Erythrocyte Antioxidant System Research Articles

Subacute chlorpyrifos-induced oxidative stress in rat erythrocytes and the protective effects of catechin and quercetin

This study examined the effects of chlorpyrifos in the rat erythrocyte antioxidant system and evaluated the ameliorating effects of catechin and quercetin on the oxidative damage induced by chlorpyrifos. Sexually mature male Wistar rats were given chlorpyrifos (5.4 mg/kg, 1/25 of the oral LD 50), catechin (20 mg/kg), quercetin (20 mg/kg), catechin plus chlorpyrifos, and quercetin plus chlorpyrifos daily via gavage for four weeks. No statistical differences were found in the catechin-only and quercetin-only groups compared with the control group. By the end of the fourth week, chlorpyrifos alone increased the levels of malondialdehyde (MDA) and decreased superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPx) activities compared with the control group in rat erythrocytes. In the catechin-plus-chlorpyrifos and quercetin-plus-chlorpyrifos groups, there were statistically significantly decreased MDA levels and increased SOD, CAT, and GPx activities compared with the chlorpyrifos-only group. Thus, it appears that catechin and quercetin ameliorate chlorpyrifos-induced oxidative stress in rat erythrocytes in vivo.

Effects of combined vanadate and magnesium treatment on erythrocyte antioxidant defence system in rats

The effect of vanadate and magnesium treatment on erythrocyte defence system was studied in outbred 2-month-old, albino male Wistar rats (14 rats/each group) which daily received: Group I (Control)—deionized water to drink; Group II—water solution of sodium metavanadate (NaVO 3; SMV) at a concentration of 0.125 mg V/mL; Group III—water solution of magnesium sulfate (MgSO 4; MS) at a concentration of 0.06 mg Mg/mL, Group IV—water solution of SMV–MS at the same concentrations over a 12-week time. The fluid intake and the concentration of reduced glutathione (GSH) as well as the activity of Cu, Zn-superoxide dismutase (Cu, Zn-SOD), catalase (CAT) and glutathione reductase (GR) were significantly decreased in the rats receiving SMV alone (Group II) or in combination with MS (Group IV) compared with Groups I and III. The cellular glutathione peroxidase (cGSH-Px) activity was unchanged in all the treated groups. The activity of glutathione S-transferase (GST) fell in the animals in Group II, compared with the rats in Groups I, III and IV; whereas in the rats in Group III its activity was higher than in the control animals. These results showed that V (as SMV) consumed by the rats with drinking water at a dose of 12 mg V/kg b.w./24 h for 12 weeks may attenuate defence system in rats’ erythrocytes (RBCs), which is probably a consequence of vanadium pro-oxidant potential. Therefore, reactive oxygen species (ROS) are suggested to be involved in the alterations in antioxidant defence system in these cells. Mg (as MS) at the dose ingested (6 mg Mg/kg b.w./24 h) at co-exposure to SMV was not able to counteract its deleterious effect. The results also provide evidence that V–Mg interactions may be involved in the decrease of erythrocyte GR activity and Mg concentration in the plasma under concomitant treatment with both metals at the doses of 12.6 mg V and 6 mg Mg/kg b.w./24 h.

Effects of antioxidant enzymes in erythrocytes on pulmonary arterial pressure during hypoxic gas breathing

Using isolated rabbit lungs (n = 72) perfused at a constant flow of 70 ml/min, we analyzed whether the antioxidant system in erythrocytes significantly contributes to maintaining pulmonary vascular responsiveness to alveolar hypoxia (HPV) in normal lungs. As a measure of HPV, we observed the difference (delta P) between mean pulmonary arterial pressure during ventilation with normoxic gas mixture (21% O2, 5% CO2 in N2) and that during hypoxic gas breathing (3% O2, 5% CO2 in N2). Autologous erythrocytes obtained from the animals treated with various substances inhibiting either superoxide dismutase (SOD), the anion channel of the membrane, catalase (CAT) or glutathione peroxidase (GSH-Px). Subsequently, delta P was systematically measured in the perfusate, whose hematocrit was adjusted to 6-7% with normal or treated erythrocytes as described above. Further, the effects of adding SOD (75 U/ml) or CAT (1000 U/ml) to the perfusate on delta P were examined. The following results were obtained. (1) Inhibition of the superoxide scavenging mechanism in erythrocytes (SOD and anion channel) exerted no significant influence on delta P. (2) Inhibition of hydrogen peroxide scavengers in erythrocytes did not alter the scope of delta P. (3) Addition of either SOD or CAT to the perfusate did not show any significant effect on delta P. The findings are highly consistent with the idea that HPV in normal lungs is essentially independent of antioxidant enzymes in erythrocytes, which are expected to be one of the important factors determining the total capacity to deal with oxidant stress in the lung.

