Red Cell Membrane Fluidity Research Articles

Red cell membrane fluidity and red cell aggregation in vascular atherosclerotic disease

Red cell membrane fluidity and red cell aggregation in vascular atherosclerotic disease

Bidis — hand-rolled, Indian cigarettes: Induced biochemical changes in plasma and red cell membranes of human male volunteers

Objective To investigate the effect of bidi smoking on erythrocyte antioxidant status, membrane fluidity. Design and methods Thirty experimental and control subjects (mean age 35 ± 5) were selected for the study. Experimental subjects smoke 22 ± 4 bidis per day for 8–10 years. Results Increase in plasma total cholesterol, LDL-cholesterol, triglycerides, lipid peroxidation, protein carbonyls with a decrease in HDL-cholesterol, thiol groups as well as increased erythrocyte catalase (CAT), superoxide dismutase (SOD), decreased glutathione peroxidase (GPx) activity and reduced glutathione (GSH) content was observed in bidi smokers. Increase in the erythrocyte membrane lipid peroxidation, cholesterol phospholipids (C/P) ratio as well as decrease in protein and Na +/K +-ATPase activity was observed. Increase in nitrite/nitrate (NOx) levels of plasma, red cell lysate was positively correlated with C/P ratio ( r = 0.614) and Na +/K +-ATPase ( r = 0.435) in bidi smokers. Conclusions Bidi smoke alters antioxidant status, red cell membrane fluidity and increases atherogenicity.

Causes of Thromboembolism in Polycythemia Vera Patients.

Our experience and review of the literature suggests that thromboembolism is a major cause of morbidity and death in polycythemia vera patients. Using methods developed by our group (Ambrus et al, Angiology 34 418–426, 1984) we determined membrane fluidity, deformability of red cell membranes. We found that compared to normal controls, red cell membranes in polycythemia vera patients were relatively stiff and the red cells less deformable when passed through microtubules. These abnormal red cell membranes also caused platelet aggregation. In the circulation of polycythemia vera patients we also found increased platelet aggregates using the detection method of Wu et al (Wu et. al, Lancet 2: 924–926 1974, Wu et. al, Thromb. Res. 7:917–924, 1975). Other factors in the thromboembolic complications includedincreased hematocrithyperviscosity syndromeincreased thromboxane A2 content of plateletsincreased tendency to disseminated intravascular coagulation (DIC) (factors involved were also investigated).Red cell membrane fluidity and platelet aggregation may be points of therapeutic attention to prevent thromboembolic complications. Suggestions of approaches to this problem by future research will be discussed.

Variations in the lipid profile of patients with chronic renal failure treated with pyridoxine

BackgroundHyperhomocysteinemia and lipid abnormalities are commonly found in patients with chronic renal failure; both are recognized as risk factors for atherosclerosis. The homocysteine-lowering effect of pyridoxine is controversial. This study was performed to determine the effect of a high dose of pyridoxine (300 mg i.v. three times a week) on plasma and red blood cell lipid profile and plasma homocysteine concentration in twelve chronic renal failure patients on regular hemodialysis. Fasting blood samples were taken at the beginning of the study (basal 1), after 30 and 60 days of treatment and 4 months after withdrawal (basal 2).ResultsPyridoxine supplementation induced a significant decrease in total plasma homocysteine level and also a lowering effect in plasma total cholesterol and triglycerides. These biochemical data increased when the samples were taken at basal 2, reaching the levels obtained at the beginning of the experiment. LDL cholesterol increased whereas HDL cholesterol was reduced during the treatment. In erythrocyte membranes vitamin B6 therapy enhanced the cholesterol/phospholipid ratio as well as the fluorescence anisotropy of diphenyl-hexatriene.ConclusionsWe conclude that high doses of pyridoxine represent an effective strategy to ameliorate both plasma homocysteine levels and lipid profiles in chronic renal failure patients, protecting them from atherosclerosis. Further research using a long-term treatment would be necessary in an attempt to restore the fatty acid pattern and the fluidity of red cell membranes.

Effect of O 2/O 3 atmosphere on the rate of osmotic hemolysis of bovine erythrocytes in the presence of some antioxidants

Purified red blood cells, exposed to an ozone atmosphere, show an increased rate of hemolysis on sudden osmotic stress. To determine this effect of ozone in the presence of natural antioxidants, bovine red blood cells, used as models, were suspended in blood plasma, or in physiological saline with one of the following antioxidants: albumin, glutathione, uric acid, glucose and a vitamin E analog (trolox). After exposure of the suspensions to oxygen and oxygen/ozone atmospheres the rates of osmotic hemolysis were measured, using a stop-flow technique, and compared with rates measured in air-exposed controls. Blood plasma, containing all natural antioxidants, caused a decreased rate of osmotic hemolysis of cells exposed to oxygen and also decreased the effect of ozone. Trolox cancelled the oxygen effects only. Albumin, glutathione and uric acid tended to protect the cells from the hemolytic effects of ozone. The antihemolytic effect of glucose, seen only in some samples, may depend on uncontrolled factors. The alteration of the rates correlates with an increased fluidity of red cell membranes exposed to ozone.

