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Iron-Induced Liver Injury: A Critical Reappraisal. Int J Mol Sci 2019; 20:ijms20092132. [PMID: 31052166 PMCID: PMC6539962 DOI: 10.3390/ijms20092132] [Citation(s) in RCA: 45] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2019] [Revised: 04/25/2019] [Accepted: 04/27/2019] [Indexed: 12/12/2022] Open
Abstract
Iron is implicated in the pathogenesis of a number of human liver diseases. Hereditary hemochromatosis is the classical example of a liver disease caused by iron, but iron is commonly believed to contribute to the progression of other forms of chronic liver disease such as hepatitis C infection and nonalcoholic fatty liver disease. In this review, we present data from cell culture experiments, animal models, and clinical studies that address the hepatotoxicity of iron. These data demonstrate that iron overload is only weakly fibrogenic in animal models and rarely causes serious liver damage in humans, calling into question the concept that iron overload is an important cause of hepatotoxicity. In situations where iron is pathogenic, iron-induced liver damage may be potentiated by coexisting inflammation, with the resulting hepatocyte necrosis an important factor driving the fibrogenic response. Based on the foregoing evidence that iron is less hepatotoxic than is generally assumed, claims that assign a causal role to iron in liver injury in either animal models or human liver disease should be carefully evaluated.
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Tulsawani R, Gupta R, Misra K. Efficacy of aqueous extract of Hippophae rhamnoides and its bio-active flavonoids against hypoxia-induced cell death. Indian J Pharmacol 2014; 45:258-63. [PMID: 23833369 PMCID: PMC3696297 DOI: 10.4103/0253-7613.111943] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/08/2012] [Revised: 12/28/2012] [Accepted: 02/26/2013] [Indexed: 11/05/2022] Open
Abstract
Objectives: To investigate the protective efficacy of aqueous extract of Hippophae rhamnoides against chronic hypoxic injury using primary rat hepatocytes. Materials and Methods: The extract was prepared using maceration method and characterized by its phenolic and flavonoid content and chemical antioxidant capacity using ferric reducing antioxidant power assay. Hepatocytes were maintained in hypoxia chamber (3% and 1% oxygen) for 72 h. The cells kept under normoxic condition served as control. The cells were treated with the extract and flavonoids; isorhamentin, kaempferol or qurecetin-3-galactoside. After the end of exposure period; cell survival, reactive oxygen species (ROS), leakage of lactate dehydrogenase (LDH), alanine aminotransferase (ALT), aspartate aminotransferase (AST), reduced glutathione (GSH), glutathione peroxidase (GPx), and superoxide dismutase (SOD) levels were measured. Results: The extract showed presence of high phenolic and flavonoid content with significant antioxidant activity in chemical assay. The cell exposed to hypoxia showed concentration dependent cell death and harbored higher reactive oxygen species. In addition, these cells showed significant leakage of intracellular LDH, ALT, and AST accompanied by the diminished levels/activities of GSH, GPx, and SOD. The treatment of cells with aqueous extract of H. rhamnoides reduced hypoxia-induced cell death and prevented increase in ROS levels and leakage of intracellular LDH, ALT, and AST from cells. Moreover, these cells maintained better levels/activities of GSH, GPx, and SOD in comparison to the respective controls. The major flavonoids present in aqueous extract of H. rhamnoides; quercetin-3-galactoside, kaempferol, and isorhamentin also prevented hypoxia induced cell injury individually or in combination, however, the protection offered by these compounds taken together could not match to that of the extract. Conclusions: Overall the findings reveal significance of aqueous extract of H. rhamnoides in controlling ROS-meditated hypoxic injury in cells and can be useful in many hepatic complications.
