Erythrocyte Membrane Fluidity Research Articles

A Selective Estrogen Receptor Modulator, Tamoxifen, and Membrane Fluidity of Erythrocytes in Normotensive and Hypertensive Postmenopausal Women: An Electron Paramagnetic Resonance Investigation

Recent studies have shown that tamoxifen, which belongs to a group called selective estrogen receptor modulators (SERM), may exert protective effects against cardiovascular diseases and stroke in postmenopausal women. On the other hand, abnormalities in physical properties of the cell membranes may underlie the defects that are strongly linked to hypertension, stroke, and other cardiovascular diseases. The present study was performed to investigate the effects of tamoxifen on cell membrane fluidity (a reciprocal value of membrane microviscosity) in normotensive and hypertensive postmenopausal women. We used an electron paramagnetic resonance (EPR) and spin-labeling method. Tamoxifen significantly decreased the order parameter (S) for 5-nitroxide stearate (5-NS) and the peak height ratio (h(o)/h(-1)) for 16-NS obtained from EPR spectra of erythrocyte membranes in normotensive postmenopausal women (mean +/- SEM, order parameter value; control 0.719 +/- 0.002, n = 41; tamoxifen 1 x 10(-7) mol/L 0.704 +/- 0.002, n = 41, P < .0001; tamoxifen 1 x 10(-6) mol/L 0.696 +/- 0.002, n = 41, P < .0001; tamoxifen 1 x 10(-5) mol/L 0.692 +/- 0.002, n = 41, P < .0001). The finding indicated that tamoxifen increased the membrane fluidity and improved the membrane microviscosity of erythrocytes. The membrane action of tamoxifen was antagonized by the estrogen receptor antagonist ICI 182,780. The effect of tamoxifen was significantly potentiated by the nitric oxide (NO) donors, l-arginine and S-nitroso-N-acetylpenicillamine, and a cGMP analog 8-bromo-cGMP. In contrast, the change evoked by tamoxifen was counteracted by the NO synthase inhibitors N(G)-nitro-l-arginine-methyl-ester and asymmetric dimethyl-l-arginine. In hypertensive postmenopausal women, the membrane fluidity of erythrocytes was significantly lower than in normotensive postmenopausal women. The effect of tamoxifen on the membrane fluidity was more pronounced in hypertensive postmenopausal women than in normotensive postmenopausal women. These results showed that tamoxifen increased the membrane fluidity of erythrocytes and improved the rigidity of cell membranes in postmenopausal women, to some extent, through the NO- and cGMP-dependent mechanisms. Furthermore, the greater effect of tamoxifen in hypertensive postmenopausal women suggests that tamoxifen could have a beneficial effect in regulating the blood rheologic behavior and in the improvement of the microcirculation in hypertension.

Hemolysis of Erythrocytes and Erythrocyte Membrane Fluidity Changes by New Lysosomotropic Compounds

This work contains the results of studies on the influence of newly synthesized lysosomotropic substances (lysosomotropes) on human erythrocytes. Six homologous series of the compounds differing in the alkyl chain length and counterions were studied. They were found to hemolyse erythrocytes and to change their osmotic resistance. The observed hemolytic effects were dependent both on the compound's structure (polar head dimension and alkyl chain length of compound) and its form (the kind of the counterion). In parallel, the influence of lysosomotropes on fluidity of the erythrocyte membrane was studied. Three different fluorescent probes were used; 1,6-diphenyl-1,3,5-hexatriene (DPH), 1-(4-trimethylammoniumphenyl)-6-phenyl-1,3,5-hexatriene, p-toluenesulfonate (TMA-DPH) and 6-dodecanoyl-2-dimethylaminonaphthalene (laurdan). Their anisotropy (DPH and TMA-DPH) or general polarization (laurdan) values after incorporation into ghost erythrocyte membranes were measured. The results obtained show that fluidity changes accompanied the effects observed in hemolytic experiments both quantitatively and qualitatively.

Erythrocyte membrane fluidity and haemoglobin haemoporphyrin conformation: features revealed in patients with heart failure

This study examined the possible involvement of abnormal erythrocyte oxygen (O 2) transport in the pathogenesis of heart failure. Haemoglobin (Hb) haemoporphyrin conformation was assessed by Raman spectroscopy (RS) of blood samples, whereas membrane fluidity was estimated at depths of 0.6–0.8 and 2.2 nm by electron-paramagnetic resonance spectroscopy of erythrocytes loaded with spin-labeled 5-doxylstearic acid and 16-doxylstearic acid, respectively. The fluidity of erythrocyte membranes from patients with heart failure was decreased in the area near the membrane surface and remained unchanged in the deeper hydrophobic membrane regions. The same differences were also detected in healthy controls subjected to chronic high-altitude hypoxia. RS demonstrated that in heart failure the total content of Hb–ligand complexes and the relative content of Hb–nitric oxide (NO) complexes with cleaved Fe 2+-globin bond was decreased, whereas content of Hb–NO complexes with preserved Fe 2+-globin bond was increased. We propose that this phenomenon contributes to the reduced O 2 tissue supply seen in patients with heart failure.

