Cypermethrin-induced plasma membrane perturbation on erythrocytes from rats: reduction of fluidity in the hydrophobic core and in glutathione peroxidase activity

The effects of treatment with the synthetic insecticide cypermethrin on plasma membrane fluidity, lipid peroxidation and antioxidant status in rat erythrocytes were investigated. Rats were treated by gavage with a low dose (12.5 mg/kg body weight per day) of cypermethrin in corn oil for 60 days. DPH and TMA-DPH fluorescence anisotropy experiments show that cypermethrin treatment, compared with controls, induced a significant decrease in erythrocyte membrane fluidity measured by DPH, while no changes were observed using TMA-DPH. Cypermethrin treatment also induced a significant increase in the lipid peroxidation, measured by the formation of conjugated dienes. The increased oxidative stress resulted in a significant decrease in the activity of glutathione peroxidase. The results are discussed in terms of preferential localization of cypermethrin in the hydrophobic core of the membrane, where it increases lipid packing and consequently decreases membrane fluidity.     

Effect of polyphenols extracts from Brassica vegetables on erythrocyte membranes (in vitro study)

The aim of this work was to estimate the in vitro effects of polyphenol extracts from Brassica vegetables (Brussels sprouts and red cabbage) on erythrocyte membranes with normal and high concentration of cholesterol. To determine the effect of phenolic compounds we prospectively studied cholesterol concentration, lipid peroxidation, membrane fluidity and ATPase activity. Polyphenol extracts from Brassica vegetables resulted in statistically significant reductions in cholesterol concentrations in hypercholesterolemic erythrocytes. For control erythrocytes, no significant reduction of cholesterol levels was observed for both extracts. Decreases in lipid peroxidation intensity were observed after incubation of hypercholesterolemic erythrocytes with the extracts. No changes in membrane fluidity for both extracts were noted for normal and hypercholesterolemic erythrocytes. The activity of ATPase decreased after incubation of normal and hypercholesterolemic erythrocytes with extract from Brassica vegetables. Our results indicate that polyphenols from red cabbage and Brussels sprout may directly influence erythrocyte membrane properties.     

The effect of atorvastatin on erythrocyte membranes and serum lipids in patients with type-2 hypercholesterolemia

BACKGROUND:. The beneficial effects of statins on clinical events may involve mechanisms that modify endothelial dysfunction, plaque stability, thrombus formation, and inflammatory responses. To determine the effect of atorvastatin on blood rheology in patients with familial hypercholesterolemia (FH), we prospectively studied serum lipid concentration, red cell cholesterol content, lipid peroxidation and erythrocyte membrane fluidity. The aim of this paper was to evaluate the effects of atorvastatin therapy on the erythrocyte membrane structure and the hypolipemic efficacy in patients with FH. MATERIALS, METHODS AND SUBJECTS STUDIED:. The study involved 31 patients with FH and 20 healthy individuals as a control group. The program lasted 20 weeks. For the first 8 weeks, the patients were on a hypolipemic diet only and for the subsequent 12 weeks, alongside the diet they were given 10 mg atorvastatin per day. Laboratory tests were carried out before and after 4 weeks and 12 weeks of the pharmacological treatment. Erythrocyte membrane fluidity was determined using the spin labeled method. The peroxidation of lipids was measured in whole erythrocytes as well as in erythrocyte plasma membranes by means of the thiobarbituric acid technique. RESULTS:. Treatment with atorvastatin reduced serum total cholesterol concentration from 310+/-29 mg/dl in a basal situation to 203+/-34 mg/dl ( P<0.001) at the end of the treatment and low-density lipoprotein (LDL) cholesterol concentration from 225+/-30 mg/dl to 126+/-30 mg/dl ( P<0.001), respectively. The changes observed in the plasma lipids correlate with a significant decrease in erythrocyte membrane cholesterol, from 2.24+/-1.69 to 1.17+/-0.75 mg/mg protein ( P<0.001) after 12 weeks of treatment. The lipid peroxidation in membranes of erythrocytes was lowered from the basal value 0.171+/-0.097 to 0.100+/-0.024 mmol/mg protein ( P<0.05) after 4 weeks of treatment and to 0.057+/-0.020 mmol/mg protein ( P<0.001) after 12 weeks of treatment, and in total erythrocytes from 4.78+/-1.49 to 3.99+/-1.39 mmol/g Hb ( P<0.02) and 2.43+/-0.87 mmol/g Hb ( P<0.001), respectively. The membrane fluidity was estimated by means of parameter S at the depth of the fifth carbon atom. Atorvastatin in hypercholesterolemic erythrocytes enhances the fluidity of the superficial layer from 0.758+/-0.009 up to the values observed in the control group 0.744+/-0.009 ( P<0.001). There is no impact on the microviscosity of the hydrophobic core observed. CONCLUSION:. Our findings suggest that the atorvastatin therapy reverses the alteration of erythrocyte plasma membrane properties. It may improve blood rheology in patients with FH. This improvement in blood properties may contribute to the well-known beneficial effects of atorvastatin on cardiovascular risk in patients with severe hyperlipidemia and atherosclerotic vascular disease.     