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Affiliation(s)
- Rajkumar Tulsawani
- Department of Biochemical Sciences, Defence Institute of Physiology and Allied Science, Lucknow Road, Timarpur, Delhi, India
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Pourahmad J, O’Brien PJ, Chan K, Shakouri A. Tetramethylphenylenediamine-induced hepatocyte cytotoxicity caused by lysosomal labilisation and redox cycling with oxygen activation. Chem Biol Interact 2008; 172:39-47. [DOI: 10.1016/j.cbi.2007.12.002] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2007] [Revised: 12/04/2007] [Accepted: 12/05/2007] [Indexed: 11/25/2022]
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Suntres ZE, Lui EMK. Antioxidant effect of zinc and zinc-metallothionein in the acute cytotoxicity of hydrogen peroxide in Ehrlich ascites tumour cells. Chem Biol Interact 2006; 162:11-23. [PMID: 16730687 DOI: 10.1016/j.cbi.2006.04.007] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2006] [Revised: 04/14/2006] [Accepted: 04/14/2006] [Indexed: 01/20/2023]
Abstract
This study was concerned with the role of zinc (Zn) and zinc-metallothionein (Zn-MT) in oxidative stress. Hydrogen peroxide-induced oxidative injury was examined in Ehrlich ascites tumour cells isolated from control host mice, mice pretreated with 10 mg/kg ZnSO4 (i.p.) to increase cellular Zn/Zn-MT levels, and mice exposed to Zn-deficient diet to reduce the cellular Zn/Zn-MT levels. The results of the present study showed that Ehrlich cells with seven-fold differences in Zn-MT concentrations could be obtained by manipulating the Zn status of host mice and that high Zn and Zn-MT levels can make Ehrlich cells more resistant to H2O2-induced oxidative injury (cell viability, lipid peroxidation, [Ca2+]i) while cells with reduced Zn/Zn-MT levels were more susceptible to this treatment. H2O2 treatment resulted in oxidation of MT thiolate groups and loss of its metal binding capacity with translocation of Zn released from oxidized MT to other cellular sites. Preincubation of Ehrlich cells with ZnSO4 in vitro also conferred some degree of resistance to H2O2 toxicity, suggesting the inherent antioxidative property of Zn ions. These data suggested that Zn-MT can be considered as an antioxidant by virtue of its thiolate groups and its Zn ions that are released in the presence of oxidative stress.
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Affiliation(s)
- Zacharias E Suntres
- Medical Sciences Division, Northern Ontario School of Medicine, Lakehead University, 955 Oliver Road, Thunder Bay, Ont., Canada P7B 5E1.
| | - Edmund M K Lui
- Department of Physiology and Pharmacology, University of Western Ontario, London, Ont., Canada N6A-5C1
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Abstract
Hydrogen peroxide is an oxidising agent that is used in a number of household products, including general-purpose disinfectants, chlorine-free bleaches, fabric stain removers, contact lens disinfectants and hair dyes, and it is a component of some tooth whitening products. In industry, the principal use of hydrogen peroxide is as a bleaching agent in the manufacture of paper and pulp. Hydrogen peroxide has been employed medicinally for wound irrigation and for the sterilisation of ophthalmic and endoscopic instruments. Hydrogen peroxide causes toxicity via three main mechanisms: corrosive damage, oxygen gas formation and lipid peroxidation. Concentrated hydrogen peroxide is caustic and exposure may result in local tissue damage. Ingestion of concentrated (>35%) hydrogen peroxide can also result in the generation of substantial volumes of oxygen. Where the amount of oxygen evolved exceeds its maximum solubility in blood, venous or arterial gas embolism may occur. The mechanism of CNS damage is thought to be arterial gas embolisation with subsequent brain infarction. Rapid generation of oxygen in closed body cavities can also cause mechanical distension and there is potential for the rupture of the hollow viscus secondary to oxygen liberation. In addition, intravascular foaming following absorption can seriously impede right ventricular output and produce complete loss of cardiac output. Hydrogen peroxide can also exert a direct cytotoxic effect via lipid peroxidation. Ingestion of hydrogen peroxide may cause irritation of the gastrointestinal tract with nausea, vomiting, haematemesis and foaming at the mouth; the foam may obstruct the respiratory tract or result in pulmonary aspiration. Painful gastric distension and belching may be caused by the liberation of large volumes of oxygen in the stomach. Blistering of the mucosae and oropharyngeal burns are common following ingestion of concentrated solutions, and