Reactivity of the microcirculation bed of the small intestine mesentery in experimental dehydration in rats

The state of mesenteric microcirculatory bed has been studied in male rats 3, 6 and 12 days after the beginning of alimentary dehydration. It has been revealed that vascular, intravascular and extravascular changes were of particular importance. Spastic reactions of arterioles and precapillary arterioles, the activation of arteriolo-venular shunting and the reduction in capillary circulation accompanied by diminution of all microvascular diameters were among the most marked vascular phenomena. The intravascular changes were represented by decreased blood flow rate, erythrocyte aggregation and leucocyte adhesion. The extravascular phenomena were characterized by the appearance of local hemorrhages.     

Microcirculatory bed of the heart during peripheral arteriovenous shunting

In the experiment performed on 108 test and 28 control dogs, by means of injection and histological methods, the effect of arteriovenous fistula on the cardiac microcirculatory bed has been studied. The arteriovenous blood shunting results in plethora and stasis in the cardiac microcirculatory bed, in dilatation of all its links, in aggregation and adhesion of the blood formed elements, in increased permeability of microvessels, in diapedesis of erythrocytes and in myocardial edema, in winding microvessels, in development of the venoarterial reaction, in hypertrophy of myocytes, recalibration and sclerosis of the microvascular walls.     

Hemodynamic effects of red blood cell aggregation

The influence of red blood cell (RBC) aggregation on blood flow in vivo has been under debate since early 1900's, yet a full understanding has still has not been reached. Enhanced RBC aggregation is well known to increase blood viscosity measured in rotational viscometers. However, it has been demonstrated that RBC aggregation may decrease flow resistance in cylindrical tubes, due to the formation of a cell-poor zone near the tube wall which results from the enhanced central accumulation of RBC. There is also extensive discussion regarding the effects of RBC aggregation on in vivo blood flow resistance. Several groups have reported increased microcirculatory flow resistance with enhanced RBC aggregation in experiments that utilized intravital microscopy. Alternatively, whole organ studies revealed that flow resistance may be significantly decreased if RBC aggregation is enhanced. Recently, new techniques have been developed to achieve well-controlled, graded alterations in RBC aggregation without influencing suspending phase properties. Studies using this technique revealed that the effects of RBC aggregation are determined by the degree of aggregation changes, and that this relationship can be explained by different hemodynamic mechanisms.     

MIcrocirculatory bed of various internal organs in modeling of the inter-atrial shunt

At modelling a congenital heart failure--defect of the interatrial septum during late stages of the experiment, dilatation of the pulmonary artery and certain changes in the microcirculatory bed of the lungs, oesophagus, stomach and colon are observed. It has been demonstrated histologically and morphometrically that in adaptive reactions of the blood bed an important role belongs to the arteriolar part and metabolic link of the microcirculatory bed of the organs investigated. The changes in the pulmonary vessels are insufficiently expressed and possibility of hypertension in the lesser circulation is not great.     

Microarchitectonics and microtopography of blood vessels of the human rectum

By means of injecting the vessels with 0.2% solution of silver nitrate after Ranvier, solutions of Indian ink and gas soot, impregnation after V.V. Kuprianov, the blood vessels of the rectal wall have been studied. The material has been obtained from 50 corpses of persons of various age, not suffering from any diseases of the gastrointestinal tract. The structural organization of the microcirculatory tract has been studied layer-by-layer, at all levels by means of atraumatic lamination of the tunics. Terminal links of the microcirculatory bed form zonal functional complexes of microvessels specific for each part of the rectum. They regularly repeat in a certain tunic and owing to this the whole organization of the microcirculatory bed acquires features of a definite polymeric structure which consists of homonomic complexes of microvessels. Their regularity, as regards their topography and quantity, definitely differs in each tunic and layer of the rectal wall. Precapillary sphincters and arteriolovenular anastomoses are revealed; they perform an active regulation of blood circulation in the organ. Diameters of the microvessels and density of the microcirculatory network have some slight fluctuations (differences) in functionally poorly active tunics of the rectal wall--the serous and submucous, especially in its rectosigmoid part. Differences of these parameters are especially expressed within the limits of the rectal ampule and its mucous and muscular tunics.     