Cigarette smoke-induced biochemical perturbations in human erythrocytes and attenuation by epigallocatechin-3-gallate--tea catechin

The protective effect of epigallocatechin-3-gallate (EGCG) against cigarette smoke (CS) induced alterations in human erythrocyte was studied using an in vitro model. Hemolysis, carboxyhemoglobin, osmotic fragility, hemin, lipid peroxidation (LPO), protein thiol, protein carbonyl, glutathione, antioxidant enzymes, membrane bound ATPases and erythrocyte ghost protein were assessed to investigate the effect of EGCG. Erythrocytes were incubated with CS and/or 10 μM EGCG under physiological conditions of temperature and pH for 2 h. CS significantly increased the percentage of hemolysis, carboxyhemoglobin, hemin, LPO and osmotic fragility in human erythrocytes whereas EGCG pretreatment significantly reduced all the above parameters. The levels of protein carbonyls significantly increased whereas the level of protein thiol decreased significantly in erythrocytes incubated with CS. EGCG pretreatment significantly decreased the levels of carbonyls and increased the level of protein thiol. The level of glutathione, antioxidant enzyme and membrane bound ATPases were decreased significantly in erythrocytes incubated with CS. However, EGCG pretreatment significantly increased the activities of GSH, antioxidant enzymes and membrane bound ATPases. CS incubated erythrocytes showed a progressive loss of the cytoskeleton proteins and formation of low molecular weight bands and protein aggregates. EGCG pretreatment of CS incubated erythrocytes showed a near normal protein profile compared to that of control erythrocytes. The present study divulges that EGCG can reduce the abnormalities of cigarette smoking by ameliorating the oxidative stress. This finding raises the possibility that EGCG may provide protection from CS induced toxicity.     

Alterations in Ca²⁺ homeostasis and oxidative damage induced by ethion in erythrocytes of Wistar rats: ameliorative effect of vitamin E

