101
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May JM, Qu ZC, Cobb CE. Human erythrocyte recycling of ascorbic acid: relative contributions from the ascorbate free radical and dehydroascorbic acid. J Biol Chem 2004; 279:14975-82. [PMID: 14752116 DOI: 10.1074/jbc.m312548200] [Citation(s) in RCA: 70] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Recycling of ascorbic acid from its oxidized forms helps to maintain the vitamin in human erythrocytes. To determine the relative contributions of recycling from the ascorbate radical and dehydroascorbic acid, we studied erythrocytes exposed to a trans-membrane oxidant stress from ferricyanide. Ferricyanide was used both to induce oxidant stress across the cell membrane and to quantify ascorbate recycling. Erythrocytes reduced ferricyanide with generation of intracellular ascorbate radical, the concentrations of which saturated with increasing intracellular ascorbate and which were sustained over time in cells incubated with glucose. Ferricyanide also generated dehydroascorbic acid that accumulated in the cells and incubation medium to concentrations much higher than those of the radical, especially in the absence of glucose. Ferricyanide-stimulated ascorbate recycling from dehydroascorbic acid depended on intracellular GSH but was well maintained at the expense of intracellular ascorbate when GSH was severely depleted by diethylmaleate. This likely reflects continued radical reduction, which is not dependent on GSH. Erythrocyte hemolysates showed both NAD- and NADPH-dependent ascorbate radical reduction. The latter was partially due to thioredoxin reductase. GSH-dependent dehydroascorbate reduction in hemolysates, which was both direct and enzyme-dependent, was greater than that of the radical reductase activity but of lower apparent affinity. Together, these results suggest an efficient two-tiered system in which high affinity reduction of the ascorbate radical is sufficient to remove low concentrations of the radical that might be encountered by cells not under oxidant stress, with back-up by a high capacity system for reducing dehydroascorbate under conditions of more severe oxidant stress.
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Affiliation(s)
- James M May
- Department of Medicine and Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, Tennessee 37232-6303, USA.
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102
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Abstract
The reactivity of the hydroperoxyl radical with coenzyme Q, as a prototypical chemical reaction involved in biological antioxidant actions, was studied theoretically. Two pathways were analyzed: the hydrogen abstraction reaction from the phenolic hydrogen on the reduced form (ubiquinol), and OOH addition on the oxidized form (ubiquinone). Optimized geometries, harmonic vibrational frequencies, and energies of the stationary points (reactants, intermediate complexes, transition states, and products) for each pathway were calculated at the BHandHLYP/6-31G level of theory. The reaction paths for the two mechanisms were traced independently, and the respective thermal rate constants were calculated using variational transition-state theory with multidimensional small-curvature tunneling. We found that the reactivity of the OOH radical is dominated by the hydrogen abstraction mechanism on ubiquinol, with a rate constant of 5.32 x 10(5) M(-1) s(-1), at 298 K. This result strongly contrasts with that, also obtained by our group, for the more reactive OH radical, which attacks ubiquinone by an addition mechanism, with a diffusion-controlled rate of 6.25 x 10(10) M(-1) s(-1), at 298 K.
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Affiliation(s)
- Joaquín Espinosa-García
- Departamento de Química Física, Facultad de Ciencias, Universidad de Extremadura, 06071 Badajoz, Spain.
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103
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Juhasz JR, Pisterzi LF, Gasparro DM, Almeida DR, Csizmadia IG. The effects of conformation on the acidity of ascorbic acid: a density functional study. ACTA ACUST UNITED AC 2003. [DOI: 10.1016/j.theochem.2003.08.042] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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104
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Espinosa-García J, Gutiérrez-Merino C. The Trapping of the OH Radical by Coenzyme Q. A Theoretical and Experimental Study. J Phys Chem A 2003. [DOI: 10.1021/jp035927a] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Affiliation(s)
- J. Espinosa-García
- Dept. de Química Física, and Dept. de Bioquímica y Biología Molecular y Genética, Facultad de Ciencias, Universidad de Extremadura, 06071 Badajoz (Spain)
| | - C. Gutiérrez-Merino
- Dept. de Química Física, and Dept. de Bioquímica y Biología Molecular y Genética, Facultad de Ciencias, Universidad de Extremadura, 06071 Badajoz (Spain)
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105
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Pepperell JR, Porterfield DM, Keefe DL, Behrman HR, Smith PJS. Control of ascorbic acid efflux in rat luteal cells: role of intracellular calcium and oxygen radicals. Am J Physiol Cell Physiol 2003; 285:C642-51. [PMID: 12724141 DOI: 10.1152/ajpcell.00587.2002] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
In luteal cells, prostaglandin (PG)F2a mobilizes intracellular calcium concentration ([Ca]i), generates reactive oxygen species (ROS), depletes ascorbic acid (AA) levels, inhibits steroidogenesis, and ultimately induces cell death. We investigated the hypothesis that [Ca]i mobilization stimulates ROS, which results in depletion of cellular AA in rat luteal cells. We used a self-referencing AA-selective electrode that noninvasively measures AA flux at the extended boundary layer of single cells and fluorescence microscopy with fura 2 and dichlorofluorescein diacetate (DCF-DA) to measure [Ca]i and ROS, respectively. Menadione, a generator of intracellular superoxide radical (O2-), PGF2a, and calcium ionophore were shown to increase [Ca]i and stimulate intracellular ROS. With calcium ionophore and PGF2a, but not menadione, the generation of ROS was dependent on extracellular calcium influx. In unstimulated cells there was a net efflux of AA of 121.5 +/- 20.3 fmol x cm-1 x s-1 (mean +/- SE, n = 8), but in the absence of extracellular calcium the efflux was significantly reduced (10.3 +/- 4.9 fmol x cm-1 x s-1; n = 5, P < 0.05). PGF2a and menadione stimulated AA efflux, but calcium ionophore had no significant effect. These data suggest two AA regulatory mechanisms: Under basal conditions, AA efflux is calcium dependent and may represent recycling and maintenance of an antioxidant AA gradient at the plasma membrane. Under luteolytic hormone and/or oxidative stress, AA efflux is stimulated that is independent of extracellular calcium influx or generation of ROS. Although site-specific mobilization of calcium pools and ROS cannot be ruled out, the release of AA by PGF2a-stimulated luteal cells may occur through other signaling pathways.
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Affiliation(s)
- John R Pepperell
- Department of Obstetrics and Gynecology, Women and Infants Hospital of Rhode Island, 101 Dudley St., Providence, RI 02905, USA.
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106
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Aime S, Digilio G, Bruno E, Mainero V, Baroni S, Fasano M. Modulation of the antioxidant activity of HO* scavengers by albumin binding: a 19F-NMR study. Biochem Biophys Res Commun 2003; 307:962-6. [PMID: 12878205 DOI: 10.1016/s0006-291x(03)01307-x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
The interaction between different HO(z.rad;) radical scavengers in a three-component antioxidant system has been investigated by means of 19F-NMR spectroscopy. This system is composed of bovine serum albumin (BSA), trolox, and N-(4-hydroxyphenyl)-trifluoroacetamide (CF(3)PAF). The antioxidant capacity of BSA and trolox has been assessed by measuring the amount of trifluoroacetamide (TFAM) arising from the radical mediated decomposition of CF(3)PAF. When assayed separately, both trolox and BSA behaved as antioxidants, as they were effective to protect CF(3)PAF from HO* radical-mediated decomposition. By contrast, trolox enhanced the production of TFAM in the presence of BSA, thus behaving as a pro-oxidant. Urate, carnosine, glucose, and propylgallate showed antioxidant properties both with or without BSA. CF(3)PAF and trolox were found to bind to BSA with association constants in the order of 5 x 10(3)M(-1) and to compete for the same binding sites. These results have been discussed in terms of BSA-catalysed cross-reactions between trolox-derived secondary radicals and CF(3)PAF.
