Role of Surface Electric Charge in Red Blood Cell Interactions

The role of the surface charge of human red blood cells (RBC's) in affecting RBC aggregation by macromolecules was studied by comparing the behavior of normal RBC's with that of RBC's treated with neuraminidase, which removes the sialic acids from the cell membrane and reduces the zeta potential. RBC aggregation in dextrans with different molecular weights (Dx 20, Dx 40, and Dx 80) was quantified by microscopic observation, measurement of erythrocyte sedimentation rate, and determination of low-shear viscosity. Dx 20 did not cause aggregation of normal RBC's, but caused considerable aggregation of neuraminidase-treated RBC's. Neuraminidase-treated RBC's also showed stronger aggregation than normal RBC's in Dx 40 and 80. Together with the electron microscopic findings that the intercellular distance in the RBC rouleaux varies with the molecular size of dextrans used, the present study indicates that the surface charge of RBC's inhibits their aggregation by dextrans and that the electrostatic repulsive force between cell surfaces may operate over a distance of 20 nm.     

Modes of rouleaux formation of human red blood cells in polyvinylpyrrolidone and dextran solutions

The mechanics by which normal human erythrocytes join on a plastic cover slip into two cell doublets and larger aggregates of rouleaux were studied microscopically. Polyvinylpyrrolidone (PVP-360) or dextran (DX-70 or DX-110) were used as the rouleau agents. The minimum concentration of the rouleau-inducing agents required to form doublets was 1 g/L for PVP-360 and 5 g/L for the DXs. Three modes of interaction were observed in Ringer's solution with PVP or DX, cresting and flipping (involving no intercellular sliding) and a sliding mode of doublet formation (involving less gravitational work and less cellular deformation). The sliding mechanism occurred in suspensions with the lower concentrations of the rouleau agent but was also observed when geometric constraints prevented the nonsliding interaction of larger groups of cells in the higher concentrations of the rouleau agent. The technique provides a sensitive index for studying the combined effect of cellular flexibility and intercellular adhesion. Significant changes were observed for reduced membrane surface charge or reduced ionic calcium.     

Aggregation behavior and electrophoretic mobility of red blood cells in various mammalian species

Differences of red blood cell (RBC) aggregation among various mammalian species has been previously reported for whole blood, for RBC in autologous plasma, and for washed RBC re-suspended in polymer solutions. The latter observation implies the role of cellular factors, yet comparative studies of such factors are relatively limited. The present study thus investigated RBC aggregation and RBC electrophoretic mobility (EPM) for guinea pigs, rabbits, rats, humans and horses; RBC were re-suspended in isotonic 500 kDa dextran solutions for the EPM and aggregation measurements, with aggregation studies also done in autologous plasma. Salient results included: (1) species-specific RBC aggregation in both plasma and dextran (horse > human > rat > rabbit approximately = guinea pig) with a significant correlation between aggregation in the two media; (2) similar EPM values in PBS for rat, human and horse, a lower value for guinea pig, and a markedly reduced EPM for rabbit RBC; (3) EPM values in dextran with a rank order identical to that for cells in PBS; (4) relative EPM results indicating formation of a polymer-poor, low viscosity depletion layer at the RBC surface (greatest depletion for horse RBC). EPM-aggregation correlations were evident and generally consistent with the Depletion Model for aggregation, yet did not fully explain differences between species; additional studies at various ionic strengths and with various dextran fractions thus seem warranted.     

Aggregation of human red blood cells after moderate heat treatment

The aggregation behaviour of normal and heat treated (48.4 degrees C, 48.8 degrees C, 49.5 degrees C) red blood cells (RBCs) suspended in dextran-saline solutions (Dx 70, Dx 173) was investigated by a laser light reflectometric method over a wide range of bridging energies. The characteristic times of rouleau formation were found to be increased after RBC heat treatment. The disaggregation shear stress is not significantly different between normal RBCs and heat treated RBCs. The loss of cell deformability is nevertheless shown to improve slightly the dissociation efficiency of the flowing liquid in a shear flow resulting in a small reduction of the disaggregation shear rate after heat treatment. Heat treatment is also shown to alter the structure of RBC network at equilibrium. These results indicate that heat induced alterations of erythrocytes only affects the mechanical properties of the cell membrane without significant changes in the macromolecular bridging energy.     