Effects of zinc and cadmium on erythrocyte antioxidant systems of a freshwater fish Oreochromis niloticus

In this work to determine the effects of metals exposure of Oreochromis niloticus on erythrocyte antioxidant systems, fish were exposed to 5.0 mg/L Zn, 1.0 mg/L Cd, and 5.0 mg/L Zn + 1.0 mg/L Cd mixtures for 7 and 14 days and reduced glutathione (GSH) level, catalase (CAT), and glucose-6-phosphate dehydrogenase (G6PD) activities were investigated. In addition, Zn or Cd levels in whole blood were studied. Erythrocyte GSH level and CAT and G6PD enzyme activities increased in response to single and combined Zn and Cd exposure. The elevation observed in the CAT activity was higher in the Cd alone, and in combination with Zn, than in Zn alone. Time-dependent alteration was not observed in all antioxidant parameters. Exposure to metals (alone and in mixture) resulted in elevatation of Zn and Cd levels in the blood. Concentration of metals in the blood of fish exposed to the Zn + Cd combination was lower than in fish exposed to the single metal. This study demonstrates that metals caused oxidative stress in fish erythrocytes, and an adaptation with an increase in CAT and G6PD activities and GSH level, which were important in the protection against metal damage, was observed.

Influence of green tea on erythrocytes antioxidant status of different age rats intoxicated with ethanol

The aim of this paper is to evaluate the effect of green tea on the erythrocyte antioxidant system of ethanol-intoxicated rats, as well as its efficacy in the prevention of lipid peroxidation. Rats (2, 12 and 24 months old) were fed on a control or an ethanol Lieber-DeCarli diet with and without green tea (7 g/L) for 5 weeks. Examination included the activity of antioxidant enzymes and the level of both non-enzymatic antioxidants and lipid peroxidation marker in rat erythrocytes. It was shown that ageing was accompanied by changes in the antioxidant enzymes activity - increase in the SOD and CAT activity and decrease in GSSG-R and GSH-Px activity, as well as in the level of non-enzymatic antioxidants - GSH, vitamin A and vitamin E. The increase in the level of lipid peroxidation marker - MDA - was also observed. Green tea consumption partially prevented lipid peroxidation process, especially in erythrocytes of 2- and 12-month-old rats. It was proved that ethanol administration caused a statistically significant decrease in the activity/level of the examined antioxidants in all age groups (the most significant in the case of 24-month-old rats) of rats, as well as an increase in the MDA level. However, ingestion of green tea by ethanol-intoxicated rats partially prevented the decrease in activity/level of all examined antioxidant parameters, as well as protected lipids against peroxidation in all age groups of rats. Obtained results confirm the beneficial effect of green tea on erythrocyte antioxidant abilities.

