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Results for “Erythrocyte Deformability”

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At least 19 recordsLinked to original sources
PubMed1983

Influence of platelet activation of erythrocyte deformability.

Erythrocyte deformability was demonstrated to be influenced by platelet activation. Deformability of erythrocytes suspended in autologous platelet poor plasma (PPP), obtained from platelet rich plasma (PRP), was significantly reduced when PRP had previously been incubated with a platelet activating substance (arachidonic acid, adrenaline or ADP). The possibility of a direct influence of the activating substance on erythrocyte deformability was examined and malondialdehyde formation was determined as an indicator of platelet activation. Erythrocyte deformability was not impaired when endoperoxide formation in platelets was blocked by an inhibitor of cyclooxigenase (acetylsalicylic acid). Plasma viscosity was not influenced by platelet activation as demonstrated by filtration and viscosimetry. Recent studies showed that prostacyclin (PGI2) increases erythrocyte deformability (1). The antagonistic action between prostacyclin released by vessel walls and products of platelet metabolism being well known, we discuss possible mechanisms of this effect and pathophysiological relevance of our results.

Aspirin↗
PubMed1995

Conductometric study of erythrocytes during centrifugation. II. Erythrocyte deformability.

Erythrocyte deformability was studied by continuous reading of sediment conductance during centrifugation. The decrease in sediment conductivity during centrifugation reflects erythrocyte deformation in the pellet. The degree of erythrocyte deformation depends on the duration of centrifugation and the magnitude of centripetal acceleration. When constant centrifugal force is applied over an extended period of time, a gradual decrease in pellet conductivity occurs. Stepwise enhancement of centripetal acceleration during centrifugation induces a rapid increase in erythrocyte deformation. After centrifugation, the relaxation of erythrocyte deformation is observed. However, the relaxation and the recovery of cell shape are incomplete. The difference in compressibility of previously centrifuged and noncentrifuged cells demonstrates that centrifugation causes irreversible alteration in erythrocyte deformability. The results show that the time-dependent resistance of erythrocyte sediment during centrifugation may serve as a useful index for the kinetics of erythrocyte deformation.

Blood Sedimentation↗
PubMedDate not supplied

Flow behavior of erythrocytes in microvessels and glass capillaries: effects of erythrocyte deformation and erythrocyte aggregation.

Flow behavior of erythrocytes in microvessels and glass capillaries with an inner diameter of 10-50 microns was compared in relation to erythrocyte deformation and erythrocyte aggregation. This study was focused on the formation of a marginal cell-free layer, and the thickness was determined using an image processor. Human erythrocytes were perfused through a part of microvascular networks isolated from rabbit mesentery and through glass capillaries. Erythrocyte deformability was modified by treating erythrocytes with diamide, diazene-dicarboxylic acid bis[N,N-dimethylamide], and erythrocyte aggregation was accelerated by adding dextran (with a molecular weight of 70,400) to the perfusion medium. The thickness of the cell-free layer increased with an increase of the inner diameter of flow channel, with lowering the hematocrit, and with increasing the flow velocity of erythrocytes, in both microvessels and glass capillaries. Furthermore, the thickness of cell-free layer decreased with decreasing erythrocyte deformability, while it increased with accelerating erythrocyte aggregation. However, the alteration of the cell-free layer in response to the changes of these hemorheological conditions was more sensitive in microvessels than in glass capillaries. The present study concludes that flow behavior of erythrocytes in microvessels is qualitatively similar to, but quantitatively different from those in glass capillaries, as far as evaluated by the change of the thickness of the marginal cell-free layer.

Animals↗
PubMed2001

Erythrocyte deformability and erythrocyte aggregation in preeclampsia.

One of the features of preeclampsia is impaired blood rheology due to altered erythrocyte aggregation and erythrocyte deformability. We investigated these two parameters which affect the viscosity of blood, along with serum and intraerythrocytic magnesium concentrations, immunoglobulin titres and fibrinogen concentration in 12 preeclamptic women. Eighteen (18) other non-preeclamptic, gestation-matched women acted as controls. Erythrocyte deformability, expressed as elongation index (EI), and erythrocyte aggregation expressed as aggregation half-time (t 1/2) were measured with the Laser-assisted Optical Rotational Cell Analyser (LORCA). Serum and intraerythrocytic magnesium concentrations were analysed by atomic absorption spectrometry, immunoglobulin titres by radial immunodiffusion and fibrinogen concentration by a clot weight technique. There was no statistically significant difference in these parameters between preeclamptics and controls suggesting that erythrocyte deformability and aggregation as well as serum and intraerythrocytic concentrations, fibrinogen levels and immunoglobulin titres are not altered in preeclampsia. Further investigations are required in severe preeclampsia and in preeclamptic women taking magnesium sulphate supplement.

