Red Cell Filterability Research Articles

Changes in the functional state of the erythrocyte membrane: Significance for red cell filterability and blood viscosity

Blood samples from nine healthy men were studied to determine the effect of ouabain and elevated serum calcium concentration on blood viscosity, measured by a rotational viscometer, and on red cell filterability by the St George's Filtrometer, giving values for clogging particles (CP) and red cell transit time (RCTT). Blood viscosity at a standardized haematocrit of 45% and red cell filterability was investigated in blood samples incubated for 1 h with Ringer's solution only (control), with ouabain (0.70 mmol/l) in plasma, or with serum calcium concentration increased by 3.0 mmol/l by addition of CaCl2. Incubation with ouabain significantly reduced erythrocyte K+ concentration and increased that of Na+. Ouabain caused a decrease in blood viscosity (p less than 0.05-0.005) compared to controls, although there was no decrease in red cell filterability parameters. When incubating with calcium, CP and RCTT increased significantly indicating 'stiffer' red cells, but there was no increase in blood viscosity. It is concluded that blood viscosity may be influenced by red cell factors not detected by CP or RCTT, which in turn appear to reflect red cell deformability with greater sensitivity and specificity than blood viscosity. It is concluded also that the functional state of the cell membrane may be of significance for the rheological properties of erythrocytes.

Hemorheological effects of oral contraceptives

To determine the hemorheological effects of oral contraceptives, 50 healthy young women took no medication for 3 cycles. Subsequently they were randomized into group A and B. Group A took Diane-35( ®), B took Microgynon( ®) each for 6 cycles. Finally 3 cycles without medication followed. Blood viscosity was quantified by ex vivo measurements of hematocrit, blood and plasma viscosity, red cell filterability, fibrinogen and colloid oncotic pressure. In group A fibrinogen rose at the end of the medication phase. In group B fibrinogen, blood and plasma viscosity increased on medication. The former 2 variables remained elevated even after discontinuation of the oral contraceptive. The data combined with those from the literature suggest that low—dose oral contraceptives lead to no biologically meaningful changes in blood rheology while higher doses induce limitations of blood fluidity which could be involved in the increment of cardiovascular risk by these medications.

Blood cell rheology in acute cerebral infarction.

Recently it has been hypothesized that leukocyte rheology could be a relevant variable of the microcirculation during cerebral ischemia. However, relatively few studies have been carried out on the rheologic behavior of leukocytes in vascular diseases. This study aimed at quantifying the filterability through Nuclepore filters (mean pore diameter 5 microns) of both leukocyte subpopulations and red blood cells in patients with acute stroke compared with age-matched healthy controls. Leukocytes were separated by density into polymorphonuclear and mononuclear cells. Filterability of the red blood cells and polymorphonuclear and mononuclear subpopulations in buffer was measured using a constant-flow and low-positive pressure system. We used one-way analysis of variance, signed rank sum, and simple and multiple regression tests for statistical analysis. Twenty consecutive male patients with acute ischemic infarction were compared with 20 age-matched healthy subjects. Mononuclear cell filterability was impaired in acute stroke (7.26 +/- 2.00) compared with the controls (5.55 +/- 1.23) (p less than 0.01). Polymorphonuclear cell filterability was less, but still significantly (p less than 0.05), impaired in acute infarction (5.75 +/- 0.87 vs. 4.19 +/- 0.43). The results show that leukocyte and, especially, mononuclear cell filterability is impaired in acute infarction, while no differences exist in red blood cell filterability.

Alteration of the mechanical properties of sickle cells by repetitive deoxygenation: role of calcium and the effects of calcium blockers.

The formation of dense, poorly deformable sickle cells was studied by subjecting pre-separated, less dense cells to repeated deoxygenation and reoxygenation for 15 h. In the presence of Ca (2 mmol/l), this process caused the number of irreversible sickled cells to increase five-fold, mean cell haemoglobin concentration to increase by 13% and cellular potassium to decrease by 22%. Also, red cell filterability through 5 microns filter pores was greatly worsened. These effects decreased but were not totally abolished when the extracellular Ca concentration was lowered to zero or 0.01 mmol/l. If a high K medium was used (135 mmol/l), cell swelling rather than shrinkage occurred. Swelling also occurred if ouabain was added to the incubation. The Ca-channel blockers nitrendipine and nisoldipine had different effects. Nitrendipine, in the range 10(-7) - 10(-5) mol/l, was partially protective against all the induced changes, but nisoldipine was not protective at 10(-8) or 10(-6) mol/l. Thus, deterioration in the properties of sickle cells appears to be linked to Ca-dependent potassium loss during repeated sickling and is inhibited by nitrendipine.