Aggregation of human RBC in binary dextran-PEG polymer mixtures

The present study was prompted by prior reports suggesting that small polymers can affect RBC aggregation induced by large macromolecules. Human RBC were washed and re-suspended in isotonic buffer solutions containing 72.5 kDa dextran (DEX 70, 2 g/dl) or 35.0 kDa poly(ethylene glycol) (PEG 35, 0.35 g/dl), then tested for aggregation in these solutions with and without various concentrations of smaller dextrans (10.5 and 18.1 kDa) or PEGs (3.35, 7.5 and 10.0 kDa). RBC aggregation was measured at stasis and at low shear using a photometric cone-plate system (Myrenne Aggregometer) and RBC electrophoretic mobility (EPM) in the various polymer solutions via an automated system (E4, HaSoTec GmbH). Our results indicate: (1) a heterogeneous effect with greater reduction of aggregation for small PEGs added to DEX 70 or for small dextrans added to PEG 35 than for small polymers of the same species; (2) for cells in DEX 70, aggregation decreased with increasing molecular mass and concentration of the small dextrans or PEGs; (3) for cells in PEG 35, small dextrans decreased aggregation with increasing molecular mass and concentration, whereas small PEGs had minimal effects with a minor influence of concentration and an inverse association between molecular mass and inhibition of aggregation. RBC EPM results indicated the expected polymer depletion for cells in DEX 70 or PEG 35, and that small PEGs yielded greater EPM values than small dextrans for cells in PEG 35 whereas the opposite was true for cells in DEX 70. Interpretation of our results in terms of the depletion model for RBC aggregations appears appropriate, and our findings are consistent with the assumption that inhibition of aggregation occurs because of an increase of small molecules in the depletion region. Our results thus suggest the merit of further studies of red blood cell aggregation in binary polymer systems.     

Modulation of free radical stress in human red blood cell membrane by forskolin and the prospects for treatment of cardiovascular disease and diabetes.

This study has examined the effect of oxidants and elevated levels of glucose on membrane lipid peroxidation of human red blood calls (RBC). Washed RBC incubated with varying concentrations of glucose at 37 degrees C for 24 hrs. showed a significant increased membrane lipid peroxidation when compared with control RBC. Addition of ferrous sulphate and ascorbic acid which are known oxidants caused greater rise in lipid peroxides compared to elevated level of glucose alone. Pre-treatment of RBC with varying doses of forskolin (4-70 microg) was associated with significantly smaller rise in lipid peroxides in a dose dependent manner. Forskolin effect was comparable with the antioxidant effect of other drugs such as vitamin E, trimetazidine, ginkocer, probucol. It is possible that forskolin at higher concentrations may have a greater antioxidant effect than other antioxidant drug. However more studies, especially animal experiments, and trials in human would be necessary to confirm our findings.     

Biochemical and biological characterization of neutrophil chemotactic protein, a novel rabbit CXC chemokine from alveolar macrophages

The role of interleukin-8 (IL-8) and related CXC chemokines has been demonstrated in many human diseases. However, more profound studies, e.g., by blocking the effect of these inflammatory mediators, request animal models and hence the identification of all human counterparts for commonly used laboratory animals. In this study, we describe the identification of a novel neutrophil chemotactic protein (NCP) of the rabbit. Intact and NH(2)-terminally truncated NCP forms and IL-8 were isolated from LPS-stimulated rabbit alveolar macrophages and purified to homogeneity by a four-step purification procedure. Determination of the complete primary structure of NCP by mass spectrometry and NH(2)-terminal sequencing of natural protein revealed high structural homology with human epithelial cell-derived neutrophil attractant-78 (ENA-78) and granulocyte chemotactic protein-2 (GCP-2), two related ELR(+)CXC chemokines. Intact NCP(1-76) was found to be 10-fold less potent than truncated NCP(7, 8-76) at inducing neutrophil chemotaxis. NCP(7,8-76) was equally potent as intact rabbit IL-8 at chemoattracting human neutrophils and at inducing calcium fluxes in rabbit neutrophils, 1 ng/mL being the minimal effective concentration. However, like IL-8, NCP failed to induce monocyte or eosinophil migration at 300-fold higher concentrations. IL-8 desensitized the calcium increase induced by NCP and vice versa. Finally, intradermal injection of NCP induced a dose-dependent and significant infiltration of neutrophils in mice skin. It can be concluded that NCP is a novel rabbit CXC chemokine that is, like IL-8, implicated in animal models used to study various human disorders in which neutrophils play an important role.     