Organophosphate (OP) insecticides have been reported to induce oxidative stress due to lipid peroxidation and alteration in defense mechanisms. It is known that calcium content in erythrocytes plays a very important in normal physiology of cells. Erythrocytes are a very convenient model to understand the susceptibility of membrane to oxidative damage induced by various xenobiotic compounds. The aim of present study was to investigate the effects of ethion induced oxidative damage, alterations in membrane bound enzymes and Ca(2+) homeostasis and a possible protective role of vitamin E. Adult male albino rats of Wistar strain were orally administered ethion and vitamin E daily for 28 days. Animals were randomly divided into four groups: control; ethion treated (2.7 mg/kgbw/day); vitamin E treated (50mg/kg of bw/day); ethion+vitamin E treated. The animals were sacrificed after 7, 14, 21 and 28 days. Erythrocyte membranes were prepared and analyzed for protein, lipid peroxidation (LPO) and membrane bound ATPases. Furthermore, Ca(2+) homeostasis as function of time and concentration was evaluated in erythrocytes. The results from the present study show that in vivo administration of ethion resulted in oxidative damage to erythrocyte membranes as evident by increased lipid peroxidation. The increased LPO following ethion intoxication was accompanied by significant decrease in the activities of Na(+)/K(+)-ATPase, Mg(2+)-ATPase and Ca(2+)-ATPase and disturbed Ca(2+)homeostasis in erythrocytes. Furthermore, vitamin E treatment had a beneficial effect by decreasing lipid peroxidation; partially restoring activities of membrane bound ATPases and Ca(2+) homeostasis. The present study suggests that ethion exerts its toxic effect by increasing LPO, altering the activity of membrane bound enzymes and disturbing Ca(2+) homeostasis. Vitamin E treatment ameliorated the toxic effects of ethion suggesting its role as a potential antioxidant.     

Anti-inflammatory and hypolipemic effects in vitro of simvastatin comparing to epicatechin in patients with type-2 hypercholesterolemia

Objective

The study involved 25 patients with type-2 hypercholesterolemia (mean age 49.3 ± 11.3). The control group consisted of 28 healthy individuals (mean age 50.7 ± 7.2).

Methods

The cholesterol concentrations in plasma membranes of erythrocytes were measured by means of Liebermann-Burchard reagent. The membrane lipid peroxidation in whole erythrocytes was determined. The membrane fluidity was estimated by spin labelled method.

Results

The in vitro study shows that the cholesterol concentration in membranes incubated with simvastatin and epicatechin decreases; in healthy donors there are no changes. Simvastatin does not lead to changes in the lipid peroxidation in the in vitro data. Epicatechin decreases the level of membrane lipid peroxidation in patients with hypercholesterolemia and in healthy donors. Simvastatin and epicatechin cause an increase in the fluidity of plasma membranes of erythrocytes.

Conclusions

Simvastatin causes the decrease in cholesterol concentration in erythrocytes membranes not only in the in vivo but also the in vitro experiments. Flavonoids have antioxidant properties in vitro. Simvastatin influences the lipid peroxidation only in vivo, not in vitro systems. This observation is an additional contribution to the statins’ pleiotropic effect.     

Antioxidant status of erythrocytes and their response to oxidative challenge in humans with argemone oil poisoning

Oxidative damage of biomolecules and antioxidant status in erythrocytes of humans from an outbreak of argemone oil (AO) poisoning in Kannauj (India) and AO intoxicated experimental animals was investigated. Erythrocytes of the dropsy patients and AO treated rats were found to be more susceptible to 2,2'-azobis (2-amidinopropane) dihydrochloride (AAPH) induced peroxidative stress. Significant decrease in RBC glutathione (GSH) levels (46, 63%) with concomitant enhancement in oxidized glutathione (172, 154%) levels was noticed in patients and AO intoxicated animals. Further, depletion of glutathione reductase (GR), glucose-6-phosphate dehydrogenase (G-6-PDH) and glutathione-S-transferase (GST) (42-52%) was observed in dropsy patients. Oxidation of erythrocyte membrane lipids and proteins was increased (120-144%) in patients and AO treated animals (112-137%) along with 8-OHdG levels in whole blood (180%) of dropsy patients. A significant reduction in alpha-tocopherol content (68%) was noticed in erythrocytes of dropsy patients and hepatic, plasma and RBCs of AO treated rats (59-70%) thereby indicating the diminished antioxidant potential to scavenge free radicals or the limited transport of alpha-tocopherol from liver to RBCs leading to enhanced oxidation of lipids and proteins in erythrocytes. These studies implicate an important role of erythrocyte degradation in production of anemia and breathlessness in epidemic dropsy.     

Morphological and biochemical perturbations in rat erythrocytes following in vitro exposure to Fenvalerate and its metabolite.