laryngospasm and haemorrhagic gastritis have been reported. Sinus tachycardia, lethargy, confusion, coma, convulsions, stridor, sub-epiglottic narrowing, apnoea, cyanosis and cardiorespiratory arrest may ensue within minutes of ingestion. Oxygen gas embolism may produce multiple cerebral infarctions. Although most inhalational exposures cause little more than coughing and transient dyspnoea, inhalation of highly concentrated solutions of hydrogen peroxide can cause severe irritation and inflammation of mucous membranes, with coughing and dyspnoea. Shock, coma and convulsions may ensue and pulmonary oedema may occur up to 24-72 hours post exposure. Severe toxicity has resulted from the use of hydrogen peroxide solutions to irrigate wounds within closed body cavities or under pressure as oxygen gas embolism has resulted. Inflammation, blistering and severe skin damage may follow dermal contact. Ocular exposure to 3% solutions may cause immediate stinging, irritation, lacrimation and blurred vision, but severe injury is unlikely. Exposure to more concentrated hydrogen peroxide solutions (>10%) may result in ulceration or perforation of the cornea. Gut decontamination is not indicated following ingestion, due to the rapid decomposition of hydrogen peroxide by catalase to oxygen and water. If gastric distension is painful, a gastric tube should be passed to release gas. Early aggressive airway management is critical in patients who have ingested concentrated hydrogen peroxide, as respiratory failure and arrest appear to be the proximate cause of death. Endoscopy should be considered if there is persistent vomiting, haematemesis, significant oral burns, severe abdominal pain, dysphagia or stridor. Corticosteroids in high dosage have been recommended if laryngeal and pulmonary oedema supervene, but their value is unproven. Endotracheal intubation, or rarely, tracheostomy may be required for life-threatening laryngeal oedema. Contaminated skin should be washed with copious amounts of water. Skin lesions should be treated as thermal burns; surgery may be required for deep burns. In the case of eye exposure, the affected eye(s) shod eye(s) should be irrigated immediately and thoroughly with water or 0.9% saline for at least 10-15 minutes. Instillation of a local anaesthetic may reduce discomfort and assist more thorough decontamination.
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Affiliation(s)
- Barbara E Watt
- National Poisons Information Service (Birmingham Centre), City Hospital, Birmingham, UK
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Kim HJ, Kim SG. Alterations in cellular Ca(2+) and free iron pool by sulfur amino acid deprivation: the role of ferritin light chain down-regulation in prooxidant production. Biochem Pharmacol 2002; 63:647-57. [PMID: 11992632 DOI: 10.1016/s0006-2952(01)00877-2] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Deficiency of sulfur amino acids occurs in certain pathophysiological states such as protein-calorie malnutrition. Sulfur amino acid deprivation (SAAD) increases oxidative stress through a decrease in GSH. Ferritin expression is induced by oxidative stress, which confers resistance to oxidative insults. The effects of SAAD on the changes in cellular Ca(2+) and free iron pool, prooxidant production and the ferritin light chain (FLC) expression were comparatively evaluated in Hepa1c1c7 and Raw264.7 cells. [Ca(2+)](i) was rapidly increased by SAAD. Sulfhydryl-containing compounds prevented the increase in [Ca(2+)](i) in cells under SAAD, supporting the role of redox-state in the regulation of [Ca(2+)](i). Thapsigargin or Ca(2+)-free medium inhibited the increase in [Ca(2+)](i), showing that Ca(2+) originated from endoplasmic reticulum as well as from extracellular source. Inhibition of Ca(2+) mobilization decreased the fluorescence of Phen Green SK inside cells, representing the inhibition of free iron release. Both inhibition of Ca(2+) mobilization and iron chelation decreased dichlorofluorescein oxidation, indicating the possibility that the increase in [Ca(2+)](i) affected that in cellular free iron and prooxidant production. FLC protein level was immunochemically detectable in Raw264.7 cells, but not in Hepa1c1c7 cells. SAAD alone (or in combination with FeSO(4)) down-regulated FLC protein expression, while SAAD increased the FLC mRNA level in both Hepa1c1c7 and Raw264.7 cells. Calcium or iron chelators prevented increases in the FLC mRNA. These results provided evidence that changes in cellular Ca(2+) and iron pool by SAAD increased cellular oxidative stress and that the down-regulation of FLC protein by SAAD would further enhance prooxidant production in spite of the increase in FLC mRNA.