Favorable effects of fish oil concentrate on risk factors for thrombosis in renal allograft recipients.

The incidence of thromboembolic complications in renal allograft recipients is very high. Since fish oil has antithrombotic properties, we administered 18 capsules of fish oil concentrate (1.5 g of eicosapentaenoic acid, EPA, and 0.7 g of docosahexaenoic acid) per day to 14 renal allograft recipients for 6 months. Another group of recipients served as controls. In the treated group the levels of EPA and docosahexaenoic acid in erythrocyte membrane lipids increased significantly after the fish oil treatment. Red blood cell filterability significantly increased in the treated group compared with the case of the control group. Epinephrine-induced platelet aggregation increased significantly in the control group, and this change was significantly different from that of the treated group (almost a null change). At the end of the study, the ratio of the main urinary metabolite of prostacyclin I2/3 to the metabolite of thromboxane A2/3 was significantly higher in the treated group than in the control group. In conclusion, we suggest that fish oil concentrate may favorably affect risk factors for thromboembolic complications in renal allograft recipients.

Effect of contrast media on whole blood filtrability

The effects of three contrast media, iohexol, iopamidol and ioxaglate, on rat erythrocytes were compared. Three parameters representative of the rheologic properties of blood were investigated: whole blood filtrability, red cell filtrability and morphology. Whole blood and red cell filtrabilities were both measured using an erythrometer and red cell morphology was observed with an optical microscope. Iohexol and iopamidol were found to cause a significant increase in filtrability indices and to modify the shape of red blood cells. Ioxaglate had less effect on these parameters than did the other two contrast media. the chemical structure seems to be a determining factor for red cell integrity. the study of blood rheology parameters in vitro may be useful as a model predictive of observations on human blood and of hemodynamic consequences

Effect of Contrast Media on Whole Blood Filtrability

The effects of three contrast media, iohexol, iopamidol and ioxaglate, on rat erythrocytes were compared. Three parameters representative of the rheologic properties of blood were investigated: whole blood filtrability, red cell filtrability and morphology. Whole blood and red cell filtrabilities were both measured using an erythrometer and red cell morphology was observed with an optical microscope. Iohexol and iopamidol were found to cause a significant increase in filtrability indices and to modify the shape of red blood cells. Ioxaglate had less effect on these parameters than did the other two contrast media. The chemical structure seems to be a determining factor for red cell integrity. The study of blood rheology parameters in vitro may be useful as a model predictive of observations on human blood and of hemodynamic consequences.

Blood Rheology in Post-Thrombotic Syndrome — A Pilot Study

Patients suffering from post-thromobotic syndrome are compared to controls in terms of ex-vivo measurements to quantify the rheological behavior of blood: blood and plasma viscosity, haematocrit, red cell aggregation, red cell filterability, erythrocyte sedimentation rate (ESR), plasma fibrinogen. The results show that plasma viscosity, red cell filterability, ESR and fibrinogen are significantly changed indicating a lack of blood fluidity in post-thrombotic disease. It is suggested that the rheological deficit and the venous pathology both contribute to a disturbed microcirculation in the affected limb.

Decreased red cell filterability in patients with acute myocardial infarction.

The red cell filterability was decreased in patients with acute myocardial infarction (AMI) when compared with healthy controls, 14.6 (12.2-16.3) units and 16.9 (15.6-17.4) units respectively, P50 (P25-P75), p less than 0.001). No significant correlations could be seen within the AMI group between the decrease in filterability and the levels of serum aspartate aminotransferase or serum lactate dehydrogenase. The erythrocyte filterability, however, correlated to the serum concentrations of hepatic enzymes in AMI. The addition of sodium lactate in vitro in physiological concentrations (0.9-3.6 mM/l final concentration) lowered the erythrocyte filterability markedly to 2.7 (0-9.8) units in a dose-dependent manner, supporting the hypothesis that the decrease in erythrocyte filterability in AMI might be caused by an increase in the lactate concentration.