Peroxiredoxin 2 and Peroxide Metabolism in the Erythrocyte

Peroxiredoxin 2 (Prx2) is an antioxidant enzyme that uses cysteine residues to decompose peroxides. Prx2 is the third most abundant protein in erythrocytes, and competes effectively with catalase and glutathione peroxidase to scavenge low levels of hydrogen peroxide, including that derived from hemoglobin autoxidation. Low thioredoxin reductase activity in the erythrocyte is able to keep up with this basal oxidation and maintain the Prx2 in its reduced form, but exposure to exogenous hydrogen peroxide causes accumulation of the disulfide-linked dimer. The high cellular concentration means that although turnover is slow, erythrocyte Prx2 can act as a noncatalytic scavenger of hydrogen peroxide and a sink for hydrogen peroxide before turnover becomes limiting. The consequences of Prx2 oxidation for the erythrocyte are not well characterized, but mice deficient in this protein develop severe hemolytic anemia associated with Heinz body formation. Prx2, also known as calpromotin, regulates ion transport by associating with the membrane and activating the Gárdos channel. How Prx2 redox transformations are linked to membrane association and channel activation is yet to be established. In this review, we discuss the functional properties of Prx2 and its role as a major component of the erythrocyte antioxidant system.

Effects of subacute exposure of dichlorvos at sublethal dosages on erythrocyte and tissue antioxidant defense systems and lipid peroxidation in rats

In this study, the effects of dichlorvos (DIC) at sublethal concentration on malondialdehyde (MDA) content and antioxidant defense system (ADS) such as reduced glutathione (GSH), glutathione reductase (GR), superoxide dismutase (SOD), and glutathione- S-transferase (GST) in various tissues of rats exposed to 0.0225 and 0.0450 millimole (mmol) DIC in drinking water were administered orally to rats ad libitum for 28 days continuously. MDA significantly increased in all the tissues except in the lungs of rats treated with both dosages of DIC. With regard to the ADS, GR significantly decreased in the erythrocytes whereas it did not change in the other tissues with two dosages of DIC. SOD activity significantly increased in the all tissues treated with both dosages of DIC. GST activity significantly increased in all the tissues except in the erythrocytes, spleen, and lungs treated with 0.0225 mmol. Meanwhile, GSH depletion in the liver and heart of rats treated with 0.0225 mmol and all the tissues except in the brain and kidney of rats treated with 0.0450 mmol of DIC were found to be significant. The observations presented led us to conclude that the administrations of DIC promote MDA content and fluctuate in the ADS in rats during the exposure.

Erythrocyte antioxidant enzyme activities and lipid peroxidation in the erythrocyte membrane of stainless-steel welders exposed to welding fumes and gases

The erythrocyte antioxidant system (superoxide dismutase, SOD; catalase, CAT) and lipid peroxidation (malondialdehyde, MDA) in the erythrocyte membrane were studied in workers continously exposed to welding fumes and gases, which are thought to be oxidant pollutants. Thirty-five welders using the manual metal arc method on stainless steel and 30 controls were studied. Plasma chromium (Cr), manganese (Mn), and cupper (Cu) levels were determined by atomic absorption spectrophotometer (AAS). The erythrocyte antioxidant system activity and lipid peroxidation in the erythrocyte membrane were evaluated. Not only the possible effects of welding fumes but also the effects of smoking were considered. The plasma concentrations of Cr, Mn, and Cu for the exposed welders were significantly higher compared to the control subjects ( p<0.001, p<0.01, p<0.001, respectively,). The erythrocyte CAT ( p<0.05) and SOD ( p<0.05) enzyme activities were significantly higher in the welders but there were not any significant changes in the MDA levels which reflect the lipid peroxidation in the erythrocyte membrane ( p>0.05). Smoking has increased the SOD activity in both controls ( p<0.05) and welders ( p<0.01) and increased the CAT activity in control subjects ( p<0.05). Moreover, regardless of smoking, there were some significant correlations between the duration of the exposure to welding fumes and antioxidant defence system (SOD: p<0.05; CAT: p<0.05). The synergistic effects of smoking and other risk factors (welding fumes and gasses), which had been shown previously by some clinical data should also be taken into account. As a consequence, the welders should be warned and informed of the synergistic effects of smoking on the adverse effect of welding fumes and gases.