Long-term prognostic value of protein C activity, erythrocyte aggregation and membrane fluidity in transmural myocardial infarction

The objective of this study was to evaluate the long-term predictive value of the haemostatic, inflammatory and haemorheologic disturbances in transmural myocardial infarction (MI). Sixty-four (59 male) consecutive survivors of a MI, with a mean age of 58.3 +/- 12.0 years, were followed over a period of 36 months. Eighteen patients had a cardiovascular event defined as the composite of death, non-fatal MI, unstable angina and stroke. The haemostatic (protein C activity-PtC, antithrombin III, plasminogen activator inhibitor-1), haemorheologic (blood fluidity and components, erythrocyte membrane fluidity) and inflammatory (polymorphonuclear elastase, leukocyte count) profiles were determined at hospital discharge, using standard methodology. Our results can be summarized as follow: (i) at hospital discharge, the subgroup of patients with events had higher leukoactivity, leukocyte count, membrane fluidity, prognosis cyte count (7833.0 +/- 1696.0 vs. 10294.0 +/- 3129.0; p = 0.011), lower PtC (100.65 +/- 19.08 vs.81.25 +/- 19.95; p = 0.002), and lower erythrocyte aggregation (14.26 +/- 5.94 vs. 11.47 +/- 3.45; p = 0.031) in relation to the ones without events; (ii) By Cox regression the protein C activity lower tertile (OR 0.169; 0.045-0.628; p = 0.008); erythrocyte membrane outer layer fluidity upper tertile (OR 0.067; 95% CI 0.011 - 0.393; p = 0.003); and erythrocyte aggregation lower tertile (OR 0.182; 0.038 - 0.876; p = 0.034) were independent predictors of the composite endpoint. We can conclude that some haemostatic, haemorheologic and inflammatory disturbances, at hospital discharge, are long-term independent predictors of recurrent cardiovascular events in transmural myocardial infarction survivors.

A calcium channel blocker, benidipine, improves cell membrane fluidity in human subjects via a nitric oxide—dependent mechanism: An electron paramagnetic resonance investigation

Recent studies have revealed that benidipine, a long-acting dihydropyridine-type of calcium (Ca) channel blocker, may exert its protective effect against vascular disorders by increasing nitric oxide (NO) production. The purpose of the present study was to investigate the effects of benidipine and NO on the membrane function in human subjects. We measured the membrane fluidity of erythrocytes by using an electron paramagnetic resonance (EPR) and spin-labeling method. Benidipine decreased the order parameter (S) for 5-nitroxide stearate (5-NS) and the peak height ratio (h(o)/h(-1)) for 16-NS obtained from EPR spectra of erythrocyte membranes in a dose-dependent manner in normotensive volunteers. The finding indicated that benidipine increased the membrane fluidity and improved the microviscosity of erythrocytes. The effect of benidipine was significantly potentiated by the NO donor, S-nitroso-n-acetylpenicillamine, and by the cyclic guanosine 3', 5'-monophosphate (cGMP) analog, 8-bromo-cGMP. In contrast, the change evoked by benidipine was counteracted by the NO synthase inhibitors, N(G)-nitro-L-arginine-methyl-ester and asymmetric dimethyl-L-arginine. These results demonstrated that benidipine increased the membrane fluidity of erythrocytes, at least in part, via the NO- and cGMP-dependent mechanism. Furthermore, the data strongly suggest that benidipine might have a beneficial effect on the rheologic behavior of erythrocytes and the improvement of the microcirculation in humans.

Pineal graft in old rats improves erythrocyte resistance to peroxyl radical-induced hemolysis

Pineal graft from young to old rats was performed and red blood cell hemolysis, induced by the water-soluble radical initiator 2,2'-azobis (2-amidino-propane) dihydrochloride (AAPH), was evaluated 6 months after graft. Pineal graft modified the hemolysis curve kinetic profile in grafted rats versus age-matched controls, the 50% hemolysis time as well as the lag time were longer, whereas the maximal amount of hemolysis was lower, and it occurred over a longer period of time. Thiobarbituric acid reactive substances production was lower in pineal-grafted rats than in controls and the age-related decrease of erythrocyte membrane fluidity was prevented by pineal graft. The present findings support an important physiological role of pineal gland in preventing age-related alterations of erythrocyte membranes and suggest a possible antioxidant action of melatonin.