Search for the pathogenesis of the differing phenotype in two compound heterozygote Hungarian brothers with the same genotypic triosephosphate isomerase deficiency.

In a Hungarian family with triosephosphate isomerase (TPI) deficiency, two compound heterozygote brothers were found with the same severe decrease in TPI activity, but only one of them had the classical symptoms. In search for the pathogenesis of the differing phenotype of the same genotypic TPI deficiency, an increase in red cell membrane fluidity was found. There were roughly 100% and 30% more 16:0/20:4 and 18:0/20:4 diacyl-phosphatidylcholine species in erythrocytes from the two TPI-deficient brothers than in the probes from healthy controls. The activities of acethylcholinesterase and calmodulin induced Ca2+ ATPase were significantly enhanced in erythrocytes from the propositus as compared with those of the neurologically symptom-free brother and other members of the TPI-deficient family as well as to those from healthy controls. Both enzymes are crucially involved in the function of nerve cells. The observed differences in membrane fluidity and enzyme activities between the erythrocytes from the phenotypically differing TPI-deficient brothers underline the importance of investigations into the effect of biophysical changes in the lipid environment of the membrane proteins on the development of disseminated focal neurological disorders of unknown pathogenic origin.

Decrease of Red Cell Membrane Fluidity and -SH Groups Due to Hyperglycemic Conditions Is Counteracted by α-Lipoic Acid1

Human red cell membranes (ghosts) were treated by 5 min of incubation with fasting or hypo- and hyperglycemic concentrations ofD-glucose. This simulation of nondiabetic or diabetic conditions revealed an influence on membrane fluidity and on protein -SH reactivity. Protein -SH groups, measured with Ellman's reagent, generally behave in the same way as membrane fluidity determined with diphenylhexatriene. Maximal values were obtained with 5 mM D-glucose, whereas decrease was observed above 10 mM D-glucose. Addition of α-lipoic acid (4 nmol/mg protein) resulted in a significant increase in membrane fluidity and titratable -SH groups at glucose concentrations of 10 mMand above. Dithiothreitol diminished titrable -SH groups and did not restore membrane fluidity. 2-Mercaptopropionylglycine was only effective in restoration of -SH groups. By contrast toD-glucose, other sugars such asL-glucose,D-fructose, or sucrose revealed no comparable changes on membrane fluidity and titratable membrane -SH groups between concentrations of 5 and 10 mM. The hyperglycemic effects ofD-glucose were corroborated with isolated, reconstituted membrane proteins and erythrocyte glucose carrier, indicating that, in general, the observed divergent biochemical/biophysical changes of the red cell membrane are influenced by the glucose transport protein GluT1. The naturalR-form and theS-form of α-lipoic acid were compared with racemicR-/S-forms for their efficiencies in alterations of red cell membrane fluidity. Decreased fluidities in presence of 10 mMglucose were found to be influenced in differentiated ways: theS-form was highly active in increasing fluidity at 4 nmol/mg and increasingly less active up to 20 nmol/mg protein. By contrast theR-form of lipoic acid was moderately efficient in increasing fluidity through a larger concentration range between 4 and 80 nmol/mg protein.

Red cell membrane fluidity in combined hyperlipidaemia

Red cell membrane fluidity in combined hyperlipidaemia

Effect of red blood cells from patients with sickle cell disease on platelet factor 3 release.

Red cells from two SS genotype and two SA genotype patients were sampled. When the samples were deoxygenated and mixed with platelet-rich plasma, they caused the release of platelet factor 3 as recorded in a coagulometer. This phenomenon was not present in control blood samples from normal individuals. Membrane changes in abnormal red cells during hypoxia may be responsible in part for platelet activation and its role in vasoocclusive crisis. Vasoocclusive crisis could be prevented by increasing the red cell membrane fluidity and inhibiting the platelet aggregation with pentoxifylline.

Chronic ethanol abuse and membrane fluidity changes in liver disease

The long-term effect of ethanol on human red cell membrane fluidity was studied, by fluorescence polarization with 1,6-diphenyl-1,3,5-hexatriene as a probe, in 11 healthy subjects, 9 chronic alcoholics without evidence of liver disease, 12 chronic alcoholics with biopsy-proven alcoholic liver disease and 9 abstemious patients with chronic active liver disease, most of them cirrhosis of the liver. Fluorescence polarization values were not significantly different in the two groups without liver disease. Patients with alcoholic and non-alcoholic liver disease showed higher fluorescence polarization values than patients without liver disease. These changes correlated with the severity of liver dysfunction and were not related to alcohol consumption. In conclusion, the decrease in fluidity of the erythrocyte membrane in alcoholic patients with chronic liver disease, is related to liver dysfunction but not to chronic ethanol ingestion. Changes in membrane fluidity in chronic alcoholics are found only in the presence of liver disease.

