oil-induced toxicity in rats.

The role of antioxidants and scavengers on argemone oil-induced enzymatic and non-enzymatic hepatic lipid peroxidation was investigated in rats. Multiple treatment of argemone oil caused a significant stimulation of NADPH-dependent enzymatic or FeSO4 or FeSO4/ADP-or ascorbic acid-dependent non-enzymatic hepatic microsomal lipid peroxidation. In vitro addition of antioxidants such as tannic acid, quercetin, butylated hydroxyanisole (BHA), butylated hydroxytoluene (BHT), alpha-tocopherol, riboflavin or glutathione (GSH) in the assay system resulted in significant protection against argemone oil-induced microsomal NADPH, or FeSO4/ADP-dependent lipid peroxidation. In vitro addition of scavengers of the superoxide anion (O2-.) radical and hydrogen peroxide (H2O2) such as superoxide dismutase (SOD) and catalase, respectively, prevented argemone oil augmented microsomal lipid peroxidation to a lesser extent as compared to the scavengers of singlet oxygen (1O2) such as 2,5-dimethylfuran (DMF), beta-carotene, and histidine or hydroxyl (OH.) radical scavengers such as ethanol, mannitol and sodium benzoate. These results suggest that primarily 1O2 and OH. radicals are involved in argemone oil-induced hepatic microsomal lipid peroxidation, and that bio-antioxidant vitamins including riboflavin, beta-carotene and alpha-tocopherol may prove useful in reducing argemone oil-induced hepatotoxicity.

Animals↗
PubMed1991

Copper(II) ethylenediaminetetraacetate complex does activate hydrogen peroxide in the presence of biological reductants.

The reaction of CuII (edta) (edta: ethylenediaminetetraacetic acid) with hydrogen peroxide (H2O2) was studied in the pH range of 6.0 to 8.0. CuII (edta) did not react with H2O2 in the all pH range examined in the absence of biological reductants. CuII (edta), however, could react with H2O2 in the presence of biological reductants such as ascorbic acid, cysteine and NADH to give thibarbituric acid (TBA) reactive substance, regardless of the pH. From these results, it is concluded that CuII (edta) cannot be bound to H2O2 and that the change of the redox potential of Cu2+ ion on ligating with edta may cause CuII (edta) to be unable to oxidize H2O2.

Edetic Acid↗
PubMed1988

The biological activity of hydrogen peroxide. IV. Enhancement of its clastogenic actions by coadministration of L-histidine.

An enhancing effect of L-histidine (L-His) was detected on the induction by hydrogen peroxide (H2O2) of chromosomal aberrations of both the chromosome type and the chromatid type, in human embryonic fibroblasts. The maximum efficiency of induction was about 8-fold higher in the presence of L-His than in the presence of H2O2 alone, at a concentration of L-His of 50 microM. D-His and DL-His showed lower enhancing effects than L-His, with approximately 2-fold and 5-fold enhancement of induction of chromosomal aberrations, respectively. L-Histidinol and L-His-methyl ester, among various derivatives of L-His tested, also enhanced this process. However, the effects of these derivatives were smaller than those of L-His in a range of concentrations equivalent to that of the most effective dose of L-His (50 microM), while they produced greater enhancement than L-His at concentrations higher than 200 microM. Other derivatives of L-His, such as L-carnosine, urocanic acid, imidazolepyruvic acid, 1-methyl-L-His, imidazolelactic acid, imidazoleacetic acid and histamine and imidazole itself did not enhance the frequency of chromosomal aberrations induced by H2O2. These results indicate that at least both the imidazole ring and the amino group are essential components of the chemical structure of L-His required for the enhancing effect. Moreover, in order to cause such an enhancing effect, L-His had to be applied together with H2O2 to cells, because the enhancing effect of L-His was not observed with cells which were washed after pretreatment with L-His. The preliminary study suggested that this enhancing effect depends on the His-peroxide adduct derived from L-His and H2O2. None of the amino acids tested other than His produced any enhancing effect on the induction of chromosomal aberrations by H2O2.

Amino Acids↗
PubMed1984

Human B lymphocytes show greater susceptibility to H2O2 toxicity than T lymphocytes.

