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The annual cycle of small ground squirrels (Spermophilus pygmaeus) consists of 2 periods: wakefulness (spring-autumn) and hibernation (winter). During the active period, ground squirrels breed (spring), accumulate fat reserves (summer) and prepare for hibernation (autumn). We suppose that the rheological properties of blood and the deformability of erythrocytes can change in different seasons of the animal's wakefulness period to adequately provide tissues with oxygen. The aim of this study was to identify possible adaptive changes in erythrocyte deformability and erythrocyte indices in ground squirrels during their active period. The deformability of erythrocytes was studied by ektacytometry in an osmotic gradient. It was found that in spring, after the arousal of ground squirrels, erythrocytes have the highest deformability (El_max), hydration (O_hyper), water permeability (El_min) and osmotic stability (∆O). In summer, compared with spring, the deformability of erythrocytes decreases, and the average volume of erythrocytes (MCV) also decreases. In autumn, before hibernation, the integral deformability of erythrocytes, their hydration, as well as the range of osmotic stability of erythrocytes increases relative to the summer period. In summer and autumn, in contrast to spring, the average concentration of hemoglobin in the erythrocyte (MCHC) increases. At low shear stress (1 Pa) in summer and autumn, osmoscan becomes a pronounced polymodal form, indicating a change in the viscoelastic properties of ground squirrel erythrocyte membranes. Thus, for the first time, we discovered seasonal variability in the deformability of ground squirrel erythrocytes, which is consistent with the spring-summer activity of animals and preparation for hibernation., (© 2023 Wiley Periodicals LLC.)

With help of comprehensive methods of piezodynamic aggregometry in a microvolume and gradient ektacytometry the study was carried out to evaluate rheological properties of erythrocyte in patients with complex pathology before and after each injection of ozonated physiological solution. It was shown that after administration of physiological saline and after each session of ozone therapy occurs reduction of minimum aggregates strength and rate of spontaneous aggregation like and microviscosity and increase of deformability and water permeability of erythrocyte membranes. Dynamics of changes in the studied parameters of erythrocytes shows the improvement of the rheological properties of blood in patients not only immediately after the procedure, but and after update of blood in 2 weeks, 1 and 2 months after the course.

Variability of deformation and aggregation properties of erythrocytes is a component part of nonspecific antihypoxic response of formation of adequate blood flow in the tissues and efficiency of the microcirculation in different sections of the vascular bed. Degree of change in these properties during neonatal adaptation to spontaneous breathing can be a marker of its abnormality. We examined 19 healthy full-term newborns in the first 1-2 and 13 children in the first 5-7 days of life. The control group consisted of 30 healthy people aged 25-35 years. It is shown that the aggregation properties of erythrocytes, reduced on the birthday, significantly increased to 5-7 day to values in adults. Erythrocyte deformability in neonates enhanced by an excess reserve of specific surface and reduced strength of the membranes to stretch. Adapting to the transition to spontaneous breathing accompanied by an emphasis on the hyperkinetic type of hemodynamics.

Hematological parameters and functional status of erythrocytes were studied by the osmotic and ammonium loads in healthy newborns and in adults. Mean erythrocyte volume of newborns more than in adults. Significant difference index of osmotic fragility of neonates were observed in the transition from swelling to hemolysis. Kinetic of erythrocyte's hemolysis in the ammonium load was studied by low-angle light scattering (LaSca-analyzer). The percentage of erythrocyte hemolysis is lower and the velocity of hemolysis is 2.5 times slower in newborns than in adults.

Purpose of the work was to explore likelihood of impairment of erythrocytes deformation and aggregation properties in a compensated magnetic field of the Earth. It was shown that complete magnetic deprivation does not alter rat's hemorheology substantially. Stress-related changes were found neither in blood nor adrenals of the animals.