Adolescent↗
PubMed1996

Deformation of erythrocytes in microvessels and glass capillaries: effects of erythrocyte deformability.

OBJECTIVE: The deformation of erythrocytes in microvessels less than 15 microns in inner diameter was analyzed using a microvascular bed isolated from rabbit mesentery. The deformation was compared with that found in glass capillaries. METHODS: Human erythrocytes were perfused through two media: first, a microvascular-bed section isolated from rabbit mesentery; and second, a set of glass capillaries. Images of deformed erythrocytes were recorded on videotape under strobe light and analyzed with an image processor. The flow velocity of the erythrocytes was determined from the difference of their positions between video frames or by a dual-spot cross-correlation technique. Erythrocyte deformability was modified with diamide, diazene dicarboxylic acid bis[N,N-dimethylamide], by crosslinking spectrins. RESULTS: Symmetrical (parachute-like or slipper-like) deformation of erythrocytes was observed only in microvessels smaller than 13 microns in inner diameter. Erythrocytes in microvessels were less deformed than those in glass capillaries with corresponding diameters, and the marginal cell-free layer was narrower. The deformation increased by increasing the flow velocity of erythrocytes, and the cell-free layer became wider. Diamide-treated cells in microvessels were less deformed than normal cells and showed slightly narrower cell-free layers. Stronger stress in narrower microvessels induced further deformation of cells. CONCLUSIONS: Erythrocyte deformation in microvessels was essentially different from that in glass capillaries, and the effect of erythrocyte deformability on the flow dynamics of erythrocytes in microvessels was properly evaluated using an isolated microvascular bed.

Animals↗
PubMed1985

[Role of erythrocyte deformability in erythrocyte transit time and bioavailability of O2].

The bioavailability of oxygen and its transfer towards all of the cells of the body essentially depends on the flow rate of red blood cells in the capillaries, which often have a smaller diameter than the red cell itself. The authors discuss the results obtained for the mean transit time of erythrocytes, based on microfiltration through artificial polycarbonate capillaries with a diameter of 5 microns, a length of 13 microns and a density of 4.10(5) pores/cm2.

Biological Availability↗
PubMed1981

Effects of insulin on erythrocyte deformability in diabetics--relationship between erythrocyte deformability and platelet aggregation.

Erythrocyte deformability was studied by the filtration technique of Reid & Dormandy using whole blood and washed erythrocytes from insulin-dependent diabetics (IDD) under insulin delivery by an artificial pancreas (AP). The same technique was employed to study deformability in vitro using normal erythrocytes incubated in the presence of insulin. Results of this study show that in IDD the initially poor erythrocyte deformability is improved within hours of insulin administration. Improved deformability was accompanied by increased levels of intra-erythrocyte ATP but without changes in levels of HbG and 23 DPG. Incubation of erythrocytes in medium containing glucose showed that deformability was significantly improved in the presence of insulin. These results indicate that insulin favourably affects erythrocyte deformability in IDD. Before and after 24 hours treatment by AP, platelet aggregation was studied in IDD by the technique of Born using platelet-rich plasma (PRP) and by a modified Breddin technique using PRP, whole blood or whole blood treated by chlorpromazine and mixtures of erythrocytes from IDD with normal PRP. Platelet hyperaggregation was only found in the presence of erythrocytes from untreated diabetics. Chlorpromazine, at a dose (10 mumole) which inhibits haemolysis without inducing platelet hyperaggregation, eliminated the above anomaly. In conclusion, it is conceivable that the insulin-induced correction of poor erythrocyte deformability eliminates excessive fragility of erythrocytes and their haemolysis wit release of ADP, thus avoiding platelet hyperaggregation.

2,3-Diphosphoglycerate↗
PubMed2004

The Microfiltrometer (MicroFM): a new filtration device for the assessment of less deformable erythrocyte subpopulations.