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Affiliation(s)
- Hye Jung Kim
- College of Pharmacy and Research Institute of Pharmaceutical Sciences, Seoul National University, 151-742, Seoul, South Korea
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Gagné F, Pardos M, Blaise C, Turcotte P, Quémerais B, Fouquet A. Toxicity evaluation of organic sediment extracts resolved by size exclusion chromatography using rainbow trout hepatocytes. CHEMOSPHERE 1999; 39:1545-1570. [PMID: 10481253 DOI: 10.1016/s0045-6535(99)00051-x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
The (geno)toxicity of sediment dichloromethane extracts and fractions obtained by size exclusion chromatography were evaluated to investigate effects based on size fractionation. In this study, three sediments were selected according to their incremental contamination in PAHs and in PCBs: Hamilton harbour, Toronto bay and lake St. Clair sediments. Heavy metals, total sulfur and elemental sulfur (S8) were also determined in the (un)fractionated sediment extracts. The liver cells were exposed to concentrations of sediment extracts and fractionated samples for 24 h at 15 degrees C, afterwhich cell viability, cytochrome P4501A1 activity, available free Zn, DNA damage and oxidative stress were determined. The results showed that the sediment extracts contained high levels of sulfur most of which was found in the low molecular weight (LMW) region, i.e., the 2000-50 atomic mass unit (amu) fraction. Elemental sulfur (S8) accounted for 14-41% of extractable sulfur and were found to elute in the post-column volume (PCV) fraction despite its molecular weight of 256 amu. Heavy metals were found mainly in the HMW (i.e. the > 2000 amu) fraction and LMW fractions and very few or none were observed in the PCV fractions. In sediment extracts, sublethal effects were present principally by the HMW and LMW fractions suggesting that some chemicals were also associated with high molecular weight compounds of extractable organic matter. Less toxicity or effect was sometimes found in the extract indicating an antagonistic effect of the contaminants. We found that cell viability and genotoxicity evaluations could be performed on the unfractionated extracts while EROD, available Zn and oxidative stress measurements should be performed on the LMW fractions because of possible antagonist or shielding effects. Considering the cytotoxic responses, the best toxicity ranking in respect to contaminant levels in sediment extract was obtained with the LMW and PCV fractions which accounted for most of the toxic responses in the chromatographic fractions. Moreover, the shielding effect could be explained, in part, by the association of LMW contaminants to large macromolecules.
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Affiliation(s)
- F Gagné
- St-Lawrence Center, Montréal, Québec, Canada
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Latour I, De Ros E, Denef JF, Buc Calderon P. Protein S-thiolation can mediate the inhibition of protein synthesis induced by tert-butyl hydroperoxide in isolated rat hepatocytes. Toxicol Appl Pharmacol 1999; 160:1-9. [PMID: 10502497 DOI: 10.1006/taap.1999.8757] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
A rapid inhibition of protein synthesis is observed when isolated rat hepatocytes are incubated in the presence of 0.25-0.5 mM of tert-butyl hydroperoxide (tBOOH). Such an inhibition occurs in the absence of a cytolytic effect by tBOOH. Iron chelators (o-phenanthroline and desferrioxiamine), protected against oxidative cell death, but they did not modify the inhibition of protein synthesis caused by tBOOH (0.5 mM), suggesting that free radicals are less implicated in such an impairment. Electron micrographs of hepatocytes under oxidative stress show disaggregation of polyribosomes but not oxidative alterations, such as blebs or mitochondrial swelling. Protein synthesis inhibition is accompanied by a decrease in reduced glutathione (GSH) and an increase in glutathione disulfide (GSSG) and the level of protein S-thiolation (protein mixed disulfides formation). Such an increase of GSSG appears as a critical event since diethylmaleate (DEM) at 0.2 mM reduced GSH content by more than 50% but did not affect either GSSG content or protein synthesis. The addition of exogenous GSH and N-acetylcysteine (NAC) to tBOOH-treated hepatocytes significantly reduced the formation of protein mixed disulfides and restored the depressed protein synthesis either completely or partially. We suggest that S-thiolation of some key proteins may be involved in protein synthesis inhibition by tBOOH.