Effect of contrast media on whole blood filtrability

The effects of three contrast media, iohexol, iopamidol and ioxaglate, on rat erythrocytes were compared. Three parameters representative of the rheologic properties of blood were investigated: whole blood filtrability, red cell filtrability and morphology. Whole blood and red cell filtrabilities were both measured using an erythrometer and red cell morphology was observed with an optical microscope. Iohexol and iopamidol were found to cause a significant increase in filtrability indices and to modify the shape of red blood cells. Ioxaglate had less effect on these parameters than did the other two contrast media. The chemical structure seems to be a determining factor for red cell integrity. The study of blood rheology parameters in vitro may be useful as a model predictive of observations on human blood and of hemodynamic consequences.

Restoration of microsieve filterability of human red cells after exposure to hyperosmolarity and lactacidosis: Effect of vinpocetine

AbstractA new technique has been utilized to assess quantitatively the filterability (i.e., the ability to pass restricted pores) of leukocyte‐free red blood cell (RBC) suspensions by means of computer‐assisted conductometry of novel precision metal microsieves with uniform pore diameters of 4.2 μm (MyNiPore®). RBCs were exposed to adverse conditions of chemical “stress” (400 mOsmol/liter, pH 6.8), thereafter, the effects of vinpocetine (Methyl‐Apo‐Vipamin, Thiemann‐Arzneimittel GmbH, Waltrop, FRG) were tested. When added in concentrations between 10−5 and 10−2 mol/liter to the “stressed” RBCs, vinpocetine restored the red cell microrheological performance (or behavior) when tested under low shear stresses. The present results suggest that in interpreting vinpocetine's effects in low flow situations, a possible protective microrheological action should be taken into consideration.

Association between bleeding and reduced red cell deformability following cardiopulmonary bypass.

In 56 patients undergoing open-heart surgery, red cell trauma during and following cardiopulmonary bypass (CPB) was monitored with a microfiltration method that estimated deformability of the cells. Red cell deformability was reduced by 38% during CPB and at a slower rate thereafter. The lowest filterability rate was reached on the second day, after which improvement began. In patients who had undergone coronary artery bypass grafting, preoperative values of red cell deformability were reached after 6 weeks. Following valve replacement, however, preoperative values were not regained during this period, which was attributed to continuous mechanical trauma by the artificial valves. A 50% reduction of red cell filterability from the end of CPB to 12 and 24 hours from the start of CPB was associated with heavy blood loss (greater than 1,000 ml) from drains. Reduced red cell deformability thus showed relationship with a bleeding tendency following use of CPB.

Ticlopidine. A review of its pharmacodynamic and pharmacokinetic properties, and therapeutic efficacy in platelet-dependent disease states.

Ticlopidine is an inhibitor of platelet action that has been used in the treatment of a variety of disease states in which platelets play a prominent role. Studies in animals and man have demonstrated that ticlopidine is a potent inhibitor of platelet aggregation induced by adenosine diphosphate (ADP), and variably inhibits aggregation due to collagen, adrenaline (epinephrine), arachidonic acid, thrombin, and platelet activating factor. Inhibition of platelet aggregation is both dose- and time-related, with its onset of activity being 24 to 48 hours, its maximal activity occurring after 3 to 5 days, and its activity still being present 72 hours after a final dose. Ticlopidine also inhibits the release reaction of platelets, prolongs bleeding time, reduces plasma levels of platelet factor 4 and beta-thromboglobulin in patients in whom these proteins are elevated, and may also inhibit platelet adhesion, increase red cell filtrability and decrease whole blood viscosity. In a large number of animal models, ticlopidine markedly inhibits thrombus formation or graft occlusion. Ticlopidine is well absorbed after oral administration. It is extensively metabolised and at least one of its metabolites is pharmacologically active. Therapeutic trials in patients with chronic arterial occlusion due to thrombangitis obliterans or arteriosclerosis obliterans, post-myocardial infarction, cerebrovascular thromboembolic disease, subarachnoid haemorrhage, vascular shunts or fistulas for haemodialysis, and sickle cell disease have shown promise for the use of ticlopidine. However, trials of patients with intermittent claudication, angina pectoris, diabetes mellitus with microvascular disease, aortocoronary bypass grafts, and vascular prostheses have had conflicting results or have shown an unfavourable side effect profile. Further studies are clearly required to establish the role of ticlopidine in many of these areas, some of which are already in progress. Overall, side effects occur in 10 to 15% of patients receiving ticlopidine. The most common side effects are gastrointestinal disturbances and skin rashes. Neither of these necessarily require discontinuation of therapy in most patients. Agranulocytosis, thrombocytopenia, and cholestatic jaundice have also been reported. Bleeding is infrequent except possibly in patients receiving ticlopidine prior to some surgical procedures.