Lymphocytes from patients with chronic lymphocytic leukemia (CLL) and from normal subjects were incubated with a glucose-glucose oxidase hydrogen peroxide (H2O2) generating system to study the effect of oxidant stress on these cells. Within 4 hr, 90% of normal but only 21% of CLL lymphocytes remained viable. When normal and CLL preparations enriched in B or T cells were exposed to H2O2, B lymphocytes from both groups were highly susceptible to oxidative damage while T lymphocytes were relatively resistant. The H2O2 scavenger catalase prevented the cytotoxicity. The present work identifies the human B lymphocyte as a cell that should be a suitable target for selective killing by H2O2-generating systems.

B-Lymphocytes↗
PubMed1987

Participation of the myeloperoxidase-H2O2-halide system in immune complex nephritis.

Neutrophils (PMNs) mediate injury in experimental glomerulonephritis (GN) in part via the release of reactive oxygen species, particularly hydrogen peroxide (H2O2). Recent kidney perfusion studies demonstrate that H2O2 can cause glomerular injury by reaction with halides in the presence of the PMN cationic enzyme myeloperoxidase (MPO) to form oxidants which can oxidize and halogenate tissue. We sought evidence for participation of the MPO system in a model of PMN-mediated immune complex (IC) GN. A PMN-dependent model of GN was developed in rats by perfusing the renal artery with concanavalin A followed by anticoncanavalin A antibody. PMN depletion abolished glomerular PMN infiltration and significantly reduced proteinuria (35 +/- 7 mg/day vs. 113 +/- 10, P less than 0.001). Rats that received Na125I (5.0 microCi) three and six hours following disease induction had more 125I incorporation in glomeruli and GBM at 48 hours than similarly treated rats that were PMN depleted (1200 cpm vs. 88 cpm, P less than 0.01). Glomerular iodination could not be demonstrated in a PMN-independent model of nephrotoxic nephritis induced with noncomplement fixing anti-GBM antibody. These data indicate that this model of PMN-mediated IC GN is associated with activation of the MPO-H2O2-halide system, which may participate in mediating glomerular injury.

Animals↗
PubMed1988

The effects of beta-adrenergic receptor agonists on the H2O2 formation in alveolar macrophage suspensions are not mediated by beta-receptors.

In the present study, the effects of beta-adrenergic receptor agonists on the hydrogen peroxide (H2O2) production in phorbol myristate acetate stimulated guinea pig alveolar macrophage suspensions have been investigated. In contrast to suggestions described in literature, our results indicate that the H2O2 production in alveolar macrophage suspensions is not mediated by beta-adrenergic receptors. Rather, it is suggested that the inhibitory effect of catecholamines in the H2O2 formation which is found after 5 minutes is the result of inhibition of the horseradish peroxidase catalysed phenol red oxidation, used as H2O2 measurement, by the catecholamines.

Adrenergic beta-Agonists↗
PubMed1990

Extramitochondrial release of hydrogen peroxide from insect and mouse liver mitochondria using the respiratory inhibitors phosphine, myxothiazol, and antimycin and spectral analysis of inhibited cytochromes.

The fumigant insecticide phosphine (PH3) is known to inhibit cytochrome c oxidase in vitro. Inhibition of the respiratory chain at this site has been shown to stimulate the generation of superoxide radicals (O2-), which dismutate to form hydrogen peroxide (H2O2). This study was performed in order to investigate the production of H2O2 by mitochondria isolated from granary weevil (Sitophilus granarius) and mouse liver on exposure to PH3. Other respiratory inhibitors, antimycin, myxothiazol, and rotenone were used with insect mitochondria. Hydrogen peroxide was measured spectrophotometrically using yeast cytochrome c peroxidase as an indicator. Insect and mouse liver mitochondria, utilizing endogenous substrate, both produced H2O2 after inhibition by PH3. Insect organelles released threefold more H2O2 than did mouse organelles, when exposed to PH3. Production of H2O2 by PH3-treated insect mitochondria was increased significantly on addition of the substrate alpha-glycerophosphate. Succinate did not enhance H2O2 production, however, indicating that the H2O2 did not result from the autoxidation of ubiquinone. NAD(+)-linked substrates, malate and pyruvate also had no effect on H2O2 production, suggesting that NADH-dehydrogenase was not the source of H2O2. Data obtained using antimycin and myxothiazol, both of which stimulated the release of H2O2 from insect mitochondria, lead to the conclusion that glycerophosphate dehydrogenase is a source of H2O2. The effect of combining PH3, antimycin, and myxothiazol on cytochrome spectra in insect mitochondria was also recorded. It was observed that PH3 reduces cytochrome c oxidase but none of the other cytochromes in the electron transport chain. There was no movement of electrons to cytochrome b when insect mitochondria are inhibited with PH3. The spectral data show that the inhibitors interact with the respiratory chain in a way that would allow the production of H2O2 from the sites proposed previously.