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Affiliation(s)
- I Latour
- Métabolisme, Université Catholique de Louvain, Bruxelles, 1200, Belgium
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Tyurin VA, Tyurina YY, Quinn PJ, Schor NF, Balachandran R, Day BW, Kagan VE. Glutamate-induced cytotoxicity in PC12 pheochromocytoma cells: role of oxidation of phospholipids, glutathione and protein sulfhydryls revealed by bcl-2 transfection. BRAIN RESEARCH. MOLECULAR BRAIN RESEARCH 1998; 60:270-81. [PMID: 9757062 DOI: 10.1016/s0169-328x(98)00181-8] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Incubation of mock-transfected PC12 rat pheochromocytoma cells (PC12) for 2 h with increasing concentrations of glutamate caused progressive loss of viability (e.g., 67% with 15 mM glutamate). In contrast, the viability of bcl-2-transfected cells (PC12/bcl-2) was unaffected by glutamate. Neither PC12 nor PC12/bcl-2 cells showed a significant incidence of apoptosis in response to glutamate. Conventional phospholipid analysis by high-performance TLC and phosphorous determination showed no significant changes in the phospholipid composition of either cell line incubated with </=15 mM glutamate. Phospholipid peroxidation was quantified in the cells using our newly developed method based on fluorescence-HPLC analysis of metabolically incorporated oxidation-sensitive and fluorescent fatty acid, cis-parinaric acid. Unlike previous studies that measured total phospholipid oxidation, this novel technology permitted quantitation of oxidative stress in different classes of labeled phospholipids (the amount of labeled phospholipids in the cells did not exceed 1% of total phospholipids). Significant peroxidation of phosphatidylcholine and phosphatidylethanolamine occurred in PC12 cells treated with >5 mM glutamate. The peroxyl radical initiator 2,2'-azobis(2,4-dimethylvaleronitrile) caused a pronounced loss of all major phospholipid classes in PC12 cells, but no loss of cell viability. No phospholipid peroxidation was detected in PC12/bcl-2 cells incubated with </=15 mM glutamate or with 2, 2'-azobis(2,4-dimethylvaleronitrile). These results directly demonstrate that peroxidation of membrane phospholipids is not responsible for the cytotoxicity of glutamate in PC12 cells. Total cellular thiol, protein thiol and GSH reserves were quantified by a previously described electron paramagnetic resonance spectrometric method. Total thiols were ca. 1.5-fold greater in PC12/bcl-2 than in PC12 cells. Glutamate (</=5 mM) caused a progressive and equally significant decrease in total thiols and GSH in both PC12 and PC12/bcl-2 cells. High glutamate concentrations caused oxidation of protein sulfhydryls in PC12 cells, but not in PC12/bcl-2 cells. The results suggest that the changes in cellular milieu caused by bcl-2 gene transfection protect PC12 cells from the toxic effects of glutamate in a manner consistent with prevention of protein sulfhydryl oxidation.
