Erythrocytes as regulators of blood vessel tone

A drop in oxygen partial pressure results in elevation of blood vessel diameter. It has been demonstrated that isolated vessels exhibit this unique feature only when they are perfused in the presence of erythrocytes. More recently, it was shown that haemoglobin plays a key role in oxygen sensing. Its deoxygenated form interacts with band 3 protein, triggering the cascade of non-identified intracellular signals involved in nitric oxide production and release of ATP interacting with P2Y purinergic receptors in endothelial cells. In this review, we summarize the data on mechanisms of ATP release from erythrocytes, as well as on its physiological and pathophysiological implications

Vasodilator effect of vascular endothelial growth factors (VEGF) in the conditions of bone tissue formation by the method of discrete traction in congenital segmental pathology

The development of the limbs in patients with congenital segmental defects is associated with defects in the vascular system of the same segment. In this case, vascular endothelial growth factors that participate in physiological angiogenesis may have effect on bone tissue formation in ontogenesis and participate in endochondral ossification. In this regard, the aim of the study was to compare the quantitative changes in growth factors (VEGF) and the contractile properties of arterioles under conditions of discrete distraction for congenital pathology of the lower leg bones. Materials and methods Subjects of the study were 12 patients with congenital pseudarthrosis of the lower leg (ICD-10 Q 74.0). Their serum was analyzed using an enzyme immunoassay. Microcirculation in the calf skin was examined by laser flowmetry (BLF21, Transonic Systems Inc., USA). We used the findings obtained from the study of blood serum in 103 somatically healthy people for control. Results Significant imbalance in serum concentrations of endothelial factors and their receptors was detected in the subjects with congenital pathology. As a result of surgical treatment, the imbalance of secretion of vascular growth factors and their receptors increased. Vasodilator effect in the precapillary vessels in the zone of the operated segment in patients with congenital pathology was not revealed by surgical intervention

Hemolysis and ATP release from human and rat erythrocytes under conditions of hypoxia: a comparative study

Red blood cells are involved not only in transportation of oxygen and carbon dioxide but also in autoregulation of vascular tone by ATP release in hypoxic conditions. Molecular mechanisms of the ATP release from red blood cells in response to a decrease in partial oxygen pressure still remain to be elucidated. In this work we have studied effects of hypoxia on red blood cell hemolysis in humans and rats and compared the effects of inhibitors of ecto-ATPase and pannexin on the release of ATP and hemoglobin from rat erythrocytes. The 20-min hypoxia at 37°C increased hemolysis of red blood cells in humans and rats 1.5- and 2.5-fold, respectively. In rat erythrocytes a significant increase in hypoxia-induced extracellular ATP level was found only in the presence of ecto-ATPase inhibitor ARL 67156. In these conditions we observed a positive correlation (R2 = 0.5003) between the increase in free hemoglobin concentration and the ATP release. Neither carbenoxolon nor probenecid, the inhibitors of low-selectivity pannexin channels, altered the hypoxia-induced ATP release from rat erythrocytes. The obtained results indicate a key role of hemolysis in the ATP release from red blood cells

Deoxygenation affects composition of membrane-bound proteins in human erythrocytes

Background/Aims: ATP release from erythrocyte plays a key role in hypoxia-induced elevation of blood flow in systematic circulation. We have previously shown that hemolysis contributes to erythrocyte ATP release triggered by several stimuli, including hypoxia, but the molecular mechanisms of hypoxia-increased membrane fragility remain unknown. Methods: In this study, we compared the action of hypoxia on hemolysis, ATP release and the composition of membrane-bound proteins in human erythrocytes. Results: Twenty minutes incubation of human erythrocytes in the oxygen-free environment increased the content of extracellular hemoglobin by ∼1.5 fold. Paired measurements of hemoglobin and ATP content in the same samples, showed a positive correlation between hemolysis and ATP release. Comparative analysis of SDS-PAGE electrophoresis of erythrocyte ghosts obtained under control and deoxygenated conditions revealed a ∼2-fold elevation of the content of membrane-bound protein with Mr of ∼60 kDa. Conclusion: Deoxygenation of human erythrocytes affects composition of membrane-bound proteins. Additional experiments should be performed to identify the molecular origin of 60 kDa protein and its role in the attenuation of erythrocyte integrity and ATP release in hypoxic conditions

Erythrocytes as regulators of blood vessel tone

A drop in oxygen partial pressure results in elevation of blood vessel diameter. It has been demonstrated that isolated vessels exhibit this unique feature only when they are perfused in the presence of erythrocytes. More recently, it was shown that haemoglobin plays a key role in oxygen sensing. Its deoxygenated form interacts with band 3 protein, triggering the cascade of non-identified intracellular signals involved in nitric oxide production and release of ATP interacting with P2Y purinergic receptors in endothelial cells. In this review, we summarize the data on mechanisms of ATP release from erythrocytes, as well as on its physiological and pathophysiological implications

Proteomics-based identification of hypoxia-sensitive membrane-bound proteins in rat erythrocytes