Erythrocytes are a convenient model to understand the membrane oxidative damage induced by various xenobiotic-prooxidants. In this investigation, we have examined the potency of Fenvalerate (FEN) and its metabolite, p-chlorophenyl isovaleric acid (p-CPIA) to induce oxidative stress response in rat erythrocytes in vitro in terms of lipid peroxidation and effects on selected antioxidant enzymes. Susceptibility of erythrocytes to FEN exposure was further investigated in terms of morphological alterations by scanning electron microscopy and protein damage by gel electrophoresis of erythrocyte ghosts. Following in vitro exposure, FEN caused a significant induction of oxidative damage in erythrocytes at concentrations beyond 0.1 mM as evidenced by increased thiobarbituric acid reactive substances (TBARS) levels. The response was both concentration and time dependent. At higher concentrations, significant decreases in the activities of vital antioxidant enzymes viz., catalase, superoxide dismutase, glutathione transferase and glutathione reductase were also discernible clearly suggesting the potency of both, parent compound and its metabolite to induce oxidative stress in erythrocytes. Scanning electron micrographs of erythrocytes following FEN exposure at higher concentrations revealed various degrees of distortion in shape and ruptured membranes. Furthermore, gel electrophoresis studies revealed consistent and significant aggregation of only band 3 protein in erythrocyte membranes exposed to either FEN or p-CPIA at higher concentrations. These in vitro findings show that FEN and its metabolite have the propensity to cause significant oxidative damage in rat erythrocytes, which is associated with marked damage to membrane proteins. These data suggest that both structural and functional perturbations may ensue in erythrocytes following exposure to FEN at higher concentrations under in vivo situations.     

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% LD50) 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.     

Effects of oxidative stress on the erythrocyte Na+,K+ ATPase activity in female hyperthyroid patients.

This study was planned to determine the effects of free-radical-induced damage on the Na+,K+-ATPase activity of erythrocytes during hyperthyroidism and 4 wk after propylthiouracil (PTU) therapy (400 mg/d). The levels of plasma thiobarbituric acid-reactive substances (TBARS) as a marker of lipid peroxidation, erythrocyte glutathione (GSH) concentration as an antioxidant, blood ATP concentration, and erythrocyte membrane Na+,K+-ATPase activity were determined in female hyperthyroid patients (n = 22, mean age 40.5 +/- 6.5 yr). Before the PTU therapy, plasma TBARS concentration was significantly higher and the levels of blood ATP and erythrocyte GSH and the activity of membrane Na+,K-+-ATPase were significantly lower in the hyperthyroid patients (n = 15 women, mean age 40.8 +/- 7.3 yr). Four weeks after PTU therapy, plasma TBARS concentration was decreased, and levels of erythrocyte GSH and blood ATP and of Na+,K+-ATPase activity of erythrocytes were elevated in the treated patients. There was a significant positive correlation between blood ATP concentration and Na+,K+-ATPase activity, and a negative correlation between plasma TBARS concentration and Na+,K+-ATPase activity before PTU. Our results might help to clarify the effects of the oxidative mechanisms on the erythrocyte membrane Na+,K+-ATPase activity in hyperthyroid patients.     

莲心碱对氧自由基引发红细胞膜损伤的保护作用

目的研究莲心碱对超氧阴离子自由基(O2.)引发的红细胞膜氧化损伤的影响。方法采用邻苯三酚自氧化产生的超氧阴离子自由基O2.致红细胞膜损伤,以此为膜过氧化损伤实验模型,以脂质过氧化产物丙二醛(MDA)、细胞膜封闭能力、细胞膜自氧化速率、膜脂流动性(MFU)为指标,观察莲心碱对红细胞膜氧化损伤的保护作用。结果O2.能引起红细胞膜脂质过氧化,丙二醛(MDA)含量、自氧化速率增加、膜流动性以及膜封闭度下降。而红细胞膜经过一定量的莲心碱(80,100,120mg.L-1)预先处理后,膜MDA含量明显减少,自氧化速率明显降低,膜流动性和膜封闭度提高。结论莲心碱对氧自由基引发的红细胞膜损伤具有一定的保护作用。     