Erythrocyte membrane alterations during ageing affect β- d-glucuronidase and neutral sialidase in elderly healthy subjects

In this study, a comparison between elderly (>70 years) and young subjects reveals that elder people are subject to a higher oxidative stress, which causes an increase in plasma hydroperoxide levels (18%) and a decrease in antioxidant defenses (25%). Moreover, the marked decrease of the erythrocyte membrane fluidity observed in elderly subjects was likely to affect the behavior of some membrane glycohydrolases. In fact, a significant decrease of β- d-glucuronidase and neutral sialidase (30 and 50%, respectively) was detected. Activity differences were also observed when erythrocytes were further distinguished according to their biological age. Striking differences between young and elderly subjects were observed for β- d-glucuronidase and neutral sialidase in young and senescent erythrocytes, respectively. Overall β- d-glucuronidase decreases with the subjects' age, while neutral sialidase levels are higher in the elderly. This is presumably due to the localization of these enzymes in distinct plasma membrane micro-domains, which are differently peroxidized. A possible role of these enzymes in signaling praecox membrane alterations has also been evidenced.

Techniques to evaluate erythrocyte deformability in diabetes mellitus

Using several rheological techniques, we examined erythrocyte deformability in different groups of diabetic subjects. The macrorheological techniques used for this evaluation were respectively whole-blood filtration, filtration of erythrocyte suspensions, polyviscosimetry and diffractometry. Whole-blood filterability, at a negative pressure of 20 cm water, was decreased in type 2 diabetics; no difference was evident at a negative pressure of 10 cm water. The filtration of erythrocyte suspensions at low haematocrit (5%) did not show differences between normal and diabetic subjects. Polyviscosimetry, which explores the filterability of erythrocyte suspensions at high haematocrit (80%) through wide pores, demonstrated an impaired behaviour especially in type 2 diabetics. Diffractometry, which measures erythrocyte elongation induced by a defined shear stress through the diffraction pattern of a laser beam, showed an alteration in type 1 diabetic subjects. The microrheological methods employed for this evaluation were those based on fluorescence spectroscopy. Labeling intact red blood cells with fluorescent probes, we determined the membrane dynamic properties and using these techniques we found a reduction of erythrocyte membrane fluidity and a decrease of red cell membrane protein lateral mobility.

S-adenosylhomocysteine hydrolase, S-adenosylmethionine, S-adenosylhomocysteine: correlations with ribavirin induced anemia

Objective is to speculate on the ribavirin induced anemia by inhibiting S-adenosylhomocysteine (SAH)-hydrolase activity. The major toxicity associated with the use of ribavirin is hemolytic anemia. This adverse effect has been ascribed to the accumulation of ribavirin triphosphate in the erythrocyte, which interferes with erythrocyte function. Ribavirin has been found to inhibit SAH-hydrolase activity in erythrocyte. SAH is further hydrolyzed to adenosine and homocysteine by SAH-hydrolase. The formation of S-adenosylmethionine (SAM) is then demethylated to SAH. SAH, the metabolite of SAM, on the other hand is a powerful inhibitor of methyltransferase enzymes, competing for the SAM binding site. A concurrent decrease in SAM and an increase in SAH levels would inhibit methylation of many tissue components including proteins, DNA, RNA, phospholipids and other small molecules. The enzyme protein carboxyl methyltransferase type II has been recently shown to play a crucial role in the repair of damaged proteins. SAM is the methyl donor of the reaction, and its demethylated product, SAH is the natural inhibitor of this reaction, as well as of most SAM-dependent methylations. The biological function of this transmethylation reaction is related to the repair or degradation of age-damaged proteins. Methyl ester formation in erythrocyte membrane proteins has been used as a marker reaction to tag these abnormal residues and to monitor their increase associated with erythrocyte ageing diseases. Liver disease is complicated by cholesterol deposition in hepatic and extrahepatic membranes. Erythrocyte membrane fluidity has been improved with the administration of SAM and correlated with the cholesterol/phospholipid ratio of the membranes. The levels of SAH-hydrolase activity were also found to undergo a sharp decrease with red cell ageing. The similarity of these alterations with certain morphofunctional characteristics of erythrocyte in some conditions as chronic renal failure, liver disease and hereditary spherocytosis makes it possible to hypothesize that the inhibition of SAH-hydrolase could constitute at least a part of ribavirin induced hemolytic anemia.

Plasma lipids and physicochemical properties of the erythrocyte plasma membrane throughout pregnancy.