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Affiliation(s)
- Silvio Aime
- Department of Chemistry I.F.M., University of Torino, Via Pietro Giuria 7, Turin I-10125, Italy
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107
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Chen WT, Lin YF, Yu FC, Kao WY, Huang WH, Yan HC. Effect of ascorbic acid administration in hemodialysis patients on in vitro oxidative stress parameters: influence of serum ferritin levels. Am J Kidney Dis 2003; 42:158-66. [PMID: 12830468 DOI: 10.1016/s0272-6386(03)00419-0] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
BACKGROUND Ascorbic acid supplementation has been recommended to circumvent resistance to erythropoietin, which sometimes occurs in iron-overloaded uremic patients. In considering the pro-oxidant effect of ascorbic acid, the authors hypothesize that adjuvant therapy with larger doses of ascorbic acid in hemodialysis patients with iron overload may raise the risk of increasing free radical generation. The oxidative stress of intravenous ascorbic acid supplementation in hemodialysis patients was evaluated in this study. METHODS Six healthy subjects and 29 hemodialysis patients were enrolled. Chemical scavenging activity of various compounds was measured by in vitro 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay. Free radical generation was determined in vitro by lucigenin-enhanced chemiluminescence (LucCL) assay on blood samples. Blood biochemistries were also measured simultaneously in hemodialysis patients 1 minute before and 5 minutes later in the presence or absence of intravenous injection of 300 mg ascorbic acid. RESULTS Ascorbic acid presented a strong antioxidant effect in DPPH chemical reaction. On the contrary, it exerted pro-oxidant effect when mixed with plasma or whole blood of healthy subjects and hemodialysis patients. The pro-oxidant effect of ascorbic acid detected by LucCL was attenuated by various iron chelators and superoxide dismutase. In hemodialysis patients, the changes of LucCL intensity were significantly higher in the ascorbic acid-treated group than those in the control group (1261.0 +/- 401.9 v 77.4 +/- 62.5 relative light unit [RLU]; P < 0.05). Adjuvant ascorbic acid therapy resulted in significantly higher LucCL intensity in hemodialysis patients with ferritin > or =600 ng/mL (1,348.2 pmol/L) than those with ferritin less than 600 ng/mL (2,296.0 +/- 763.8 v 414.3 +/- 88.0 RLU; P<0.05). The changes of LucCL intensity were positively correlated with serum ferritin level (R2=0.8673; P<0.05). However, there was no significant correlation between the responses of LucCL intensity to ascorbic acid administration and transferrin saturation (R2=0.195; P=0.0665). CONCLUSION Persons with excess ascorbic acid supplement in the blood or plasma generate iron-chelator-suppressible chemiluminescents suggestive of free radical formation. Whether the findings occur in vivo or that the free radicals generated in vitro lead to toxicity in patients is not known from this study. These results suggest that either lower parenteral dose or lower infusion rate of ascorbic acid may be more appropriate for adjuvant therapy in iron-overloaded uremic patients.
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Affiliation(s)
- Wei-Teing Chen
- Graduate Institute of Medical Sciences, National Defense Medical Center, Taipei, Taiwan, ROC, China
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108
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Willis MS, Wians FH. The role of nutrition in preventing prostate cancer: a review of the proposed mechanism of action of various dietary substances. Clin Chim Acta 2003; 330:57-83. [PMID: 12636926 DOI: 10.1016/s0009-8981(03)00048-2] [Citation(s) in RCA: 111] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
BACKGROUND Dietary modifications to prevent prostate cancer (PCa) continue to gain attention as research demonstrates that various dietary nutrients/supplements are related to decreased risk of developing prostate cancer (PCa). Several studies have focused on the antioxidant and nonantioxidant effects of various dietary substances in the prevention of PCa. Research into the mechanisms by which PCa is prevented, or its disease severity is reduced by dietary micronutrients and vitamins continues to enrich our understanding of the mechanisms by which PCa is initiated and progresses. METHODS We reviewed the literature on dietary nutrients with antioxidant properties that have been shown to have a positive effect in reducing the incidence or preventing the occurrence of PCa including carotenoids (e.g., lycopene), retinoids (e.g., vitamin A), vitamin E, vitamin C, selenium, and polyphenols. Other nutrients examined included vitamin D and calcium. RESULTS Many dietary micronutrients have demonstrated significant and complex effects on PCa cell proliferation, differentiation, and signaling related to the initiation, progression, and regression of PCa. CONCLUSION Understanding the mechanisms by which various dietary nutrients exert their effects on PCa may make it possible to design effective drugs for treating PCa and to promote better nutrition and lifestyle changes in those at risk for PCa.
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Affiliation(s)
- Monte S Willis
- Department of Pathology, The University of Texas Southwestern Medical Center, Dallas, USA.
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109
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Maulén NP, Henríquez EA, Kempe S, Cárcamo JG, Schmid-Kotsas A, Bachem M, Grünert A, Bustamante ME, Nualart F, Vera JC. Up-regulation and polarized expression of the sodium-ascorbic acid transporter SVCT1 in post-confluent differentiated CaCo-2 cells. J Biol Chem 2003; 278:9035-41. [PMID: 12381735 DOI: 10.1074/jbc.m205119200] [Citation(s) in RCA: 94] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Human cells acquire vitamin C using two different transporter systems, the sodium-ascorbic acid co-transporters with specificity for ascorbic acid, and the facilitative glucose transporters with specificity for dehydroascorbic acid. There is no information on the mechanism of vitamin C transport across the intestinal barrier, a step that determines the bioavailability of vitamin C in humans. We used the colon carcinoma cell line CaCo-2 as an in vitro model for vitamin C transport in enterocyte-like cells. The results of transport kinetics, sodium dependence, inhibition studies, and reverse transcriptase-PCR analysis indicated that CaCo-2 cells express the sodium-ascorbate co-transporters SVCT1 and SVCT2, the dehydroascorbic acid transporters GLUT1 and GLUT3, and a third dehydroascorbic acid transporter with properties expected for GLUT2. Analysis by real time quantitative PCR revealed that the post-confluent differentiation of CaCo-2 cells was accompanied by a marked increase (4-fold) in the steady-state level of SVCT1 mRNA, without changes in SVCT2 mRNA levels. Functional studies revealed that the differentiated cells expressed only one functional ascorbic acid transporter having properties expected for SVCT1, and transported ascorbic acid with a V(max) that was increased at least 2-fold compared with pre-confluent cells. Moreover, post-confluent Caco-2 cells growing as monolayers in permeable filter inserts showed selective sorting of SVCT1 to the apical membrane compartment, without functional evidence for the expression of SVCT2. The identification of SVCT1 as the transporter that allows vectorial uptake of ascorbic acid in differentiated CaCo-2 cells has a direct impact on our understanding of the mechanism for vitamin C transport across the intestinal barrier.