This study examines the action of hypoxia on integrity, fluidity and protein composition of red blood cell (RBC) membrane. Twenty-min exposure to oxygen-free environment decreases rat RBC integrity documented by 3-fold elevation of hemoglobin release without any action on the membrane fluidity estimated by electron magnetic resonance spectroscopy of spin-labeled stearic acid analogues. The proteomics technology in combination with relative label free quantification analysis revealed a dozen of membrane-bound proteins, including elevated content of hemoglobin, reproducibly affected by hypoxia. Mapping the identified proteins in the KEGG pathway database we found that the proteins of multi subunit Cullin-Rbx E3 ubiquitin ligase complex are presented in normoxic RBC ghosts but not in the hypoxic samples. Our results suggest that Cullin-Rbx E3 complex, associated with RBC membrane in normoxia, provides detection and deletion of membrane proteins damaged by reactive oxygen species. In hypoxic conditions, deoxy-Hb binds to band 3 protein, resulting in dissociation of Cullin-Rbx E3 complex from RBC membrane and impaired clearance of damaged cytoskeleton proteins. These rearrangements of membrane proteins might be involved in attenuated membrane integrity revealed in hypoxic RBC

The serum vascular endothelial growth factor levels in patients with high-energy trauma complicated with infection

Introduction There is a lack of studies analyzing the molecular aspects of body functioning in purulent complications of bone tissue. The purpose of the review was to explore the serum vascular endothelial growth factor (VEGF) levels in patients with high-energy trauma complicated with infection. Material and methods The study included 36 individuals who sustained a high-energy injury. The participants were identified as no-infection patients (Group I) and those who developed infection during treatment (Group II). Enzyme immunoassay was employed to quantify VEGF with Thermofisher immunoassay analyzer (USA). The study was performed according to the methodology from the R & D Systems kit manual (Angiopoietin-1 and -2 (Ang-1, Ang-2)), platelet-derived growth factors (PDGF-AB, PDGF-BB), Invitrogen (epidermal growth factor (EGF), vascular endothelial growth factor (VEGF), RayBiotech (macrophage stimulating protein (MSP), Biomerika Inc. (Calcitonin-calciotonin) USA) and Immunodiagnostic (bone sialoprotein (BSP) (Germany). HITACHI HI Vision Avius ultrasound scanner was used to explore vessels of the soft tissues and the periosteum at the site of regeneration (defect). Results There were no differences in the serum growth factor levels among the participants by gender. Patients of Group II showed 60% reduction in the Ang-2 and VEGF concentration as compared with that in the no-infection group. The serum EGF concentration was 1.6 times higher in individuals suffering from complications of high-energy trauma than in no-infection patients. There were no significant differences in platelet-derived growth factor PDGF-AB, PDGF-BB between the groups. Сhanges in the VEGF concentration were confirmed by the results of Doppler ultrasonography. Conclusion The findings suggest that the VEGFs examined can be additional diagnostic and prognostic markers for the cohort of patients

Proteomics-based identification of hypoxia-sensitive membrane-bound proteins in rat erythrocytes

This study examines the action of hypoxia on integrity, fluidity and protein composition of red blood cell (RBC) membrane. Twenty-min exposure to oxygen-free environment decreases rat RBC integrity documented by 3-fold elevation of hemoglobin release without any action on the membrane fluidity estimated by electron magnetic resonance spectroscopy of spin-labeled stearic acid analogues. The proteomics technology in combination with relative label free quantification analysis revealed a dozen of membrane-bound proteins, including elevated content of hemoglobin, reproducibly affected by hypoxia. Mapping the identified proteins in the KEGG pathway database we found that the proteins of multi subunit Cullin-Rbx E3 ubiquitin ligase complex are presented in normoxic RBC ghosts but not in the hypoxic samples. Our results suggest that Cullin-Rbx E3 complex, associated with RBC membrane in normoxia, provides detection and deletion of membrane proteins damaged by reactive oxygen species. In hypoxic conditions, deoxy-Hb binds to band 3 protein, resulting in dissociation of Cullin-Rbx E3 complex from RBC membrane and impaired clearance of damaged cytoskeleton proteins. These rearrangements of membrane proteins might be involved in attenuated membrane integrity revealed in hypoxic RBC

The serum vascular endothelial growth factor levels in patients with high-energy trauma complicated with infection

Introduction There is a lack of studies analyzing the molecular aspects of body functioning in purulent complications of bone tissue. The purpose of the review was to explore the serum vascular endothelial growth factor (VEGF) levels in patients with high-energy trauma complicated with infection. Material and methods The study included 36 individuals who sustained a high-energy injury. The participants were identified as no-infection patients (Group I) and those who developed infection during treatment (Group II). Enzyme immunoassay was employed to quantify VEGF with Thermofisher immunoassay analyzer (USA). The study was performed according to the methodology from the R & D Systems kit manual (Angiopoietin-1 and -2 (Ang-1, Ang-2)), platelet-derived growth factors (PDGF-AB, PDGF-BB), Invitrogen (epidermal growth factor (EGF), vascular endothelial growth factor (VEGF), RayBiotech (macrophage stimulating protein (MSP), Biomerika Inc. (Calcitonin-calciotonin) USA) and Immunodiagnostic (bone sialoprotein (BSP) (Germany). HITACHI HI Vision Avius ultrasound scanner was used to explore vessels of the soft tissues and the periosteum at the site of regeneration (defect). Results There were no differences in the serum growth factor levels among the participants by gender. Patients of Group II showed 60% reduction in the Ang-2 and VEGF concentration as compared with that in the no-infection group. The serum EGF concentration was 1.6 times higher in individuals suffering from complications of high-energy trauma than in no-infection patients. There were no significant differences in platelet-derived growth factor PDGF-AB, PDGF-BB between the groups. Сhanges in the VEGF concentration were confirmed by the results of Doppler ultrasonography. Conclusion The findings suggest that the VEGFs examined can be additional diagnostic and prognostic markers for the cohort of patients