Antioxidant Status of Red Blood Cells Is a Modifying Factor of Clinical Manifestation of Unstable Hemoglobin Variant Hana [α2β2 63 (E7) His-Asn)

Hemoglobin Hana [α2β2 63 (E7) His-Asn)] was described in a Moravian family from the Czech Republic as an unstable hemoglobin variant with mild Heinz body hemolytic anemia, elevated levels of methemoglobin (12–13%), and variable reticulocytosis (1.8–11%) in the proband and her sister.1 Surprisingly, their mother is asymptomatic, although she expresses the same aberrant variant of the β-globin gene. We did not detect any differences in the globin gene expression (based on wild-type and mutant globin mRNA from reticulocytes and βA and βHana chains measured by HPLC).1 Iron metabolism indices were within normal range in all family members. G6PD status in both parents was normal. To test whether the erythrocyte antioxidant capacity affects severity of this unstable hemoglobinopathy, key antioxidant parameters, including content of reduced (GSH) and oxidized glutathione (GSSG), activity of superoxide dismutase (SOD), catalase (CAT), and NADH-methemoglobin reductase (MetHb RED) were examined. Our results revealed that erythrocytes of both children exhibited lower GSH content, the ratio of GSSG/GSH was increased 6 to 7 times, and their catalase activity was decreased to 71–77% of the average control activity (Table 1). The increased ratio of GSSG/GSH could be related to the accumulation of peroxides in erythrocytes of the children and reflects lower ability of the enzyme antioxidant system to eliminate free oxygen radicals. In contrast, erythrocytes of their mother exhibited normal values of all these measured parameters except the activity of SOD, which was increased by 32% above normal level (Table 1). Activities of some antioxidant enzymes are altered in cigarette smokers2 and the mother is a heavy smoker (with elevated CO-Hb to 5.5%). We hypothesize she might benefit from higher SOD activity caused by activation of “oxidative stress genes” and that could, in turn, enhance the ability of her erythrocytes to deal with superoxide and hydrogen peroxide accumulation which results in more efficient prevention of hemoglobin oxidation. In the children, the decrease in hydrogen peroxide catabolizing capacity due to lower erythrocyte catalase activity strongly associates with a more severe clinical manifestation of this unstable hemoglobinopathy. Our findings suggest that alterations (either inherent or caused by extrinsic factors) in the levels of red blood cell antioxidant defense enzymes represent modifying factors affecting the clinical manifestation of Heinz body hemolytic anemia associated with an unstable hemoglobin variant.Table 1:Levels of erythrocyte antioxidant systems in the family membersUnaffected MotherDaughter 1 with HADaughter 2 with HANormal controls (n = 10)RangeGSHa(μmol/g Hb)3.72.92.73.9±0.63.3–4.5GSSG/GSHb0.351.91.50.27±0.20.12–0.42MetHb RED (U/g Hb)15151416±2.813–19SOD (U/g Hb)2707232519332052±3111741–2363CAT (U/g Hb)282227245320±57263–377a - spectrophotometry, b - HPLC-MS

Changes in the erythrocyte anti-oxidant system of offspring of dams treated with Vitamin A and β-carotene during gestation

The aim of this study was to determine the changes in the erythrocyte anti-oxidant defence system and lipid peroxidation as thiobarbituric acid substance (TBARS) of lambs of which the dams were injected with Vitamin A and β-carotene during pregnancy. The lambs of 32 Tuj sheep, aged 4–5 years and weighing approximately 57 ± 5.6 kg each, were used in the study. The ewes were divided into four groups of eight sheep each. The oestrous cycles of all the ewes were synchronised. After synchronisation, a ram was placed with each group. The first group was used as the control and given a placebo. The other groups received 8 mg/kg β-carotene (Group II ), 200,000 IU Vitamin A (Group III) and a combination of 100,000 IU Vitamin A and 4 mg/kg β-carotene (Group IV) intramuscularly at 30-day intervals, 15 days before breeding and during gestation. On the 1st and 15th day after parturition, blood samples were taken of lambs in order to measure the plasma levels of Vitamin E and lipid peroxidation (LPO) and the activity of glutathione peroxidase (GSHP X) and the levels of glutathione (GSH) in the erythrocytes. In this study, a significant difference ( p < 0.001) was observed in the plasma levels of Vitamin E of the lambs in Groups II, III and IV, compared to the lambs of the control group after birth. However, plasma levels of Vitamin E of the lambs were little affected 2 weeks after birth. The erythrocyte GSHP X activity of the lambs increased in Groups II, III and IV, compared to the control group after birth ( p < 0.001). The injection of Vitamin A and/or β-carotene had a preventative effect on the elevation of plasma LPO levels in the lambs ( p < 0.001) and improved the erythrocyte GSH levels of the lambs in Groups II, III and IV ( p < 0.001). Findings indicate that an increased supressor activities against free radical elevation was obtained with Vitamin A and β-carotene injections. This provides a transfer of protective substances from the ewes to the lambs which may have supported the anti-oxidant defence system and also the survival and elevated growth rates of the lambs.