A compensatory mechanism improving red cell membrane fluidity in hemodialysed patients

A fluorescence polarization technique with 1,6-diphenyl 1,3,5-hexatriene as a fluorescent probe was used to determine the fluidity of red cell membranes from hemodialysed patients before and after dialysis. After dialysis, there was a decrease in fluidity and activation energy values revealed a significantly changed distribution. The membrane lipid composition showed a significant increase in cholesterol after dialysis ( p < 0.001) and a significant reduction in saturated fatty acids ( p < 0.01) with an increase in unsaturated fatty acids ( p < 0.05). A compensatory mechanism could be suggested involving a reduction of saturated fatty acids in response to the increase in the cholesterol phospholipid ratio. This could lead to an optimization of membrane fluidity.

Vascular atherosclerotic disease: evaluation of the whole-blood f ilterability and red cell membrane microrheological pattern after intravenous administration of a single dose of pentoxifylline

A study was carried out in 10 patients with vascular atherosclerotic disease to investigate the effects of a single dose of 300 mg pentoxifylline, given by intravenous infusion over 30 minutes, on various macrorheological and microrheological parameters. Measurements were made at baseline, at the end of the intravenous infusion and again 30 minutes later, of whole-blood filterability, erythrocyte membrane fluidity (using pyrene as probe) and transverse fluidity gradient (using fluorescent fatty acids as probes). The results showed that there was a significant variation in whole-blood filterability and the red cell membrane fluidity gradient after pentoxifylline. No difference, however, was noted for the membrane fluidity. These data suggest, therefore, that pentoxifylline plays a role in affecting the red cell membrane microrheological pattern.

Effect of chronic ethanol abuse on the physico-chemical properties of erythrocyte membranes in man

Chronic alcoholics (> 150 g/day) showing minor serum and histological changes have been studied, compared to healthy non alcoholic subjects, and the following parameters have been considered: S. (Serum)cholesterol (CH), S.phospholipids (PH), S.folate level, and mean corpuscular volume (MCV). Erythrocyte ghosts have been studied for CH and PH content and membrane fluidity using diphenylhexatriene as a probe. All alcoholics showed decreased fluidity of red cell membrane with increased CH/PH ratio, even in patients showing normal MCV or minimal alterations of functional tests, suggesting that changes in red cell membrane fluidity represent an early sign of ethanol abuse. These likely reflect the diffuse interaction of ethanol with biological membranes. The administration of N5-Methyltetrahydrofolate produced an increase of membrane fluidity over the 3 weeks considered, associated with modest changes of MCV. The latter were delayed with respect to changes in fluidity. If changes of red cell membrane fluidity are a sensitive index of alcohol abuse, they could be a useful marker for detection and follow-up of chronic alcoholism.

Lipid fluidity of red cell membranes assessed with different fluorescent probes.

Lipid fluidity of red cell membranes assessed with different fluorescent probes.

Altered red cell membrane fluidity during schizogonic development of malarial parasites ( Plasmodium falciparum and P. lophurae)

The plasma membranes of human or duckling erythrocytes infected with malarial parasites ( Plasmodium falciparum and P. lophurae respectively) were stained by the fluorescent dye merocyanine 540 in the presence of serum. Unparasitized erythrocytes from infected ducklings or from in vitro cultures remained unstained in the presence of serum. Because merocyanine 540 has a greater affinity for fluid phased or disordered lipid bilayers the results suggest that upon infection of the red blood cell the erythrocyte plasma membrane becomes disordered or is increased in its fluidity. Such alterations of the host erythrocyte are probably due to parasite-induced modifications in the underlying spectrin network (required for lipid leaflet asymmetry) as well as changes in erythrocyte membrane lipid composition.