The physiopathological relevance of plasma lipid concentrations is supported by the observation that they might affect the physicochemical properties of the plasma membrane of circulating cells and might be crucial in the pathological conditions complicating pregnancy. Plasma and erythrocyte membrane lipid composition, membrane fluidity and function [membrane-bound enzyme sodium/potassium adenosine triphosphatase (Na+/K+-ATPase) activity] were studied in 24 healthy women in the nonpregnant condition and at 12, 24 and 38 weeks' gestation. The plasma showed an increase in total and high density lipoprotein (HDL) cholesterol, triglyceride (TG) and phospholipid (PL) levels. In the erythrocyte membrane we found the cholesterol/phospholipid (C/PL) ratio increased and the saturated to unsaturated fatty acid (FA) ratio (Sat/Unsat) significantly reduced; fluorescence polarization showed an initial increase during pregnancy and a progressive decrease afterwards; Na+/K+-ATPase activity was progressively reduced. A generalized alteration in the composition and function of the maternal erythrocyte membrane is present during a physiological pregnancy, and these modifications may involve a more complex physiopathogenetic mechanism.

Leptin and membrane fluidity of erythrocytes in essential hypertension: an electron paramagnetic resonance investigation

There has been an indication that leptin, the product of the human obesity gene, actively participates not only in metabolic regulation but also in the control of blood pressure. Recently, it has been proposed that abnormalities in the physical property of cell membranes may underlie the defects that are strongly linked to hypertension, stroke, and other cardiovascular diseases. We have shown previously that leptin significantly increased the membrane fluidity and improved the microviscosity of erythrocytes in humans through the nitric oxide-dependent mechanism. In the present study, we examined the effects of leptin on membrane fluidity of erythrocytes in subjects with essential hypertension by means of an electron paramagnetic resonance (EPR) and spin-labeling method. The values of the order parameter (S) and the peak height ratio (ho/h-1) obtained from the EPR spectra of erythrocytes were significantly greater in patients with essential hypertension (HT) than in age-matched normotensive subjects (NT) (S: HT 0.719 ± 0.002, n = 16, NT 0.713 ± 0.001, n = 29, P < .05; ho/h-1: HT 5.17 ± 0.02, n = 16, NT 5.05 ± 0.02, n = 29, P < .05). The finding indicated that the erythrocyte membrane fluidity was lower in patients with HT than in NT. Leptin decreased S and ho/h-1 in a dose-dependent manner in both NTs and HTs. The effect of leptin on the membrane fluidity was significantly more pronounced in HTs than in NTs (percent change in S: leptin 10 −8 g/mL, HT −3.4% ± 0.2%, n = 16, NT −2.3% ± 0.1%, n = 29, P < .05; leptin 10 −7 g/mL, HT −4.3% ± 0.3%, n = 16, NT −3.3% ± 0.1%, n = 29, P < .05). The results of the present study showed that leptin might have a crucial role in the regulation of the rheologic behavior of erythrocytes and the microcirculation in hypertension.