The hardware of a new filtration device, the Microfiltrometer (MicroFM), is described. The different components of the device; impedance meter, power supply, measuring cell and its 5-micron Oligopore filter are described and it is shown how they are interrelated and interfaced to a computer for data acquisition. The properties of the filter and the general functioning principle of the device are also elucidated. For each run, the MicroFM generates elementary signals from individual passages of many hundreds of red blood cells (RBCs) through micropores of a given 5-micron Oligopore filter. Analysis of each elementary signal provides two complementary parameters, the transit time tau of the explored RBC and the change in electrical impedance deltaZ caused by the temporary flow of the considered RBC through a particular micropore of the filter. These two parameters can be utilized for reliable assessment of erythrocyte deformability on a cellular level.

Cell Size↗
PubMed1990

Erythrocyte deformability in diabetes and erythrocyte membrane lipid composition.

Erythrocyte deformability was assessed in 40 diabetic patients, 24 insulin-dependent (IDD) and 16 non-insulin-dependent (NIDD), by measuring the initial filtration flow rate of whole blood, isolated red blood cells (RBC), and isolated RBC membranes with the Hanss hemorheometer, and its relationship to the plasma and ghost membrane lipid composition was investigated. RBC deformability was significantly reduced, whereas the deformability of the isolated RBC membranes did not differ significantly from the controls. In the plasma, the triglycerides were high, the high-density lipoprotein (HDL) cholesterol was reduced, and the ratio of total cholesterol over HDL cholesterol was high as compared with the controls. The RBC lipid composition expressed in mumol lipids/10(10) RBC showed significantly lower levels of free cholesterol, sphingomyelines, and phosphatidylcholine, which are the lipids principally located on the outer layer of the RBC membranes. These data suggest that in both IDD and NIDD patients, there may be a relation between these modifications in the RBC lipid composition and rheological impairment of the RBC.

Cholesterol↗
PubMedDate not supplied

Agglutination-induced erythrocyte deformation by two blood group A-specific lectins: studies by light and electron microscopy.

The adhesive energy in lectin-induced agglutination can be assessed by the deformation of erythrocytes in aggregates. Helix pomatia (HPA) and Dolichos biflorus (DBA) specifically agglutinated blood group A erythrocytes and induced a change in curvatures of cells at the end of the aggregates. The curvatures changed from concavity to convexity with increasing lectin concentrations. HPA-induced aggregates achieved the theoretical maximal end cell curvature of 0.27 microns-1 at 2-3 micrograms/ml; DBA-induced aggregates approached 0.23 microns-1, requiring 400 micrograms/ml. At any given lectin concentration, HPA showed greater surface binding, caused higher cell curvatures, induced larger aggregate size, and had greater adhesive energies, as compared to DBA. HPA and DBA are globular proteins with a diameter of approximately 5.5 nm and approximately 6.1 nm, respectively, as revealed by the negative staining electron microscopy. The former induced uniform intercellular spacing (approximately 15 nm), whereas the latter induced both smooth (approximately 20 nm) and ruffled spacings. The uniform intercellular spacing was not a function of lectin concentrations. Microscopic studies of erythrocyte deformation provided morphological correlates of biophysical findings of differential adhesive energies induced by these two blood group A-specific lectins.

ABO Blood-Group System↗
PubMed1980

Evaluation and modification of whole blood filtration in the measurement of erythrocyte deformability in pregnancy and the newborn.

This study was designed to investigate the deformability of erythrocytes from pregnant women and full-term newborn infants, with healthy female adults as a comparison, using a whole blood filtration method. Delay in measurement, white cells, haematocrit, plasma viscosity, temperature and pH all significantly affected the rate of whole blood filtration and could thereby obscure or exaggerate changes in erythrocyte deformability. A new method was developed which eliminated or minimized these sources of error and the study was completed. Fetal erythrocytes were found to be significantly less deformable than adult erythrocytes which were in turn found to be significantly less deformable than erythrocytes from pregnant women. These differences appear to be related to the varying plasma fibrinogen concentrations in the three groups of subjects. The significance of these findings in the special haemodynamic situations found in the neonate and during pregnancy are discussed.

Adult↗
PubMed1987

Spin label study of erythrocyte deformability. Ca2+-induced loss of deformability and the effects of stomatocytogenic reagents on the deformability loss in human erythrocytes in shear flow.

