Biomedical subjects

A Boveris

Publications and source records attributed to A Boveris.

At least 55 records · Page 3Linked to original sources

PubMed1995

Hydroxyl radical generation during mitochondrial electron transfer and the formation of 8-hydroxydesoxyguanosine in mitochondrial DNA.

Production of hydroxyl radicals (HO.) by substrate-supplemented beef heart submitochondrial particles was studied by electron paramagnetic resonance in conjunction with the spin trap 5,5'-dimethyl-1-pirroline-N-oxide (DMPO). Supplementation of submitochondrial particles with NADH or succinate in the presence of antimycin resulted in the formation hydroxyl-, alpha-hydroxyethyl-, and methyl radical adducts. The latter two adducts were derived from HO. attack of ethanol or dimethyl sulfoxide (DMSO), respectively, the solvents used for the inhibitors of the respiratory chain. These ESR signals were slightly increased by superoxide dismutase and abolished by catalase. Further support for the production of HO. during mitochondrial electron transfer was furnished by kinetic competition experiments with DMSO as the HO. scavenger. This approach yielded a kappa SCAVENGER/kappa DMPO value of 1.7, in agreement with a competitive spin trapping of free HO. using DMSO as a scavenger. The scission of H2O2 to HO. requires consideration of a Fenton chemistry, i.e., the participation of metals or redox active metal pools in mitochondria to drive this reaction. The effect of several metal chelators on the formation of both HO. and H2O2 was examined. Bathophenantroline, bathocuproine, and desferrioxamine decreased the DMPO-HO. signal and increased accumulation of H2O2. Conversely, EDTA or diethylenetriaminepentaacetic acid substantially increased the DMPO-HO. signal intensity and decreased H2O2 accumulation. These different results were rationalized in terms of the reduction potential of the redox couples involved, i.e., that of the ligated metal and those encompassed in the one-electron reduction of superoxide radical and of hydrogen peroxide. The formation of 8-hydroxydesoxyguanosine in mitochondrial DNA was examined under experimental conditions in which H2O2 production by isolated mitochondria was enhanced. The formation of 8-hydroxydesoxyguanosine increased with increasing rates of H2O2 formation. The biological significance of H2O2 and HO. formation during mitochondrial electron transfer is discussed in terms of oxidative damage of mitochondrial DNA and the implications for mitochondrial functions and aging.

8-Hydroxy-2'-Deoxyguanosine↗

PubMed1995

Lung damage in paraquat poisoning and hyperbaric oxygen exposure: superoxide-mediated inhibition of phospholipase A2.

Paraquat poisoning and hyperbaric oxygen exposure are well established models of oxidative stress in lung. The aim of this study was focused on the contribution of oxygen free radicals and other cytotoxic species, such as lipid hydroperoxides, to the overall toxicity. Adult Wistar rats were injected with paraquat (30 or 60 mg/kg b.w.) or exposed to hyperbaric oxygen (0.2 MPa), and several parameters of lung damage were measured. Both treatments resulted in increased spontaneous lung chemiluminescence, number of lung PMN, malondialdehyde content, lung edema, and pleural liquid. Of note, spontaneous lung chemiluminescence, used to monitor the steady-state concentration of oxygen free radicals in vivo, did not increase significantly after either treatment. The increase in spontaneous lung chemiluminescence started after PMN migration, being both maxima separated by a delay time of 4-6 h. After PMN migrated and became activated in the lung, the survival of the animals started to decline. Thus, PMN can be considered as additional sources of oxygen free radicals supported by the subsequent increase in chemiluminescence. Their role in lung damage was evidenced by the increase in lung edema, augmented pleural liquid, and decreased survival after PMN migration. Lipid hydroperoxide concentration in lung membranes was also increased after either treatment. This increased concentration may be a consequence of an increased rate of lipid peroxidation, initiated by oxidative stress on lipid membranes, or by an inhibition of their catabolism. Ester lipid hydroperoxides normally produced in membranes cannot be catabolized directly by the glutathione peroxidase-reductase system unless phospholipase A2 catalyses the release of free lipid hydroperoxides. In both experimental models, phospholipase A2 activity was decreased to almost negligible values. Betamethasone (1 mg/ml; IV) administered to the rats 3 h before paraquat injection accelerated the decrease in survival and phospholipase A2 inactivation. Inactivation of phospholipase A2, detected in paraquat or oxygen exposed rats, could be attributed to a O2(.-)-driven Fenton reaction. However, phospholipase A2 inactivation by betamethasone pretreatment may be attributed to the presence of lipocortin, a corticosteroid-inducible factor and inhibitor of phospholipase A2. Besides the mechanism underlying the inactivation of phospholipase A2, the increase in lipid hydroperoxides may indicate their role as long-lived cytotoxic species that contribute to the damage already initiated by oxidative stress. Indeed, lipid hydroperoxides are very well known modifiers of membrane physical properties.

