Changes in electrokinetic properties of erythrocytes under the influence of pentoxifylline and new hemorheologically active substances.

We studied the impact of compounds RU-1202 and SUM-55 on electrophoretic mobility of "young" and "old" erythrocytes fractionated in a density gradient. The test compounds are shown to increase electrophoretic mobility of erythrocytes, compound SUM-55 being superior to the reference drug pentoxifylline.

[Role of protein kinases of human red cell membrane in deformability and aggregation changes].

The proteomic analysis has showed that red cell membrane contains several kinases and phosphatases. Therefore the aim of this study was to investigate the role of protein kinases of human red cell membrane in deformability and aggregation changes. Exposure of red blood cells (RBCs) to some chemical compounds led to change in the RBC microrheological properties. When forskolin (10 microM), an adenylyl cyclase (AC) and a protein kinase A (PKA) stimulator was added to RBC suspension, the RBC deformability (RBCD) was increased by 20% (p < 0.05). Somewhat more significant deformability rise appeared after RBC incubation with dB-AMP (by 26%; p < 0.01). Red cell aggregation (RBCA) was significantly decreased under these conditions (p < 0.01). Markedly less changes of deformability was found after RBC incubation with protein kinase stimulator C (PKC)--phorbol 12-myristate 13-acetate (PMA). This drug reduced red cell aggregation only slightly. It was inhibited red cell tyrosine phosphotase activity by N-vanadat and was obtained a significant RBCD rise and RBCA lowering. The similar effect was found when cells were incubated with cisplatin as a tyrosine protein kinase (TPK) activator. It is important to note that a selective TPK inhibitor--lavendustin eliminated the above mention effects. On the whole the total data clearly show that the red cell aggregation and deformation changes were connected with an activation of the different intracellular signaling pathways.

[The estimation of microcirculation state in cerebrovascular disorders by data of laser Doppler flowmetry and hemorheological parameters].

UNLABELLED: The study was aimed to evaluate microvascular blood flow and theological blood properties in healthy volunteers (n = 27) and patients with cerebral accident (n = 30). To study cutaneous blood flow we used the multifunctional laser analyzer of blood microcirculation LAKK (LAZMA, Moscow) with spectrophotometric channel and wavelet analysis of blood flow oscillations. Viscosity of the whole blood, plasma, RBC aggregability and deformability were assessed. RESULTS: microcirculation index was by 25% (p < 0.05) lower in patients compared to the control group. Computing amplitude-frequency range of blood flow oscillations revealed notable changes in the blood flow regulation mechanisms under cerebrovascular accident: the amplitudes of all active rhythms (endothelial, neurogenic and myogenic ones) were increased. In spite of such activization of regulatory mechanisms, aimed to keep essential blood supply to tissue, index of specific oxygen consumption by tissue was decreased by 21% (p < 0.05) under cerebrovascular disorders. Blood rheological properties in patients group were impaired compared to the healthy group: blood viscosity was increased because of elevated plasma viscosity, increased RBS aggreagation and decreased erythrocyte deformability. Thus, our results demonstrated the decrease of tissue perfusion, activization of vasodilating mechanisms, impaired blood rheology and the decrease of oxygen supply to tissue in patients with cerebrovascular accident. Statistical analysis revealed a number of significant correlations between the hemorheological parameters and passive rhythms of microcirculation in norm. In patients blood viscosity correlated to the amplitude of active regulatory rhythms (endothelial, neurogenic and myogenic oscillations). Close interralations between rheological and microcirculation parameters testified the important role of hemorheological factors in maintenance of microvascular blood flow and oxygen delivery to tissue.

Red blood cell aggregation changes are depended on its initial value: Effect of long-term drug treatment and short-term cell incubation with drug.

This study was designed to investigate whether the red cell aggregation depends on its initial level under drug therapy or cell incubation with bioactive chemical compounds. Sixty six subjects were enrolled onto this study, and sub-divided into two groups: the first group of patients (n = 36) with cerebral atherosclerosis received pentoxifylline therapy (400 mg, thrice daily) for 4 weeks. The patients of the second group were initially treated with Epoetin beta 10,000 units subcutaneously thrice a week, for 4 weeks. The second group - adult anemic patients (n = 30) with the confirmed diagnosis of solid cancer (Hb < 100 g/L). After 4 weeks of pentoxifylline treatment the red cell aggregation increased (p < 0.05) in the patients with initially low RBCA. On the other hand in the patients with initially high RBCA treatment with pentoxifylline reduced it markedly (p < 0.01). In vitro experiments with pentoxifylline RBC incubation resulted in a decrease of the initially high RBCA by 47% (p < 0.01), whereas in the sub-group with initially low RBCA it increased. It was observed that after 4 weeks of epoetin-beta treatment 75% the anemic patients with initially high RBCA had an aggregation lowering. The drop of aggregation was about 34% (p < 0.01). At the same time 25% of the study patients had a significant RBCA increase (p < 0.05) after treatment. The initially low red cell aggregation after incubation with epoetin-beta was markedly increased by 122% (p < 0.05). On the contrary initially high RBCA was reduced by 47% (p < 0.05). When forskolin (10 µM) was added to the RBC suspensions the RBCA was increased in sub-group of subjects with initially low aggregation and it was decreased in sub-group with initially high one. The similar RBCA changes were observed when RBC suspensions were incubated with vinpocetine, calcium ionophore (A23187), Phorbol 12-myristate 13-acetate (PMA) as a protein kinase C (PKC) stimulator. A major finding of this study is that the red cell aggregation effects of some drugs depend markedly on the initial, pre-treatment aggregation status of the patients. These results demonstrate that the different red blood cell aggregation responses to the biological stimuli depend strongly on the initial, pre-treatment status of the subject and the most probably it is connected with the crosstalk between the adenylyl cyclase signaling pathway and Ca2+ regulatory mechanism.