Animals↗
PubMed1991

Intracellular production of reactive oxygen species in human neutrophils following activation by the soluble stimuli FMLP, dioctanoylglycerol and ionomycin.

The stimuli, sn-1, 2-dioctanoylglycerol; (DG8) the calcium specific ionophore, ionomycin, and the chemotactic peptide formylmethionyl-leucyl-phenylalanine (FMLP) can interact with normal human neutrophils and activate their superoxide/hydrogen peroxide generating NADPH-oxidase. In response to the peptide as well as DG8, the neutrophils produced both superoxide (O2-) and hydrogen peroxide (H2O2). Since interaction between the cells and ionomycin was not associated with any notable superoxide production and hydrogen peroxide was induced only in the presence of azide, a potent inhibitor of the hydrogen peroxide-consuming enzymes catalase and myeloperoxidase, we conclude that this stimulus can generate oxygen metabolites intracellularly. Since the DG8-induced production of hydrogen peroxide was increased in the presence of azide, whereas the FMLP-induced response was largely unaffected, we concluded that the three stimuli differ in their capacity to generate oxygen metabolites intracellularly. The use of sn-1,2-didecanoylglycerol (DG10) as stimulating agent did not result in any detectable activation of the NADPH-oxidase. However, preincubation caused an increased (primed) response during stimulation with the chemotactic peptide FMLP. The response of primed neutrophils to FMLP proceeds with a time-course different from that seen in normal cells. From the results presented on FMLP-induced activity in the presence of azide, we conclude that FMLP causes normal cells to produce oxygen radicals which are released from the cells. However, the primed cells are also capable of generating oxygen metabolites that are retained inside the cells. In fact, measurement of the intracellularly generated metabolites discloses this to be the predominant part of the response.

Adult↗
PubMed1990

The influence of pH on OH. scavenger inhibition of damage to deoxyribose by Fenton reaction.

Hydroxyl radicals (OH.) can be formed in aqueous solution by direct reaction of hydrogen peroxide (H2O2) with ferrous salt (Fenton reaction). OH. damage to deoxyribose, measured as formation of thiobarbituric acid-reactive material, was evaluated at different pHs to study the mechanism of action of classical OH. scavengers. OH. scavenger effect on Fe2+ oxidation was also evaluated in the same experimental conditions. In the absence of OH. scavengers, OH. damage to deoxyribose is higher at acidic compared to neutral and moderately basic pH. At acidic pH deoxiribose is per se able to inhibit Fe2+ oxidation by H2O2. Most of OH. scavengers tested inhibit deoxyribose damage and Fe2+ oxidation in a similar manner: both inhibitions are most relevant at acidic pH and decrease by increasing the pH. These results are not due to OH. scavenger inhibition of Fenton reaction. The influence of pH on the parameters studied appears to be due to the competition of deoxyribose and OH. scavengers for iron. These results suggest the prominent role of iron binding in the degradation of deoxyribose and in the OH. scavenging ability of different compounds. Results obtained with triethylenetetramine, a iron chelator with a low rate constant with OH., confirm that both deoxyribose and the OH. scavengers interact with iron bringing about a site specific Fenton reaction; that the OH. formed at these sites oxidize these molecules to their radical forms which in turn reduce the Fe3+ produced by Fenton reaction. The results presented indicate that most of classical OH. scavengers exert their effect predominantly by preventing the site specific reaction between Fe2+ and H2O2 on the deoxyribose molecule.