Animals↗

PubMed1995

Oxidative stress by acute acetaminophen administration in mouse liver.

Acetaminophen was given to mice at a single dose of 375 mg/kg. In situ liver chemiluminescence, H2O2 steady-state concentration, and the liver concentrations of total and oxidized glutathione were measured 15, 30, and 60 min after acetaminophen administration. Increases of 145% and 72% in spontaneous chemiluminescence and H2O2 concentration were observed 15 min after the injection, respectively. Total glutathione was decreased by acetaminophen administration at all the times studied. The maximal decrease, 83%, was found 60 min postinjection. The ratio GSH/GSSG was found significantly decreased at all the times studied. Microsomal superoxide production was increased by 2.4-fold by addition of acetaminophen. The activities of the antioxidant enzymes superoxide dismutase, catalase, and glutathione peroxidase were determined. Catalase was slightly inhibited (30%) 15 min after acetaminophen administration. No significant changes were found in superoxide dismutase activity. Se and non-Se glutathione peroxidase activities were decreased by 40% and 53% respectively, 15 min after acetaminophen administration. The decrease in catalase and glutathione peroxidase would result in an increased steady state level of H2O2 and hydroperoxides, contributing to cell injury. Damaged hepatocytes were observed, and severe lesions and necrosis appeared 60 min after acetaminophen administration. Our results indicate the occurrence of oxidative stress as a possible mechanism for acetaminophen-induced hepatotoxicity.

Acetaminophen↗

PubMed1995

Isoproterenol-dependent decrease in oxygen uptake and respiratory enzyme activities in rat myocardial tissue and mitochondria.

OBJECTIVE: Myocardial damage induced by isoproterenol is believed to be secondary to increased oxygen demands on the heart. Our objective was to test an additional primary action of isoproterenol on tissue and mitochondrial oxidative metabolism and to compare these effects with the effects of other adrenergic agents in the presence of adrenergic inhibitors. DESIGN: Prospective, dose-response study. SETTING: Research laboratory at a university hospital. SUBJECTS: Fifty Sprague-Dawley female rats (200 to 350 g), slightly anesthetized with ether and divided into several groups. INTERVENTIONS: In 26 rats, the heart was removed, cut into fine slices (0.5-mm thickness), and placed in an ice-cold buffer. In 22 animals, the hearts were perfused in the Langendorff manner and chopped and processed for mitochondrial studies. MEASUREMENTS AND MAIN RESULTS: We determined the following: a) the direct "in vitro" effects of isoproterenol and related catecholamines on normal oxygen uptake using myocardial slices; b) rat heart oxygen consumption and mitochondrial oxygen uptake from isolated organs, perfused with isoproterenol; c) measurements of enzyme activities in submitochondrial particles from the same perfused hearts; and d) the direct effects of isoproterenol on normal mitochondria isolated from normal nonperfused hearts. The oxygen uptake was determined polarographically with a Clark-type electrode and enzymatic activities were assayed by spectrophotometric reduction of cytochrome c at 550 nm with different mitochondrial substrates. Isoproterenol (0.01 to 100 nM) decreased the oxygen uptake by the heart slices in a dose-dependent manner. In comparison, epinephrine or norepinephrine per se did not change the parameter. However, with the addition of alpha-adrenergic receptor inhibitors, oxygen uptake decreased to values similar to those values obtained with isoproterenol. Also, mitochondria isolated from hearts perfused with isoproterenol had decreased state 3 respiratory rates (by 50%) and decreased respiratory control ratios (by 30%), without changes in adenosine 5'-diphosphate/oxygen ratios. The respiratory chain enzyme activities were also lowered. CONCLUSIONS: The data suggest that while isoproterenol increases "in vivo" oxygen uptake by the working rat heart, isoproterenol can simultaneously decrease maximal adenosine 5'-diphosphate-induced mitochondrial oxygen uptake and in vitro myocardial tissue oxygen uptake, probably by modifying the mitochondrial respiratory enzymes. This action could be counteracted by alpha-adrenergic agonist effects.

