Effect of acute normovolemic hemodilution on distribution of blood flow and tissue oxygenation in dog skeletal muscle.

Acute normovolemic hemodilution (ANH) is efficient in reducing allogenic blood transfusion needs during elective surgery. Tissue oxygenation is maintained by increased cardiac output and oxygen extraction and, presumably, a more homogeneous tissue perfusion. The aim of this study was to investigate blood flow distribution and oxygenation of skeletal muscle. ANH from hematocrit of 36 +/- 3 to 20 +/- 1% was performed in 22 splenectomized, anesthetized beagles (17 analyzed) ventilated with room air. Normovolemia was confirmed by measurement of blood volume. Distribution of perfusion within skeletal muscle was determined by using radioactive microspheres. Tissue oxygen partial pressure was assessed with a polarographic platinum surface electrode. Cardiac index (3.69 +/- 0.79 vs. 4.79 +/- 0.73 l. min-1. m-2) and muscle perfusion (4.07 +/- 0.44 vs. 5.18 +/- 0.36 ml. 100 g-1. min-1) were increased at hematocrit of 20%. Oxygen delivery to skeletal muscle was reduced to 74% of baseline values (0.64 +/- 0.06 vs. 0.48 +/- 0.03 ml O2. 100 g-1. min-1). Nevertheless, tissue PO2 was preserved (27.4 +/- 1.3 vs. 29.9 +/- 1. 4 Torr). Heterogeneity of muscle perfusion (relative dispersion) was reduced after ANH (20.0 +/- 2.2 vs. 13.9 +/- 1.5%). We conclude that a more homogeneous distribution of perfusion is one mechanism for the preservation of tissue oxygenation after moderate ANH, despite reduced oxygen delivery.     

The Rho kinase inhibitor Y-27632 increases erythrocyte deformability and low oxygen tension-induced ATP release

Low oxygen (O(2)) tension and mechanical deformation are stimuli for ATP release from erythrocytes. It has been shown previously that rabbit erythrocytes made less deformable with diamide, a thiol cross-linking agent, release less ATP in response to low O(2) tension, suggesting a link between these two stimuli. In nonerythroid cells, activation of the Rho/Rho kinase signaling pathway has been reported to decrease cell deformability by altering Rho kinase-dependent cytoskeleton-protein interactions. We investigated the hypothesis that the Rho kinase inhibitor Y-27632 would increase erythrocyte deformability and thereby increase low O(2) tension-induced ATP release from erythrocytes. Here we show that Y-27632 (1 μM) increases erythrocyte deformability (5%) and increases low O(2) tension-induced ATP release (203%) from healthy human erythrocytes. In addition, we found that, when erythrocytes were made less deformable by incubation with diamide (100 μM), Y-27632 restored both deformability and low O(2) tension-induced ATP release to levels similar to those measured in the absence of diamide. These findings suggest that the Rho kinase inhibitor Y-27632 is able to reverse the diamide-induced decrease in erythrocyte deformability and rescue low O(2) tension-induced ATP release. These results further support a link between erythrocyte deformability and ATP release in response to low O(2) tension.     

肠淋巴液引流对失血性休克大鼠红细胞流变性的影响

目的:观察肠淋巴液引流对失血性休克大鼠红细胞流变性指标以及血液黏度的作用。方法:Wistar雄性大鼠均分为假休克组、休克组(复制失血性休克模型)、引流组(复制失血性休克模型,自低血压1 h引流休克肠淋巴液)。在低血压3 h或相应时间,经腹主动脉取血,检测红细胞参数、红细胞电泳、红细胞沉降率(ESR)以及血液黏度,计算红细胞聚集指数、红细胞变形指数。结果:与假休克组比较,休克组红细胞数量、红细胞比积(HCT)、血红蛋白(Hb)、平均红细胞血红蛋白浓度(MCHC)、红细胞电泳率与迁移率、红细胞变形指数、全血黏度、全血低切与高切相对黏度和还原黏度显著降低,休克组平均红细胞体积、红细胞电泳时间、ESR、血沉方程K值与校正K值、红细胞聚集性指数、血浆黏度显著升高;引流组MCHC、红细胞电泳率与迁移率、全血黏度、全血低切与高切还原黏度均显著降低,引流组红细胞体积分布宽度(RDW-SD)显著增加。同时,引流组HCT、RDW-SD、红细胞变形指数、全血黏度、全血低切与高切相对黏度显著高于休克组;ESR、血沉方程K值与校正K值、红细胞聚集性指数、血浆黏度显著低于休克组。结论:休克肠淋巴液引流可改善失血性休克大鼠红细胞流变行为,从而改善血液流变性。     

