Resistivity of Red Blood Cells Against High-Intensity, Short-Duration Electric Field Pulses Induced by Chelating Agents

The interaction of human red blood cells (RBCs) with diethylenetriamine-pentaacetic acid (DTPA) or its Gd-complex (Magnevist, a widely used clinical magnetic resonance contrast agent containing free DTPA ligands) led to the following, obviously interrelated phenomena. (i) Both compounds protected erythrocytes against electrohemolysis in isotonic solutions caused by a high-intensity DC electric field pulse. (ii) The inhibition of electrohemolysis was observed only when cells were electropulsed in low-conductivity solutions. (iii) The uptake of Gd-DTPA by electropulsed RBCs was relatively low. (iv) (Gd-) DTPA reduced markedly deformability of erythrocytes, as revealed by the electrodeformation experiments using high-frequency electric fields. Taken together, the results indicate that (Gd-) DTPA produce stiffer erythrocytes that are more resistant to electric field exposure. The observed effects of the chelating agents on the mechanical properties and the electropermeabilization of RBCs must have an origin in molecular changes of the bilayer or membrane-coupled cytoskeleton, which, in turn, appear to result from an alteration of the ionic equilibrium (e.g., Ca²⁺ sequestration) in the vicinity of the cell membrane. Received: 19 January 1999/Revised: 1 April 1999     

The effects of suspending medium viscosity on erythrocyte deformation and haemolysis in vitro

Fresh adult human erythrocytes were suspended in isotonic pH adjusted solutions containing various concentrations of Dextran T.500. The cells were subjected to uniform hydrodynamic shear stress in a Ferranti Shirley Cone and Plate Viscosimeter. The amount of lysis incurred at any given combination of explosure parameters was markedly affected by the viscosity of the suspending medium. Optical diffraction patterns obtained whilst the cells were undergoing shear demonstrated that cellular deformation was also a function of viscosity. Consequently, the distorted shape of the stressed cell must play a crucial role in the haemolytic process.     

Erythrocyte membrane elasticity during in vivo ageing

Changes in the ability of senescent erythrocytes to pass through the micro-circulation may cause them to be trapped in the spleen and removed from the blood. To help understand this process we have measured erythrocyte membrane elasticity, to see whether it changes during in vivo ageing. Human and rabbit red cells were fractionated by isopycnic sedimentation to obtain samples of aged and young cells. These were subjected to micropipette analysis in order to determine their membrane shear elastic modulus. We found that the membrane rigidity did not significantly alter as red cells aged. Previously we have also demonstrated that the changed size and shape of aged cells is unlikely to explain their removal from the circulation (Nash, G.B. and Wyard, S.J. (1981) Biorheology, in the press). Thus we conclude that the lifespan of erythrocytes is not determined by factors related to membrane flexibility or cell shape but may depend on changes in their viscous properties (as suggested by Williams, A.R. and Morris, D.R. (1980), Scand. J. Haematol. 24, 57–62).     

Deformability and adhesive force of artificial platelets measured by atomic force microscopy

Platelet glycoprotein GPIaIIa is an adhesive protein that recognizes collagen. We have investigated polymerized albumin particles conjugated with recombinant GPIaIIa (rGPIaIIa-poly Alb) for their platelet-like function. To evaluate the feasibility of these particles to achieve the hemostatic process, we measured the deformability (Young’s modulus and spring constant) and the adhesive force of the particles using atomic force microscopy, which can measure the mechanical properties of individual cells. Our results showed that the Young’s modulus of these particles was 2.3-fold larger than that of natural platelets and 12-fold larger than that of human red blood cells. The Young’s modulus of the particles may have been determined by the properties of the polymerized albumin particle, although the glycoprotein of the platelet surface also contributed to the higher modulus. Our results also showed that the adhesive force of the rGPIaIIa-poly Alb with the collagen ligand was 52% of that of natural platelets. These two mechanical properties (deformability and adhesive force) of cells or particles, such as rGPIaIIa-poly Alb, are important specifications for the optimum design of platelet substitutes.     

Effect of carbonyl compounds on red blood cells deformability

The effect of Maillard reaction on red blood cells (RBC) deformability was investigated. Exposure of RBC to carbonyl compounds (dl-glyceraldehyde, glyoxal, glycolaldehyde, 3-deoxyglucosone, and d-glucose) leading to Maillard reaction caused a marked decrease in RBC deformability even at 1 mM level. The decrease rate depended on the kind of carbonyl compounds, in which both dl-glyceraldehyde and glyoxal significantly decreased the RBC deformability (p < 0.05). In addition, the decrease rate also differed among volunteers tested, indicating that the sensitivity against carbonyl compounds varies among them. In order to elucidate the mechanism of the decrease in RBC deformability, RBC was exposed to carbonyl compounds in the presence of aminoguanidine which is the inhibitor of AGE formation in Maillard reactions. Aminoguanidine inhibited the decrease in RBC deformability by dl-glyceraldehyde and glyoxal. When Hb which has a high reactivity with carbonyl compounds was incubated with those carbonyl compounds, dl-glyceraldehyde and glyoxal showed the high reactivity with Hb compared with other carbonyl compounds. These results indicate that Maillard reaction between RBC proteins and carbonyl compounds leads to the decrease in RBC deformability. On the other hand, generated by carbonyl compounds involved in lowering the deformability only to a negligible level.     