Inhibition of polymer-induced red blood cell aggregation by poloxamer 188

Previous reports have suggested that non-ionic poloxamer surfactants of appropriate molecular mass and composition can reduce red blood cell (RBC) aggregation in whole blood and in RBC-plasma suspensions. We have thus evaluated this phenomenon for RBC aggregated by several water-soluble polymers, using poloxamer 188 (P188), a non-ionic, tri-block molecule (total molecular mass of 8.40 kDa, 80% polyoxyethylene). Human RBC were washed, then re-suspended in isotonic solutions of dextran 70 (70.3 kDa), dextran 500 (476 kDa), PVP (360 kDa) or P-L-GLU (61.2 kDa); density-separated RBC were also studied. RBC aggregation was quantitated via a computerized Myrenne Aggregometer (extent, strength) and by the Microscopic Aggregation Index (MAI) method. Over the range of 0.5 to 5 mg/ml, poloxamer 188 inhibited both the extent and strength of aggregation in a dose-dependent manner, with the magnitude of the decrease related to polymer type (e.g., at 5 mg/ml, 62% decrease for dextran 70 vs. 14% decrease for P-L-GLU); MAI results with dextran 70 also showed a dose-dependent decrease. Poloxamer 188 at 5 mg/ml was more effective with younger, less-dense cells. Based upon the depletion model for polymer-induced aggregation, these findings suggest that poloxamer 188 acts by penetrating the depletion layer near the glycocalyx, thereby reducing the osmotic gradient between the intercellular gap and the suspending medium. Regardless of the specific mechanism(s) of action, poloxamers appear to offer interesting approaches for future basic science and clinical studies, and thus the possibility for greater insight into RBC aggregation.     

Effects of chitooligosaccharides on human red blood cell morphology and membrane protein structure

Recent studies of chitosan have increased the interest in its conversion to chitooligosaccharides (COSs) because these compounds are water-soluble and have potential use in several biomedical applications. Furthermore, such oligomers may be more advantageous than chitosans because of their much higher absorption profiles at the intestinal level, which permit their facilitated access to systemic circulation and potential distribution throughout the entire human body. In that perspective, it is important to clarify their effect on blood further, namely, on human red blood cells (RBCs). The aim of this work was thus to study the effect of two COS mixtures with different molecular weight (MW) ranges, <3 and <5 kDa, at various concentrations (5.0-0.005 mg/mL) on human RBCs. The interactions of these two mixtures with RBC membrane proteins and with hemoglobin were assessed, and the RBC morphology and surface structure were analyzed by optical microscopy (OM) and atomic force microscopy (AFM). In the presence of either COS mixture, no significant hemolysis was observed; however, at COS concentrations >0.1 mg/mL, changes in membrane binding hemoglobin were observed. Membrane protein changes were also observed with increasing COS concentration, including a reduction in both alpha- and beta-spectrin and in band 3 protein, and the development of three new protein bands: peroxiredoxin 2, calmodulin, and hemoglobin chains. Morphologic evaluation by OM showed that at high concentrations COSs interact with RBCs, leading to RBC adhesion, aggregation, or both. An increase in the roughness of the RBC surface with increasing COS concentration was observed by AFM. Overall, these findings suggest that COS damage to RBCs was dependent on the COS MW and concentration, and significant damage resulted from either a higher MW or a greater concentration (>0.1 mg/mL).     

Acute Free-Iron Exposure Does Not Explain the Impaired Haemorheology Associated with Haemochromatosis

Introduction

Given the severity of the current imbalance between blood donor supply and recipient demand, discarded blood drawn from the routine venesections of haemochromatosis (HFE-HH) patients may serve as a valuable alternative source for blood banks and transfusion. We investigated whether functional or biochemical differences existed between HFE-HH and control blood samples, with particular focus upon the haemorheological properties, to investigate the viability of venesected blood being subsequently harvested for blood products.

Methods

Blood samples were collected from HFE-HH patients undergoing venesection treatment (n = 19) and healthy volunteers (n = 8). Moreover, a second experiment investigated the effects of a dose-response of iron (0, 40, 80, 320 mM FeCl₃) on haemorheology in healthy blood samples (n = 7). Dependent variables included basic haematology, iron status, haematocrit, red blood cell (RBC) aggregation (native and standardised haematocrit) and “aggregability” (RBC tendency to aggregate in a standard aggregating medium; 0.4 L/L haematocrit in a Dx70), and RBC deformability.