Copper↗
PubMed1988

Activation of macrophages by Entamoeba histolytica extracts in mice.

The effect of Entamoeba histolytica extracts on the production of inflammatory macrophages and the release of hydrogen peroxide (H2O2) and superoxide (O2-) from these cells was examined in C57BL/6 mice. Two different strains of E. histolytica, either virulent (IP:0682:1) or nonvirulent (DKB), were used in this study. The number of macrophages recovered from the peritoneal cavity of mice treated 5 days previously with 150 micrograms of either strain of amoebic extracts was significantly higher than in the saline-treated groups. Macrophages from mice treated with 150 micrograms of the IP:0682:1 strain of amoebic extracts exhibited a powerful burst of oxidative metabolis when triggered with phorbol myristate acetate (PMA). Extract from the non-virulent strain was much less effective in activating macrophages for the production of oxidative metabolites. Thus, a crude extract preparation from E. histolytica, particularly the virulent strain, induces a strong macrophage inflammatory response in which the cells also produce high levels of H2O2 and O2-.

Animals↗
PubMed1992

Impairment of sodium-coupled uptakes by hydrogen peroxide in alveolar type II cells: protective effect of d-alpha-tocopherol.

Hydrogen peroxide (H2O2) is likely to play an important role in oxidant alveolar epithelium injury. We investigated the effect of H2O2 on uptake of phosphate, alanine in cultured rat alveolar type II cells. H2O2 induced inhibition of Na-dependent component of phosphate and alanine uptakes in time- and concentration-dependent manner. Twenty minutes exposure to 2.5 mM H2O2 decreased the maximum velocity (Vmax) of phosphate and alanine uptake by 50 and 62%, respectively, whereas Michaelis constant (Km) values were unchanged. H2O2 also decreased Na-K-ATPase activity, measured by ouabain-sensitive rubidium influx, and this effect was independent of H2O2-induced ATP depletion. A lipid-soluble antioxidant, d-alpha-tocopherol (20 microM, 24 h), prevented H2O2-induced decrease in Na-coupled uptake and Na-K-ATPase activity. These results indicate that H2O2 affects Na-dependent phosphate and alanine uptakes and suggest that this effect may be related at least, in part, to a decrease in Na transmembrane gradient, since H2O2 also affects Na-K-ATPase activity. The protective effect of d-alpha-tocopherol suggests that peroxidation of the membrane lipids is likely to be involved in the observed effects.

Adenosine Triphosphate↗
PubMed1986

Reactive oxygen species: production and role in the kidney.

Reactive oxygen species (ROS) are formed by incomplete reduction of molecular oxygen. They include superoxide anion (O2-.), hydrogen peroxide (H2O2), hydroxyl radical (OH.), and singlet oxygen (1O2). ROS may induce different types of cell injury, particularly lipid peroxidation and membrane damage. ROS have been shown to play an essential role in the mechanisms of experimental models of several renal diseases: ischemic acute renal failure, renal graft rejection, acute glomerulonephritis, and toxic renal diseases. They are produced by the renal cells and also by the inflammatory bone marrow-derived cells invading the renal tissue. ROS, regardless of their origin, may degrade the glomerular basement membrane and alter the glomerular and tubular cell functions. Particularly, they produce an increase in cyclic AMP synthesis and prostaglandin production in the glomeruli. Recent studies have shown that the glomerular mesangial cells themselves generated ROS on stimulation by phagocytosis of foreign particles or exposure to the complement membrane attack complex or platelet-activating factor. Production of ROS is in narrow relationship with the metabolism of arachidonic acid. Conversion of this fatty acid via the lipoxygenase pathway is associated with an increase of ROS, whereas its transformation into prostaglandins via the cyclooxygenase pathway results in the opposite effect. Production of ROS in activated mesangial cells can be inhibited by glucocorticoids via a receptor-mediated mechanism. The fact that some of these characteristics are different in leukocytes suggests the possibility in the future of the more specific pharmacological control of the inflammatory process in the glomerular mesangium.