Decreased deformability in aging erythrocytes

Deformability of bovine erythrocytes separated according to density (and age) was estimated by a modified Teitel's filterability test, the centrifugational test of Sirs, and viscosity measurements of cell suspensions. Both youngest and oldest erythrocytes were found to be less deformable than middle-aged cells, a result speaking against any chief role for deformability in the recognition of senescent erythrocytes and their removal from the circulation.     

The effect of copper on erythrocyte deformability. A possible mechanism of hemolysis in acute copper intoxication

Although the development of hemolytic anemia as a complication of acute copper intoxication is well documented, the precise mechanism by which copper produces accelerated erythrocyte destruction is unknown. Normal erythrocyte survival depends in part on the ability of the cell to deform and pass through narrow areas of microcirculation in the liver and especially in the spleen. In the present study, it is demonstrated that toxic concentrations of copper rapidly and markedly reduce erythrocyte deformability. This reduction in cell deformability is associated with a marked increase in membrane permeability and osmotic fragility of copper-treated cells. Further, the decrease in deformability occurs despite normal levels of cell ATP and the apparent absence of oxidative damage to the cell. These observations indicate that copper-mediated changes in the erythrocyte membrane may be responsible for reducing the flexibility of the cell. The loss of deformability could act to reduce erythrocyte survival and thus explain the hemolysis associated with copper intoxication in vivo.     

低强度激光血管内照射对实验性糖尿病兔血液流变性质的影响

本实验用３８只实验性糖尿病兔,分别采用１．２ｍｗ、１．５ｍｗ、２．２ｍｗ×５０分钟三组不同剂量Ｈｅ—Ｎｅ激光,分两批作一次性血管内照射,测定其红细胞变形能力等８项血液流变学指标,并观察指标随时间的变化。结果表明：（１）激光照射后血液粘度降低,红细胞聚集性降低,且在２４小时内就有反映,５—７天仍然有效;（２）能提高红细胞变形能力,以照射后第３天最明显。５—７天后会回复照射前水平。此结果可为低强度激光血管内照射临床应用选择照射频度提供参考（３）可改善红细胞刚度,但时间上反映较迟     

Effect of curcumin extract against oxidative stress on both structure and deformation capability of red blood cell

The normal deformability of erythrocytes plays an important role in ensuring blood mobility, erythrocyte longevity, and microcirculation, which is the ability of erythrocytes to change shapes in response to external forces. However, the effects of curcumin extracts on the deformability of erythrocytes have not yet been evaluated. Accordingly, in this study, we explored the effects of pre-treatment with curcumin extract on erythrocyte deformation and erythrocyte band 3 (SLC4A1; EB3) expression. We also evaluated the associations between EB3 expression and erythrocyte deformability induced by hydrogen peroxide. Blood samples were divided into the control group, pre-treatment group (treated with curcumin extract or vitamin C), and negative control group, and oxidant stress parameters, antioxidant status, erythrocyte deformability and elasticity, and EB3 modifications were evaluated using immunoblotting and immunofluorescence staining. Hydrogen peroxide significantly increased oxidative stress parameters, modulus elasticity values and clustered EB3 levels and induced conjugation of membrane proteins to form high-molecular-weight complexes (p < 0.05). Erythrocyte deformability and elasticity were significantly decreased in the treated groups compared with those in the control group. Overall, our findings suggested that pre-treatment with curcumin extracts increased antioxidant status, reduced EB3 cross-linking, and improved erythrocyte deformability, to an even better extent than vitamin C. These results provide important insights into the effects of treatment with curcumin extracts on erythrocyte damage and suggest that curcumin may have applications in antioxidant therapy.     

Effect of blood storage on erythrocyte/wall interactions: implications for surface charge and rigidity

In this report, we study, under flow conditions, the interactions of stored erythrocytes with an artificial surface: a microelectrode whose charge density ranges from –15 to +27 μC/cm². Interactions consist of red cells slowly circulating on the microelectrode and exerting a real contact with the electrode. Interaction is detected and measured by transient fluctuations of the electrolyte resistance obtained by impedance measurement of the microelectrode. Effects of aging induced by storage of whole blood at 4 °C show that the surface charge of erythrocytes rapidly decreases when blood is stored for more than 6 days under our experimental conditions. In comparison with trypsin-treated erythrocytes, an eight day storage induces a 60% decrease in the surface charge of red cells. After two weeks of storage, red cells are no longer negatively charged, presumably be cause of removal of sialic acid. Cells rigidity is significant after 6 days of storage and influences the electrical contact. Membrane rigidity increase could arise from the surface charge decrease. Finally, the surface charge decrease could be of importance in the use of stored blood. Received: 30 October 1996 / Accepted: 12 November 1996