Animals↗

PubMed1994

Kinetics of nitric oxide and hydrogen peroxide production and formation of peroxynitrite during the respiratory burst of human neutrophils.

Nitric oxide (.NO) release, oxygen uptake and hydrogen peroxide (H2O2) production elicited by increasing phorbol 12-myristate 13-acetate (PMA) concentrations were measured in human neutrophils. Half-maximal activities were sequentially elicited at about 0.0001-0.001 micrograms PMA/ml (.NO) and 0.001-0.01 micrograms PMA/ml (H2O2). At saturated PMA concentrations, .NO production, oxygen uptake and H2O2 release were 0.56 +/- 0.04, 3.32 +/- 0.52 and 1.19 +/- 0.17 nmol.min-1.10(6) cells-1. .NO production accounts for about 30% of the total oxygen uptake. Luminol-dependent chemiluminescence, reported to detect NO reactions in other inflammatory cells, was also half-maximally activated at about 0.001-0.01 micrograms PMA/ml. Preincubation with NG-monomethyl-L-arginine (L-NMMA) decreased O2 uptake and .NO release but increased H2O2 production, while superoxide dismutase (SOD) increased .NO detection by 30%. Chemiluminescence was also reduced by preincubation with L-NMMA and/or SOD. The results indicate that .NO release is part of the integrated response of stimulated human neutrophils and that, in these cells, kinetics of .NO and O2.- release favour the formation of other oxidants like peroxynitrite.

Humans↗

PubMed1994

Brain and liver lipid peroxidation levels following acute and short-term lindane administration in the rat.

Oxidative stress-related parameters in rat brain and liver were evaluated following acute (60 mg/kg i.p., 2 and 24 h after dosing) or short-term (1000 ppm in the diet for 90 days) lindane administration. Both treatments elicited a significant accumulation of lindane in brain and liver, with convulsions observed in short-term and 24-h lindane-treated rats. In these conditions, lindane exposure did not alter brain lipid peroxidation, assessed as thiobarbituric acid reactants formation and spontaneous chemiluminescence, parameters that were enhanced in the liver. The activities of antioxidant enzymes in the brain (superoxide dismutase, catalase, glutathione peroxidase, glutathione reductase and glucose 6-phosphate dehydrogenase) were not modified by acute lindane treatment, while brain glutathione content was significantly reduced by 13%. It is concluded that lindane does not alter the oxidative stress status of the brain as occurs in liver, regardless of the time of exposure of rats to either acute or short-term administration of the insecticide.

Animals↗

PubMed1994

Oxidative stress in muscle and liver of rats with septic syndrome.

Sepsis, as infection associated to systemic manifestations, was produced in rats by cecal ligation and double perforation. Sham-operated rats were used as controls. The spontaneous chemiluminescence of rat adductor muscle and liver were measured at 6, 12, 24, and 30 h after the surgical procedure. Muscle chemiluminescence showed a maximal increase of about twofold (control emission 10 +/- 1 cps/cm2) after 6-12 h of sepsis, while liver chemiluminescence increased by about 80% (control emission: 11 +/- 1 cps/cm2) after 24 h of sepsis. The activities of muscle antioxidant enzymes were found maximally diminished after 12 h of sepsis: 46% decrease for Mn-superoxide dismutase, 83% decrease for catalase, and 55% decrease for glutathione peroxidase. In liver, only catalase activity showed a 52% decrease after 24 h of sepsis. State 3 oxygen uptake of muscle mitochondria with either malate-glutamate or succinate as substrates was 40% decreased after 12 h of sepsis in both cases. State 4 oxygen uptake of muscle mitochondria was not affected. The rate of H2O2 production of muscle mitochondria after 12 h of sepsis with either malate-glutamate or succinate as substrates was increased about 2.5 times but was not affected when assayed in the presence of as rotenone and antimycin. The oxygen uptake of liver mitochondria isolated from septic rats did not show differences as compared with those of control rats after 6 to 24 h of sepsis. Oxidative stress appears to occur in skeletal muscle early at the onset of the septic syndrome, with inhibition of active mitochondrial respiration and inactivation of antioxidant enzymes.(ABSTRACT TRUNCATED AT 250 WORDS)

Analysis of Variance↗

PubMed1994

Gill diffusion as a physiological mechanism for hydrogen peroxide elimination by fish.