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HomeStrokeVol. 35, No. 4Smoking, Estrogen, and Membrane Microviscosity in Women Free AccessLetterPDF/EPUBAboutView PDFView EPUBSections ToolsAdd to favoritesDownload citationsTrack citationsPermissions ShareShare onFacebookTwitterLinked InMendeleyReddit Jump toFree AccessLetterPDF/EPUBSmoking, Estrogen, and Membrane Microviscosity in Women Kazushi Tsuda, MD, FAHA and Ichiro Nishio, MD Kazushi TsudaKazushi Tsuda Division of Cardiology, Department of Medicine, Wakayama Medical University, Wakayama, Japan Search for more papers by this author and Ichiro NishioIchiro Nishio Division of Cardiology, Department of Medicine, Wakayama Medical University, Wakayama, Japan Search for more papers by this author Originally published11 Mar 2004https://doi.org/10.1161/01.STR.0000122623.80379.b6Stroke. 2004;35:e71Other version(s) of this articleYou are viewing the most recent version of this article. Previous versions: March 11, 2004: Previous Version 1 To the Editor:We read with great interest the recent article by Dr. Kurth et al1 dealing with the relationship between smoking and hemorrhagic stroke in women. The results of their prospective study demonstrated that the risk of total hemorrhagic stroke, such as intracerebral hemorrhage and subarachnoid hemorrhage, was increased in women who are current cigarette smokers. The authors proposed that smoking may cause structural damage to the arterial wall and be a risk factor for both ischemic and hemorrhagic stroke in women.Numerous studies have shown that estrogen may protect the brain from experimental stroke, such as global brain ischemia and subarachnoidal hemorrhage.2 One of the mechanisms underlying the protective effect of estrogen may be the enhancement of nitric oxide (NO) production. There is evidence showing that vascular endothelial function is markedly influenced by estrogen, and is improved by hormone replacement therapy in postmenopausal women.3 In an in vitro study presented earlier, we demonstrated that 17 β-estradiol increased membrane fluidity (a reciprocal value of membrane microviscosity) of erythrocytes and improved the rigidity of cell membranes in postmenopausal women via the NO- and cGMP-dependent mechanisms.4 In a separate series of experiments, we showed that hormone replacement therapy restored the membrane microviscosity in elderly women with a concomitant increase in plasma NO metabolite level.5 These findings suggest that, because abnormalities in membrane microviscosity could cause a disturbance in rheological behavior and microcirculation, estrogen-deficiency might be involved in the pathogenesis of vascular complications in women. In this context, it can be speculated that changes in plasma estrogen level might modify the onset and outcome of stroke in women. Mueck and Seeger6 proposed that smoking can reduce the efficacy of orally administered estrogen in women. Although the authors mentioned that use of hormone replacement therapy and postmenopausal status did not substantially change the effect of estimates of the association between smoking and hemorrhagic stroke, we would like to know whether the endogenous sex hormones might be different between smokers and non-smokers in women. It would be important to assess more precisely the relationship between estrogen status and vascular complications in women.1 Kurth T, Kase CS, Berger K, Gaziano JM, Cook NR, Buring JE. Smoking and risk of hemorrhagic stroke in women. Stroke. 2003; 34: 2792–2795.LinkGoogle Scholar2 Hurn PD, Brass LM. Estrogen and stroke: a balanced analysis. Stroke. 2003; 34: 338–341.LinkGoogle Scholar3 Higashi Y, Sanada M, Sasaki S, Nakagawa K, Goto C, Matsuura H, Ohama K, Chyayama K, Oshima T. Effect of estrogen replacement therapy on endothelial function in peripheral resistance arteries in normotensive and hypertensive postmenopausal women. Hypertension. 2001; 37: 651–657.CrossrefMedlineGoogle Scholar4 Tsuda K, Kinoshita Y, Kimura K, Nishio I, Masuyama Y. Electron paramagnetic resonance investigation on modulatory effect of 17β-estradiol on membrane fluidity of erythrocytes in postmenopausal women. Arterioscler Thromb Vasc Biol. 2001; 21: 1306–1312.CrossrefMedlineGoogle Scholar5 Tsuda K, Kinoshita-Shimamoto Y, Mabuchi Y, Nishio I. Hormone replacement therapy improves membrane fluidity of erythrocytes in postmenopausal women: an electron paramagnetic resonance investigation. Am J Hypertens. 2003; 16: 502–507.CrossrefMedlineGoogle Scholar6 Mueck AO, Seeger H. Smoking, estradiol metabolism, and hormone replacement therapy. Arzneimittelforschung. 2003; 53: 1–11.MedlineGoogle ScholarstrokeahaStrokeStrokeStroke0039-24991524-4628Lippincott Williams & WilkinsResponseKurth Tobias, , MD, ScD and Buring Julie E., , ScD01042004Tsuada and Nishio postulate a potential beneficial effect of estradiol on the arterial wall, although the effect of estradiol on the vascular system in the brain remains controversial.1In addition, recent randomized trial data provided evidence that postmenopausal hormone therapy increases the risk of ischemic stroke.2 Plasma estradiol levels were only measured in a small case-control study3 from participants of the Women’s Health Study. Preliminary results did not show statistically significant differences of plasma estradiol levels according to smoking status among users and non-users of postmenopausal hormone therapy. With respect to exogenous hormones, we showed that current smokers were less likely to utilize postmenopausal hormone therapy (see Table 1 in Reference 4). In our data, although based on a small number of cases, postmenopausal hormone use did not significantly modify the association between smoking and total hemorrhagic stroke. Previous Back to top Next FiguresReferencesRelatedDetails April 2004Vol 35, Issue 4 Advertisement Article InformationMetrics https://doi.org/10.1161/01.STR.0000122623.80379.b6PMID: 15017015 Originally publishedMarch 11, 2004 PDF download Advertisement