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Affiliation(s)
- Nancy P Maulén
- Departamento de Fisiopatologia, Facultad de Ciencias Biológicas, Universidad de Concepción, Barrio Universitario S/N, Concepción, Chile
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110
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Luo J, Li N, Robinson JP, Shi R. The increase of reactive oxygen species and their inhibition in an isolated guinea pig spinal cord compression model. Spinal Cord 2002; 40:656-65. [PMID: 12483500 DOI: 10.1038/sj.sc.3101363] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
STUDY DESIGN In vitro studies using isolated guinea pig spinal cord. OBJECTIVES To develop an alternative model using isolated guinea pig spinal cord, which can be used to screen antioxidants for in vivo SCI treatment. SETTING Department of Basic Medical Sciences, Purdue University, West Lafayette, Indiana, USA. METHODS The compression injury was induced by a constant-displacement of 5-s compression of spinal cord using a modified forceps possessing a spacer. Reactive oxygen species (ROS) were evaluated using three distinct methods: fluorescence microscopy, lipid peroxidation assay, and flow cytometry. RESULTS The injury-mediated ROS increases are comparable with other in vivo studies and consistent with our previous observation using a similar injury model and measured with electrophysiological and anatomical technique. Further, ascorbic acid, hypothermia, or the combination of both significantly suppressed superoxide and lipid peroxidation. The combination treatment was the most effective when compared with ascorbic acid or hypothermia alone. CONCLUSION This in vitro model has the advantage of replicating some of the in vivo conditions while gaining the ability to control the experimental conditions. This in vitro model is suitable to study the mechanisms of ROS generation and degradation and can also be used to critically evaluate the effective suppressor of ROS in the contents of spinal cord traumatic injury.
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Affiliation(s)
- J Luo
- Center for Paralysis Research, Department of Basic Medical Sciences, School of Veterinary Medicine, Purdue University, West Lafayette, Indiana 47907, USA
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111
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Wright MV, Kuhn TB. CNS neurons express two distinct plasma membrane electron transport systems implicated in neuronal viability. J Neurochem 2002; 83:655-64. [PMID: 12390527 DOI: 10.1046/j.1471-4159.2002.01176.x] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Trans-plasma membrane electron transport is critical for maintaining cellular redox balance and viability, yet few, if any, investigations have studied it in intact primary neurons. In this investigation, extracellular reduction of 2,6-dichloroindophenol (DCIP) and ferricyanide (FeCN) were measured as indicators of trans-plasma membrane electron transport by chick forebrain neurons. Neurons readily reduced DCIP, but not FeCN unless CoQ(1), an exogenous ubiquinone analog, was added to the assays. CoQ(1) stimulated FeCN reduction in a dose-dependent manner but had no effect on DCIP reduction. Reduction of both substrates was totally inhibited by epsilon-maleimidocaproic acid (MCA), a membrane-impermeant thiol reagent, and slightly inhibited by superoxide dismutase. Diphenylene iodonium, a flavoenzyme inhibitor, completely inhibited FeCN reduction but had no affect on DCIP reduction, suggesting that these substrates are reduced by distinct redox pathways. The relationship between plasma membrane electron transport and neuronal viability was tested using the inhibitors MCA and capsaicin. MCA caused a dose-dependent decline in neuronal viability that closely paralleled its inhibition of both reductase activities. Similarly capsaicin, a NADH oxidase inhibitor, induced a rapid decline in neuronal viability. These results suggest that trans-plasma membrane electron transport helps maintain a stable redox environment required for neuronal viability.
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Affiliation(s)
- M V Wright
- Institute of Arctic Biology, University of Alaska, Fairbanks, Alaska, USA
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112
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Martín-Romero FJ, Gutiérrez-Martín Y, Henao F, Gutiérrez-Merino C. The NADH oxidase activity of the plasma membrane of synaptosomes is a major source of superoxide anion and is inhibited by peroxynitrite. J Neurochem 2002; 82:604-14. [PMID: 12153484 DOI: 10.1046/j.1471-4159.2002.00983.x] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Plasma membrane vesicles from adult rat brain synaptosomes (PMV) have an ascorbate-dependent NADH oxidase activity of 35-40 nmol/min/(mg protein) at saturation by NADH. NADPH is a much less efficient substrate of this oxidase activity, with a Vmax 10-fold lower than that measured for NADH. Ascorbate-dependent NADH oxidase activity accounts for more than 90% of the total NADH oxidase activity of PMV and, in the absence of NADH and in the presence of 1 mm ascorbate, PMV produce ascorbate free radical (AFR) at a rate of 4.0 +/- 0.5 nmol AFR/min/(mg protein). NADH-dependent *O2- production by PMV occurs with a rate of 35 +/- 3 nmol/min/(mg protein), and is a coreaction product of the NADH oxidase activity, because: (i) it is inhibited by more than 90% by addition of ascorbate oxidase, (ii) it is inhibited by 1 micro g/mL wheat germ agglutinin (a potent inhibitor of the plasma membrane AFR reductase activity), and (iii) the KM(NADH) of the plasma membrane NADH oxidase activity and of NADH-dependent *O2- production are identical. Treatment of PMV with repetitive micromolar ONOO- pulses produced almost complete inhibition of the ascorbate-dependent NADH oxidase and *O2- production, and at 50% inhibition addition of coenzyme Q10 almost completely reverts this inhibition. Cytochrome c stimulated 2.5-fold the plasma membrane NADH oxidase, and pretreatment of PMV with repetitive 10 microm ONOO- pulses lowers the K0.5 for cytochrome c stimulation from 6 +/- 1 (control) to 1.5 +/- 0.5 microm. Thus, the ascorbate-dependent plasma membrane NADH oxidase activity can act as a source of neuronal.O2-, which is up-regulated by cytosolic cytochrome c and down-regulated under chronic oxidative stress conditions producing ONOO-.
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Affiliation(s)
- Francisco Javier Martín-Romero
- Departamento de Bioquímica y Biología Molecular y Genética, Facultad de Ciencias and Escuela de Ingenierías Agrarias, Universidad de Extremadura, Badajoz, Spain
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113
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Martín-Romero FJ, García-Martín E, Gutiérrez-Merino C. Inhibition of oxidative stress produced by plasma membrane NADH oxidase delays low-potassium-induced apoptosis of cerebellar granule cells. J Neurochem 2002; 82:705-15. [PMID: 12153494 DOI: 10.1046/j.1471-4159.2002.01023.x] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
From 1 to 3 h after the onset of cerebellar granule cells (CGC) apoptosis in a low-K+(5 mm KCl) medium there was a large decay of NADH and a 2.5-fold increase of the rate of reactive oxygen species (ROS) production (measured using CGC loaded with dichlorodihydrofluorescein). During the same time period, the ascorbate-dependent NADH oxidase activity, which accounted for more than 90% of both total NADH oxidase activity and NADH-dependent *O2- production of CGC lysates, increased 2.5- to threefold. The stimulation of the ascorbate-dependent NADH oxidase activity by oxidized cytochrome c, 2.5-fold at saturation with a K(0.5) of 4-5 microm cytochrome c, can at least partially explain this activation. The plasma membrane ascorbate-dependent NADH oxidase activity accounted for more than 70% of the total activity (both in terms of NADH oxidase and *O2- release) of CGC lysates. 4-Hydroxyquinazoline (4-HQ), which was found to block this apoptotic process, prevented the increase of ROS production. 4-HQ protection against cell viability loss and DNA fragmentation correlated with the inhibition by 4-HQ of the ascorbate-dependent NADH oxidase activity of CGC lysates, showing the same K(0.5)-value (4-5 mm 4-HQ). The efficient blockade of CGC apoptosis by addition of superoxide dismutase to the medium further supports the neurotoxic role of *O2- overproduction by the plasma membrane ascorbate-dependent NADH oxidase.