Effect of lipid peroxidation on the fluidity of erythrocyte ghost and phospholipid liposomal membranes

The effects of lipid peroxidation on the fluidity of the lipid bilayers of the human erythrocyte ghosts and egg-lecithin phospholipid liposomes have been studied. For the measurements of the peroxidation extent and the fluidity of the membranes, the thiobarbituric acid-reactive substances and the fluorescence depolarization of 1,6-diphenyl-1,3,5-hexatriene labelled into the membrane were employed, respectively. The lipid peroxidation was performed in hypoxanthine/xanthine oxidase/ferrous ion, and hydrogen peroxide/ferrous ion systems. The results of these experiments show that both of the xanthine oxidase and hydrogen peroxide systems effectively induced the lipid peroxidation of the ghosts, and the liposomal membranes, respectively. The lipid peroxidation decreased the fluidity of the, membranes, especially at the very early stage of the peroxidation reaction. The decrease in the fluidity of membrane by the lipid peroxidation has been ascribed to the alteration of the polyunsaturated acyl chains of lipids and cross-linkings among the membrane components. However, under drastic condition of lipid peroxidation, the fluidity of the membrane rather increased possibly due to the deterioration of the membrane integrity by the peroxidation. Morphological change of the erythrocyte on peroxidation has also been observed.     

The effect of daunorubicin and glutaraldehyde treatment on the structure of erythrocyte membrane.

The effect of daunorubicin (DNR) and glutaraldehyde on erythrocyte membrane structure was examined by Electron Spin Resonance spectroscopy. Human erythrocytes were incubated with daunorubicin and then with glutaraldehyde to prevent drug efflux. We have demonstrated that DNR alone caused changes in membrane fluidity mainly in the hydrophobic regions of the lipid bilayer. When DNR-preincubated erythrocytes were treated with glutaraldehyde, the alterations in fluidity were observed in the polar regions as well as in the deeper regions of the cell membrane. The incorporation of drug and glutaraldehyde into human erythrocytes also caused conformational alterations in membrane cytoskeletal proteins and changes in the internal viscosity of the cells. The results suggest that glutaraldehyde in the drug-pretreated erythrocytes may lead to significant perturbations in the organization of the plasma membrane lipids and proteins.     

Dapsone hydroxylamine induces premature removal of human erythrocytes by membrane reorganization and antibody binding

BACKGROUND AND PURPOSE

N-hydroxylation of dapsone leads to the formation of the toxic hydroxylamines responsible for the clinical methaemoglobinaemia associated with dapsone therapy. Dapsone has been associated with decreased lifespan of erythrocytes, with consequences such as anaemia and morbidity in patients treated with dapsone for malaria. Here, we investigated how dapsone and/or its hydroxylamine derivative (DDS-NHOH) induced erythrocyte membrane alterations that could lead to premature cell removal.

EXPERIMENTAL APPROACH

Erythrocytes from healthy donors were subjected to incubation with dapsone and DDS-NHOH for varying times and the band 3 protein tyrosine-phosphorylation process, band 3 aggregation, membrane alteration and IgG binding were all examined and compared with erythrocytes from two patients receiving dapsone therapy.

KEY RESULTS

The hydroxylamine derivative, but not dapsone (the parent sulphone) altered membrane protein interactions, leading both to aggregation of band 3 protein and to circulating autologous antibody binding, shown in erythrocytes from patients receiving dapsone therapy. The band 3 tyrosine-phosphorylation process can be used as a diagnostic system to monitor membrane alterations both in vitro, assessing concentration and time-dependent effects of DDS-NHOH treatment, and in vivo, evaluating erythrocytes from dapsone-treated patients, in resting or oxidatively stimulated conditions.