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Affiliation(s)
- V A Tyurin
- Department of Environmental and Occupational Health, University of Pittsburgh, Pittsburgh, PA 15238, USA
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Ollinger K, Roberg K. Nutrient deprivation of cultured rat hepatocytes increases the desferrioxamine-available iron pool and augments the sensitivity to hydrogen peroxide. J Biol Chem 1997; 272:23707-11. [PMID: 9295314 DOI: 10.1074/jbc.272.38.23707] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
Primary cultures of rat hepatocytes were subjected to amino acid and serum deprivation for 4 h. This treatment augmented the sensitivity to ensuing hydrogen peroxide exposure for 30 min. The by nutrient deprivation-increased autophagocytosis was confirmed by transmission electron microscopy and uptake of the lysosomotropic weak base acridine orange within the intracellular acidic vacuolar apparatus. The desferrioxamine-available pool of iron increased 2.5-fold during deprivation, compared with control cells. Furthermore, amino acid deprivation increased the cellular protein turnover, measured by radioactive labeling with -3H-Leu. Exposure to 40 microM ascorbic acid specifically decreased the turnover of ferritin, as estimated by enzyme-linked immunosorbent assay, and prevented an increase of the desferrioxamine-available iron pool, resulting in protection against hydrogen peroxide-induced cell killing. Thus, hepatocytes with nutrient deprivation-enhanced autophagocytosis contain a larger pool of catalytically active iron than control cells. This iron pool is mainly derived from the turnover (autophagocytosis) of cytosolic ferritin and is probably situated in the lysosomes. Furthermore, nutrient-deprived cells show augmented sensitivity to hydrogen peroxide-induced oxidative stress, since the enhanced availability of iron in low molecular weight form results in an increased potential of intralysosomal Fenton chemistry, that may cause lysosomal rupture with release of potent hydrolytic enzymes.
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Affiliation(s)
- K Ollinger
- Department of Pathology II, Faculty of Health Sciences, Linköping University, S-581 85 Linköping, Sweden.
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Kozlov AV, Bini A, Gallesi D, Giovannini F, Iannone A, Masini A, Meletti E, Tomasi A. 'Free' iron, as detected by electron paramagnetic resonance spectroscopy, increases unequally in different tissues during dietary iron overload in the rat. Biometals 1996; 9:98-103. [PMID: 8574097 DOI: 10.1007/bf00188097] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
'Free' iron concentration, as determined by electron paramagnetic resonance (EPR) spectroscopy, and lipid peroxidation (LPO), as determined by thiobarbituric acid test, were assessed in the lung, heart, liver, spleen, brain and kidney of rats subjected to experimental iron overload. Two tests, Desferal- and NO-available iron, were used to measure 'free' iron and gave comparable results. The most pronounced accumulation of 'free' iron was observed in liver, kidney and spleen. Differences between control and iron loaded animals increased during the initial 90 days of treatment. Between 90 and 180 days 'free' iron concentration reached a steady state level, or even decreased, as in the case of liver. Lipid peroxidation level, measured in the organs of both treated and matched controls, did not give any significant difference during the initial 90 days of treatment. A significant augmentation was observed in liver, kidney, spleen and heart at 180 days. The results of the present research show that, under conditions of moderate siderosis, the occurrence of LPO is partially related to the level of 'free' iron.
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Affiliation(s)
- A V Kozlov
- Department of Biomedical Science, University of Modena, Italy
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Lefebvre V, Buc-Calderon P. Desferal prevents against cell lysis induced by hydrogen peroxide to hypoxic hepatocytes: a role for free iron in hypoxia-mediated cellular injury. Chem Biol Interact 1995; 94:37-48. [PMID: 7820879 DOI: 10.1016/0009-2797(94)03319-4] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Isolated hepatocytes incubated under hypoxic conditions were more sensitive to H2O2-mediated injury as compared to cells kept under aerobic conditions, but only for the highest H2O2 concentration tested (8 mM). At lower concentrations (2 and 4 mM) cells were still able to detoxify H2O2 even under hypoxic conditions. Reoxygenation of hypoxic hepatocytes did not result in a cytolytic effect, whereas reoxygenation in the presence of H2O2 resulted in an enhanced cytotoxicity. The duration of previous hypoxia (before H2O2 addition) did not affect the lytic effect induced by H2O2. Enzymatic activities of both catalase and glutathione peroxidase were unchanged over 2 h of incubation under hypoxic conditions. Preincubation of hepatocytes in the presence of Desferal (5 mM) resulted in the abolition of H2O2-mediated lytic effects. A role for free iron, released from intracellular stores and acting on H2O2 to yield reactive oxygen species is discussed.
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Affiliation(s)
- V Lefebvre
- Département des Sciences Pharmaceutiques, Université Catholique de Louvain, Bruxelles, Belgium
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