Acute Disease↗
PubMed1991

Evidence for the formation of superoxide ion from the reaction of Cu(II)-ethylenediamine complex with hydrogen peroxide.

Formation of superoxide ion (O2-) from the reaction of CuII(en)2 (en: ethylenediamine) with hydrogen peroxide (H2O2) was first determined spectrophotometrically by use of nitro blue tetrazolium (NBT) in aqueous solutions. From this result, it has been suggested that superoxide ion is generated as an intermediate at the first reaction step between CuII(en)2 and H2O2.

Copper↗
PubMed1987

Suppression of human lymphocyte proliferation by activated neutrophils or H2O2: surviving cells have an altered T helper/T suppressor ratio and an increased resistance to secondary oxidant exposure.

Either activated neutrophils (PMNs) or nanomole amounts of reagent hydrogen peroxide (H2O2) were found to cause catalase-reversible suppression of concanavalin A (Con A)-stimulated human lymphocyte proliferation. Suppression required PMN activation and occurred with PMN/lymphocyte ratios found in peripheral blood. Inhibition by reagent H2O2 occurred with 10-40 nmol H2O2/1 X 10(6) lymphocytes, a noncytolethal amount which is produced readily by PMA-activated PMNs. Lymphoblasts recovered from suppressed cultures were two- to fourfold less sensitive than control lymphoblasts to a second exposure to H2O2. These relatively H2O2-resistant lymphoblasts also scavenge H2O2 at higher rates than do control lymphoblasts. Progeny lymphocytes from suppressed cultures contain an unusually high percentage of T helper cells with a concomitant decrease in T suppressors. These studies demonstrate a potential immunoregulatory role for phagocyte-released oxidants, especially H2O2, and suggest a possible additional mechanism to explain the excess of T helpers observed in situations of chronic inflammation.

Antigens, Surface↗
PubMed1988

A role for reduced oxygen species in heat induced cell killing and the induction of thermotolerance.

A model suggesting a role for superoxide (O2-) and hydrogen peroxide (H2O2) in heat induced cytotoxicity and development of thermotolerance is proposed: (1) Heat shock increases cellular generation of O2- and H2O2 in proportion to the severity of the heat shock. (2) Heat induced generation of O2- or H2O2 in excess of the ability of the antioxidant enzymes to remove these toxic species causes heat induced cell injury and cytotoxicity. This damage is caused by lipid peroxidation, leading to disruption of the cytoskeleton and calcium metabolism. (3) The flux of O2- and H2O2 generated by heat shock induces the synthesis of additional antioxidant enzymes. Other treatments which induce thermotolerance also cause oxidative stress and induce the antioxidant enzymes. The ability of various agents to modify heat induced cytotoxicity and development of thermotolerance is reviewed in light of this model.

Animals↗
PubMed1984

Myeloperoxidase reduces the opsonizing activity of immunoglobulin G and complement component C3b.

The effect of myeloperoxidase, hydrogen peroxide (H2O2) and a halide (Cl) on the opsonizing molecules in immunoglobulin G (IgG) and complement factor C3b was assayed. At concentrations of the enzyme (1 microgram/ml) that can be found in the extracellular fluid during inflammation, the myeloperoxidase-H2O2-Cl system inhibited the opsonizing effect of IgG and C3b measured as phagocytic uptake and superoxide generation. The effect was related to the enzymatic peroxidative activity of the protein. The presence of albumin (10 mg/ml) reduced the effect of myeloperoxidase with 10-20%. Taurine, which in the presence of myeloperoxidase-H2O2-Cl forms hydrophilic chloramines, and D-penicillamine, which scavenges HOCl, neutralize the inhibitory effect of myeloperoxidase. This suggests that either hypochlorous acid or lipophilic chloramines may exert its effect by oxidizing free sulphydryl groups exposed on the opsonizing ligands. Since the myeloperoxidase-H2O2-halide system also affects chemotactic factors, leukotrienes, proteinases and membrane receptors, the system may in several ways affect the development of the inflammatory response.

Complement C3b↗