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Affiliation(s)
- Francisco Javier Martín-Romero
- Departamento de Bioquímica y Biología Molecular y Genética, Facultad de Ciencias and Escuela de Ingenierías Agrarias, Universidad de Extremadura, Spain
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114
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Trommer H, Böttcher R, Pöppl A, Hoentsch J, Wartewig S, Neubert RHH. Role of ascorbic acid in stratum corneum lipid models exposed to UV irradiation. Pharm Res 2002; 19:982-90. [PMID: 12180551 DOI: 10.1023/a:1016414422106] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
PURPOSE The effects of ascorbic acid on Stratum corneum lipid models following ultraviolet irradiation were studied adding iron ions as transition metal catalysts. METHODS Lipid peroxidation was quantified by the thiobarbituric acid assay. The qualitative changes were studied on a molecular level by mass spectrometry. To elucidate the nature of free radical involvement we carried out electron paramagnetic resonance studies. The influence of ascorbic acid on the concentration of hydroxyl radicals was examined using the spin trapping technique. Moreover, we checked the vitamin's ability to react with stable radicals. RESULTS Ascorbic acid was found to have prooxidative effects in all lipid systems in a concentration dependent manner. The degradation products of ascorbic acid after its prooxidative action were detected. The concentration of the hydroxyl radicals in the Fenton assay was decreased by ascorbic acid. The quantification assay of 2,2-diphenyl-1-picrylhydrazyl hydrate showed reduced concentration levels of the stable radical caused by ascorbic acid. CONCLUSIONS Considering human skin and its constant exposure to UV light and oxygen, an increased pool of iron ions in irradiated skin and the depletion of co-antioxidants, the administration of ascorbic acid in cosmetic formulations or in sunscreens could unfold adverse effects among the Stratum corneum lipids.
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Affiliation(s)
- Hagen Trommer
- Martin-Luther-University Halle-Wittenberg, School of Pharmacy, Institute of Pharmaceutics and Biopharmaceutics, Halle, Saale, Germany
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115
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Holmes ME, Mwanjewe J, Samson SE, Haist JV, Wilson JX, Dixon SJ, Karmazyn M, Grover AK. Dehydroascorbic acid uptake by coronary artery smooth muscle: effect of intracellular acidification. Biochem J 2002; 362:507-12. [PMID: 11853561 PMCID: PMC1222413 DOI: 10.1042/0264-6021:3620507] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Dehydroascorbic acid (DHAA) enters cells via Na(+)-independent glucose transporters (GLUT) and is converted to ascorbate. However, we found that Na(+) removal inhibited [(14)C]DHAA uptake by smooth-muscle cells cultured from pig coronary artery. The uptake was examined for 2-12 min at 10-200 microM DHAA in either the presence of 134 mM Na(+) or in its absence (N-methyl D-glucamine, choline or sucrose replaced Na(+)). This inhibition of DHAA uptake by Na(+) removal was paradoxical because it was inhibited by 2-deoxyglucose and cytochalasin B, as expected of transport via the GLUT pathway. We tested the hypothesis that this paradox resulted from an inefficient intracellular reduction of [(14)C]DHAA into [(14)C]ascorbate upon intracellular acidosis caused by the Na(+) removal. Consistent with this hypothesis: (i) the Na(+)/H(+)-exchange inhibitors ethylisopropyl amiloride and cariporide also decreased the uptake, (ii) Na(+) removal and Na(+)/H(+)-exchange inhibitors lowered cytosolic pH, with the decrease being larger in 12 min than in 2 min, and (iii) less of the cellular (14)C was present as ascorbate (determined by HPLC) in cells in Na(+)-free buffer than in those in Na(+)-containing buffer. This inability to obtain ascorbate from extracellular DHAA may be detrimental to the coronary artery under hypoxia-induced acidosis during ischaemia/reperfusion.
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Affiliation(s)
- Melanie E Holmes
- Department of Medicine, McMaster University, Hamilton, Ontario, Canada L8N 3Z5
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116
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Fiorani M, De Sanctis R, De Bellis R, Dachà M. Intracellular flavonoids as electron donors for extracellular ferricyanide reduction in human erythrocytes. Free Radic Biol Med 2002; 32:64-72. [PMID: 11755318 DOI: 10.1016/s0891-5849(01)00762-6] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Abstract
Reduction of extracellular ferricyanide [Fe(CN)(6)](-3) to ferrocyanide by intact cells reflects the activity of a trans-plasma membrane oxidoreductase that, in human red blood cells, utilizes ascorbic acid as an electron donor. We herein report that the flavonoids quercetin and myricetin, while inhibiting dehydroascorbic acid uptake-and thus the erythrocyte ascorbic acid content-effectively stimulate the extracellular reduction of ferricyanide. Other flavonoids such as rutin, acacetin, apigenin, and genistein do not show the same effect. The notion that quercetin or myricetin may serve as an intracellular donor for a trans-plasma membrane oxidoreductase is supported by the following lines of evidence: (i) they afford direct reduction of ferricyanide; (ii) extracellular reduction of ferricyanide was not mediated by direct effects of the flavonoids released by the cells and was abolished by the sulphydryl reagent parachloromercuribenzenesulfonic acid (pCMBS); (iii) the intracellular concentrations of quercetin or myricetin well correlate with increases in ferricyanide reduction; (iv) the intracellular concentration of the flavonoids dramatically declines after ferricyanide exposure. Taken together, the results presented in this study demonstrate that myricetin and quercetin, which accumulate in large amounts in red blood cells, act as intracellular substrates of a pCMBS-sensitive trans-plasma membrane oxidoreductase. This may represent a novel mechanism whereby these flavonoids exert beneficial effects under oxidative stress conditions.
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Affiliation(s)
- Mara Fiorani
- Giorgio Fornaini Institute of Biological Chemistry, Università degli Studi di Urbino, Via Saffi 2, 60129 Urbino, Italy.
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117
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Abstract
Reactive oxygen species (ROS) are known mediators of intracellular signaling cascades. Excessive production of ROS may, however, lead to oxidative stress, loss of cell function, and ultimately apoptosis or necrosis. A balance between oxidant and antioxidant intracellular systems is hence vital for cell function, regulation, and adaptation to diverse growth conditions. Thioredoxin reductase (TrxR) in conjunction with thioredoxin (Trx) is a ubiquitous oxidoreductase system with antioxidant and redox regulatory roles. In mammals, extracellular forms of Trx also have cytokine-like effects. Mammalian TrxR has a highly reactive active site selenocysteine residue resulting in a profound reductive capacity, reducing several substrates in addition to Trx. Due to the reactivity of TrxR, the enzyme is inhibited by many clinically used electrophilic compounds including nitrosoureas, aurothioglucose, platinum compounds, and retinoic acid derivatives. The properties of TrxR in combination with the functions of Trx position this system at the core of cellular thiol redox control and antioxidant defense. In this review, we focus on the reactions of the Trx system with ROS molecules and different cellular antioxidant enzymes. We summarize the TrxR-catalyzed regeneration of several antioxidant compounds, including ascorbic acid (vitamin C), selenium-containing substances, lipoic acid, and ubiquinone (Q10). We also discuss the general cellular effects of TrxR inhibition. Dinitrohalobenzenes constitute a unique class of immunostimulatory TrxR inhibitors and we consider the immunomodulatory effects of dinitrohalobenzene compounds in view of their reactions with the Trx system.