Membrane effects of nitrite-induced oxidation of human red blood cells.

The aim of our investigation was to study the red blood cell (RBC) membrane effects of NaNO(2)-induced oxidative stress. Hyperpolarization of erythrocyte membranes and an increase in membrane rigidity have been shown as a result of RBC oxidation by sodium nitrite. These membrane changes preceded reduced glutathione depletion and were observed simultaneously with methemoglobin (metHb) formation. Changes of the glutathione pool (total and reduced glutathione, and mixed protein-glutathione disulfides) during nitrite-induced erythrocyte oxidation have been demonstrated. The rates of intracellular oxyhemoglobin and GSH oxidation highly increased as pH decreased in the range of 7.5-6.5. The activation energy of intracellular metHb formation obtained from the temperature dependence of the rate of HbO(2) oxidation in RBC was equal to 16.7+/-1.6 kJ/mol in comparison with 12.8+/-1.5 kJ/mol calculated for metHb formation in hemolysates. It was found that anion exchange protein (band 3 protein) of the erythrocyte membrane does not participate significantly in the transport of nitrite ions into the erythrocytes as band 3 inhibitors (DIDS, SITS) did not decrease the intracellular HbO(2) oxidation by extracellular nitrite.     

Effects of erythrocyte flexibility on microvascular perfusion and oxygenation during acute anemia

Responses to exchange transfusion using red blood cells (RBCs) with normal and reduced flexibility were studied in the hamster window chamber model during acute moderate isovolemic hemodilution to determine the role of RBC membrane stiffness in microvascular perfusion and tissue oxygenation. Erythrocyte stiffness was increased by 30-min incubation in 0.02% glutaraldehyde solution, and unreacted glutaraldehyde was completely removed. Filtration pressure through 5-microm pore size filters was used to quantify stiffness of the RBCs. Anemic conditions were induced by two isovolemic hemodilution steps using 6% 70-kDa dextran to a hematocrit (Hct) of 18% (moderate hemodilution). The protocol continued with an exchange transfusion to reduce native RBCs to 75% of baseline (11% Hct) with either fresh RBCs (RBC group) or reduced-flexibility RBCs (GRBC group) suspended in 5% albumin at 18% Hct; a plasma expander (6% 70-kDa dextran; Dex70 group) was used as control. Systemic parameters, microvascular perfusion, capillary perfusion [functional capillary density (FCD)], and oxygen levels across the microvascular network were measured by noninvasive methods. RBC deformability for GRBCs was significantly decreased compared with RBCs and moderate hemodilution conditions. The GRBC group had a greater mean arterial blood pressure (MAP) than the RBC and Dex70 groups. FCD was substantially higher for RBC (0.81 +/- 0.07 of baseline) vs. GRBC (0.32 +/- 0.10 of baseline) and Dex70 (0.38 +/- 0.10 of baseline) groups. Microvascular tissue Po(2) was significantly lower for Dex70 and GRBC vs. RBC groups and the moderate hemodilution condition. Results were attributed to decreased oxygen uploading in the lungs and obstruction of tissue capillaries by rigidified RBCs, indicating that the effects impairing RBC flexibility are magnified at the microvascular level, where perfusion and oxygenation may define transfusion outcome.     

