We estimated hemorheological parameters of vein blood samples and cutaneous microvascular blood flow in patients with acute ischemic stroke and in controls. The worsened blood rheological properties were registered in patients with stroke: the enhanced whole blood viscosity was due to the substantial increase of plasma viscosity and the impairment of microrheological blood properties: elevated erythrocyte aggregability and decreased deformability compared to the healthy group. The decrease of oxygen consumption fixed by rheological methods and by laser Doppler flowmetry led us to conclude that the tissue hypoxia took place in patients with stroke. The regulatory mechanisms aimed to maintain blood supply to tissue were activated under cerebral infarction and the impact of unfavorably changed rheological blood properties was markedly enhanced. Revealed close interrelations between rheological and microcirculation parameters testified the important role of hemorheological factors in maintenance of microvascular blood flow and oxygen delivery to tissue.

This study was designed to investigate the dependency of the red blood cell deformability upon activation of extra- and intracellular signaling pathways. Exposures of red blood cells (RBCs) to catecholamines and to insulin led to positive change in the RBC deformability. When forskolin, a stimulator of adenylyl cyclase (AC), was added to RBC suspension, the RBC deformability was increased. Somewhat more significant deformability rise appeared after RBC incubation with dB-AMP. The inhibitors of phosphodiesterase (PDE) activity increased red cell deformability. These results revealed a considerable role of the AC-cAMP signaling system in the regulation of red blood cell deformability. The rise of the red blood cell Ca ²⁺ influx, stimulated by mechanical loading or A23187 was accompanied by a marked lowering of RBC deformability. At the same time blocking of Ca ²⁺ entry into RBC by verapamil or Ca ²⁺ chelating by EGTA led to significant deformability rise. The comparison of the effect of the different protein kinases on the red blood cell deformability showed that it was altered more considerable under PKA activation by forskolin or dB-cAMP than by other protein kinases. There was a lesser but quite statistically significant effect of tyrosine protein kinase (TPK) on RBC microrheology. Whereas the microrheological effect of PKC was not so considerable. The problem of the short-term regulation of red blood cell microrheology is examined. The latter includes: the modes of activation of extra- and intracellular molecular signaling pathways, ligand - receptor interaction, second messengers, membrane protein phosphorylation. On the whole the total data clearly show that the red cell deformability changes are connected with activation of different extra - and intracellular signaling pathways. It seems reasonable to suppose that red blood cell deformability changes were mainly associated with activation of the AC-cAMP-PKA pathway, and with decrease of Ca ²⁺ entry into cells.

Generalized restricted blood flow is hallmark of CHF of any etiology, but the extent of microcirculation restriction and the role of intrinsic blood properties in heart failure remains unknown. The aim of this study was to estimate the microvascular blood flow and hemorheological properties in chronic heart failure to test the hypothesis that CHF patients have altered peripheral blood flow which contributes to the tissue perfusion disturbances. Cutaneous microvascular blood flow was estimated by Laser Doppler and Optical Tissue Oximetry techniques. Whole blood and plasma viscosity were measured by capillary viscometer, red blood cell aggregation was evaluated by direct microscopic method, erythrocyte deformability was assessed as elongation index in flow microchamber. Hematocrit-to-viscosity ratio was used as index of oxygen transport efficacy. Depression of the regulatory mechanisms of microvascular blood flow as well as decreased tissue perfusion indicated the restricted blood flow in microcirculatory network in CHF. Increased blood and plasma viscosity, enhanced red blood cell aggregation and decreased erythrocyte deformability were registered in CHF. Complex impairment of peripheral blood flow in CHF including restricted microcirculation, attenuated regulatory mechanisms and impaired hemorheological properties caused the reduced oxygen utilization contributing to symptoms and advance of heart failure.

Cancer progression is associated with activation of blood coagulation. Blood coagulation process, platelet hemostasis and hemorheological properties were evaluated in patients with solid tumors (n = 27) before and after surgery and in healthy contro

Exposure of red blood cells (RBCs) to catecholamines (epinephrine, phenylephrine, an agonist of α1 -adrenergic receptors, clonidine, an agonist of α2 -adrenergic receptors and isoproterenol, an agonist of β-adrenergic receptors) led to change in the