Hydrogen peroxide is metabolized by the specific enzymatic action of catalase and glutathione peroxidase in animal tissues. The relatively low catalase and glutathione peroxidase activities found in the blood of fish may be related to the ability of gills to eliminate hydrogen peroxide into the aquatic environment. Poecilia vellifera releases hydrogen peroxide apparently by gill diffusion into the environment, resulting in a steady-state H2O2 concentration of about 0.6 microM in the surrounding water. This physiological mechanism resembles ammonia excretion by teleost fish.

Animals↗

PubMed1994

Liver oxygen uptake dependence and mitochondrial function in septic rats.

Defective oxygen consumption and a pathological dependence of oxygen uptake on O2 supply have been considered important events in sepsis. To relate these features with tissue and mitochondrial metabolism, we studied oxygen uptake in whole isolated and perfused rat liver at two O2 supply levels, in the same liver slices, and in isolated liver mitochondria. Experimental sepsis in rats was induced by cecal ligation and double-gauge puncture. The results showed that liver and tissue slices from septic animals had a 60% greater O2 uptake than that of controls and that, during sepsis, liver O2 uptake was markedly dependent on O2 supply. Concomitantly, mitochondrial O2 uptake was nearly 30% greater with malate-glutamate as substrate, but not with succinate; lowering O2 concentration in the medium did not alter the enhanced function. In submitochondrial, only NADH-dehydrogenase activity was 100% higher in septic samples. At least, in some tissues, O2 dependence is a function of O2 availability, sensitized by increased mitochondrial O2 uptake related to changes in respiratory enzymes.

Adenosine Diphosphate↗

PubMed1993

Hydrogen peroxide metabolism and oxidative stress in cortical, medullary and papillary zones of rat kidney.

The cortical, medullary and papillary regions of rat kidney were evaluated for a series of parameters related to hydrogen peroxide metabolism and oxidative stress. The rates of oxygen uptake, prostaglandin synthesis and malondialdehyde production by kidney slices were: 47, 0.003 and 0.051 mumol/h g wet wt., respectively, in cortex, 32, 0.023 and 0.035 in medulla and 22, 0.034 and 0.007 in papilla. The activities of superoxide dismutase, catalase and glutathione peroxidase were: 144 +/- 16 U/g wet wt., 880 +/- 100 pmol/g wet wt. and 177 +/- 16 U/g wet wt. in cortex; 97 +/- 9 U/g wet wt., 550 +/- 50 pmol/g wet wt. and 142 +/- 18 U/g wet wt. in medulla; and 23 +/- 2 U/g wet wt., 90 +/- 9 pmol/g wet wt. and 147 +/- 5 U/g wet wt. in papilla. Hydrogen peroxide steady-state concentrations were 0.09 +/- 0.01, 0.07 +/- 0.01 and 0.08 +/- 0.01 microM whereas alpha-tocopherol content was 21 +/- 2, 23 +/- 1 and 34 +/- 3 mumol/g wet wt. and hydroperoxide-initiated chemiluminescence was 22 +/- 2, 33 +/- 2 and 14 +/- 1 cpm. 10(-3)/mg prot for cortex, medulla and papilla, respectively. After 60 min ischemia-30 min reperfusion hydroperoxide-initiated chemiluminescence and hydrogen peroxide steady-state concentration increased by 30% and 60% in cortex and 80% and 60% in medulla, whereas alpha-tocopherol content decreased by 30%, 50% and 2% in cortex, medulla and papilla, respectively. The reperfusion/control ratio of hydroperoxide-initiated chemiluminescence and hydrogen peroxide steady-state concentrations in cortex and medulla indicate the occurrence of oxidative stress after ischemia-reperfusion. The lower sensitivity to oxidative stress found in papilla could be explained by the relatively high relationship of alpha-tocopherol content to hydrogen peroxide production rate in this sub-organ.

Animals↗

PubMed1993

Oxidative stress produced by suprahepatic occlusion and reperfusion.