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Affiliation(s)
- J Nordberg
- Medical Nobel Institute for Biochemistry, Department of Medical Biochemistry and Biophysics, Karolinska Institute, Stockholm, Sweden
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118
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Aldini G, Yeum KJ, Russell RM, Krinsky NI. A method to measure the oxidizability of both the aqueous and lipid compartments of plasma. Free Radic Biol Med 2001; 31:1043-50. [PMID: 11677037 DOI: 10.1016/s0891-5849(01)00684-0] [Citation(s) in RCA: 79] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
The lipophilic radical initiator (MeO-AMVN) and the fluorescent probe C11BODIPY581/591 (BODIPY) were used to measure the lipid compartment oxidizability of human plasma. Aqueous plasma oxidizability was initiated by the aqueous peroxyl radical generator, AAPH, and 2',7'-dichlorodihydrofluorescein (DCFH) was employed as the marker of the oxidative reaction. The distribution in aqueous and lipid compartments of the two radical initiators was determined by measuring the rate of consumption of the plasma hydrophilic and lipophilic endogenous antioxidants. In the presence of AAPH (20 mM), the order of consumption was: ascorbic acid > alpha-tocopherol > uric acid > beta-carotene, indicating a gradient of peroxyl radicals from the aqueous to the lipid phase. When MeO-AMVN was used (2mM), beta-carotene was consumed earlier than uric acid and almost at the same time as alpha-tocopherol, reflecting the diffusion and activation of MeO-AMVN in the lipophilic phase. The rate of BODIPY oxidation (increase in green fluorescence) significantly increased after the depletion of endogenous alpha-tocopherol and beta-carotene, whereas it was delayed for 180 min when AAPH was used instead of MeO-AMVN. The measurement of lipid oxidation in plasma was validated by adding to plasma the two lipophilic antioxidants, alpha-tocopherol and beta-carotene, whose inhibitory effects on BODIPY oxidation were dependent on the duration of the preincubation period and hence to their lipid diffusion. DCFH oxidation induced by AAPH only began after uric acid, the main hydrophilic plasma antioxidant, was consumed. In contrast, when MeO-AMVN was used, DCFH oxidation was delayed for 120 min, indicating its localization in the aqueous domain. In summary, the selective fluorescence method reported here is capable of distinguishing the lipophilic and hydrophilic components of the total antioxidant capacity of plasma.
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Affiliation(s)
- G Aldini
- Istituto Chimico Farmaceutico TossicologicoUniversity of Milan, Milan, Italy
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119
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Abstract
Ascorbic acid may be involved in the defense against oxidant stress in endothelial cells. Such a role requires that the cells effectively recycle the vitamin from its oxidized forms. In this work, we studied the ability of cultured bovine aortic endothelial cells (BAECs) to take up and reduce dehydroascorbic acid (DHA) to ascorbate, as well as the dependence of ascorbate recycling on intracellular GSH. BAECs took up and reduced DHA to ascorbate much more readily than they took up ascorbate. Although BAECs in culture did not contain ascorbate, ascorbate accumulated to concentrations of 2-3 mM in BAECs following incubation with 400 microM DHA. Extracellular ferricyanide oxidized intracellular ascorbate, which was recycled by the cells. Reduction of DHA, either when added to the cells or when generated in response to ferricyanide, caused significant decreases in intracellular GSH concentrations. Depletion of intracellular GSH with 1-chloro-2,4-dinitrobenzene, diethylmaleate, and diamide almost abolished the ability of the cells to reduce DHA to ascorbate. DHA reduction by thioredoxin reductase was evident in dialyzed cell extracts, but occurred at rates far lower than direct GSH reduction of DHA. These results suggest that maximal rates of DHA reduction, and thus recycling of ascorbate from DHA, are dependent upon GSH in these cells.
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Affiliation(s)
- J M May
- Department of Medicine, Vanderbilt University School of Medicine, 715 Medical Research Building II, Nashville, TN 37232-6303, USA.
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120
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Mure K, Rossman TG. Reduction of spontaneous mutagenesis in mismatch repair-deficient and proficient cells by dietary antioxidants. Mutat Res 2001; 480-481:85-95. [PMID: 11506802 DOI: 10.1016/s0027-5107(01)00172-5] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
Cells lacking mismatch repair (MMR) exhibit elevated levels of spontaneous mutagenesis. Evidence exists that MMR is involved in repair of some DNA lesions besides mismatches. If some oxidative DNA lesions are substrates for MMR, then the excess mutagenesis in MMR(-) cells might be blocked by dietary antioxidants. Effects of the dietary antioxidants ascorbate, alpha-tocopherol, (-)-epigallocatechin gallate (EGCG) and lycopene on spontaneous mutagenesis were studied using mismatch repair-deficient (hMLH1(-)) human colon carcinoma HCT116 cells and HCT116/ch3 cells, in which normal human chromosome 3 has been added to restore mismatch repair. HCT116 cells have a 22-fold higher spontaneous mutation rate compared with HCT116/ch3 cells. HCT116 cells cultured in 1% fetal bovine serum (FBS) have twice the spontaneous mutation rate of those cultured in 10% FBS, most likely due to reduction in serum antioxidants in the low serum medium. As expected, alpha-tocopherol (50 microM) and ascorbate (284 microM) reduced spontaneous mutagenesis in HCT116 cells growing in 1% serum more dramatically than in cells cultured in 10% serum. The strongest antimutagenic compound was lycopene (5 microM), which reduced spontaneous mutagenesis equally (about 70%) in HCT116 cells growing in 10 and 1% FBS and in HCT116/ch3 cells. Since lycopene was equally antimutagenic in cells growing in low and high serum, it may have another antimutagenic mechanism in addition to its antioxidant effect. Surprisingly, EGCG (10 microM) was toxic to cells growing in low serum. It also reduced spontaneous mutagenesis equally (nearly 40%) in HCT116 and HCT116/ch3 cells. The large proportion of spontaneous mutagenesis that can be blocked by antioxidants in mismatch repair-deficient cells support the hypothesis that a major cause of their excess mutagenesis is endogenous oxidants. Blocking spontaneous mutagenesis, perhaps with a cocktail of antioxidants, should reduce the risk of cancer in people with a genetic defect in mismatch repair as well as other individuals.
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Affiliation(s)
- K Mure
- The Nelson Institute of Environmental Medicine and The Kaplan Cancer Center, New York University School of Medicine, 57 Old Forge Road, Tuxedo, NY 10987, USA
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121
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Lee JS, Huh WK, Lee BH, Baek YU, Hwang CS, Kim ST, Kim YR, Kang SO. Mitochondrial NADH-cytochrome b(5) reductase plays a crucial role in the reduction of D-erythroascorbyl free radical in Saccharomyces cerevisiae. BIOCHIMICA ET BIOPHYSICA ACTA 2001; 1527:31-8. [PMID: 11420140 DOI: 10.1016/s0304-4165(01)00134-9] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
The relevance of NADH-cytochrome b(5) reductase to the NADH-dependent reduction of D-erythroascorbyl free radical was investigated in Saccharomyces cerevisiae. MCR1, which is known to encode NADH-cytochrome b(5) reductase in S. cerevisiae, was disrupted by the insertion of URA3 gene into the gene of MCR1. In the mcr1 disruptant cells, the activity of NADH-D-erythroascorbyl free radical reductase almost disappeared and the intracellular level of D-erythroascorbic acid was about 11% of that of the congenic wild-type strain. In the transformant cells carrying MCR1 in multicopy plasmid, the intracellular level of D-erythroascorbic acid and the activity of NADH-D-erythroascorbyl free radical reductase increased up to 1.7-fold and 2.1-fold, respectively. Therefore, it indicated that the MCR1 product, mitochondrial NADH-cytochrome b(5) reductase, plays a key role in the NADH-dependent reduction of D-erythroascorbyl free radical in S. cerevisiae. On the other hand, the mcr1 disruptant cells were hypersensitive to hydrogen peroxide and menadione, and overexpression of MCR1 made the cells more resistant against oxidative stress. These results suggested that the mitochondrial NADH-cytochrome b(5) reductase functions as NADH-D-erythroascorbyl free radical reductase and plays an important role in the response to oxidative damage in S. cerevisiae.