Erythrocyte antioxidant system in Down syndrome

It has been emphasized that an increased oxidative damage can exist in Down syndrome (DS), and that superoxide dismutase (SOD-1) seems to play a role in the pathogenesis of this disorder. We have studied the antioxidant system SOD-1, catalase, glutathione peroxidase (GSH-Px) and reduced glutathione (GSH) in erythrocytes of DS adults in order to evaluate if these cells are protected against oxidant stress. SOD-1 and GSH-Px were significantly increased while catalase and GSH activities were normal. These results suggest that the erythrocytes of these individuals have an unbalanced antioxidant system which may participate in the manifestations of DS.

Influence of Epoietinum Therapy on the Oxidative Stress in Haemodialysis Patients

Background: The causes of oxidative stress in haemodialysis (HD) patients are still controversial. Beside the uraemic state and dialysis-related factors, adjuvant drug therapies such as epoietinum (rHuEpo) and intravenous iron were involved. Methods: Several parameters related to oxidative stress were assessed by spectrophotometry in stable HD patients, treated for at least 2 months with epoietinum (n = 14; mean dose = 97.7 ± 19.1 U/kg/week) or not (n = 15), none of them on iron therapy, and in 13 controls. Plasma thiobarbituric acid-reactive substances (TBARS) were used as markers of reactive species generation. Erythrocyte and plasma antioxidant systems, reflected by non-protein erythrocyte thiols, and erythrocyte enzyme activities – superoxide dismutase (SOD), glutathione peroxidase, catalase and plasma total thiols, respectively – were also investigated. Results: There were no differences between HD subgroups regarding haemoglobin levels. Plasma TBARS was increased in all HD patients as opposed to controls, irrespective of rHuEpo therapy. In addition, no change in antioxidant status parameters between rHuEpo-treated and -untreated patients was observed. Except for SOD, the other antioxidant indices were higher in all HD patients versus controls. Conclusions: These results suggest that (1) chronic HD patients appear to have simultaneously enhanced reactive species generation and antioxidative systems efficiency, and (2) epoietinum therapy did not change their oxidative status, at least in the absence of concomitant iron supplementation and at similar haemoglobin levels.

Adaptations of the antioxidant system in erythrocytes of trained adult rats: Impact of intermittent hypobaric-hypoxia at two altitudes

We have investigated the effects of daily exposure to intermittent hypobaric-hypoxia to two simulated altitudes (5700 m and 6300 m) in adult male rats that had been regularly swim trained in normoxia at sea level prior to exposures. Superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GSH-Px) along with the oxidative stress (OS) indices, malondialdehyde (MDA) and protein carbonyl content were measured in erythrocytes and their membranes. Hemoglobin increased in the trained animals exposed to 5700 m and in untrained rats exposed to 6300 m. Osmotic fragility in terms of hemolysis increased in altitude exposed animals. SOD increased in those exposed to 6300 m, while CAT increased in trained rats exposed to 5700 m and to 6300 m unlike in untrained rats where CAT increased only at 6300 m. GSH-Px showed varying degrees of elevation in all animals exposed to both altitudes. Erythrocyte membranes showed significant elevations in malondialdehyde (MDA) at 6300 m, while elevated protein carbonyls were noticeable at both altitudes in whole cells and membranes. These results suggest a positively associated elevation in protein oxidation with altitude in trained rats. At 5700 m, animals were less stressed, unlike at 6300 m, as seen from the magnitude of elevations in the OS indices and from the responses of the antioxidant enzymes.