CONCLUSIONS AND IMPLICATIONS

DDS-NHOH-induced alterations of human erythrocytes can be directly monitored in vitro by tyrosine-phosphorylation level and formation of band 3 protein aggregates. The latter, together with antibody-mediated labelling of erythrocytes, also observed after clinical use of dapsone, may lead to shortening of erythrocyte lifespan.     

The combined effect of IDA and glutaraldehyde on the properties of human erythrocytes

The effect of IDA and glutaraldehyde on the properties of human erythrocytes was examined by Electron Spin Resonance spectroscopy and fluorescence measurements. In this study glutaraldehyde was used as the agent linking the drug to the erythrocyte membrane. We have demonstrated that idarubicin (IDA) alone caused only negligible changes of the membrane fluidity. When IDA preincubated erythrocytes were treated with glutaraldehyde, the alterations in the fluidity were observed in the polar parts as well as in the deeper regions of the cell membrane. The incorporation of drug and glutaraldehyde into human erythrocytes also caused conformational alterations of membrane cytoskeletal proteins and changes in the internal viscosity of the cells. Our data suggest that glutaraldehyde in idarubicin-pretreated erythrocytes may potentiate the drug toxicity leading to significant perturbations in the organization of the plasma membrane lipids and proteins.     

Status of lipid peroxidation, glutathione, ascorbic acid, vitamin E and antioxidant enzymes in patients with pregnancy--induced hypertension

The exact pro-oxidant and antioxidant status in pregnancy--induced hypertension patients is still not clear. To add a new insight to the question, changes in the erythrocyte lipid peroxidation products (malondialdehyde; MDA), levels of glutathione (GSH), ascorbic acid and plasma vitamin E (non enzymatic antioxidant parameters) and activities of antioxidant enzymes superoxide dismutase (SOD), glutathione peroxidase (GPx), catalase in erythrocytes were studied in thirty five patients with pregnancy--induced hypertension and thirty five healthy pregnant normotensive cases. It was observed that there was a significant increase in erythrocyte MDA levels, activities of SOD, GPx and a significant decrease in erythrocyte GSH, ascorbic acid, plasma vitamin E levels and catalase activity in patients with pregnancy--induced hypertension when compared to controls. The results of our study have shown higher oxygen free radical production, evidenced by increased levels of MDA and decreased levels of GSH, ascorbic acid, vitamin E and Catalase activity supports the oxidative stress in pregnancy--induced hypertension. The increased activities of antioxidant enzymes may be a compensatory regulation in response to increased oxidative stress. The decreased concentrations of glutathione and antioxidant vitamin status supports the hypothesis that lipid peroxidation is an important causative factor in the pathogenesis of preeclampsia.     

Structural component changes of erythrocytes caused by oxidative stress generated by indoxyl sulfate

Indoxyl sulfate (IS) belongs to groups of uremic toxins binding to proteins. This compound may contribute to the generation of oxidative stress in chronic kidney disease (CKD) patients. We hypothesized that a high concentration of IS in the blood may induce structural changes of erythrocyte components and thus may contribute to CKD progression.In the present study, we evaluated the influence of IS on hemolysate and membrane proteins' conformational state, lipid membrane fluidity, and internal viscosity in erythrocytes. We examined thiols, carbonyl groups, peroxides, and TBARS levels in erythrocyte incubated with IS.The treatment of erythrocytes with IS led to increase in lipid membrane fluidity, decrease in the internal viscosity of the cells and the motion of the spin labels attached to hemolysate proteins. We did not observe conformational changes in plasma membrane proteins; however, in the plasma membranes of erythrocytes incubated with IS, a decrease in the content of thiol groups and increase in the carbonyls levels and peroxides and TBARS in comparison with the control was observed.The obtained results indicate that IS induces the oxidative damage of erythrocyte components. This may be an important factor that affects the functional properties of erythrocytes in CKD patients.     