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Affiliation(s)
- J S Lee
- Laboratory of Biophysics, School of Biological Sciences, and Institute of Microbiology, Seoul National University, 151-742, Seoul, South Korea
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122
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Baoutina A, Dean RT, Jessup W. Trans-plasma membrane electron transport induces macrophage-mediated low density lipoprotein oxidation. FASEB J 2001; 15:1580-2. [PMID: 11427492 DOI: 10.1096/fj.00-0704fje] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Affiliation(s)
- A Baoutina
- Cell Biology Group, The Heart Research Institute, 145 Missenden Rd., Camperdown, Sydney, NSW, 2050, Australia.
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123
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Karu TI, Pyatibrat LV, Kalendo GS. Cell attachment modulation by radiation from a pulsed light diode (lambda = 820 nm) and various chemicals. Lasers Surg Med 2001; 28:227-36. [PMID: 11295757 DOI: 10.1002/lsm.1043] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
BACKGROUND AND OBJECTIVE Adhesive interactions between cells and extracellular matrices play a regulative role in wound repair processes. The objective of this investigation is to study the mechanisms of light action on cellular adhesion in vitro. The adhesion of HeLa cells to a glass matrix is evaluated after irradiation with a pulsed near-infrared (IR) diode and treatment with various chemicals. STUDY DESIGN/MATERIALS AND METHODS A semiconductor diode (820 +/- 10 nm, 10Hz, 16--120 J/m(2)) is used for irradiation of the cell suspension. In parallel experiments, various chemicals (mannitol, melatonin, ethanol, ascorbic acid, superoxide dismutase, catalase, rotenone, azide, dinitrophenol (DNP), methylene blue, and hydrogen peroxide) are added to the cell suspension before or after the irradiation procedure. The cell-glass adhesion is studied by using the adhesion assay technique (Lasers Surg. Med. 1996;18:171). RESULTS It has been found that cell-glass adhesion increases in a dose-dependent manner after irradiation. The treatment of the cells with antioxidants (free radical scavengers), e.g., mannitol, melatonin, ethanol, and ascorbic acid, as well as with the ionophore DNP, eliminated the light effect. The respiratory chain inhibitors rotenone and azide strongly modified the light effect, depending on the dose. The oxidative agents hydrogen peroxide (in a low concentration) and methylene blue increased the cell adhesion. Superoxide dismutase did not modify the light effect. The effect of the catalase (stimulative or suppressive) was dependent on its concentration and treatment sequence. Preirradiation was found to decrease (or normalize to the control level) the suppressive effects of some chemicals. CONCLUSION The results obtained are evidence that first, pulsed IR radiation with certain parameters modulates the cell-matrix attachment. second, free radical and redox processes are involved in the cell-matrix interaction, probably at some stage(s) of the photosignal transduction. Third, both types of the primary reactions in the respiratory chain, namely, the increase of the electron flow and production of the reactive oxygen species, cause a transient oxidative stress in the cytoplasm.
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Affiliation(s)
- T I Karu
- Institute of Laser and Informatic Technologies, Russian Academy of Sciences, 142190 Troitsk, Moscow Region, Russian Federation.
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124
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Fiorani M, De Sanctis R, Menghinello P, Cucchiarini L, Cellini B, Dachà M. Quercetin prevents glutathione depletion induced by dehydroascorbic acid in rabbit red blood cells. Free Radic Res 2001; 34:639-48. [PMID: 11697039 DOI: 10.1080/10715760100300531] [Citation(s) in RCA: 60] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
Exposure of rabbit red blood cells to dehydroascorbic acid (DHA) caused a significant decline in glutathione content which was largely prevented by quercetin, whereas it was insensitive to various antioxidants, iron chelators or scavengers of reactive oxygen species. This response was not mediated by chemical reduction of either extracellular DHA or intracellular glutathione disulfide. In addition, the flavonoid did not affect the uptake of DHA or its reduction to ascorbic acid. Rather, quercetin appeared to specifically stimulate downstream events promoting GSH formation.
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Affiliation(s)
- M Fiorani
- Istituto di Chimica Biologica Giorgio Fornaini, Università degli Studi di Urbino, Via Saffi, 2, 61029 Urbino, Italy.
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125
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del Castillo-Olivares A, Núñez de Castro I, Medina MA. Dual role of plasma membrane electron transport systems in defense. Crit Rev Biochem Mol Biol 2001; 35:197-220. [PMID: 10907796 DOI: 10.1080/10409230091169203] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
Because oxidative stress is one of the main sources of severe cellular damage, cells have different defense weapons against reactive oxygen species. Ubiquitous plasma membrane redox systems play a role in defense against oxidative stress damage. On the other hand, a tightly controlled and localized production of reactive oxygen species by a plasma membrane NADPH oxidase can be used as a potent microbicidal weapon. This dual, prooxidant and antioxidant role of plasma membrane electron transport systems in defense is studied and discussed.
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Affiliation(s)
- A del Castillo-Olivares
- Department of Biochemistry and Molecular Biology, Medical College of Virginia, Virginia Commonwealth University, Richmond 23298-0614, USA
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126
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Kuropteva ZV, Zhumabaeva TT, Baider LM, Aleshchenko AV. Ascorbic acid induces nitric oxide production in human leukocytes. DOKL BIOCHEM BIOPHYS 2001; 376:7-9. [PMID: 11712134 DOI: 10.1023/a:1018883622689] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Affiliation(s)
- Z V Kuropteva
- Emanuel Institute of Biochemical Physics, Russian Academy of Sciences, ul. Kosygina 4, Moscow, 117334 Russia
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127
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López-Lluch G, Blázquez MV, Pérez-Vicente R, Macho A, Burón MI, Alcaín FJ, Muñoz E, Navas P. Cellular redox state and activating protein-1 are involved in ascorbate effect on calcitriol-induced differentiation. PROTOPLASMA 2001; 217:129-136. [PMID: 11732330 DOI: 10.1007/bf01289422] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
Ascorbate has been related to the differentiation of several mesenchymal cells including haematopoietic cells. We have previously demonstrated that ascorbate enhances the activity of 1 alpha,25-dihydroxyvitamin D3 (1 alpha,25(OH)2D3) on monocytic differentiation of HL-60 cells. Here, we show that ascorbate-mediated modification of cellular redox state and AP-1 (activating protein-1) DNA binding during early phases are related to the enhancing effect of ascorbate on differentiation. Ascorbate, but not its fully oxidized form, dehydroascorbate, or an ascorbate analogue with a low rate of oxidation, ascorbate-2-phosphate, enhanced the differentiation induced by 1 alpha,25(OH)2D3, modified cytosolic reactive oxygen species levels and mitochondrial redox potential (delta psi m), and modulated AP-1 DNA binding in HL-60 cells. Ascorbate itself increased AP-1 binding to DNA in noninduced cells, whereas it inhibited AP-1 binding in 1 alpha,25(OH)2D3-induced cells. However, ascorbate increased the mRNA levels of c-jun, junB, and c-fos in 1 alpha,25(OH)2D3-induced cells. Taken together, these results suggest that the enhancing effect of ascorbate on HL-60 differentiation induced by 1 alpha, 25(OH)2D3 is related to its effect on the cellular redox state and the modulation of AP-1 activity.