The dose-dependent action of naloxone on systemic and portal circulation in acute blood loss in rats

Using the method of contact luminescent biomicroscopy of the liver and the intestine coupled with the ultrasonic measurement of systemic blood pressure, blood flow velocity in the portal vein and hepatic artery it has been established that in rats with acute decompensatory hemorrhage naloxone increases blood pressure and improves the state of protal macro and microcirculation only after i. v. injection of large dose (5 mg/kg). Naloxone does not influence the dynamics of acute compensatory hemorrhage and the development of the posthemorrhagic microcirculatory disturbances (local microstases, microthromboses, erythrocyte aggregation).     

ACTH inhibits the development of primary decompensation of the systemic and portal circulation in acute blood loss in rats]

Using the method of contact luminescent biomicroscopy of the liver and intestine coupled with the measurement of systemic blood pressure by micromanometer and ultrasonic registration of blood flow velocity in portal vein and hepatic artery it has been established that in rats with acute decompensatory hemorrhage fragments of ACTH (1-24) and (4-10) improve the state of portal macro- and microcirculation and increase the life span 2-3-fold. ACTH does not influence the dynamics of acute compensatory hemorrhage and the development of the posthemorrhagic microcirculatory disturbances (local microstases, microthromboses, erythrocyte aggregation).     

The interdependent contributions of gravitational and structural features to perfusion distribution in a multiscale model of the pulmonary circulation

Recent experimental and imaging studies suggest that the influence of gravity on the measured distribution of blood flow in the lung is largely through deformation of the parenchymal tissue. To study the contribution of hydrostatic effects to regional perfusion in the presence of tissue deformation, we have developed an anatomically structured computational model of the pulmonary circulation (arteries, capillaries, veins), coupled to a continuum model of tissue deformation, and including scale-appropriate fluid dynamics for blood flow in each vessel type. The model demonstrates that both structural and the multiple effects of gravity on the pulmonary circulation make a distinct contribution to the distribution of blood. It shows that postural differences in perfusion gradients can be explained by the combined effect of tissue deformation and extra-acinar blood vessel resistance to flow in the dependent tissue. However, gravitational perfusion gradients persist when the effect of tissue deformation is eliminated, highlighting the importance of the hydrostatic effects of gravity on blood distribution in the pulmonary circulation. Coupling of large- and small-scale models reveals variation in microcirculatory driving pressures within isogravitational planes due to extra-acinar vessel resistance. Variation in driving pressures is due to heterogeneous large-vessel resistance as a consequence of geometric asymmetry in the vascular trees and is amplified by the complex balance of pressures, distension, and flow at the microcirculatory level.     

Pathomorphism of experimental pancreatic necrosis after endolymphatic administration of contrical

Histological and electron microscopic studies of canine pancrease were conducted with biochemical control of pancreatic enzyme activity before and after treatment of experimental hemorrhagic pancreatonecrosis. 30-60 minutes after the disease induction microfocal pancreatonecrosis was revealed, while 6-8 hours later subtotal hemorrhagic pancreatonecrosis with changes in microcirculatory vessels of the pancreas manifested in erythrostasis, thrombosis and fibrinoid wall necrosis accompanied by the increase of pancreatic enzyme activity and decrease in blood, lymph and serum antienzyme activity developed. The treatment of experimental pancreatonecrosis with endolymphatic injection of contrical resulted in the morphologically confirmed attenuation of the necrosis intensity, limitation of necrotic zone size, blood circulation recovery in microcirculatory system, marked decrease of proteolytic enzyme activity and increase of blood serum and central lymph antienzyme activity.     

Regulatory characteristics of the different components of the mesenteric microcirculatory bed in rats

Heterogeneous tonic reactions of the different parts of the mesentery microcirculatory bed to intravenous infusions of noradrenaline and their cessation were revealed. It is assumed that venules play a more important role in the organization of blood circulation in the capillaries and arteriolo-venular anastomoses than arterioles.     