Appearance of an erythrocyte population with decreased deformability and hemoglobin content following sepsis

With the use of the cecal ligation and puncture model in mice, this study tested whether sepsis-induced decreased erythrocyte deformability is restricted to a subpopulation of cells. Erythrocyte subpopulations were isolated by centrifugal elutriation. Lineweaver-Burk conversion of deformability-response curves to shear stress was used to determine the shear stress at half-maximal cell elongation (K(EI)) and maximal cell elongation (EI(max)). Sepsis decreased erythrocyte deformability in whole blood. K(EI) values were elevated (2.7 vs. 2.1 Pa) and EI(max) values decreased (0.56 vs. 0.50) in sepsis compared with sham mice. K(EI) values for cells eluted at 7 ml/min (smallest and oldest cells) were similar; however, K(EI) values for cells eluted at 8 ml/min were greater in septic than sham animals (2.50 vs. 2.10). Younger and larger subpopulations of erythrocytes (eluted at 9, 10, and 11 ml/min) also showed a tendency of decreased deformability in sepsis. Mean corpuscular hemoglobin content was decreased in cells eluted at 7 and 8 ml/min in sepsis (4.5 and 10.2 pg) compared to sham (7.4 and 11.4 pg) mice. This study indicates that an erythrocyte subpopulation that represents 20% of circulating cells shows the most pronounced decrease in cell deformability during sepsis. Increased rigidity together with decreased corpuscular hemoglobin content in these cells may contribute to microcirculatory dysfunction and immune modulation during sepsis.     

Studies on the effects of lipopolysaccharide on lipid peroxidation of erythrocyte and its reversal by mannitol and glycerol.

Gram-negative sepsis often produces endotoxin (LPS) which causes infection. Reduction in tissue perfusion due to microcirculatory failure may lead to septic shock. We studied the effect of LPS on lipid peroxidation of erythrocyte. In vitro studies using 50 microg to 250 microg LPS/ml blood showed increased lipid peroxidation of erythrocyte in a dose-dependent manner. The increased effect of lipid peroxidation does not occur with LPS when erythrocytes were washed to remove plasma and leukocytes. Mannitol and glycerol, known scavengers of hydroxyl radical, arrest the elevation in lipid peroxidation of erythrocytes after LPS treatment. Hemolysis of erythrocytes was reduced with low doses of LPS. Plasma lipid peroxidation was elevated after treatment of blood with LPS. From the results we suggest that the peroxidation of erythrocyte lipid caused by LPS may probably play a role in the production of septic shock.     

肠系膜淋巴管结扎对急性失血大鼠红细胞流变性的影响

目的:观察结扎肠系膜淋巴管(MLD)对急性失血大鼠红细胞流变性的影响。方法:20只Wistar雄性大鼠随机均分为失血组与结扎组。所有大鼠经右侧颈总动脉匀速放血(失血量为全血量的1/4),结扎组失血后结扎MLD,失血组仅在MLD下穿线。记录24h存活情况。24h后,将存活大鼠经左侧颈总动脉迅速放血,测定实验前后的红细胞沉降率(ESR)、红细胞电泳、红细胞压积(Hct),计算红细胞聚集与变形指数。结果:急性失血后24h,结扎组大鼠存活情况(9只)略好于失血组(6只)。急性失血后24h,与实验前相比,失血组与结扎组的ESR、血沉方程K值、校正K值、红细胞电泳时间均显著升高或延长,红细胞变形性降低,失血组的红细胞聚集指数显著升高、红细胞电泳长度与迁移率均显著降低;结扎组的ESR、血沉方程K值、校正K值、红细胞聚集指数、电泳时间较失血组显著降低,红细胞电泳长度与迁移率、变形性较失血组显著升高。结论:急性失血导致大鼠红细胞聚集性升高、红细胞电泳能力及变形性降低,结扎MLD可改善急性失血导致的红细胞流变性异常。     

Oxygen delivery to skeletal muscle fibers: effects of microvascular unit structure and control mechanisms