In this article the spontaneous chemiluminescence and the steady-state concentration of hydrogen peroxide were determined in rat liver as indicators of oxidative stress in the tissue. Hydroperoxide-initiated chemiluminescence and the activity of antioxidant enzymes (catalase, superoxide dismutase and glutathione peroxidase) were also measured to evaluate antioxidant defenses and serum activity of lactate dehydrogenase and aspartate aminotransferase. Mitochondrial morphology and mitochondrial respiratory control ratio were measured as indicators of cell and mitochondrial damage. Xanthine dehydrogenase and xanthine oxidase activities were determined as a possible source of oxyradicals. No significant changes were observed after 10 or 30 min of vena cava occlusion in any of the measured parameters. In contrast, 10 min of occlusion followed by 10 min of reperfusion increased chemiluminescence (from 18 +/- 3 to 32 +/- 5 cps/cm2), hydrogen peroxide (from 0.10 +/- 0.01 to 0.17 +/- 0.01 mumol/L), lactate dehydrogenase (from 80 +/- 2 to 330 +/- 30 U/L), and aspartate aminotransferase (from 42 +/- 2 to 100 +/- 10 U/L). Liver reperfusion was also associated with mitochondrial swelling and decreased mitochondrial respiratory control (from 5.6 +/- 0.3 to 2.6 +/- 0.1). The activity of the antioxidant enzymes and xanthine oxidase was instead without change. After 30 min of vena cava occlusion and 10 min of reperfusion a more marked increase in chemiluminescence (37 +/- 5 cps/cm2), hydrogen peroxide (0.30 +/- 0.01 mumol/L), lactate dehydrogenase (730 +/- 10 U/L) and aspartate aminotransferase (140 +/- 10 U/L) was observed. No further changes were found in either mitochondrial morphology or respiratory control (2.4 +/- 0.1) in isolated mitochondria.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1993

Induction of antioxidant enzymes and DT-diaphorase in human blood mononuclear cells by light stress.

Human blood mononuclear cells exposed to visible light increase their antioxidant enzyme (superoxide dismutase, catalase, and glutathione peroxidase) and DT-diaphorase activities. The activities of CuZn-superoxide dismutase (3.70 +/- 0.25 U/mg protein), catalase (4.60 +/- 0.39 U/mg protein), and DT-diaphorase (1.40 +/- 0.11 mumol DCPIP/min.mg protein) increased 1.5-fold when mononuclear cells were exposed at 38 W/m2 for 4 h. Se-containing glutathione peroxidase activity (6.76 +/- 0.21 mU/mg protein) increased 1.3 times after 3 h of exposure to 38 W/m2. Conversely, Mn-superoxide dismutase (2.20 +/- 0.20 U/mg protein), succinate dehydrogenase (0.86 +/- 0.04 mumol DCPIP/min.mg protein), and cytochrome oxidase (0.54 +/- 0.04 min-1 (k')/mg protein) activities remained constant during this period of exposure. The treatment of cells with cycloheximide prevented the response triggered by light exposure. These results introduce new insight to the adaptive response of human cells to light stress suggesting that: (a) the response observed might be ascribed to synthesis of stress proteins rather than to activation of a preexisting pool, and (b) that DT-diaphorase and CuZn-superoxide dismutase may operate biologically in a concerted fashion resulting in antioxidant activity.

Adult↗

PubMed1993

Cellular stress by light and rose bengal in human lymphocytes.

Human lymphocyte cultures were supplemented with 10(-8)-10(-4) M Rose Bengal and irradiated with fluorescent light (Philips 40-W daylight-fluorescent lamp, 380-550 nm) and chromosomal aberrations and catalase and superoxide dismutase activities in the cells were determined. Chromosomal lesions and both enzymatic activities increased additively or synergistically in human lymphocytes after Rose Bengal supplementation and fluorescent light irradiation. Chromosomal lesions (expressed as chromosomal aberrations/cells) were (a) 0.12 +/- 0.03, (b) 0.18 +/- 0.12, (c) 1.58 +/- 0.11 and (d) 3.20 +/- 0.17 in the following conditions: (a) control; (b) after 3 h light irradiation, (c) supplemented with 10(-5) M Rose Bengal and (d) with dye treatment and light irradiation. Superoxide dismutase activity was: (a) 16.5 +/- 1.5; (b) 19.5 +/- 1.2; (c) 29.2 +/- 1.5 and (d) 35.4 +/- 2.1 U/mg protein and catalase activity was: (a) 10.3 +/- 0.5, (b) 12.8 +/- 0.7, (c) 22.4 +/- 0.5 and (d) 27.6 +/- 1.1 U/mg protein in the same experimental conditions. These findings suggest that Rose Bengal supplementation plus fluorescent light irradiation of human lymphocytes lead to the synthesis of superoxide dismutase and catalase in a manner similar to the heat-shock response. A threshold of chromosomal damage (about 2 chromosomal aberrations/cell) is apparently required to activate oxidative stress genes.