Hemo- and lymphomicrocirculatory bed of the broad ligament of the uterus in the presence of collateral circulation

Structural adaptation of the vascular bed in the broad ligament of the dog uterus has been studied at various time of the experimental phlebohypertension. Restitution of the circulation after the posterior vena cava occulsion occurs phasically. The venous collateralies are not formed at one time and it is connected with the venous pressure level in the inferiocaval system and with some changes in the construction of the microcirculatory bed. Basing on the morphometry data, a general equation has been derived which reflects dynamics of the microangiological parameters and demonstrates unidirectionness of the adaptive reactions in the vascular bed at the disturbed venous circulation. Using principles of the system-structural analysis and the mathematical graph theory, we consider the microcirculatory system of the broad ligament of the uterus as a graph-system and study the reorganization of the microcirculatory network at a venous congestion. Realization of the compensatory possibilities is reached in the microcirculatory bed by a changed relationships in the number of the intervascular connections. The latter are estimated according to the graph-schemes of the microvascular bed. Morphokinetics of the connections between the vessels is characterized by widening or narrowing the borders of the "adaptive norm" and by changing the microangioarchitectonics. At the same time, there is noted formation of specialized microhemoangioconstructions. Morphofunctional state of the lymphatic system is connected with reorganization of the angioarchitectonics. This is certain manifestation of the law of the lymphatic and blood beds "synergism". Thus, the structural changes of the vascular bed are aimed to support a certain hemodynamic level.     

Pulsatile flow during cardiopulmonary bypass preserves postoperative microcirculatory perfusion irrespective of systemic hemodynamics

The onset of nonpulsatile cardiopulmonary bypass is known to deteriorate microcirculatory perfusion, but it has never been investigated whether this may be prevented by restoration of pulsatility during extracorporeal circulation. We therefore investigated the distinct effects of nonpulsatile and pulsatile flow on microcirculatory perfusion during on-pump cardiac surgery. Patients undergoing coronary artery bypass graft surgery were randomized into a nonpulsatile (n = 17) or pulsatile (n = 16) cardiopulmonary bypass group. Sublingual mucosal microvascular perfusion was measured at distinct perioperative time intervals using sidestream dark field imaging, and quantified as the level of perfused small vessel density and microvascular flow index (vessel diameter < 20 μm). Microcirculation measurements were paralleled by hemodynamic and free hemoglobin analyses. The pulse wave during pulsatile bypass estimated 58 ± 17% of the baseline blood pressure waveform. The observed reduction in perfused vessel density during aorta cross-clamping was only restored in the pulsatile flow group and increased from 15.5 ± 2.4 to 20.3 ± 3.7 mm/mm(2) upon intensive care admission (P < 0.01). The median postoperative microvascular flow index was higher in the pulsatile group [2.6 (2.5-2.9)] than in the nonpulsatile group [2.1 (1.7-2.5); P = 0.001]. Pulsatile flow was not associated with augmentation of free hemoglobin production and was paralleled by improved oxygen consumption from 70 ± 14 to 82 ± 16 ml·min(-1)·m(-2) (P = 0.01) at the end of aortic cross-clamping. In conclusion, pulsatile cardiopulmonary bypass preserves microcirculatory perfusion throughout the early postoperative period, irrespective of systemic hemodynamics. This observation is paralleled by an increase in oxygen consumption during pulsatile flow, which may hint toward decreased microcirculatory heterogeneity during extracorporeal circulation and preservation of microcirculatory perfusion throughout the perioperative period.     