The number of perfused capillaries in skeletal muscle varies with muscle activation. With increasing activation, muscle fibers are recruited as motor units consisting of widely dispersed fibers, whereas capillaries are recruited as groups called microvascular units (MVUs) that supply several adjacent fibers. In this study, a theoretical model was used to examine the consequences of this spatial mismatch between the functional units of muscle activation and capillary perfusion. Diffusive oxygen transport was simulated in cross sections of skeletal muscle, including several MVUs and fibers from several motor units. Four alternative hypothetical mechanisms controlling capillary perfusion were considered. First, all capillaries adjacent to active fibers are perfused. Second, all MVUs containing capillaries adjacent to active fibers are perfused. Third, each MVU is perfused whenever oxygen levels at its feed arteriole fall below a threshold value. Fourth, each MVU is perfused whenever the average oxygen level at its capillaries falls below a threshold value. For each mechanism, the dependence of the fraction of perfused capillaries on the level of muscle activation was predicted. Comparison of the results led to the following conclusions. Control of perfusion by MVUs increases the fraction of perfused capillaries relative to control by individual capillaries. Control by arteriolar oxygen sensing leads to poor control of tissue oxygenation at high levels of muscle activation. Control of MVU perfusion by capillary oxygen sensing permits adequate tissue oxygenation over the full range of activation without resulting in perfusion of all MVUs containing capillaries adjacent to active fibers.     

Red blood cell extrudes nucleus and mitochondria against oxidative stress

Mammal red blood cells (erythrocytes) contain neither nucleus nor mitochondria. Traditional theory suggests that the presence of a nucleus would prevent big nucleated erythrocytes to squeeze through these small capillaries. However, nucleus is too small to hinder erythrocyte deformation. And, there is no sound reason to abandon mitochondria for the living cells. Here, we found that mammal erythrocyte reactive oxygen species (ROS) levels kept stable under diabetes, ischemia reperfusion, and malaria conditions or in vitro sugar/heme treatments, whereas bird erythrocyte ROS levels increased dramatically in these circumstances. Nuclear and mitochondrial extrusion may help mammal erythrocytes to better adapt to high-sugar and high-heme conditions by limiting ROS generation.     

Interpretation of near-infrared spectroscopy signals: a study with a newly developed perfused rat brain model.

Using a newly developed perfused rat brain model, we examined direct effects of each change in cerebral blood flow (CBF) and oxygen metabolic rate on cerebral hemoglobin oxygenation to interpret near-infrared spectroscopy signals. Changes in CBF and total hemoglobin (tHb) were in parallel, although tHb showed no change when changes in CBF were small (< or =10%). Increasing CBF caused an increase in oxygenated hemoglobin (HbO(2)) and a decrease in deoxygenated hemoglobin (deoxy-Hb). Decreasing CBF was accompanied by a decrease in HbO(2), whereas changes in direction of deoxy-Hb were various. Cerebral blood congestion caused increases in HbO(2), deoxy-Hb, and tHb. Administration of pentylenetetrazole without increasing the flow rate caused increases in HbO(2) and tHb with a decrease in deoxy-Hb. There were no significant differences in venous oxygen saturation before vs. during seizure. These results suggest that, in activation studies with near-infrared spectroscopy, HbO(2) is the most sensitive indicator of changes in CBF, and the direction of changes in deoxy-Hb is determined by the degree of changes in venous blood oxygenation and volume.     

Cerebral and intestinal perfusion and metabolism in normocythemic hyperviscous hypoxic newborn pigs.