Adult↗

PubMed1993

Active oxygen species in the liver of rats submitted to chronic hypobaric hypoxia.

The spontaneous in situ liver chemiluminescence of female rats submitted to 4,400 m (simulated altitude) for 2 mo and of their corresponding controls at sea level was determined as an approach to the measurement of the intracellular steady-state concentrations of singlet oxygen and oxygen free radicals. Spontaneous liver chemiluminescence was decreased by approximately 40% in hypoxic rats, whereas CCl4-induced chemiluminescence was unchanged. Liver mitochondria isolated from hypoxic rats showed a 53% decreased rate of H2O2 production and an increased content of cytochrome b (36%), with normal content of cytochromes c1, c, and a-a3. Superoxide dismutase showed a 26% decrease in activity, whereas catalase and glutathione peroxidase activities were not significantly decreased by this extent of hypoxia. Cytochrome P-450 and glutathione contents were unchanged. There were no significant differences in the hydroperoxide-initiated chemiluminescence (an estimation of tissue chain-breaker antioxidants) of homogenates, mitochondria, and microsomes. Results suggest that in chronic hypoxia there is a lower rate of generation of active oxygen species in liver, leading to a decreased steady-state concentration of singlet oxygen.

Altitude↗

PubMed1993

Time course and mechanism of oxidative stress and tissue damage in rat liver subjected to in vivo ischemia-reperfusion.

The time course of oxidative stress and tissue damage in zonal liver ischemia-reperfusion in rat liver in vivo was evaluated. After 180 min of ischemia, surface chemiluminescence decreased to zero, state 3 mitochondrial respiration decreased by 70-80%, and xanthine oxidase activity increased by 26% without change in the water content and in the activities of superoxide dismutase, catalase, and glutathione peroxidase. After reperfusion, marked increases in oxyradical production and tissue damage were detected. Mitochondrial oxygen uptake in state 3 and respiratory control as well as the activities of superoxide dismutase, catalase, and glutathione peroxidase and the level of nonenzymatic antioxidants (evaluated by the hydroperoxide-initiated chemiluminescence) were decreased. The severity of the post-reperfusion changes correlated with the time of ischemia. Morphologically, hepatocytes appeared swollen with zonal cord disarrangement which ranged from mild to severe for the tissue reperfused after 60-180 min of ischemia. Neutrophil infiltration was observed after 180 min of ischemia and 30 min of reperfusion. Mitochondria appear as the major source of hydrogen peroxide in control and in reperfused liver, as indicated by the almost complete inhibition of hydrogen peroxide production exerted by the uncoupler carbonylcyanide p-(trifluoromethoxy) phenylhydrazone. Additionally, inhibition of mitochondrial electron transfer by antimycin in liver slices reproduced the inhibition of state 3 mitochondrial respiration and the increase in hydrogen peroxide steady-state concentration found in reperfused liver. Increased rates of oxyradical production by inhibited mitochondria appear as the initial cause of oxidative stress and liver damage during early reperfusion in rat liver.

Animals↗

PubMed1992

Reduction of reperfusion injury with preoperative rapid intravenous infusion of taurine during myocardial revascularization.