Plasma TBARS, blood GSH concentrations, and erythrocyte antioxidant enzyme activities in regularly menstruating women with ovulatory and anovulatory menstrual cycles

Background: Vigorous physical activity and subsequent depressed ovarian hormone secretion resulting in anovulatory menstrual cycles can affect erythrocyte antioxidant system in premenopausal women and contribute to attenuated protection against oxidative stress. Methods: A total of 17 regularly menstruating women participated in the study. Prospective subjects monitored their basal body temperature (BBT) for 3 months prior to the study. Plasma progesterone concentration was assayed between the 7th and 9th day and again between the 22nd and 25th day of the menstrual cycle and made possible the classification of participants as either ovulating or non-ovulating. Plasma 17-β-estradiol concentration was determined on the same menstrual cycle days as progesterone. Plasma thiobarbituric acid-reacting substances (TBARS) served as an index of plasma lipid peroxidation. Whole blood-reduced glutathione (GSH) concentration and glutathione peroxidase (GSH-PX) activity and erythrocyte catalase (CAT), superoxide dismutase and glutathione reductase (GSH-RX) represented red cells antioxidants. Results: In non-ovulating women, the lack of progesterone peak between the 22nd and 25th day of the menstrual cycle was demonstrated. In addition, markedly lower ( P<0.008) plasma 17-β-estradiol concentrations in non-ovulating females than in ovulating ones in the follicular phase was noted. In the luteal phase, plasma 17-β-estradiol levels in non-ovulating subjects tended to be lower ( P<0.06) than in ovulating counterparts. Mean concentrations of plasma thiobarbituric-reacting substances and blood-reduced glutathione and mean activities of glutathione reductase, glutathione peroxidase and catalase did not differ significantly in ovulating and non-ovulating women. In non-ovulating women, both between the 7th and 9th day and the 22nd and 25th day of the menstrual cycle, erythrocyte superoxide dismutase (SOD) activity was higher ( P<0.02) than in their ovulating counterparts. In ovulating subjects, significant and inverse correlation was demonstrated between circulating estradiol and SOD activity in collected data from both follicular and luteal phases. Conclusions: Current results indicate that persistent ovarian hormone disturbances in regularly menstruating women, and resultant anovulation did not affect plasma lipid peroxidation and GSH-dependent erythrocyte antioxidant defense. However, lower plasma estradiol concentrations resulted in attenuated erythrocyte SOD inhibition and elevated enzyme activity. The mechanism of inhibitory estradiol action on erythrocyte SOD activity as well as the importance of this effect for antioxidant protection merits further studies.

In vivo changes in antioxidant systems and protective role of melatonin and a combination of vitamin C and vitamin E on oxidative damage in erythrocytes induced by chlorpyrifos-ethyl in rats.

Reactive oxygen species (ROS) may be involved in the toxicity of chlorpyrifos-ethyl (CE) [O,O-diethyl-O-(3,5,6-trichloro-2-pyridyl)phosphorothioate]. We have, therefore, examined the in vivo effects of CE on the rat erythrocyte antioxidant system and evaluated the ameliorating effects of melatonin and a combination of vitamin E and vitamin C on the oxidative damage induced by CE. The experimental groups were: (1) control group, (2) CE-treated group (CE), (3) vitamin E plus vitamin C treatment group (Vit), (4) melatonin-treated group (Mel), (5) vitamin E plus vitamin C plus CE treatment group (Vit + CE), and (6) melatonin plus CE treatment group (Mel + CE). Vitamin E and vitamin C were administered intramuscularly once a day for 6 consecutive days at 150 and 200 mg/kg, respectively, in the Vit and Vit + CE groups. Melatonin was administered intramuscularly at 10 mg/kg per day for 6 consecutive days in the Mel and Mel + CE groups. At the end of the fifth day, the rats of CE, Vit + CE and Mel + CE groups were treated orally with the first of two equal doses of 41 mg/kg CE, the second oral dose being given 21 h later. Blood samples were taken 24 h after the first CE administration. Levels of thiobarbituric acid reactive substance (TBARS), antioxidant defence potential (AOP), and the activities of superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), and catalase (CAT) were determined in erythrocytes. In comparison with the control group, oral administration of CE significantly (P < 0.05) stimulated TBARS activity while significantly (P < 0.05) inhibiting AOP and the activities of SOD and CAT. However, GSH-Px activity remained unchanged by CE treatment. Treatment with melatonin and vitamins E plus C significantly (P < 0.05) reduced the CE-induced increase of TBARS, and overcame the inhibitory effect of CE on SOD and CAT, but not on AOP. Melatonin treatment significantly (P < 0.05) increased only GSH-Px activity, irrespective of the effect of CE. These results suggest that CE treatment increases in vivo lipid peroxidation and decreases antioxidant defence by increasing oxidative stress in erythrocytes of rats, and melatonin and a combination of vitamin E and vitamin C can reduce this lipoperoxidative effect.