We studied the effects of hypoxia on cerebral cortical and intestinal perfusion and metabolism in normocythemic hyperviscous newborn pigs. Seven pigs were made hyperviscous by an injection of cryoprecipitate, increasing viscosity from 5.8 +/- 0.9 to 9.0 +/- 1. 2 (SD) cycles/s. Six normoviscous pigs received 0.9% NaCl. Reducing the inspired O(2) decreased the arterial O(2) content (Ca(O(2))) from 9.5 +/- 1.6 to 3.6 +/- 1.3 ml O(2)/100 ml. Increases in brain and decreases in gastrointestinal blood flow at the lower Ca(O(2)) values were similar between the groups. During hypoxia, blood flow to stomach, distal intestinal mucosa, and large intestines was lower (-50, -23, and -28%, respectively) in the hyperviscous than normoviscous group. At the lower Ca(O(2)) values, cerebral cortical vascular resistance decreased in both groups and intestinal vascular resistance increased (+257%) in the hyperviscous but not in the normoviscous group. During hypoxia, systemic oxygen delivery decreased, extraction increased, and uptake did not change; cerebral cortical O(2) delivery, extraction, and uptake did not change; and intestinal O(2) delivery decreased, extraction increased, and uptake did not change in both groups. Our study demonstrated that 1) during hypoxia, increases in systemic O(2) extraction compensated for decreases in delivery and systemic uptake did not change; vasodilation sustained cerebral cortical O(2) delivery and preserved metabolism; increases in intestinal oxygen extraction offset decreases in delivery and uptake was preserved; and 2) nonpolycythemic hyperviscosity did not have a major influence on cardiovascular or metabolic responses to hypoxia, except for modest effects on intestinal resistance and perfusion to certain gastrointestinal regions. We conclude that, under normocythemic conditions, a moderate increase in viscosity does not have a major impact on hemodynamic or metabolic adjustments to hypoxia in newborn pigs.     

Imaging hemoglobin oxygen saturation in sickle cell disease patients using noninvasive visible reflectance hyperspectral techniques: effects of nitric oxide

Sickle cell disease is characterized by microvascular occlusion and hemolytic anemia, factors that impair tissue oxygen delivery. We use visible reflectance hyperspectral imaging to quantitate skin tissue hemoglobin oxygen saturation (HbO2) and to determine whether changes in blood flow during nitric oxide (NO) stimulation or gas administration (therapies proposed for this disease) improve skin tissue oxygen saturation in five patients with sickle cell disease. Compared with six healthy African-American subjects, sickle cell patients exhibited higher forearm blood flows (7.4 +/- 1.8 vs. 3.2 +/- 0.4 ml.min-1.100 ml tissue-1, P = 0.037) but significantly reduced percentages of skin HbO2 (61.0 +/- 0.2 vs. 77.5 +/- 0.2%, P < 0.001). Administration of acetylcholine to patients increased blood flow by 15.1 +/- 3.8 ml.min-1.100 ml tissue-1 and the percentage of skin HbO2 by 4.1 +/- 0.3% (P = 0.02, P < 0.001, respectively, from baseline values). Sodium nitroprusside, a direct NO donor, increased blood flow by 3.9 +/- 1.1 ml/min and the percentage of skin HbO2 by 2.9 +/- 0.3% (P = 0.02, P < 0.001, respectively). NO inhalation had no effect on forearm blood flow, yet increased the percentage of skin HbO2 by 2.3 +/- 0.3% (P < 0.001). Percentages of skin HbO2 were exponentially related to blood flow (R = 0.97, P < 0.001), indicating a limit to skin tissue oxygen saturation at high blood flows. Thus, for acetylcholine infusion leading to blood flows sevenfold greater than those of healthy resting African-American subjects, patients still exhibited lower percentages of skin HbO2 (65.2 +/- 0.2 vs. 77.5 +/- 0.2%, P < 0.001). Visible reflectance hyperspectral imaging demonstrates that either the stimulation or the administration of NO pharmacologically or by gas inhalation improves, but does not normalize, skin tissue oxygen saturation in patients with sickle cell disease.     

Alterations of hemorheological parameters and tubulin content in erythrocytes from diabetic subjects

Treatment of human erythrocytes with high glucose concentrations altered the content and distributions of three tubulin isotypes, with consequent reduction of erythrocyte deformability and osmotic resistance. In erythrocytes from diabetic subjects (D erythrocytes), (i) tubulin in the membrane-associated fraction (Mem-Tub) was increased and tubulin in the sedimentable fraction (Sed-Tub) was decreased, (ii) deformability was lower than in erythrocytes from normal subjects (N erythrocytes), and (iii) detyrosinated/acetylated tubulin content was higher in the Mem-Tub fraction and tyrosinated/acetylated tubulin content was higher in the Sed-Tub fraction, in comparison with N erythrocytes. Similar properties were observed for human N erythrocytes treated with high glucose concentrations, and for erythrocytes from rats with streptozotocin-induced diabetes. In N erythrocytes, high-glucose treatment caused translocation of tubulin from the Sed-Tub to Mem-Tub fraction, thereby reducing deformability and inducing acetylation/tyrosination in the Sed-Tub fraction. The increased tubulin acetylation in these cells resulted from inhibition of deacetylase enzymes. Increased tubulin acetylation and translocation of this acetylated tubulin to the Mem-Tub fraction were both correlated with reduced osmotic resistance. Our findings suggest that (i) high glucose concentrations promote tubulin acetylation and translocation of this tubulin to the membrane, and (ii) this tubulin is involved in regulation of erythrocyte deformability and osmotic fragility.     