Hemorheological implications of perfluorocarbon based oxygen carrier interaction with colloid plasma expanders and blood

Perfluorocarbon (PFC) emulsions used as artificial oxygen carriers lack colloid osmotic pressure (COP) and must be administered with colloid‐based plasma expanders (PEs). Although PFC emulsions have been widely studied, there is limited information about PFC emulsion interaction with PEs and blood. Their interaction forms aggregates due to electrostatic and rheological phenomena, and change blood rheology and blood flow. This study analyzes the effects of the interaction between PFC emulsions with blood in the presence of clinically‐used PEs. The rheological behavior of the mixtures was analyzed in vitro in parallel with in vivo analysis of blood flow in the microcirculation using intravital microscopy, when PEs were administered in a clinically relevant scenario. The interaction between the PFC emulsion and PE with blood produced PFC droplets and red blood cell (RBCs) aggregation and increased blood viscosity in a shear dependent fashion. The PFC droplets formed aggregates when mixed with PEs containing electrolytes, and the aggregation increased with the electrolyte concentration. Mixtures of PFC with PEs that produced PFC aggregates also induced RCBs aggregation when mixed with blood, increasing blood viscosity at low shear rates. The more viscous suspension at low shear rates produced a blunted blood flow velocity profile in vivo compared to nonaggregating mixtures of PFC and PEs. For the PEs evaluated, human serum albumin produced minimal to undetectable aggregation. PFC and PEs interaction with blood can affect sections of the microcirculation with low shear rates (e.g., arterioles, venules, and pulmonary circulation) when used in a clinical setting, because persistent aggregates could cause capillary occlusion, decreased perfusion, pulmonary emboli or focal ischemia. © 2013 American Institute of Chemical Engineers Biotechnol. Prog., 29:796–807, 2013     

Applications of artificial ionization

Summary The effects of positive and negative ions on man and on animals have been widely studied by numerous teams of researchers. It is well-known that negative ions have beeeficial effects on chronic and allergy-related bronchopathies in man; they stimulate the activity of the endocrine glands and psychomotor, muscular and cerebral functions. They have a beneficial effect on general circulation, and in particular on the microcirculatory system, such that they are suggested for use in prophylaxis and prevention of senescence, in acute, chronic and allergy-related pneumopathies, and in neuro-vegetative dystonia. The use of artificial negative ion producers may be a useful tool for both preventive and therapeutic purposes, as well as hygienic/domestic applications. Systematic measurements ere taken of negative ions artificially produced in a confined space. The spatial distribution of artificially-produced negative ions in a confined space is presented. Applications relative to artificial generators are also suggested in order to obtain repeatable experimental conditions.     

Determination of circulation disturbance in the rat lungs in modelling of chronic obstructive disease

Development of chronic obstructive pulmonary disease (COPD) involves not only the bronchial and respiratory areas of the lungs, but also the system of pulmonary circulation, which begins with the defeat of capillary blood flow. One of radiological methods of studying lung microcirculatory functions is perfusion scintigraphy. We designed the technique of radiological examination and identified its abilities in determination of the role of vascular dysfunctions in experimental model of development of COPD. We assessed the results of pharmacological agents that affect the microcirculatory bed of the lungs and smooth muscles of pulmonary arteries in rats. Studies have shown the promise of the possibility of using the drug sulodexide for studying impaired endothelial function in clinical practice.     

Development of the microcirculatory bed of the human tongue in the prenatal period

Morphofunctional regularities of formation and development of the blood microcirculatory bed in the human tongue have been studied in the prenatal period of morphogenesis. 119 human embryos and fetuses at the age of 5 weeks--9 months have been investigated. A complex of methods have been used: common histological (hematoxylin--eosin, after van Gieson and Mallory), injection of the lingual vessels with 20% suspension of Indian ink--gelatin, transmissive electron microscopy. General regularities of organogenesis, stages of the blood microcirculatory bed development and peculiarities of the process on formation of the primary protocapillary lingual blood bed are revealed. Regularities in structure of the terminal vascular constructions are studied for each structural element of the organ--mucosal membrane, muscles, glands, lingual tonsil. For these elements at the ultrastructural level certain features of the organic specificity in the structure of the blood microcirculatory bed links are determined.     