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Affiliation(s)
- G López-Lluch
- Laboratorio Andaluz de Biología, Universidad Pablo de Olavide, Sevilla, Carretera de Utrera, Km 1.0, 41013 Sevilla, Spain
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128
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Manfredini S, Vertuani S, Manfredi B, Rossoni G, Calviello G, Palozza P. Novel antioxidant agents deriving from molecular combinations of vitamins C and E analogues: 3,4-dihydroxy-5(R). Bioorg Med Chem 2000; 8:2791-801. [PMID: 11131170 DOI: 10.1016/s0968-0896(00)00205-4] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Molecular combinations of two antioxidants (i.e., ascorbic acid and the pharmacophore of alpha-tocopherol), namely the 2,3-dihydroxy-2,3-enono-1,4-lactone and the chromane residues, have been designed and tested for their radical scavenging activities. When evaluated for their capability to inhibit malondialdehyde (MDA) production in rat liver microsomal membranes, the 3,4-dihydroxy-5R-2(R,S)-(6-hydroxy-2,5,7,8-tetramethylchroman-2(R,S)yl-methyl)-1,3]dioxolan-4S-yl]-5H-furan-2-one (11a-d), exhibited an interesting activity. In particular the 5R,2R,2R,4S and 5R,2R,2S,4S isomers (11c,d) displayed a potent antioxidant effect compared to the respective synthetic alpha-tocopherol analogue (5) and natural alpha-tocopherol or ascorbic acid, used alone or in combination. Moreover, the mixture of stereoisomers 11a-d also proved to be effective in preventing damage induced by reperfusion on isolated rabbit heart, in particular at the higher concentration of 300 microM. In view of these results our study represents a new approach to potential therapeutic agents for applications in pathological events in which a free radical damage is involved. Design, synthesis and preliminary biological activity are discussed.
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Affiliation(s)
- S Manfredini
- Dipartimento di Scienze Farmaceutiche, Università di Ferrara, Italy.
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129
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Conrad ME, Umbreit JN, Moore EG, Hainsworth LN, Porubcin M, Simovich MJ, Nakada MT, Dolan K, Garrick MD. Separate pathways for cellular uptake of ferric and ferrous iron. Am J Physiol Gastrointest Liver Physiol 2000; 279:G767-74. [PMID: 11005764 DOI: 10.1152/ajpgi.2000.279.4.g767] [Citation(s) in RCA: 85] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Separate pathways for transport of nontransferrin ferric and ferrous iron into tissue cultured cells were demonstrated. Neither the ferric nor ferrous pathway was shared with either zinc or copper. Manganese shared the ferrous pathway but had no effect on cellular uptake of ferric iron. We postulate that ferric iron was transported into cells via beta(3)-integrin and mobilferrin (IMP), whereas ferrous iron uptake was facilitated by divalent metal transporter-1 (DMT-1; Nramp-2). These conclusions were documented by competitive inhibition studies, utilization of a beta(3)-integrin antibody that blocked uptake of ferric but not ferrous iron, development of an anti-DMT-1 antibody that blocked ferrous iron and manganese uptake but not ferric iron, transfection of DMT-1 DNA into tissue culture cells that showed enhanced uptake of ferrous iron and manganese but neither ferric iron nor zinc, hepatic metal concentrations in mk mice showing decreased iron and manganese but not zinc or copper, and data showing that the addition of reducing agents to tissue culture media altered iron binding to proteins of the IMP and DMT-1 pathways. Although these experiments show ferric and ferrous iron can enter cells via different pathways, they do not indicate which pathway is dominant in humans.
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Affiliation(s)
- M E Conrad
- USA Cancer Center, University of South Alabama, Mobile, Alabama 36688, USA.
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130
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VanDuijn MM, Tijssen K, VanSteveninck J, Van Den Broek PJ, Van Der Zee J. Erythrocytes reduce extracellular ascorbate free radicals using intracellular ascorbate as an electron donor. J Biol Chem 2000; 275:27720-5. [PMID: 10871632 DOI: 10.1074/jbc.m910281199] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Ascorbate is readily oxidized in aqueous solution by ascorbate oxidase. Ascorbate radicals are formed, which disproportionate to ascorbate and dehydroascorbic acid. Addition of erythrocytes with increasing intracellular ascorbate concentrations decreased the oxidation of ascorbate in a concentration-dependent manner. Concurrently, it was found, utilizing electron spin resonance spectroscopy, that extracellular ascorbate radical levels were decreased. Control experiments showed that these results could not be explained by leakage of ascorbate from the cells, inactivation of ascorbate oxidase, or oxygen depletion. Thus, this means that intracellular ascorbate is directly responsible for the decreased oxidation of extracellular ascorbate. Exposure of ascorbate-loaded erythrocytes to higher levels of extracellular ascorbate radicals resulted in the detection of intracellular ascorbate radicals. Moreover, efflux of dehydroascorbic acid was observed under these conditions. These data confirm the view that intracellular ascorbate donates electrons to extracellular ascorbate free radical via a plasma membrane redox system. Such a redox system enables the cells to effectively counteract oxidative processes and thereby prevent depletion of extracellular ascorbate.
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Affiliation(s)
- M M VanDuijn
- Department of Molecular Cell Biology, Sylvius Laboratory, Leiden University Medical Center, P. O. Box 9503, 2300 RA Leiden, The Netherlands
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131
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Himmelreich U, Emling M, Drew KN, Serianni AS, Kuchel PW. 13C NMR evidence of the failure of human erythrocytes to metabolize ascorbate and dehydroascorbate to lactate. Free Radic Biol Med 2000; 28:1607-10. [PMID: 10938456 DOI: 10.1016/s0891-5849(00)00272-0] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
13C-NMR spectroscopy was used to record time courses of the metabolism of [1-(13)C]-L-ascorbic acid (AA) and [2-(13)C]-L-ascorbic acid and their dehydro-counterparts (DHAA) by human erythrocytes. Under a range of experimental conditions, but most notably in the absence of glucose in the incubation medium, no (13)C-NMR signal for lactate emerged during any of the 5 h time courses. The NMR resonances that did emerge over time were assigned to diketogulonic (DKG) acid and CO(2). Only very minor resonances from degradation products of DKG appeared from samples that contained physiologically high concentrations of DHAA. These results are in contrast with those in a recent report that lactate is derived from AA in human erythrocytes. However, an explanation for this possible artifact is given.
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Affiliation(s)
- U Himmelreich
- Department of Biochemistry, University of Sydney, Sydney, NSW, Australia
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132
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Abstract
Vitamin E was originally considered a dietary factor of animal nutrition especially important for normal reproduction. The significance of vitamin E has been subsequently proven as a radical chain breaking antioxidant that can protect the integrity of tissues and play an important role in life processes. More recently alpha-tocopherol has been found to possess functions that are independent of its antioxidant/radical scavenging ability. Absorption in the body is alpha-tocopherol selective and other tocopherols are not absorbed or are absorbed to a lesser extent. Furthermore, pro-oxidant effects have been attributed to tocopherols as well as an anti-nitrating action. Non-antioxidant and non-pro-oxidant molecular mechanisms of tocopherols have been also described that are produced by alpha-tocopherol and not by beta-tocopherol. alpha-Tocopherol specific inhibitory effects have been seen on protein kinase C, on the growth of certain cells and on the transcription of some genes (CD36, and collagenase). Activation events have been seen on the protein phosphatase PP2A and on the expression of other genes (alpha-tropomyosin and Connective Tissue Growth Factor). Non-antioxidant molecular mechanisms have been also described for gamma-tocopherol, delta-tocopherol and tocotrienols.