Smoking, Estrogen, and Membrane Microviscosity in Women

HomeStrokeVol. 35, No. 4Smoking, Estrogen, and Membrane Microviscosity in Women Free AccessLetterPDF/EPUBAboutView PDFView EPUBSections ToolsAdd to favoritesDownload citationsTrack citationsPermissions ShareShare onFacebookTwitterLinked InMendeleyReddit Jump toFree AccessLetterPDF/EPUBSmoking, Estrogen, and Membrane Microviscosity in Women Kazushi Tsuda, MD, FAHA and Ichiro Nishio, MD Kazushi TsudaKazushi Tsuda Division of Cardiology, Department of Medicine, Wakayama Medical University, Wakayama, Japan Search for more papers by this author and Ichiro NishioIchiro Nishio Division of Cardiology, Department of Medicine, Wakayama Medical University, Wakayama, Japan Search for more papers by this author Originally published11 Mar 2004https://doi.org/10.1161/01.STR.0000122623.80379.b6Stroke. 2004;35:e71Other version(s) of this articleYou are viewing the most recent version of this article. Previous versions: March 11, 2004: Previous Version 1 To the Editor:We read with great interest the recent article by Dr. Kurth et al1 dealing with the relationship between smoking and hemorrhagic stroke in women. The results of their prospective study demonstrated that the risk of total hemorrhagic stroke, such as intracerebral hemorrhage and subarachnoid hemorrhage, was increased in women who are current cigarette smokers. The authors proposed that smoking may cause structural damage to the arterial wall and be a risk factor for both ischemic and hemorrhagic stroke in women.Numerous studies have shown that estrogen may protect the brain from experimental stroke, such as global brain ischemia and subarachnoidal hemorrhage.2 One of the mechanisms underlying the protective effect of estrogen may be the enhancement of nitric oxide (NO) production. There is evidence showing that vascular endothelial function is markedly influenced by estrogen, and is improved by hormone replacement therapy in postmenopausal women.3 In an in vitro study presented earlier, we demonstrated that 17 β-estradiol increased membrane fluidity (a reciprocal value of membrane microviscosity) of erythrocytes and improved the rigidity of cell membranes in postmenopausal women via the NO- and cGMP-dependent mechanisms.4 In a separate series of experiments, we showed that hormone replacement therapy restored the membrane microviscosity in elderly women with a concomitant increase in plasma NO metabolite level.5 These findings suggest that, because abnormalities in membrane microviscosity could cause a disturbance in rheological behavior and microcirculation, estrogen-deficiency might be involved in the pathogenesis of vascular complications in women. In this context, it can be speculated that changes in plasma estrogen level might modify the onset and outcome of stroke in women. Mueck and Seeger6 proposed that smoking can reduce the efficacy of orally administered estrogen in women. Although the authors mentioned that use of hormone replacement therapy and postmenopausal status did not substantially change the effect of estimates of the association between smoking and hemorrhagic stroke, we would like to know whether the endogenous sex hormones might be different between smokers and non-smokers in women. It would be important to assess more precisely the relationship between estrogen status and vascular complications in women.1 Kurth T, Kase CS, Berger K, Gaziano JM, Cook NR, Buring JE. Smoking and risk of hemorrhagic stroke in women. Stroke. 2003; 34: 2792–2795.LinkGoogle Scholar2 Hurn PD, Brass LM. Estrogen and stroke: a balanced analysis. Stroke. 2003; 34: 338–341.LinkGoogle Scholar3 Higashi Y, Sanada M, Sasaki S, Nakagawa K, Goto C, Matsuura H, Ohama K, Chyayama K, Oshima T. Effect of estrogen replacement therapy on endothelial function in peripheral resistance arteries in normotensive and hypertensive postmenopausal women. Hypertension. 2001; 37: 651–657.CrossrefMedlineGoogle Scholar4 Tsuda K, Kinoshita Y, Kimura K, Nishio I, Masuyama Y. Electron paramagnetic resonance investigation on modulatory effect of 17β-estradiol on membrane fluidity of erythrocytes in postmenopausal women. Arterioscler Thromb Vasc Biol. 2001; 21: 1306–1312.CrossrefMedlineGoogle Scholar5 Tsuda K, Kinoshita-Shimamoto Y, Mabuchi Y, Nishio I. Hormone replacement therapy improves membrane fluidity of erythrocytes in postmenopausal women: an electron paramagnetic resonance investigation. Am J Hypertens. 2003; 16: 502–507.CrossrefMedlineGoogle Scholar6 Mueck AO, Seeger H. Smoking, estradiol metabolism, and hormone replacement therapy. Arzneimittelforschung. 2003; 53: 1–11.MedlineGoogle ScholarstrokeahaStrokeStrokeStroke0039-24991524-4628Lippincott Williams & WilkinsResponseKurth Tobias, , MD, ScD and Buring Julie E., , ScD01042004Tsuada and Nishio postulate a potential beneficial effect of estradiol on the arterial wall, although the effect of estradiol on the vascular system in the brain remains controversial.1In addition, recent randomized trial data provided evidence that postmenopausal hormone therapy increases the risk of ischemic stroke.2 Plasma estradiol levels were only measured in a small case-control study3 from participants of the Women’s Health Study. Preliminary results did not show statistically significant differences of plasma estradiol levels according to smoking status among users and non-users of postmenopausal hormone therapy. With respect to exogenous hormones, we showed that current smokers were less likely to utilize postmenopausal hormone therapy (see Table 1 in Reference 4). In our data, although based on a small number of cases, postmenopausal hormone use did not significantly modify the association between smoking and total hemorrhagic stroke. Previous Back to top Next FiguresReferencesRelatedDetails April 2004Vol 35, Issue 4 Advertisement Article InformationMetrics https://doi.org/10.1161/01.STR.0000122623.80379.b6PMID: 15017015 Originally publishedMarch 11, 2004 PDF download Advertisement