Patterns in the development of the ultrastructure of elements of the microcirculatory system in the early stages of human embryogenesis

By means of transmissive electron microscopy methods, general regularities in development of the microcirculatory system have been studied at early stages of the human prenatal ontogenesis in functionally different organs. Ultrastructure of two cell types has been described in the mesenchyme of human embryos. Formation mechanisms of the primary blood vessels belonging to the protocapillary type are revealed. Structural peculiarities of the primary protocapillary network differentiating into various links of the secondary organospecific hemomicrocirculatory bed are distinguished. Certain stageness in development of the microcirculatory system is stated, its blood circulatory compartment including. Two stages are determined in development of the microcirculatory system: prevascular and vascular microcirculation. The latter includes the precirculatory and circulatory phases.     

Microcirculation, hemodynamics and blood rheology in peritonitis during plasmapheresis

By means of biomicroscopy, electrophysiological and hemorheological techniques effect of plasmapheresis with use of various plasma -substituting solutions and their combination on microcirculation, hemodynamics and rheology of blood at peritonitis has been studied in the experiment on 329 white non-inbred rats and on 50 mature dogs. Three periods of disturbances in hemomicrocirculation of the small intestine mesentery at peritonitis have been revealed: I (3-6h)--a relative well-being and compensatory reactions in the system of hemomicrocirculation; II (9-15h)--development of disturbances in the aggregate state of blood; III (18-24h)--pronounced disturbances in hemomicrocirculation. Plasmapheresis at peritonitis facilitates: to better functioning of the microcirculatory system, namely, a sharp increasing of the blood flow rate, joining into the blood flow of capillaries that did not function previously and increasing functional capacity of the capillary bed; decreasing blood viscosity and aggregation of erythrocytes. Plasmapheresis applied at peritonitis produces a favourable effect to hemodynamics, evident as an increasing minute and stroke volume of the blood flow, cardiac index, the left ventricle activity and decrease in peripheral vascular resistance.     

The circulatory influence on development of age-related macular degeneration and hearing and equilibrium impairments

This study attempts to answer the question if any level of head and neck circulation takes a part in development of Age-Related Macular Degeneration (ARMD) and hearing and equilibrium impairments. Condition of large blood vessels was examined by Color-Doppler ultrasound, and carotid and ophthalmic arteries were included. The microcirculatory changes were examined directly by fundus photography and fluorescein angiography and indirectly testing hearing and equilibrium. The study group included 40 patients (21 females, 19 males) aging from 53 to 84 years with different stages of ARMD. The control group included 40 patients (18 females, 22 males) aging from 51 to 82 years without ARMD. Patients were inhabitants of Primorsko-Goranska County. There was no relationship between ARMD and condition of large blood vessels because significant stenosis of carotid arteries was found in 2 patients (5%) in study group and 3 patients (7.5%) in the control group (p > 0.05). On the contrary, we found correlation between ARMD and hearing (p = 0.0127) and equilibrium impairments (p = 0.0242). Fluorescein angiograms shows raised number of ischemic retinal capillaries in patients with ARMD (p = 0.0053). Results lead to conclusion that circulatory disorders on microcirculatory level take a great part in development of ARMD and hearing and equilibrium impairments in the elderly. The key is damage of sensory cells of the retina and inner ear caused by microcirculatory disorders. Interesting data was noticed that 9 patients with more serious ARMD on one side of head had greater hearing loss on the same side. If we find a new treatment for microcirculatory disorders, maybe we can treat both sensory impairments in earlier stage.     

Blood aggregation and the system of microcirculation in experimental atherosclerosis, its spontaneous regression and hemosorption

Blood aggregate state and microcirculation were studied during development and spontaneous regression of experimental atherosclerosis and following hemosorption. It has been shown that experimental atherosclerosis is not only accompanied by changes in blood lipid composition, but also by disturbances in the structure and function of microcirculatory bed. Normalization of blood lipid composition and recovery of blood aggregate state and microcirculatory bed structure and function were not observed during spontaneous regression. Repeated hemosorption enhances atherosclerosis regression, normalizes lipid composition of blood and biological membranes and promotes the recovery of microcirculation.