Oxidative damage of erythrocytes: a possible mechanism for premature hemolysis in experimental visceral leishmaniasis in hamsters.

Visceral leishmaniasis is accompanied by severe anemia and pancytopenia. Reactive oxygen species are known to contribute to the pathogenesis of several red blood cell (RBCs) disorders. The present study reveals the extent of oxidative stress and the efficacy of the primary antioxidant system in erythrocytes of hamsters in the progressive anemic response at different stages of leishmanial infection. Increased intracellular precipitation of Heinz bodies secondary to oxidative denaturation of hemoglobin and enhanced formation of malonyldialdehyde suggest oxidative damage of erythrocytes, both in the hemoglobin and cell membrane, respectively. Decreased activities of superoxide dismutase and catalase in the infected animals indicate the generation of O2*- and H2O2, which in turn may produce the highly reactive *OH species. Decreases in the reduced glutathione level along with the decreased activities of glutathione reductase and glutathione peroxidase point to a deficient antioxidant defense system during the post-infection period. Accentuated degradation of both cytoskeletal and integral membrane proteins after 3 months of infection may eventually lead to membrane destabilization and early lysis of erythrocytes in experimental visceral leishmaniasis.

Oxidative stress and haemodialysis: role of inflammation and duration of dialysis treatment.

Oxidative stress has long been demonstrated in haemodialysis patients. However, the factors influencing their oxidative status have not been characterized extensively in these patients. Therefore, the present study was designed to investigate the influence of a large number of factors known to be associated with oxidative stress. In the present cross-sectional study, we determined the plasma levels of lipid and protein oxidation markers in 31 non-smoking haemodialysis patients and 18 non-smoking healthy subjects, together with various components of the antioxidant system at the plasma and erythrocyte level. No influence of age, diabetes or iron overload on oxidative markers and plasma and erythrocyte antioxidant systems was detected in these haemodialysis patients. The lack of an association between iron overload and oxidative status may be related to the lower level of plasma ascorbate in haemodialysis patients, since ascorbate favours the generation of free iron from ferritin-bound iron. Interestingly, plasma C reactive protein (CRP) levels measured by highly sensitive CRP assay were correlated positively with plasma levels of thiobarbituric acid reactive substances (r=0.38, P<0.04) and negatively with plasma alpha-tocopherol levels (r=-0.46, P<0.01). Moreover, significant inverse correlations were observed between duration of dialysis treatment and plasma levels of alpha-tocopherol (r=-0.49, P<0.02) and ubiquinol (r=-0.40, P<0.05). Our results suggest that inflammatory status and duration of dialysis treatment are the most important factors relating to oxidative stress in haemodialysis patients.