S-adenosylhomocysteine hydrolase, S-adenosylmethionine, S-adenosylhomocysteine: correlations with ribavirin induced anemia

Objective is to speculate on the ribavirin induced anemia by inhibiting S-adenosylhomocysteine (SAH)-hydrolase activity. The major toxicity associated with the use of ribavirin is hemolytic anemia. This adverse effect has been ascribed to the accumulation of ribavirin triphosphate in the erythrocyte, which interferes with erythrocyte function. Ribavirin has been found to inhibit SAH-hydrolase activity in erythrocyte. SAH is further hydrolyzed to adenosine and homocysteine by SAH-hydrolase. The formation of S-adenosylmethionine (SAM) is then demethylated to SAH. SAH, the metabolite of SAM, on the other hand is a powerful inhibitor of methyltransferase enzymes, competing for the SAM binding site. A concurrent decrease in SAM and an increase in SAH levels would inhibit methylation of many tissue components including proteins, DNA, RNA, phospholipids and other small molecules. The enzyme protein carboxyl methyltransferase type II has been recently shown to play a crucial role in the repair of damaged proteins. SAM is the methyl donor of the reaction, and its demethylated product, SAH is the natural inhibitor of this reaction, as well as of most SAM-dependent methylations. The biological function of this transmethylation reaction is related to the repair or degradation of age-damaged proteins. Methyl ester formation in erythrocyte membrane proteins has been used as a marker reaction to tag these abnormal residues and to monitor their increase associated with erythrocyte ageing diseases. Liver disease is complicated by cholesterol deposition in hepatic and extrahepatic membranes. Erythrocyte membrane fluidity has been improved with the administration of SAM and correlated with the cholesterol/phospholipid ratio of the membranes. The levels of SAH-hydrolase activity were also found to undergo a sharp decrease with red cell ageing. The similarity of these alterations with certain morphofunctional characteristics of erythrocyte in some conditions as chronic renal failure, liver disease and hereditary spherocytosis makes it possible to hypothesize that the inhibition of SAH-hydrolase could constitute at least a part of ribavirin induced hemolytic anemia.

Plasma lipids and physicochemical properties of the erythrocyte plasma membrane throughout pregnancy

Background. The physiopathological relevance of plasma lipid concentrations is supported by the observation that they might affect the physicochemical properties of the plasma membrane of circulating cells and might be crucial in the pathological conditions complicating pregnancy. Methods. Plasma and erythrocyte membrane lipid composition, membrane fluidity and function [membrane-bound enzyme sodium/potassium adenosine triphosphatase (Na+/K+-ATPase) activity] were studied in 24 healthy women in the nonpregnant condition and at 12, 24 and 38 weeks' gestation. Results. The plasma showed an increase in total and high density lipoprotein (HDL) cholesterol, triglyceride (TG) and phospholipid (PL) levels. In the erythrocyte membrane we found the cholesterol/phospholipid (C/PL) ratio increased and the saturated to unsaturated fatty acid (FA) ratio (Sat/Unsat) significantly reduced; fluorescence polarization showed an initial increase during pregnancy and a progressive decrease afterwards; Na+/K+-ATPase activity was progressively reduced. Conclusions. A generalized alteration in the composition and function of the maternal erythrocyte membrane is present during a physiological pregnancy, and these modifications may involve a more complex physiopathogenetic mechanism.

In utero exposure to tobacco and alcohol modifies neurobehavioral development in mice offspring: consideration a role of oxidative stress

Objective: To determine whether in utero tobacco and alcohol exposure induces long-term neurobehavioral alterations and whether oxidative stress/damage is a possible causal factor. Methods: Gravid mice were subjected to tobacco smoking and alcohol consumption. Their offspring were subsequently evaluated in developmental and behavioral tests. Antioxidative enzymes and erythrocyte membrane fluidity of adult offspring were measured. Results: The intrauterine tobacco and alcohol exposure has resulted in significant reduced postnatal body and organ weights accompanied by reduced gestational body weight gain in their mothers. Such exposure also induced remarkable developmental delay in neonatal reflexes and notable behavioral deficit in adulthood, namely reduced motive coordination and locomotor activity as well as impaired learning and memory abilities. Furthermore, the formation of malondialdehyde (MDA) increased significantly whereas the activities of superoxide dismutase (SOD), glutathione peroxidase (GSH-PX), catalase (Cat) and glutathione S-transferases (GST) decreased in the cerebral cortex and liver of prenatal intoxicated offspring. The embryonic intoxication also markedly reduced erythrocyte membrane fluidity in offspring. Conclusion: Our study shows the long-term neurotoxicity associated with prenatal tobacco and alcohol exposure, and suggests that the deleterious outcome may be in relation to increased free radicals formation and oxidative stress.