In experiments on Wistar rats and guinea pigs, dynamics of blood hematological parameters and of erythrocyte deformability index (DI) was studied from birth to the 3-month age. In rats, significant changes were revealed in the picture of blood for the first month of postnatal ontogenesis. The number of erythrocytes and leukocytes sharply increased, the number of reticulocytes decreased, their ratio in the degree of maturity was changed. The mean erythrocyte volume and their acidic resistance also decreased. Prior to the 4-week age, DI increased, which was accompanied by an increase in the hemoglobin hydration and flattening of the erythrocyte shape. Then ID decreased and erythrocytes acquired the more spherical shape. After the critical period of 3-4 weeks the studied parameters reached plateau. In guinea pigs, at this period of ontogenesis the hematologic parameters had sufficiently stable values, except for a DI decrease from birth to 1.5 months, then it rose without reaching the initial values. Like in the case with rats, DI had a close correlation with the erythrocyte parameter of shape (O min).

We assessed character and extent of coronary vessels involvement in 27 patients with non ST-elevation acute coronary syndrome (NSTEACS) and compared angiography data with rheological properties of erythrocytes of patients and 30 practically healthy men. Stenoses of main branches of coronary vessels were found almost in 3/4 of cases. In 4 patients without stenoses in main branches of coronary arteries we revealed lowering of blood flow velocity related to small vessel disease (syndrome X). In 2 cases there were no changes in coronary circulation. Extent of vessel involvement was the least in patients with non Q-wave myocardial infarction as initial manifestation of ischemic heart disease and the greatest in patients with unstable angina after myocardial infarction. Patients with NSTEACS had elevated aggregation capacity and lowered deformability of erythrocytes. Degree of these changes did not depend on clinical peculiarities of development of the disease, extent of obstructions, character of vessels involvement. Positive correlation between was found content of cholesterol and degree of elevation of rate of erythrocyte aggregation.

In experiments on Wistar male rats, on a specially constructed computer installation, O2 consumption by the animals in comparison with changes of hematological, biochemical, and rheological blood properties is studied after anemization--acute bloodletting (12-15% of the total blood mass). An increase of the O2 consumption by the organism and tissues by 18-28% has been revealed for the first 7 days after the bloodletting, in spite of a pronounced decrease of hematocrit, and of the amount of erythrocytes and hemoglobin in peripheral blood by 20-25% of the initial level. There was a 5-10-fold increase of the content of immature erythrocyte forms--reticulocytes and a progressive rise of cell acidic resistance, which is characteristic of young erythrocyte forms. An increase of O2 consumption at a decrease of the blood oxygen capacity (a low hemoglobin level) seems to be due to the more efficient transport and yield of O2 to tissues. At the 3rd 7th day after the bloodletting, activity of Na,K-ATPase has been shown to increase by 60% and 20%, respectively. Analysis of the erythrocyte rheological properties has shown that the maximal firmness of aggregates (Uq) and the aggregation rate (1/T) decrease progressively beginning from 3 days after the bloodletting; index of deformability (I(max)) turned out to be elevated by 7-11%, probably due to an increase of the cell membrane elasticity. The conclusion is made that changes of erythrocyte rheological properties are interconnected with changes of the Na,K-ATPase activity and are directed to optimization of blood circulation in large vessels and the capillary network.

In experiments on Wistar rats, dynamics of blood hematological and rheological parameters has been studied from birth to the 3-month age. Results of the study indicate an intensive activity of the red bone marrow anlagen during the first 3 weeks of postnatal ontogenesis. This is manifested in an increase of the number of cells in the erythron system, a change of erythrocyte acidic resistance, and a shift in the leukocytic formula. The boundary between the 2nd and 3rd postnatal weeks is critical: there occur a sharp deceleration of erythropoiesis and a change of the age-related erythrocyte composition and the blood leukocyte ratio towards those characteristic of adult rats. The rise in the number of leukocytes and erythrocytes does not cease after having passed this period. Until the 4-week age, the deformability index increases, which is accompanied by an increase of hemoglobin hydration and by improvement of the erythrocyte toroid form. Subsequently, inversion of these processes occurs.