Interrelationship between hemolysis and lipid peroxidation of human erythrocytes induced by silicic acid and silicate dusts

Silicic acid and silicate dusts (slate dust and chrysotile asbestos) cause hemolysis of erythrocytes in vitro. The peroxidation of polyunsaturated fatty acids (PUFA) of erythrocyte membrane lipids is also enhanced by incubating the erythrocytes with silicic acid and silicate dusts in in vitro. Hemolysis of erythrocytes elicited by silicic acid and silicate dusts is inhibited significantly by polyvinyl-pyrrolidone and dipalmitoyl lecithin (DPL). These agents, however, have no effect on silicic acid and silicate dust induced peroxidation of erythrocyte membrane lipids. On the other hand, peroxidation of erythrocyte membrane lipids, induced by silicic acid and silicate dusts, is inhibited almost completely by adding superoxide dismutase and catalase to the incubation system, whilst the hemolysis of erythrocytes induced by silicic acid and silicate dusts is unaffected by these agents. Similarly the lysis of erythrocytes, induced by silicic acid and silicate dusts, proceeds at a much faster rate than silicic acid and silicate dust induced lipid peroxidation. These results indicate that silicic acid and silicate dust induced hemolysis and lipid peroxidation represent two independent processes.     

Adriamycin Induces Protein Oxidation in Erythrocyte Membranes

Abstract: Adriamycin is an anthracycline antineoplastic agent whose clinical effectiveness is limited by severe side effects, including cardiotoxicity. A current hypothesis for adriamycin cardiotoxicity involves free radical oxidative stress. To investigate this hypothesis in a model system, we applied the technique of immunochemical detection of protein carbonyls, known to be increased in oxidized proteins, to study the effect of adriamycin on rat erythrocyte membranes. Erythrocytes obtained from adriamycin-treated rats demonstrated an increase of carbonyl formation in their membrane proteins. Yet, in separate experiments when adriamycin was incubated with rat erythrocyte ghosts, there was no significant increase of membrane protein carbonyls detected. In contrast, isolated erythrocytes incubated with an adriamycin-Fe³⁺ complex exhibited a robust carbonyl incorporation into their membrane proteins in a time-dependent manner. The level of carbonyl formation was dependent upon the concentration of Fe³⁺ known to form the adriamycin-Fe³⁺ complex. When the time course between protein carbonyl formation and lipid peroxidation was compared, protein carbonyl detection occurred earlier than lipid peroxidation as assayed by thiobarbituric acid reactive substances formation. These results are consistent with the notion that oxidative modification of membrane proteins may contribute to the development of the acute adriamycin-mediated toxicity.     

Lambda-cyhalothrin-induced changes in oxidative stress biomarkers in rabbit erythrocytes and alleviation effect of some antioxidants.

Erythrocytes are a convenient model to understand the membrane oxidative damage induced by various xenobiotic-prooxidants. This study was designed to investigate (1) the possibility of lambda-cyhalothrin (LC), a type II pyrethroid, to induce oxidative stress response in rabbit erythrocytes in vitro and its effect on selected antioxidant enzymes and (2) the role of vitamin C (VC; 20mM) and vitamin E (VE; 2mM) in alleviating the cytotoxic effects of LC. Erythrocytes were divided into three groups. The first group, previously prepared erythrocytes was incubated for 4h at 37 degrees C with different concentrations (0, 0.1, 0.5, 1, 2.5, 5mM) of LC. The second and third groups were preincubated with VC or VE, respectively for 20 min and followed by LC incubation for 4h. Following in vitro exposure, LC caused a significant induction of oxidative damage in erythrocytes at different concentrations as evidenced by increased thiobarbituric acid reactive substances (TBARS) levels. However, a significant decrease in the content of sulfhydryl groups (SH-groups), and the activities of acetylcholinesterase (AChE), superoxide dismutase (SOD), catalase (CAT) and glutathione S-transferase (GST) were observed. The response was concentration dependent. VC or VE pretreated erythrocytes showed a significant protection against the cytotoxic effects induced by LC on the studied parameters. In conclusion, antioxidant vitamins especially VE could be able to ameliorate LC-induced oxidative stress by decreasing lipid peroxidation and altering antioxidant defense system in erythrocytes.