Parameters of microcirculation in paired formations after single aspirin administration: laser Doppler flowmetry data.

Laser Doppler flowmetry showed that aspirin can induce blood flow reduction and transitory manifold increase or decrease in vascular tone in rat skin and kidneys. The dynamics is more illustrative when parameters of individual animals are evaluated and depends on the areas of blood flow recording. Deaths and reduction of narcotic sleep duration were noted in concomitant use of nembutal and aspirin.

[Techniques for experimental and clinical studies of erythrocyte deformability].

Deformability is an important property of red blood cells and ensures the efficiency of their transport in the microcirculatory vascular system, as well as tissue oxygenation. A study of erythrocyte deformability uses different methods: filtration through about 5.0-microm pores, laser difractometry techniques and a focus of attention has recently been on a procedure for measuring the deformability of erythrocytes in a flow microchamber. The authors have developed a procedure for the recording of erythrocyte deformability and for the computer-aided treatment of an obtained image to have an accurate quantitative assessment of this important microrheological property of the cells. Comparison of the suspension viscosity of erythrocytes at high shift rates and the erythrocyte lengthening index (ELI) in the flow microchamber yielded a high correlation (p = -0.917; p < 0.01). That of ELI in the fractions of young and old cells also supported the high sensitivity of the procedure. Analysis of changes in the degree of erythrocyte deformability (in accordance with ELI), by applying three values of shift strain, revealed an almost linear relationship of the lengthening of fixed cells to the applied shift pressure. The known rheomodulator pentoxiphylline caused a significant erythrocyte deformability increase that was recorded by both methods (in the flow microchamber and at viscosimetry of erythrocyte suspensions with the hematocrit being equal to 40%). Thus, findings suggest that the method for the recording of erythrocyte deformability in the flow microchamber with the computer-aided analysis of images allows one to adequately measure this property of red blood cells.

[Red blood cell aggredation: mechanisms, adrenergic regulation].

Red blood cell aggregation is a complex multiple-factor process and exerts a substantial effect on realization of basic blood function: oxygen transport. Insufficient knowledge about mechanisms of erythrocyte aggregation in normal conditions and, especially, in pathological conditions, complicates the control and correction of possible negative consequences of this process. On addition, red blood cell aggregation process is a suitable model for the elucidation of basic patterns of intercellular interactions. The paper presents contemporary data on mechanisms of erythrocyte aggregation and contribution of plasma and membrane erythrocyte properties to this process. Currently available data on intracellular signal pathways are discussed.

Major alterations in body fluid status and blood rheology.

Since the dehydration causes a loss of body water, we studied the rheological properties of blood in the course of water deprivation. Subjects used in this study were 64 white male rats divided into 4 groups: control (n=19) and 3 experimental groups which underwent water deprivation for 3 days (n=15), 6 days (n=15) and 10 days (n=15). The results obtained indicate that under dehydration animals have higher blood and plasma viscosity and erythrocyte aggregation index than in the control group. After 3 days of dehydration these changes are due to the loss of intravascular water. The water deprivation for 10 days causes significant disturbances in blood composition as well as changes of red blood cell membrane properties whereas blood and plasma volume return to control values.

The effect of dehydration on macro- and microrheological blood properties.

It is known that intensive physical activity causes a loss of water. Since physical capacity is highly dependent upon fluidity of blood, the rheological characteristics of which are largely determined by water content, the aim of our study was to estimate rheological properties of blood under dehydration. To model the state of dehydration, the water deprivation was performed on rats (n=49) for 3 and 10 days. We registered hematocrit, apparent plasma viscosity; apparent viscosity, rigidity index (Tk), structural parameter (k), and extent of aggregation ("M" and "M1" indices) were determined in both unfractionated and density separated RBC suspensions in autologous plasma at Ht=40. The Ht/viscosity ratio as index of oxygen supply to tissues was calculated. The results of our study indicated that water deprivation caused progressive reduction of blood and plasma fluidity. The increase of Ht (22%, p<0.001) and significant elevation of erythrocyte aggregation (205%, p<0.001) were observed. In spite of Ht increase, oxygen transport was decreased by 18% (p<0.05). RBC rigidity was increased under water deprivation (13.6%, p<0.05) as well as during aging. Significant correlation was found between indices of aggregation and Tk and k indices in the course of dehydration. Thus, our data indicated that dehydration caused impairment of blood and RBC rheological properties.

[Hemorheological profiles in patients with arterial hypertension and bronchial asthma]. / Gemoreologicheskie profili u patsientov s arterial'noí gipertenzieí i bronkhial'noí astmoí.

Hemorheological parameters were studied in patients with essential hypertension (men and women) and those with bronchial asthma. The rheological findings were established as a hemorheological profile. The latter is a set of macro- and microrheological parameters under various pathological conditions. The data show that blood viscosity was increased and correlate with blood pressure in hypertensive patients. There were more significant changes in the male populations of the two groups. The main cause of decreased blood fluidity and oxygen transport efficiency under these conditions is associated with hemoconcentration, elevated plasma levels of protein and increased plasma viscosity. The findings suggest that with the concept of a hemorheological profile one can correct rheological disturbances under various clinical conditions.