In experiments of Wistar male rats, changes are studied of erythrocyte hematological, biochemical (activitities of transport ATPases), and rheological properties (capability for aggregation and deformability) 7 days after bloodletting of 12-15 % of the total blood mass. It has been shown that alongside with an elevation of erythrocyte volume and of the number of immature cells - reticulocytes, there was a statistically significant increase of Na,K-ATPase and Ca-ATPase activities in the whole erythrocytes and their membrane preparations - ghosts, the increment of activity in the case of Na,K-ATPase being essentially higher in the whole cells. This indicates the appearance of an enzyme activator inside the erythrocytes. There are also revealed a decrease of firmness of erythrocyte aggregates, a deceleration of spontaneous aggregation, and an increase of index of erythrocyte deformability. The conclusion is made that changes of erythrocyte rheological properties are interconnected with changes of the Na,K-ATPase activity and are directed to optimization of blood circulation in large vessels and capillary network.

Analyzed were aggregation and deformation parameters of erythrocytes and their correlation in rats stressed by immobilization, cold, hunger, and cold combined with hunger, and their controls. Under the above experimental conditions, the aggregation rate of erythrocytes grows up without any pronounced changes in the deformation characteristics. There was a direct positive correlation between the aggregation and deformation parameters of erythrocytes under stress. It is assumed that this phenomenon represents a universal mechanism of adaptation of the blood viscosity regulation in mammals.

Correlations of rheological determinants of the erythrocyte viscous characteristics were studied in normal subjects and coronary patients treated traditionally and with photohemotherapy. A rigid relationship between erythrocyte deformability and aggregation was detected in the patients. Blood exposure to He-Ne laser and UV is a potent method for correcting the blood rheology. Physiological significance of the rigid relationship of erythrocyte deformability and aggregation consists in the maintenance of the structure of flowing blood, characteristic of its native status, and represents an additional mechanism of realization of the adaptive potential of blood viscosity regulation in mammals.

Blood samples of healthy male subjects exposed to three-wk hypoxia were analyzed for deformation and aggregation of erythrocytes. Results of the investigation showed that breathing a hypoxic mixture increases blood viscosity by way of raising rigidity of erythrocytes and fastness of their aggregates. A direct correlation between the deformability index and rate of aggregation was established. The physiological effect of this phenomenon is explained by the compensatory reaction of organism in support of the circulation structure and the breathing function of blood in hypoxic conditions.

Modern techniques of studying the main features of the blood viscosity: membrane elasticity, deformability and aggregability of the erythrocytes, are reviewed.

Deformation properties of erythrocytes have been studied using osmotic gradient ectacytometric procedure in rats with spontaneous hereditary hypertension (SHR), normal tension rats from Wistar-Kyoto strain and albino rats from Wistar strain. It was shown that high intrinsic viscosity and, to a less extent, changes in their form account for the increased rigidity of the erythrocytes from SHR rats. No significant changes in visco-elastic properties of the membrane were found. The degree of hydration of haemoglobin significantly increases in the order SHR-WKY-Wistar.

Analysis of the blood clinical characteristics carried out in the patients with essential hypertension (EH) and in normal subjects has shown two groups of values for every parameter. In EH the ratio between these parameters is shifted towards an increased number of cases with a lowered count of red cells, the hematocrit value and the volume of a red cell being elevated.

The standard clinical parameters of red blood, morphometric characteristics, membrane resistance and electrolyte balance of red blood cells of white rats exposed to acute immobilization were investigated. It was found that the immobilization of rats in small-size cages produced statistically significant changes in the concentration of ascorbic acid in the adrenals and oxycorticosteroids in plasma, as well as erythrocytosis, reduction of red blood cell size, planocytosis and decrease of intracellular sodium. The above parameters did not return to the norm 24 hours after 3-hour immobilization. It is suggested to use the amount of plasma per red blood cell as a stress-marker in red blood.