Results

Indices of RBC deformability were significantly decreased for HFE-HH when compared with healthy controls: RBC deformability was significantly decreased at 1–7 Pa (p < 0.05), and the shear stress required for half maximal deformability was significantly increased (p < 0.05) for HFE-HH. RBC aggregation in plasma was significantly increased (p < 0.001) for HFE-HH, although when RBC were suspended in plasma-free Dx70 no differences were detected. No differences in RBC deformability or RBC aggregation/aggregability were detected when healthy RBC were incubated with varying dose of FeCl₃.

Conclusion

HFE-HH impairs the haemorheological properties of blood; however, RBC aggregability was similar between HFE-HH and controls when cells were suspended in a plasma-free medium, indicating that plasma factor(s) may explain the altered haemorheology in HFE-HH patients. Acute exposure to elevated iron levels does not appear (in isolation) to account for these differences. Further consideration is required prior to utilising routine venesection blood for harvesting RBC concentrates due to the potential risk of microvascular disorders arising from impaired haemorheology.     

Occurrence of hemolytic activity in the skin secretion of the caecilian siphonops paulensis.

The skin secretion of the caecilian Siphonops paulensis (SpSS) induces a time-and dose-dependent hemolytic response on red blood cells (RBC). When RBC from various animals species were subjected to the action of SpSS, a range of sensitivities was evident, sheep erythrocytes being the most susceptible, human, mouse and rabbit having moderate susceptibility, cow, snake and toad erythrocytes being more resistant, while S. paulensis RBC were entirely resistant. The hemolytic activity of SpSS was inhibited at temperatures higher than 60 degrees C. Both trypsin- and chymotrypsin-treated SpSS were ineffective in inducing RBC lysis. The treatment of SpSS with sheep RBC ghosts reduced its activity. There is no phospholipase activity in the SpSS.     

Blood isoprene concentrations in humans and in some animal species.

The concentrations of isoprene, the main hydrocarbon of human breath, were measured in the blood of humans and of different animal species (rat, rabbit, dog, ewe, cow). In human blood, the concentrations of isoprene were between 15 and 70 nmol/liter (mean value of 37 +/- 25 (SD) nmol/liter). In the blood of the different animal species tested, traces of isoprene were unambiguously detected by mass spectrometry, but the levels were always lower than 1 nmol/liter.     

Effects of dextran molecular weight on red blood cell aggregation

The reversible aggregation of human red blood cells (RBC) by proteins or polymers continues to be of biologic and biophysical interest, yet the mechanistic details governing the process are still being explored. Although a depletion model with osmotic attractive forces due to polymer depletion near the RBC surface has been proposed for aggregation by the neutral polyglucose dextran, its applicability at high molecular mass has not been established. In this study, RBC aggregation was measured over a wide range of dextran molecular mass (70 kDa to 28 MDa) at concentrations ≤2 g/dL. Our results indicate that aggregation does not monotonically increase with polymer size; instead, it demonstrates an optimum dextran molecular mass around 200-500 kDa. We used a model for depletion-mediated RBC aggregation to calculate the expected depletion energies. This model was found to be consistent with the experimental results and thus provides new insight into polymer-RBC interactions.     

Effect of procaine hydrochloride on the aggregation behavior and suspension viscoelasticity of human red blood cells

The present study examined the effects of procaine hydrochloride (PRHCL), a cationic local anesthetic, on the aggregation behavior of human red blood cells (RBC); the effects of PRHCL on RBC suspension viscoelasticity, cell shape, volume and density were also investigated. Four indices of RBC aggregation, induced by autologous plasma or 3 g% dextran T70, were evaluated by a computerized light transmission method, and the viscous and elastic components of the complex viscosity were determined by oscillatory viscometry. Low concentrations of PRHCL (8 x 10(-5) to 8 x 10(-4) M) significantly (p less than 0.05 or better) reduced the extent of aggregation (maximal decrease of 22% at 8 x 10(-4) M), but did not alter the viscoelastic components, cell shape, volume or density. The anti-aggregating effect of PRHCL (8 x 10(-4) M) in plasma significantly (p less than 0.005) decreased with time; this temporal effect was abolished by addition of eserine (1 x 10(-4) M). High concentrations of PRHCL (8 x 10(-2) M) caused: 1) increased extent of aggregation and decreased strength of the aggregates (p less than 0.01 or better); 2) elevation of both viscoelastic components for cells in plasma or buffer; 3) a discocyte-stomatocyte shape change; 4) decreased cell density (p less than 0.001) without alteration of cell volume. Our results at low concentrations of PRHCL suggest a mechanism based on an increase of RBC negative surface potential; at the highest concentration, the effects are most likely due to altered cell shape and deformability, and to decreased RBC negative surface potential.     