Erythrocyte deformability in canine septic shock and the efficacy of pentoxifylline and a leukotriene antagonist.

Decreased microcirculatory flow in the case of endotoxic shock has been extensively reported. The flexibility of the red blood cell plays an important role in tissue perfusion. The present study with a canine shock model was designed to investigate the changes in erythrocyte flow properties during septic shock. Deformabilities of canine erythrocytes were found to decrease considerably 6 hr after infusion of Escherichia coli organisms (P less than 0.05). Pretreatment of dogs with pentoxifylline reduced the effect by improving erythrocyte deformability significantly and by increasing animal survival times. The leukotriene antagonist LY171883 also increased survival time, but did not change red cell filterability. The mortality of the dogs was not affected by either pentoxifylline or the leukotriene antagonist. Both drugs aided the concentration recovery of circulating leukocytes by 6 hr post-E. coli infusion.

In vitro and ex vivo effects of indobufen on red blood cell deformability.

We have studied the effect of indobufen, a cyclo-oxygenase blocking agent which has proved useful in patients with obstructive vascular disease, on red blood cell (RBC) filterability in vitro and in a pilot study ex vivo. The addition of indobufen in vitro to blood samples from 10 healthy volunteers did not significantly modify RBC deformability. We evaluated the ex vivo effect of indobufen (200 mg bd) in 14 patients with obstructive vascular disease. A significant improvement in RBC deformability was noted on the 5th, 14th, and 28th days of treatment, 2 h after the morning dose. Acetylsalicylic acid given to 6 similar patients had no effect suggesting that the positive haemorheological effect of indobufen is probably not linked to its cyclooxygenase blocking effect.

Blood rheology in myocardial infarction and hypertension.

Blood rheology was studied in patients with acute myocardial infarction (AMI) and essential hypertension (EH), and the results were correlated with in vivo hemodynamic functions. Blood viscosity (eta B) was elevated as a result of sequential changes of a number of parameters, including increases in hematocrit, plasma fibrinogen and alpha 2-globulin, an enhancement of red cell aggregation and a reduction of red cell filterability in plasma. Total peripheral resistance (TPR) was elevated upon admission, due to increases in both the vascular hindrance (ZS) and eta B. During recovery, the eta B became normalized; alterations in eta B were accompanied by parallel changes in TPR and an inverse change in plasma volume (PV). In EH patients, the increase in eta B showed a correlation with arterial pressure. For both established and borderline hypertensives, the rheological changes were most prominent in the high renin subgroups. In mild EH, the elevation of eta B was compensated by a decrease in ZS (vasodilation), keeping the TPR essentially normal. In EH with higher arterial pressure, the elevation of eta B was accompanied by a normal ZS without compensatory vasodilation, and hence TPR rose to exacerbate the hypertension. These results suggest that the elevation of eta B may be an early event in the development of EH and that its role must be considered with concurrent cardiovascular functions. In EH there is a significant correlation between left ventricular mass and eta B. Experimental manipulations of the hematocrit level in spontaneously hypertensive rats led to a corresponding variation of arterial pressure. The available data implicate a significant role of eta B in the pathophysiology of AMI and EH. Further interdisciplinary, longitudinal studies are needed tin order to unravel the complicated pathophysiological changes in myocardial infarction and hypertension.