To assess a possible free-radical scavenging action of taurine during coronary artery bypass grafting, 12 patients were randomly divided into two equal groups. One to 3 hours before surgery, they received a rapid intravenous infusion of either placebo (group 1) or taurine (5 gm) (group 2). During surgery, biopsy samples were taken before ischemia (preischemic samples) and after 10 minutes of reperfusion (reperfusion samples). Lipoperoxidation was determined by hydroperoxide-initiated chemiluminescence of heart homogenates, and myocardial cell damage was assessed by electron microscopy. The values for chemiluminescence in preischemic and reperfusion samples from group 1 were 7500 +/- 1600 and 18,600 +/- 4600 cpm/mg of protein, respectively (p less than 0.03). This difference was not observed in group 2 where the values were 10,050 +/- 2700 and 11,800 +/- 4200 cpm/mg of protein, for preischemic and reperfusion samples, respectively. The number of severely damaged mitochondria (grades 3 and 4) in reperfusion samples from group 1 increased significantly compared to preischemic samples (25 +/- 8% vs 12 +/- 3%, p less than 0.01). Conversely no differences were observed between the number of severely damaged mitochondria in reperfusion and preischemic samples from group 2 (8 +/- 3% vs 8 +/- 2%). The number of damaged and necrotic myocytes increased in group 1 after reperfusion from 22 +/- 9% to 34 +/- 10% (p less than 0.03) and from 10 +/- 7% to 26 +/- 20% (p = NS), respectively. No changes were observed between reperfusion and preischemic samples in group 2. Treatment with taurine seems to reduce lipoperoxidation and decrease cell damage at the time of reperfusion.

Biopsy↗

PubMed1992

Reduction of myocardial damage by cloricromene during ischemia-reperfusion in the rabbit.

We studied the effect of cloricromene on myocardial damage during ischemia and reperfusion. The left anterior descending coronary artery was occluded in 20 rabbits and cloricromene (6.2 micrograms/kg/min) (n = 10) or placebo (n = 10) were continuously infused. After 10 minutes of occlusion, a first biopsy was obtained from the apex. After 30 minutes, the artery was reopened and after 10 minutes a second biopsy was taken. Both samples were used for chemiluminescence and electron microscopy. The group given placebo showed displacement of the ST segment throughout the ischemic period and arrhythmias during reperfusion; while, in the group given cloricromene, there were transient ST segment elevations in 5 animals, which reverted as the infusion was increased. The chemiluminescence values were 7100 +/- 1300 cpm/mg protein and 14900 +/- 2300 (p less than 0.01) for the first and second biopsies of the control group and 5900 +/- 900 and 6100 +/- 900 (NS) for the first and second biopsies of the cloricromene-treated group. In the group given placebo, the second biopsy showed early signs of irreversible myocyte injury and infarction, whereas samples from the group given cloricromene showed a preservation of myocyte architecture. During ischemia, the percentage of normal mitochondria was lower in the placebo group (p less than 0.0001); and, on reperfusion, the percentage of severely damaged mitochondria was increased in the placebo group (p less than 0.0001). The direct addition of cloricromene in vitro to myocardial homogenates did not reduce hydroperoxide-induced chemiluminescence.

Animals↗

PubMed1991

Superoxide anion and hydrogen peroxide metabolism in soybean embryonic axes during germination.

The total rate of mitochondrial O2- production in the presence of NADH as substrate increased from 200 to 1340 pmol/min per axis between 2 and 30 h of imbibition. The activities of the enzymes involved in hydroperoxide metabolism, e.g., superoxide dismutase, catalase, peroxidase and glutathione and ascorbate peroxidases, markedly changed during the germination of soybean embryonic axes. Superoxide dismutase was the enzymatic activity affected the most during the initial stages of germination. Intracellular O2- steady-state concentration, calculated from the rate of O2- production and superoxide dismutase activity, showed a 2-fold increase from 2 x 10(-8) M to 4 x 10(-8) M in germination phase I, declined in phase II to 2 x 10(-8) M and remained constant over the rest of the incubation period. The reaction of H2O2 and luminol catalyzed by Co2+ was utilized to measure H2O2 diffused out of the soybean axes after 5 to 10 min of incubation. The catalase-sensitive luminol emission of diffusates prepared from axes previously imbibed from 2 to 30 h corresponded to a H2O2 intracellular steady-state concentration in the range of 0.3 to 0.9 microM. The activity of metal-containing antioxidant enzymes was determined in the extracellular fluid. Cell wall peroxidase activity increased from 10 to 300 mumol/min per mg protein and appears as a potentially important pathway for H2O2 utilization. Hydrogen peroxide metabolism in soybean embryonic axes during early inhibition appears to have the following main features: (a) mitochondrial membranes are the most important source of cytosolic O2- and H2O2; (b) H2O2 is regulated at a steady-state concentration of 0.3-0.9 microM; (c) catalase is the main enzyme in terms of H2O2 utilization; (d) H2O2 exo-diffusion is quantitatively important destiny of intracellular H2O2; and (e) extracellular peroxidase located at the cell wall affords an enzymatic system able to use diffused H2O2.

Catalase↗