Effect of hypoxia on erythrocyte deformability in different species

The contribution of erythrocyte deformability to the pulmonary vascular resistance during hypoxia in different animal species has not been examined. We hypothesized that the increase in pulmonary vascular resistance during hypoxia was partially due to erythrocytes (RBC's) becoming less deformable during hypoxia, and therefore their transit in the capillaries becomes restricted. To test this, we measured an index of deformability of RBC's from six animal species (dog, pig, cat, rabbit, hamster, rat) during normoxic and hypoxic condition, and compared the changes in deformability with the pulmonary hypoxic pressor response (HPR) which has been reported in the same species. Deformability was indexed as the resistance that a Hemafil polycarbonate membrane (Nucleopore filter, 4.7 micron pores) offers to a 10% suspension of RBC's. The RBC suspension was either normoxic (PO2 = 150 torr) or hypoxic (PO2 = 50 torr). We found that hypoxia decreased RBC deformability; the largest decrease occurred in rat RBC's, a small but significant decrease was observed in the RBC's of cats, rabbits and hamsters, but no change was detected in RBC's of dogs or pigs. In general, such changes in deformability do not correlate well with the HPR in intact or in isolated lungs, for example the pig, had the largest HPR but the smallest change in RBC deformability. In some species, however, there was a positive correlation between RBC deformability and HPR, for example rats, rabbits and cats are usually better responders than dogs and hamsters, similarly the deformability of RBC's in rats, rabbits and cats were also more influenced by hypoxia than RBC's from dogs. The limiting factors in this relationship are the artificial conditions which were used to measure deformability and HPR, both may be different than in the intact conditions. Nevertheless the present data show that erythrocytes of some species can become less flexible during hypoxia, and hence may impede the transit in the capillaries. Therefore we propose that the hypoxic pressor response in the pulmonary vasculature may be partly due to smooth muscle contraction (vasoconstriction) and partly due to a decrease in erythrocyte deformability (capillary obstruction). Both components are likely to be species dependent.     

Effect of the absence or presence of various protein supplements on further development of bovine oocytes during in vitro maturation

The evaluation of culture medium for bovine oocytes has progressed toward more defined conditions during the last few years. The main objective of this study was to evaluate different sources of albumin as a protein supplement during in vitro maturation (IVM) of bovine oocytes in synthetic oviduct fluid medium (SOF). The replacement of protein with polyvinyl pyrrolidone (PVP) or polyvinyl alcohol (PVA) was also evaluated. The effect of recombinant human FSH on cumulus expansion and nuclear maturation in SOF containing BSA (BSA-V) or PVP-40 was also studied. Addition of BSA-V during IVM retarded nuclear maturation when compared with addition of PVP-40 or use of SOF alone. The inclusion of different concentrations of BSA-V, fetal calf serum (FCS), or PVA during IVM had no positive effect on the developmental capacity of the oocytes compared with the use of SOF alone with no supplement but significantly decreased the percentage of embryos reaching the morula and blastocyst stages. However, when BSA-V was replaced with purified BSA, BSA that was essentially free of fatty acids, or chicken egg albumin, embryonic development rates were restored. The presence of PVP-40 but not PVP-360 during IVM significantly increased morula and blastocyst production. These results indicate that although SOF alone can support bovine oocyte maturation, a high proportion of morulae and blastocysts can be produced from IVM oocytes cultured in medium containing PVP-40. These studies are the first to show that the effect of FSH on nuclear maturation and cumulus expansion is dependent on substrates present in IVM medium.     