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Affiliation(s)
- A Azzi
- Institute of Biochemistry and Molecular Biology, Bühlstrasse 28, 3012 Bern (Switzerland) University of Bern, Bern, Switzerland.
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133
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Fernandes MA, Geraldes CF, Oliveira CR, Alpoim MC. Chromate-induced human erythrocytes haemoglobin oxidation and peroxidation: influence of vitamin E, vitamin C, salicylate, deferoxamine, and N-ethylmaleimide. Toxicol Lett 2000; 114:237-43. [PMID: 10713489 DOI: 10.1016/s0378-4274(00)00167-3] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
In order to attenuate or to prevent chromate-induced human erythrocytes injury, the influence of vitamin E, vitamin C, salicylate, deferoxamine, and N-ethylmaleimide on chromate-induced human erythrocytes haemoglobin oxidation and peroxidation were investigated. It was observed that pretreatment of human erythrocytes with vitamin E (20 microM), vitamin C (1 mM), salicylate (3 mM), and deferoxamine (4 mM) significantly increased (P=0.0001) chromate-induced human erythrocytes haemoglobin oxidation in a time dependent manner, while it was significantly decreased (P=0.0001) by pretreatment with N-ethylmaleimide (1 mM). In contrast, pretreatment of human erythrocytes with deferoxamine (4 mM) immediately inhibited (P=0.0001) chromate-induced human erythrocytes peroxidation, while it was significantly increased (P=0.0001) by pretreatment with N-ethylmaleimide (1 mM) during the first 4 h of cells exposition to chromate. For time periods superior to 6 h pretreatment with N-ethylmaleimide (1 mM) significantly decreased (P=0.0001) chromate-induced human erythrocytes peroxidation. It was concluded that care must be taken as these drugs are used to prevent against toxicity induced by chromium(VI) compounds.
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Affiliation(s)
- M A Fernandes
- Departamento de Zoologia, Faculdade de Ciências, Universidade de Coimbra, 3004-517, Coimbra, Portugal
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Baker MA, Lawen A. Plasma membrane NADH-oxidoreductase system: a critical review of the structural and functional data. Antioxid Redox Signal 2000; 2:197-212. [PMID: 11229526 DOI: 10.1089/ars.2000.2.2-197] [Citation(s) in RCA: 44] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
The observation in the early 1970s that ferricyanide can replace transferrin as a growth factor highlighted the major role plasma membrane proteins can play within a mammalian cell. Ferricyanide, being impermeant to the cell, was assumed to act at the level of the plasma membrane. Since that time, several enzymes isolated from the plasma membrane have been described, which, using NADH as the intracellular electron donor, are capable of reducing ferricyanide. However, their exact modes of action, and their physiological substrates and functions have not been solved to date. Numerous hypotheses have been proposed for the role of such redox enzymes within the plasma membrane. Examples include the regulation of cell signaling, cell growth, apoptosis, proton pumping, and ion channels. All of these roles may be a result of the function of these enzymes as cellular redox sensors. The emergence of many diverse roles for ferricyanide utilizing redox enzymes present in the plasma membrane might also, in part, be due to the numerous redox enzymes present within the membrane; the poor molecular characterization of the enzymes may be the reason for some of the diverging results reported in the literature as various researchers may be working on different enzymes. Here we review the diverse proposals given for structure and function to the plasma membrane NADH-oxidoreductase system(s) with a specific focus on those enzyme activities which can couple ferricyanide and NADH. Although they are still ill-defined enzymes, evidence is rising that they are of utmost significance for cellular regulation.
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Affiliation(s)
- M A Baker
- Department of Biochemistry and Molecular Biology, Monash University, Clayton, Australia
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135
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Goldenberg H, Landertshamer H, Laggner H. Functions of vitamin C as a mediator of transmembrane electron transport in blood cells and related cell culture models. Antioxid Redox Signal 2000; 2:189-96. [PMID: 11229525 DOI: 10.1089/ars.2000.2.2-189] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Vitamin C (ascorbic acid) is an important physiological antioxidant. Within cells, it is practically always present in the reduced form. Several enzymatic and nonenzymatic mechanisms have been reported to maintain this status. In the extracellular environment, oxidation of ascorbate leads to loss of vitamin because the oxidized form, dehydroascorbic acid, is unstable under physiological conditions. The intermediate ascorbate free radical, although rather long-lived for a free radical, quickly disproportionates into the two other forms, also leading to loss of vitamin. Protection from loss can only be achieved by cellular regeneration mechanisms, i.e., by uptake of dehydroascorbic acid and either storage or recycling, and by plasma-membrane mediated reduction of extracellular free radical or dehydroascorbic acid. Moreover, intracellular ascorbate can also serve as an electron donor for transmembrane reduction of external electron acceptors. However, the physiological significance of this function is as yet unknown. The results presented in the literature are sometimes conflicting as to the relative contributions of these different possibilities, which seem to differ in different cell types. In this short review, the various pathways of regeneration of ascorbate and their relative contributions to the avoidance of vitamin loss in plasma or cell culture medium are discussed.
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Affiliation(s)
- H Goldenberg
- Department of Medical Chemistry, University of Vienna, Austria.
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136
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May JM, Qu ZC. Ascorbate-dependent electron transfer across the human erythrocyte membrane. BIOCHIMICA ET BIOPHYSICA ACTA 1999; 1421:19-31. [PMID: 10561468 DOI: 10.1016/s0005-2736(99)00107-8] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
Reduction of extracellular ferricyanide by intact cells reflects the activity of an as yet unidentified trans-plasma membrane oxidoreductase. In human erythrocytes, this activity was found to be limited by the ability of the cells to recycle intracellular ascorbic acid, its primary trans-membrane electron donor. Ascorbate-dependent ferricyanide reduction by erythrocytes was partially inhibited by reaction of one or more cell-surface sulfhydryls with p-chloromercuribenzene sulfonic acid, an effect that persisted in resealed ghosts prepared from such treated cells. However, treatment of intact cells with the sulfhydryl reagent had no effect on NADH-dependent ferricyanide or ferricytochrome c reductase activities of open ghosts prepared from treated cells. When cytosol-free ghosts were resealed to contain trypsin or pronase, ascorbate-dependent reduction of extravesicular ferricyanide was doubled, whereas NADH-dependent ferricyanide and ferricytochrome c reduction were decreased by proteolytic digestion. The trans-membrane ascorbate-dependent activity was also found to be inhibited by reaction of sulfhydryls on its cytoplasmic face. These results show that the trans-membrane ferricyanide oxidoreductase is limited by the ability of erythrocytes to recycle intracellular ascorbate, that it does not involve the endofacial NADH-dependent cytochrome b(5) reductase system, and that it is a trans-membrane protein that contains sensitive sulfhydryl groups on both membrane faces.
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Affiliation(s)
- J M May
- Departments of Medicine, Vanderbilt University School of Medicine, Nashville, TN 37232-6303, USA.
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137
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Affiliation(s)
- B FREI
- Linus Pauling Institute, Oregon State University, Corvallis, Oregon 97331-6512, USA
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