Isolation of the Putative Biosynthetic Gene Cluster of 1-Deoxynojirimycin by Bacillus amyloliquefaciens 140N,Its Production and Application to the Fermentation of Soybean Paste

α-Tocotrienol (α-T3) has been suggested to protect cellular membranes against free radical damage. This study was done to estimate the effect of α-T3 on free radical-induced impairment of erythrocyte deformability by comparing it to α-tocopherol (α-T). An erythrocyte suspension containing 2,2′-azobis (2-amidinopropane) dihydrochloride (AAPH) was forced to flow through microchannels with an equivalent diameter of 7 μm for measuring erythrocyte deformability. A higher concentration of AAPH caused a marked decrease in erythrocyte deformability with concomitant increase of membranous lipid peroxidation. Treatment of erythrocytes with α-T or α-T3 suppressed the impairment of erythrocyte deformability as well as membranous lipid peroxidation and they also increased erythrocyte deformability even in the absence of AAPH. In these cases, the protecting effect of α-T3 was significantly higher than that of α-T. We emphasize that higher incorporating activity of α-T3 into erythrocyte membranes seems to be the most important reason for higher protection against erythrocyte oxidation and impairment its deformability.     

Erythrocyte deformability is a nitric oxide-mediated factor in decreased capillary density during sepsis

Erythrocyte deformability has been recognized as a determinant of microvascular perfusion. Because nitric oxide (NO) is implicated in the modulation of red blood cell (RBC) deformability and NO levels increase during sepsis, we tested the hypothesis that a NO-mediated decrease in RBC deformability contributes to decreased functional capillary density (CD) in remote organs. With the use of a peritonitis model of sepsis in the rat [cecal ligation and perforation (CLP)] and aminoguanidine (AG) to prevent increases in NO, we measured CD in skeletal muscle (intravital microscopy), mean erythrocyte membrane deformability (; micropipette aspiration), systemic NO production [plasma nitrite/nitrate (NO(x)) chemiluminescence], and NO accumulation in RBC [NO bound to hemoglobin (HbNO) detected by electron paramagnetic resonance spectroscopy]. In untreated CLP animals relative to sham, NO(x) increased 254% (P < 0.05), stopped flow capillaries increased 149% (P < 0.05), and decreased 12.7% (P < 0.05), with a subpopulation (5%) of RBC with deformabilities below the normal range. AG prevented increases in NO(x), accumulation of HbNO, and decreases in both and functional CD. We found no evidence of leukocyte plugging postcapillary venules. Our findings suggest that decreased functional CD during sepsis resulted from a NO-mediated decrease in erythrocyte deformability.     

Hypoxic exercise training causes erythrocyte senescence and rheological dysfunction by depressed Gardos channel activity