Oxidant/Antioxidant Status of Erythrocytes from Patients with Chronic Renal Failure: Effects of Hemodialysis

Objective: It has been suggested that oxidative processes may be increased in patients with chronic renal failure (CRF), and that this is a possible factor contributing to the development of anemia and atherosclerosis, characteristic complications of CRF. The aim of this study was to investigate erythrocyte oxidant/antioxidant status in patients with CRF and to elucidate possible effects of hemodialysis on erythrocyte antioxidant system. Methods: Fasting blood samples were obtained from 33 patients with CRF and from 12 healthy controls. Of the patients, 17 subjects were under regular hemodialysis. Values of the activities of antioxidant enzymes, namely superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), catalase (CAT) and antioxidant potential, nonenzymatic superoxide radical scavenger activity (NSSA) and levels of thiobarbituric acid reagent substances (TBARS) were measured in the erythrocytes from both patients and controls. Results: Antioxidant potential and NSSA values were found to be significantly decreased, while TBARS levels were increased in the erythrocytes of patients. SOD activity was found to be unchanged, but GSH-Px and CAT activities were significantly lower in the patient group. Moreover, the erythrocyte TBARS level in the hemodialysis group was higher than in the controls and nonhemodialysis patients. Conclusion: The results suggest that antioxidant potential is reduced due to impaired antioxidant system in erythrocytes from patients with CRF and that oxidant stress causes significant peroxidation. Hemodialysis is determined to further increase oxidative reactions. These changes seem to contribute to the occurrence of some complications of CRF. Therefore, it has been suggested that antioxidant supplementation may give beneficial results for these patients.

Affinity of hemoglobin for oxygen and prooxidant-antioxidant equilibrium after administration of lipopolysaccharide during correction of the L-arginine—NO pathway

Effects of correction of the L-arginine—NO pathway on the fever reaction, oxygen transport function of the blood, and prooxidant-antioxidant equilibrium in rats injected intramuscularly with lipopolysaccharide were studied. pH, Pco2, Po2, and the index of hemoglobin oxygen affinity (p50) were measured in mixed venous blood. Levels of Schiff bases, α-tocopherol, and catalase activity were determined in erythrocytes and in the liver, kidneys, and heart. NO synthase inhibitor attenuated the fever reaction and decreased p50 to 28.89±0.83 mm Hg (in rats administered with lipopolysaccharide, p50 was 34.21±1.63 mm Hg). The increase in the content of Schiff bases and the exhaustion of the antioxidant system in erythrocytes and tissues were less pronounced in rats injected with the NO synthase inhibitor than in animals receiving lipopolysaccharide only. Various parameters of the prooxidant-antioxidant equilibrium correlated with p50. Thus, hemoglobin oxygen affinity and NO are important factors involved in the maintenance of the prooxidant-antioxidant equilibrium in the body.

Lipid peroxidative damage on pyrethroid exposure and alterations in antioxidant status in rat erythrocytes: a possible involvement of reactive oxygen species

Pyrethroid pesticides are used preferably over organochlorines and organophosphates due to their high effectiveness, low toxicity to non-target organisms and easy biodegradibility. However, it is possible that during the pyrethroid metabolism, there is generation of reactive oxygen species (ROS) and pyrethroids may produce oxidative stress in intoxicated rats. The present study was therefore, undertaken to determine pyrethroid-induced lipid peroxidation (LPO) and to show whether pyrethroid intoxication alters the antioxidant system in erythrocytes. A single dose of cypermethrin and/or fenvalerate (0.001% LD 50) was administered orally to rats and the animals were sacrificed at 0, 1, 3, 7 and 14 days of treatment. The results showed that lipid peroxidation (LPO) in erythrocytes increased within 3 days of pyrethroid treatment. The increased oxidative stress resulted in an increase in the activity of antioxidant enzymes such as superoxide dismutase (SOD) and catalase (CAT). The increase in reduced glutathione (GSH) content in erythrocytes may probably be an initial adaptive response to increased oxidative stress in pyrethroid intoxicated rats. Erythrocytes and serum acetylcholinesterase (AChE) activity was measured in pyrethroid-induced oxidative stress as it may mimic inhibition in target tissues such as muscle and brain. The inhibition in erythrocytes and serum AChE activity was partially relieved over a period of time indicating recovery from pyrethroid intoxication. The increase in erythrocyte LPO correlated with the inhibition in erythrocyte AChE activity and so erythrocyte AChE can be a marker enzyme in pyrethroid toxicity. The results show oxidative stress and alteration in antioxidant enzymes in erythrocytes of pyrethroid intoxicated rats.