The Ca2+-induced loss of deformability in human erythrocytes and the recovery of the lost deformability by stomatocytogenic reagents were investigated by means of a new flow electron paramagnetic resonance (EPR) spin label method, which provides information on deformation and orientation characteristics of spin labeled erythrocytes in shear flow. The Ca2+-induced loss of deformability is attributed mainly to the increase in intracellular viscosity resulting from efflux of intracellular potassium ions and water (Gardos effect). Partial recovery of the lost deformability is demonstrated in the presence of stomatocytogenic reagents, such as chlorpromazine, trifluoperazine, W-7, and calmidazolium (R24571). The recovery can not be explained solely by suppression of the Gardos effect due to the reagents. Incorporation of an optimal amount of the reagents into the membrane appears to compensate for the membrane modification due to Ca2+ ions to restore a part of the lost deformability.

Calcimycin↗
PubMed2002

[The influence of select pathophysiologic factors of acute pancreatitis on erythrocytes' deformability examined in vitro].

Deformability of erythrocytes is essential factor in maintenance of blood flow in microcirculation. Deformability of erythrocytes during sepsis, including severe acute pancreatitis, decreases. The aim of the study was to examine in vitro influence of most common etiological factors and determinants of severity of acute pancreatitis on deformability of erythrocytes measured by means of laser diffractometry. We found that ethanol, bilirubin, sodium taurocholate have no effect on deformability of erythrocytes. Trypsin revealed positive effect on deformability of erythrocytes. Acetaldehyde and superoxide anion decrease deformability of erythrocytes in low shear stresses, whereas platelet activating factor and lipopolysaccharide are potent to decrease the deformability of erythrocytes mainly in high shear stresses.

Acetaldehyde↗
PubMed1975

Effect of oral contraceptives and pregnancy on erythrocyte deformability and surface charge.

Erythrocyte deformability and surface charge were studied in normal premenopausal women, oral contraceptive users, and pregnant women. The increased incidence of thrombosis in women taking oral contraceptives could not be explained by decreased erythrocyte deformability or surface charge. However, the decreased erythrocyte deformability of late pregnancy may relate to thrombosis during this period and to increased hemolysis in patients with certain hemoglobinopathies.

Adenosine Triphosphate↗
PubMed2001

Direct measurement of erythrocyte deformability in diabetes mellitus with a transparent microchannel capillary model and high-speed video camera system.

To measure erythrocyte deformability in vitro, we made transparent microchannels on a crystal substrate as a capillary model. We observed axisymmetrically deformed erythrocytes and defined a deformation index directly from individual flowing erythrocytes. By appropriate choice of channel width and erythrocyte velocity, we could observe erythrocytes deforming to a parachute-like shape similar to that occurring in capillaries. The flowing erythrocytes magnified 200-fold through microscopy were recorded with an image-intensified high-speed video camera system. The sensitivity of deformability measurement was confirmed by comparing the deformation index in healthy controls with erythrocytes whose membranes were hardened by glutaraldehyde. We confirmed that the crystal microchannel system is a valuable tool for erythrocyte deformability measurement. Microangiopathy is a characteristic complication of diabetes mellitus. A decrease in erythrocyte deformability may be part of the cause of this complication. In order to identify the difference in erythrocyte deformability between control and diabetic erythrocytes, we measured erythrocyte deformability using transparent crystal microchannels and a high-speed video camera system. The deformability of diabetic erythrocytes was indeed measurably lower than that of erythrocytes in healthy controls. This result suggests that impaired deformability in diabetic erythrocytes can cause altered viscosity and increase the shear stress on the microvessel wall.

Adult↗
PubMedDate not supplied

[Erythrocyte deformability: physiological aspects].

Analysis of published and author's data on the physiological role of deformability of erythrocytes, general mechanisms of modifications and disturbances, assessment methods, and the role of this blood feature for assessing the body status. This parameter is one of the most labile features of blood that shows highly sensitive reaction to practically any changes in metabolic process in erythrocytes and in a whole body. Degradation of deformability of erythrocytes under various types of oxygen deficit deteriorates functioning of the system of oxygen transportation at various levels: heart, vascular flow, oxygen-transporting blood function. Under hypoxia the parameters of oxygen-transporting blood function, of peroxide oxidation of lipids and of the antioxidation system correlate well with degradation of deformability of erythrocytes. Therefore, this parameter can be used an integrated criterion of disturbances in oxygen supply, and of prooxidation-antioxidation body status. Deformability of erythrocytes is a factor generating adequate the oxygen supply to tissue, and its degradation aggravates substitution of the oxidase pattern of oxygen utilization with the oxygenase pattern. This parameter is extremely important for the body functional status.

Animals↗