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Biochemical assessments of oxidative stress, erythrocyte membrane fluidity and antioxidant status in professional soccer players and sedentary controls.

Physical exercise is characterized by an increase in oxygen consumption by the whole body. This leads to a decrease in antioxidant levels that could promote both an increase in the markers of lipoprotein peroxidation and damage to the erythrocyte membrane with consequent modification of membrane fluidity. Different markers of oxidative stress, erythrocyte membrane fluidity and antioxidant status were determined in 20 professional soccer players and 20 sedentary controls. Plasma lipoperoxides and kinetics of Cu-stimulated plasma peroxidation were measured together with hydrosoluble (albumin, uric acid and vitamin C), liposoluble (vitamin E and bilirubin) and enzymatic (superoxide dismutase and glutathione peroxidase) serum antioxidants. Erythrocyte membrane rigidity was determined by measuring fluorescence anisotropy (rs) of the fluorescent probe 1, 3, 5 diphenylexatriene. The sportsmen showed higher levels of the following plasmatic antioxidants: ascorbic acid (P<0.0001), uric acid (P<0.0001), alpha-tocopherol (P=0.03) and superoxide dismutase activity (P=0.0001). According to this evidence, the lipoperoxide levels (P=0.0158), the duration of the latency phase of plasma peroxidation (P=0.0123) and erythrocytes membrane fluidity (P=0.0152) were found to be significantly higher in the soccer players. Athletes undergoing regular and adequate training show improved antioxidant status together with a more fluid membrane status, which could contribute to improving both peripheral resistance to insulin and all the functional metabolic interchanges in the cellular membrane.

Electron paramagnetic resonance study of erythrocyte membrane fluidity in renal transplant recipients

Renal transplantation (KTx) patients receiving calcineurin inhibitors—cyclosporine (CsA) or tacrolimus (TAC)—are known to be at risk for the development of posttransplant hemolytic uremic syndrome. The syndrome has been reported to occur more often with CsA than TAC treatment. It has also been noted that CsA affects erythrocyte membrane fluidity. The aim of this study was to investigate whether the impairment of erythrocyte membrane fluidity is similar among patients under treatment with different calcineurin inhibitors (CsA or TAC). Venous blood was collected from 29 KTx patients and from nine healthy volunteers. To investigate the fluidity of intact erythrocyte membranes spin label electron paramagnetic resonance spectroscopy was applied. Comparison of values for controls versus CsA-treated patients demonstrated a significant decrease in membrane viscosity in the hydrophobic region of the lipid bilayer among CsA-treated patients, whereas there was no significant difference between control and patients treated with TAC. There was no significant difference in the molecular order close to the polar heads of lipid molecules among all groups. The observed changes in erythrocyte membrane fluidity among CsA-treated patients and the lack of this phenomenon in the TAC group may correlate with more frequent prevalence of hemolytic anemia among CsA than TAC-treated patients.

Melatonin protects against lipid peroxidation and membrane rigidity in erythrocytes from patients undergoing cardiopulmonary bypass surgery.

The first aim of this study was to test whether there are changes in erythrocyte lipid peroxidation products and membrane fluidity during cardiac surgery involving cardiopulmonary bypass. Secondly, in vitro tests were performed to examine whether melatonin alters induced lipid peroxidation and reduced membrane fluidity in erythrocytes from these patients. Fifteen patients undergoing cardiac surgery involving cardiopulmonary bypass (CPB) were selected. Five blood samples were taken at different times during surgery for analysis of thiobarbituric acid reactive substances (TBARS) content and membrane fluidity of the erythrocytes. TBARS are an index of the level of lipid peroxidation. The results revealed an increase in TBARS levels and a parallel decrease in erythrocyte membrane fluidity (increased membrane rigidity) after the onset of CPB with respect to the reference sample. Likewise, in vitro induction of lipid peroxidation in the erythrocyte samples from CPB patients followed a similar pattern. The changes in TBARS levels and membrane fluidity were suppressed by pre-incubation of erythrocytes with melatonin prior to the induction (by 70 microm Fe2+ + 250 microm ascorbate) of lipid peroxidation in a concentration-dependent manner. The results constitute a persuasive argument for the use of melatonin for preventive and therapeutic purposes during CPB.