Pressure-induced Hemolysis Research Articles

Correlation between sphingomyelin and the membrane stability of mammalian erythrocytes.

Lipid compositions of mammalian erythrocyte membranes are different among species. Therefore, the information on hemolysis from mammalian erythrocytes is useful to understand membrane properties of human erythrocytes. In this work, pressure-induced hemolysis and hypotonic one were examined using erythrocytes of human, sheep, cow, cat, dog, pig, horse, rat, and mouse. Pressure-induced hemolysis was suppressed by membrane sphingomyelin, whereas hypotonic hemolysis decreased upon increment of cell diameter. Mass spectra of erythrocyte membrane lipids demonstrated that sphingomyelin with an acyl chain 24:1 was associated with the suppression of pressure-induced hemolysis. In cow erythrocytes, pressure-induced hemolysis was greatly suppressed and the detachment of cytoskeletal proteins from the membrane under hypotonic conditions was also inhibited. Taken together, these results suggest that sphingomyelin with 24:1 fatty acid plays an important role in the stability of the erythrocyte membrane, perhaps via cholesterol.

Effects of Cholesterol on Membrane Stability of Human Erythrocytes.

Human erythrocytes contain abundant cholesterol as membrane lipids. Cholesterol contributes to the stability and function of the membrane. Membrane stability of the erythrocyte has been mainly examined under hypotonic conditions, but not under high hydrostatic pressure. So, the effect of cholesterol on the membrane stability of human erythrocyte was examined under a pressure of 200 MPa. As with hypotonic hemolysis, the pressure-induced hemolysis was enhanced by depletion of cholesterol from the intact erythrocyte membrane, whereas suppressed by cholesterol loading to the intact one. Enhancement of such hemolysis was associated with the suppression of fragmentation, whereas the hemolysis was suppressed by the facilitation of vesiculation. Cholesterol induced the tight linkage of the lipid bilayer with cytoskeleton. Taken together, these results suggest that the erythrocyte membrane stability is affected by such tight linkage by cholesterol.

Membrane perturbations induced by the interactions of zinc ions with band 3 in human erythrocytes

Of group 12 metals, zinc is an essential element to maintain our life, but other metals such as cadmium and mercury are toxic in cellular activities. Interactions of these metals with biomembranes are important to understand their effects on our living cells. Here, we describe the membrane perturbations induced by these metals in human erythrocytes. Of these metals, Zn2+ ions only induced the erythrocyte agglutination. Histidine residues in extracellular domains of band 3 participated in Zn2+-induced agglutination. Interestingly, it was found that band 3-cytoskeleton interactions play an important role in Zn2+-induced agglutination. In contrast with Hg2+ and Cd2+ ions, Zn2+ ions greatly suppressed pressure-induced hemolysis by cell agglutination. Such a suppression was removed upon dissociation of agglutinated erythrocytes by washing, indicating the reversible interactions of Zn2+ ions with erythrocyte membranes. Excimer fluorescence of pyrene indicated that spectrin is denatured by a pressure of 200MPa irrespective of hemolysis suppression. Taken together, these results suggest that the agglutination of erythrocytes due to the interactions of Zn2+ ions with band 3 is stable under pressure, but spectrin, cytoskeletal protein, is denatured by pressure

Membrane damages under high pressure of human erythrocytes agglutinated by concanavalin A

Human erythrocytes are agglutinated by lectins such as concanavalin A (Con A). The behaviors of agglutinated erythrocytes under pressure are less well understood. Here, we report the effects of erythrocyte agglutination on pressure-induced membrane damages. Small clumps of intact erythrocytes by Con A were dissociated by a pressure of 200MPa. Further, the observation by scanning electron microscopy demonstrated the generation of vesicles, fragmented particles, and membrane hole. On the other hand, large clumps of trypsin-digested erythrocytes by Con A seemed to be stable against 200MPa. However, the erythrocytes dissociated from such pressure-treated clumps by methyl α-mannopyranoside also showed the existence of vesicles and fragmented particles except for the membrane hole. Pressure-induced hemolysis was greatly suppressed in such large clumps. Similar suppressive effects were observed in erythrocytes packed by centrifugation. However, the hemolysis occurred when the erythrocytes dissociated from 200MPa-treated large clumps by methyl α-mannopyranoside were incubated at 0°C and atmospheric pressure. Pyrene excimer fluorescence due to spectrin denaturation was observed in Con A-agglutinated ghosts that were exposed to a pressure of 200MPa. These results suggest that upon pressure treatment of tightly agglutinated erythrocytes, the hemolysis is greatly suppressed, but membrane damages occur such as spectrin denaturation and vesiculation.