Increased Cholesterol and Decreased Fluidity of Red Cell Membranes (Spur Cell Anemia) in Progressive Intrahepatic Cholestasis

Progressive hemolytic anemia occurred in a 4 1/2-year-old girl with familial intrahepatic cholestasis; a peripheral smear contained bizarre spiculated "spur" red cells. Analysis of this patient's fresh red cells revealed a 59% increase in cholesterol content with a normal phospholipid content and therefore an increase in the cholesterol/phospholipid molar ratio to 1.35 (normal = 0.92). A similar abnormality of lipid composition was present in serum lipoproteins. The lipid abnormality in red cell membrane was associated with a decrease in membrane fluidity, as assessed by the fluorescence polarization of the hydrophobic probe 1,6-diphenyl-1,3,5-hexatriene. Following incubation with patient's plasma, normal cells acquired a spur-shaped morphology with an associated decrease in osmotic fragility and a 25% increase in cholesterol content. The patient's cells, during incubation with normal plasma, acquired morphologic features of spiculated spherocytes with an increase in osmotic fragility and a 21% decrease in cholesterol content. Chenodeoxycholate and lithocholate were present in markedly elevated concentrations in serum. These studies show that a process identical to spur cell anemia in alcoholic cirrhosis may accompany severe liver disease in children with intrahepatic cholestasis.

Fluorescence depolarization studies of red cell membrane fluidity. The effect of exposure to 1.0-GHz microwave radiation.

The internal viscosity of human red blood cell membranes was investigated during exposure to continuous wave 1.0-GHz microwave radiation using fluorescence measurements of a lipid seeking molecular probe, diphenyl-hexatriene. Samples were exposed in a Crawford cell arranged so that fluorescence was measured during microwave exposure; specific absorption rates calculated from electrical measurements were approximately 0.6, 2 and 15 W/kg. Measurements were obtained at selected temperatures between 15 degrees C and 40 degrees C and as a function of the duration of exposure at 23 degrees C. Arrhenius-type plots of the temperature profile data were linear and showed no difference between exposed and control samples. The exposure duration data also showed no difference between exposed and control samples except for a small effect of elevated temperature at the highest exposure. The activation energy for motion of the fluorescent probe in its environment within the membrane lipid was not affected by the application of the microwave energy and no evidence for a lipid phase transition was found. These results indicate that the increased cation efflux from red cells, observed by others at certain transition temperatures during microwave exposure, was more likely to have been caused by alteration of the membrane bound protein than by changes in the lipid constituents of the red cell membrane.

Factors influencing the lipid composition and fluidity of red cell membranes in vitro: production of red cells possessing more than two cholesterols per phospholipid.

Factors influencing the lipid composition and fluidity of red cell membranes in vitro: production of red cells possessing more than two cholesterols per phospholipid.

The influence of temperature on red cell deformability

This study was undertaken to examine the influence of temperature on physical properties of red cell membranes. Red cells adhering to cover slips were subjected to fluid shear stress in a rotating disc apparatus for 1 min or for 10 min at temperatures ranging from 2 degrees to 50 degress C. They were fixed while subject to shear stress by addition of glutaraldehyde and then processed for examination and photography by reflected-light microscopy. Cell dimensions were obtained with a computerized planimeter. At shear stresses under 2 dynes/sq cm, cells changed shape from biconcave discs to tear drops, the dimensions of which were influenced very little by temperature or duration of shear stress. Above 2 dynes/sq cm, filamentous processes or “tethers” developed at attachment points of cells to cover slips. Tether length and the percentage of cells possessing tethers increased markedly with increasing temperature and duration of shear stress. At approximately 48 degrees C, a dramatic change occurred over a narrow temperature range such that cells were markedly elongated and irregularly deformed by a shear stress of 1 dyne/sq cm or less. These observations demonstrate that elongation of human red cells subjected to fluid shear stress in a rotating disc system is markedly influenced by temperature as well as by magnitude and duration of shear stress. They also indicate that significant increases in red cell membrane fluidity occur between 2 degrees and 24 degrees-37 degrees C and again between 48 degrees and 50 degrees C.

The Influence of Temperature on Red Cell Deformability

This study was undertaken to examine the influence of temperature on physical properties of red cell membranes. Red cells adhering to cover slips were subjected to fluid shear stress in a rotating disc apparatus for 1 min or for 10 min at temperatures ranging from 2 degrees to 50 degress C. They were fixed while subject to shear stress by addition of glutaraldehyde and then processed for examination and photography by reflected-light microscopy. Cell dimensions were obtained with a computerized planimeter. At shear stresses under 2 dynes/sq cm, cells changed shape from biconcave discs to tear drops, the dimensions of which were influenced very little by temperature or duration of shear stress. Above 2 dynes/sq cm, filamentous processes or "tethers" developed at attachment points of cells to cover slips. Tether length and the percentage of cells possessing tethers increased markedly with increasing temperature and duration of shear stress. At approximately 48 degrees C, a dramatic change occurred over a narrow temperature range such that cells were markedly elongated and irregularly deformed by a shear stress of 1 dyne/sq cm or less. These observations demonstrate that elongation of human red cells subjected to fluid shear stress in a rotating disc system is markedly influenced by temperature as well as by magnitude and duration of shear stress. They also indicate that significant increases in red cell membrane fluidity occur between 2 degrees and 24 degrees-37 degrees C and again between 48 degrees and 50 degrees C.