Bupivacaine Alters Red Blood Cell Properties

Cord blood was incubated with lidocaine, mepivacaine, bupivacaine, or buffer and red blood cell filterability was determined. Only bupivacaine at either 1 or 2 micrograms/ml prolonged filterability by an average of 58 to 65% over red cells treated with buffer alone. Tritiated bupivacaine was bound to a greater extent to red cell ghosts from cord blood (24.6 +/- 5.8%) than to adult red cell ghosts (14.6 +/- 2.6%). Finally, we determined red cell survival in 13-day-old rats injected with bupivacaine or buffer. At 2 h after injection, buffer-treated animals had a red cell survival of 96.9 +/- 3.3%, whereas 2-h survival was reduced to 82.6 +/- 8.7% for the animals injected with bupivacaine. Our results suggest that the neonatal jaundice associated with maternal anesthesia, especially bupivacaine, may be related to the observations that these agents cross the placenta, bind to the red cell membrane and reduce its filterability, resulting in shortened red cell survival.

Haemorheological markers in 89 patients with stage II peripheral vascular disease (PVD).

Although it is universally accepted that the grade of reduction of district blood flow in PVD is directly correlated to alteration of the haemorheological pattern, there is still no uniformity of opinion regarding the existence of a specific rheological alteration in PVD. The scope of our study was to discover the existence of possible PVD-specific markers; we thus carried out a comparative evaluation of the rheological characteristics in blood of controls and patients affected with PVD. Eighty-nine males between the ages of 50 and 65 years (median 58 +/- 1 SE) were studied, all with a stage II vascular pathology with clinical onset of less than three months. Exclusion criteria were: diabetes mellitus, hyperlipaemia, stable hypertension, presence of vascular disease in other districts, cardio-circulatory problems and serious medical or surgical pathologies, previous vascular surgery, a history of acute thrombo-embolic episodes, and chronic alcoholism. Each patient, after a drug wash-out of 20 days, was monitored for haemorheological parameters. At the same time, the above parameters were measured in a group of 50 male controls of the same age range. All 139 subjects were smokers (10-15 cigarettes average per day). Our results indicate that modification in the bio-humoral (fibrinogen and plasma globulins) parameters, a reduced red blood cell filterability and a relative increase in the number of activated polymorphonucleate cells are probably specific haemorheological markers of the clinical onset of PVD.

Cardiovascular risk factors and hemorheology: Physical fitness, stress and obesity

To date there is little information about hemorheological data in the presence of secondary risk factors. Inter- and intraindividual comparisons of hemorheological parameters show that fitness has a significant influence on blood fluidity as quantified by ex vivo measurements of blood and plasma viscosity, red cell filterability and red cell aggregation. In fitter individuals blood is more fluid. Similar observations can be made with stress. Prolonged psychoemotional stress leads to a loss in blood fluidity and red cell filterability. Finally a comparison between excessively obese patients and healthy controls reveals a deterioration in hemorheological parameters in the obese group. These results, together with reports from the literature suggest that all accepted cardiovascular risk factors are associated with abnormalities in the flow properties of blood. It is proposed that partly the same phenomena are involved in the genesis of atherosclerotic lesions and influence rheological properties of blood.

Changes in membrane properties of rat red blood cells induced by cadmium accumulating in the membrane fraction.

When rat red blood cells were incubated in a cadmium (Cd)-free medium following 1-h pretreatment with 0.5 mM CdCl2, incorporated Cd was retained in the cell during 14-h incubation and progressively accumulated in the membrane fraction, especially in the cytoskeleton fraction. In parallel to this accumulation, red cell filterability decreased and echinocytic cells increased, although intracellular ATP was maintained at the control level. The echinocytic shape was maintained in ghosts and cytoskeletons prepared from the Cd-loaded cells. In addition, the association of bands 2.1, 3, 4.2, and 4.5 with cytoskeletons increased and dissociation of cytoskeletal networks at low ionic strength decreased as the incubation time increased. Pretreatment of red blood cells with Cd also induced a release of small vesicles. These vesicles contained hemoglobin but were depleted of spectrin and actin, showing a phospholipid composition similar to that of red cell ghosts. These results suggest that the organization of cell membranes, especially cytoskeletal networks, is altered by Cd accumulation in the cytoskeleton fraction, which results in acceleration of age-related changes of red blood cells such as shape change and decreased filterability.