Pressure-induced hemolysis of in vivo aged human erythrocytes is enhanced by inhibition of water transport via aquaporin-1

Human erythrocytes are fractionated into young, intermediate, and old cells according to their densities. Pressure-induced hemolysis reflects sensitively membrane perturbations. Therefore, the hemolysis of erythrocytes at 200 MPa was examined using fractionated cells. Pressure-induced hemolysis of old (or in vivo aged) erythrocytes was enhanced, compared with those of young and intermediate cells which showed the same hemolytic values. Flow cytometric analysis showed less fragmentation of old erythrocytes under pressure. Moreover, the water transport through the membrane was suppressed in old erythrocytes than intermediate ones. The low permeability of water in old erythrocytes was confirmed by osmotic hemolysis using a hypotonic buffer. These results suggest that water transport via aquaporin-1 (AQP1) is inhibited in old erythrocytes. As the number of AQP1 molecules remained constant in old erythrocytes, the function of AQP1 may be reduced.

Enhancement of Pressure-Induced Hemolysis by Aquaporin-1 Inhibitors in Human Erythrocytes

Abstract Pressure-induced hemolysis reflects sensitively membrane perturbations in erythrocytes. The functions of transporters and channels are inhibited by sodium p-chloromercuribenzoate (pCMB). So, we tested the effects of pCMB on hemolysis of human erythrocytes at 200 MPa. Pressure-induced hemolysis was enhanced by pCMB, but restored by dithiothreitol. Such effects of pCMB were also observed in N-ethylmaleimide-pretreated erythrocytes. Similar hemolytic properties were observed by aquaporin-1 (AQP1) inhibitors such Hg2+ and Au3+, but not by inhibitors of Na+–K+ pump, Gardos channels, and glucose transporter. In fact, the results of atomic absorption spectrometry showed the binding of mercury to AQP1. From the 1H spin–spin relaxation time of water, we found that pressure-induced hemolysis was enhanced upon inhibition of water transport. Flow cytometric analysis demonstrated the enhancement of hemolysis by suppression of fragmentation under pressure. Detachment of cytoskeletal proteins from the membrane by low ionic strength buffer was unaffected by pCMB. Moreover, diameters of vesicles released from intact and pCMB-treated erythrocytes at 200 MPa were 438 and 584 nm, respectively. In both vesicles, spectrin contents were almost the same. Taken together, these data suggest that pCMB bound to AQP1 inhibits water transport and enhances the hemolysis due to the suppression of fragmentation under pressure, but not affect membrane–cytoskeleton interactions.

Reinvestigation of Drugs and Chemicals as Aquaporin-1 Inhibitors Using Pressure-Induced Hemolysis in Human Erythrocytes

Recently, we have found that pressure-induced hemolysis is enhanced by inhibiting water transport via aquaporin-1 (AQP1), as seen in p-chloromercuribenzoate (pCMB)-treated erythrocytes. So, using this method we reinvestigated the functions as AQP1 inhibitors of drugs and chemicals such as acetazolamide, sodium nitroprusside, tetraethylammonium ions (TEA(+)), and dimethylsulfoxide (DMSO). The values of hemolysis at 200 MPa were almost unaffected by acetazolamide or sodium nitroprusside, decreased by TEA(+), and increased significantly by DMSO. Furthermore, the erythrocytes were exposed to pCMB in the presence of TEA(+) or DMSO. The enhancement effect of pCMB on pressure-induced hemolysis was unaffected by TEA(+) but attenuated by DMSO. Taken together, these results suggest that, of drugs and chemicals examined here, DMSO only is an AQP1 inhibitor, but the effect of DMSO is small compared with pCMB.

Hemolytic properties of human erythrocytes under hydrostatic pressure.

Membrane structure of human erythrocytes has been intensively studied as a prototype of biological membranes. However, it is not well elucidated about the interactions between membrane components such as membrane proteins and phospholipids. As compared with hypotonic hemolysis, high pressure-induced hemolysis is very sensitive to chemical or enzymatic modification of membrane proteins. The present paper describes that the high pressure technique provides unique information about an investigation of membrane structure.