Effect of procaine hydrochloride on the electrophoretic mobility of human red blood cells

The interaction of cationic anesthetics with biological membranes and the resulting alterations of membrane electrokinetic properties continue to be of current interest. The present study was designed to examine the effects of procaine hydrochloride (PRHCL) on the mobility of human red blood cells (RBC); electrophoretic measurements were made on RBC suspended in phosphate-buffered saline (PBS, pH = 5.0, 7.4, or 9.2), autologous plasma or 3 g% dextran T70/PBS (pH = 7.4), with PRHCL concentrations from 8 x 10(-6) to 8 x 10(-2) M. Low concentrations of PRHCL (8 x 10(-5)-8 x 10(-3) M) significantly (p less than 0.001) increased RBC mobility, with a maximal increase of 8.2% at 8 x 10(-4) M. Conversely, a higher PRHCL concentration (8 x 10(-2) M significantly (p less than 0.001) decreased RBC mobility. Both glutaraldehyde fixation and lipid extraction abolished any PRHCL-induced increase in RBC mobility; the observed increases in mobility for normal cells are, thus, consistent with a mechanism based on expansion of the RBC membrane glycocalyx. Microelectrophoretic methods were also used to study the effect of PRHCL (8 x 10(-4) and 8 x 10(-2) M) on RBC membrane calcium binding, with the results indicating that PRHCL competes with calcium for neuraminate binding sites. We conclude that the observed changes in RBC electrokinetic properties reflect incorporation of PRHCL into the RBC membrane; such changes may be of importance in modulating cell-cell interactions.     

用电导法研究悬浮介质中大分子物质对红血球细胞(RBC)聚集的一种抑制效应

通常认为悬浮介质中的大分子物质促进RBC聚集的桥联作用,使RBC聚集,但在高浓度时,大分子物质反而抑制RBC聚集。过去认为主要是高浓度大分子物质影响了RBC表面势能,但我们在研究中发现,在一定条件下低浓度的大分子物质也能抑制红细胞聚集。这说明:大分子物质对RBC聚集的抑制效应,不仅能通过改变RBC膜表面势能实观,还能通过其它途径实现,这种途径之一就是影响RBC膜的力学性质。     

Action of hydroxyethyl starch on the flow properties of human erythrocyte suspensions

Hydroxyethyl starch (HES) has often been used as a plasma expander, but questions still remain concerning the mechanisms by which it produces changes in the rheological properties of blood and erythrocyte (RBC) suspensions under various flow conditions. The present investigation has shown that the dynamic viscosity of HES (232,000 and 565,000 daltons) solutions rises in a nonlinear fashion with increasing HES concentration, and for a given concentration of HES exhibits Newtonian behavior at shear rates between 0.15 to 124 sec-1. At low (less than 0.9 sec-1) shear rates the apparent viscosity of a 40% RBC suspension increases with lower concentrations of HES because of RBC aggregation. At higher concentrations of HES, increases in suspension viscosity are due to an increase in the viscosity of the continuous phase since the RBC are largely disaggregated. At high (greater than 36 sec-1) shear rates the relative viscosity (eta/eta O) of RBC suspensions slowly decreases with increasing HES concentration. At low shear rates eta/eta O increases and then decreases with increasing HES concentration. Evidence of the concentration-dependent effects of HES on RBC aggregation is provided not only by the viscometric analysis but also from measurements of erythrocyte sedimentation rate (ESR) and the zeta sedimentation ratio (ZSR). HES is a more potent aggregating agent in phosphate buffered saline (PBS) than it is in plasma. Polymer size has only a slight effect on the extent of RBC aggregation produced, but does have a significant effect on the concentration of polymer at which maximum aggregation occurs. The viscosity-corrected electrophoretic mobility of RBC in HES rises monotonically with the concentration of HES in the suspending medium. Decreases in the extent of RBC aggregation with increasing polymer concentrations probably result from an increase in the electrostatic repulsive forces between the cells.     

Specific transport of S-nitrosocysteine in human red blood cells: Implications for formation of S-nitrosothiols and transport of NO bioactivity within the vasculature

The transport of various S-nitrosothiols, NO and NO donors in human red blood cells (RBC) and the formation of erythrocytic S-nitrosoglutathione were investigated. Of the NO species tested only S-nitrosocysteine was found to form S-nitrosoglutathione in the RBC cytosol. L-Serine, L-cysteine and L-lysine inhibited formation of S-nitrosoglutathione. Incubation of RBC pre-incubated with S-[15N]nitroso-L-cysteine with native plasma or platelet-rich plasma led to formation of S-[15N]nitrosoalbumin and inhibited platelet aggregation, respectively. The specific transporter system of S-nitroso-L-cysteine in the RBC membrane may have implications for formation of S-nitrosoalbumin and S-nitrosohemoglobin and for transport of NO bioactivity within the vasculature.