Despite enhancing cardiopulmonary and muscular fitness, the effect of hypoxic exercise training (HE) on hemorheological regulation remains unclear. This study investigates how HE modulates erythrocyte rheological properties and further explores the underlying mechanisms in the hemorheological alterations. Twenty-four sedentary males were randomly divided into hypoxic (HE; n = 12) and normoxic (NE; n = 12) exercise training groups. The subjects were trained on 60% of maximum work rate under 15% (HE) or 21% (NE) O(2) condition for 30 min daily, 5 days weekly for 5 wk. The results demonstrated that HE 1) downregulated CD47 and CD147 expressions on erythrocytes, 2) decreased actin and spectrin contents in erythrocytes, 3) reduced erythrocyte deformability under shear flow, and 4) diminished erythrocyte volume changed by hypotonic stress. Treatment of erythrocytes with H(2)O(2) that mimicked in vivo prooxidative status resulted in the cell shrinkage, rigidity, and phosphatidylserine exposure, whereas HE enhanced the eryptotic responses to H(2)O(2). However, HE decreased the degrees of clotrimazole to blunt ionomycin-induced shrinkage, rigidity, and cytoskeleton breakdown of erythrocytes, referred to as Gardos effects. Reduced erythrocyte deformability by H(2)O(2) was inversely related to the erythrocyte Gardos effect on the rheological function. Conversely, NE intervention did not significantly change resting and exercise erythrocyte rheological properties. Therefore, we conclude that HE rather than NE reduces erythrocyte deformability and volume regulation, accompanied by an increase in the eryptotic response to oxidative stress. Simultaneously, this intervention depresses Gardos channel-modulated erythrocyte rheological functions. Results of this study provide further insight into erythrocyte senescence induced by HE.     

Protective effect of alpha-tocotrienol against free radical-induced impairment of erythrocyte deformability

Alpha-tocotrienol (alpha-T3) has been suggested to protect cellular membranes against free radical damage. This study was done to estimate the effect of alpha-T3 on free radical-induced impairment of erythrocyte deformability by comparing it to alpha-tocopherol (alpha-T). An erythrocyte suspension containing 2,2'-azobis (2-amidinopropane) dihydrochloride (AAPH) was forced to flow through microchannels with an equivalent diameter of 7 microm for measuring erythrocyte deformability. A higher concentration of AAPH caused a marked decrease in erythrocyte deformability with concomitant increase of membranous lipid peroxidation. Treatment of erythrocytes with alpha-T or alpha-T3 suppressed the impairment of erythrocyte deformability as well as membranous lipid peroxidation and they also increased erythrocyte deformability even in the absence of AAPH. In these cases, the protecting effect of alpha-T3 was significantly higher than that of alpha-T. We emphasize that higher incorporating activity of alpha-T3 into erythrocyte membranes seems to be the most important reason for higher protection against erythrocyte oxidation and impairment its deformability.     

Effects of nitric oxide and prostacyclin on deformability and aggregability of red blood cells of rats ex vivo and in vitro.

Although many diseases of the heart and circulatory system have been linked with insufficient deformability and increased aggregability of red blood cells, there are only a few drugs which can modulate these biological functions of erythrocytes. Here, we show evidences that iloprost, stable prostacyclin analogue and SIN-1, active metabolite of molsidomine which spontaneously releases NO, may be sufficient pharmacological tools for modulating red blood cell deformability and aggregability. Deformability of red blood cells was measured by shear stress laser diffractometer (Rheodyn SSD) and expressed in percent of red blood cell deformability index (DI). MA-1 (Myrenne) erythrocyte aggregometer was used for photometric measurements of aggregability in arbitrary units (MEA) of mean extent of aggregation. Experiments were carried out on rats ex vivo and in vitro using whole rat blood or isolated erythrocytes. Ex vivo SIN-1 (infusion 2 mg/kg/min i.v.) and iloprost (bolus injection 10 microg/kg i.v.) significantly improved erythrocyte deformability and aggregability at 5-15 min after administration. L-NAME (10 mg/kg i.v.)- inhibitor of nitric oxide synthase, and aspirin (1 mg/kg i.v.) caused worsening of deformability of erythrocytes in experiments ex vivo. Studies in vitro also revealed improvement of red blood cell deformability and aggregability by SIN-1 (3 microM, 15 min incubation at 22 degrees C) or iloprost (1 microM, 15 min incubation at 22 degrees C) and this phenomenon appeared not only in whole blood but also in isolated red cells. It is concluded that NO- and prostacyclin-induced improvement of red blood cell deformability and aggregability results from direct action of these compounds on erythrocytes. NO-donors and iloprost could be useful in the treatment of disorders of blood fluidity.