Effects of intracellular pH on high pressure-induced hemolysis of anion transport inhibitor-treated erythrocytes

Effects of anion transport inhibitors such as 4,4′-diisothiocyanostilbene-2,2′-disulfonate (DIDS) and 4-acetamido-4′-isothiocyanostilbene-2,2′-disulfonate on hemolysis of human erythrocytes at 200 MPa were examined by changing intracellular pH (7.2–7.9). These inhibitors suppressed the hemolysis at neutral pH but enhanced it at alkaline pH. However, such an enhancement was suppressed by cross-linking of membrane proteins using diamide. From the near-UV CD spectra of band 3 and the relation between hemolysis and anion transport in intact or trypsin-treated erythrocytes, it was found that such hemolytic properties were characterized by the binding of inhibitors to band 3. In addition, spectrin detachment from the erythrocyte membrane by high pressure was considerably suppressed by DIDS treatment at neutral pH, but not by DIDS labeling at alkaline pH. These results suggest that the interaction of the cytoplasmic domain of band 3 with the cytoskeleton, which is induced by the binding of ligands to the exofacial domain of band 3, is dependent on the intracellular pH, i.e., the linking is tightened at neutral pH but relaxed at alkaline pH.

Effects of chemical modification of membrane thiol groups on hemolysis of human erythrocytes under hydrostatic pressure

Membrane stability of the human erythrocyte under high pressure was examined by modifying membrane SH-groups with NEM or diamide. Hemolysis at 200 MPa of chemically modified erythrocytes was significantly suppressed by the prolonged incubation of them in a reagent-free medium above 30°C prior to the application of high pressure. However, there was no detectable change regarding membrane phospholipid distribution, CD spectra and SDS-PAGE of membrane proteins, and intracellular K + concentration during the incubation. On the other hand, the data of protein-spin labeling and SH-group content showed that the SH-groups buried in membrane proteins appeared on their surface by conformational changes of membrane proteins induced during the incubation. The extraction of peripheral proteins from NEM-treated membranes in 0.1 N NaOH was considerably suppressed by the incubation. These results suggest that, upon chemical modification of membrane SH-groups, protein-protein interactions are modulated during prolonged incubation above 30°C so that high pressure-induced hemolysis is suppressed.

Hemolytic properties of Ca(2+)-treated human erythrocytes under hydrostatic pressure.

The effect of intracellular Ca2+ on high pressure-induced hemolysis of human erythrocytes was examined. Red cells were incubated with Ca2+ (0.01-1 mM) in the presence of ionophore A23187. The Ca(2+)-loaded cells were subjected to a pressure of 200 mPa. Treatment with 0.1 mM Ca2+ had the greatest suppressive effect on the hemolysis. On removal of intracellular Ca2+, red cells showed a morphological change from echinocytes to normal discocytes but the hemolysis remained unaltered. Measurement of intracellular K+ and viscosity demonstrated that the suppressive effect of Ca2+ on the hemolysis is irreversible and is largely associated with the increase of intracellular viscosity induced by K+ efflux.

Vesiculation Induced by Hydrostatic Pressure in Human Erythrocytes

When human erythrocytes were subjected to hydrostatic pressure (1.1-2.0 kbar), it was found that membrane vesicles were released from the red cells above 1.4 kbar. As with hemolysis under high pressure, the amount of released vesicles was increased with increasing pressure but decreased by the cross-linking of membrane proteins with diamide. Vesicles obtained at 2.0 kbar were heterogeneous in size but similar to intact erythrocytes in phospholipid composition. Although it has been reported that spectrin-free vesicles are released by echinocytogenic agents, pressure-induced vesicles did contain considerable and similar amounts of spectrin irrespective of the difference in size. These results suggest that vesiculation by high pressure is associated with the disruption of the membrane skeleton, as previously seen in pressure-induced hemolysis [Yamaguchi et al. (1989) J. Biochem. 106, 1080-1085].

Hemolysis of Human Erythrocytes under Hydrostatic Pressure Is Suppressed by Cross-Linking of Membrane Proteins

The effects of cross-linking of membrane proteins on hemolysis of human erythrocytes under high pressure (2.0 kbar) were examined. The membrane proteins were cross-linked by oxidation of their SH-groups with diamide (0.05-0.5 mM) under different pressures (1-1,000 bar) at which no hemolysis occurs. As the pressure during diamide treatment was raised, the degree of hemolysis under 2.0 kbar and the quantity of cytoskeletal proteins extracted in a low ionic strength medium were gradually decreased. However, both values were increased by reduction with dithiothreitol. From the determination of membrane SH-groups, it was found that cross-linking of membrane proteins by diamide was accelerated under pressure. Only in erythrocytes treated with diamide under pressure were parts of spectrin and ankyrin, in addition to band 3 and band 4.2 proteins, extracted by using Triton X-100. One- and two-dimensional SDS-PAGE of membrane proteins showed that cross-linking of the membrane with cytoskeletal meshwork through linking proteins, in addition to that of membrane proteins themselves, was formed only in the diamide treatment under pressure. These results indicate that pressure-induced hemolysis is greatly suppressed by the supramolecular-weight polymers formed among membrane proteins, and that the high pressure technique is useful for cross-linking membrane proteins with diamide.