Redistribution of erythrocytes in the rat mesenteric microcirculation during reperfusion following short-term ischemia

The erythrocyte redistribution in the rat mesentery microvessels and the development of postischemic microcirculatory disturbances were influenced by the thrombosis in narrow parts of arterioles and the increase in leukocyte adhesion to venule walls obstructing the blood outflow. The presence of branches and anastomoses in microvascular bed had a pronounced effect on reperfusion disturbances.     

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.     

Condition of the internal arterial and microcirculatory bed of the neck muscles of the dog after simultaneous ligation of the common carotid and vertebral arteries

In 21 mongrel dogs changes in the intraorganic arterial and microcirculatory bed of the cervical muscles have been studied after a simultaneous ligation of the common carotid and vertebral arteries. The most pronounced changes of rearrangement are observed during early periods after the operation (up to two months). The form, size of the arterial loops and direction of the blood stream change in them. On the base of the arterio-arterial anastomoses collateralies are formed, their degree of development is progressing with the increase of the postoperative time. The arteriolo-arteriolar anastomoses in small loops convert into microvascular collateralies that are of importance only during early postoperative stages. The new conditions of hemodynamics at the arteriolar level result in a dependent rearrangement in other links of the microcirculatory bed, where a number of compensatory-adaptive mechanisms are revealed. After the magistral by-pass ways are completely formed, the changes observed disappear and the microcirculatory network acquires the features specific for intact animals.     

Morphologic changes in the microcirculatory bed at stages of prolonged experimental fasting in animals

In 40 white male rats with body mass 180-200 g, by means of silver nitrate impregnation, morphological changes have been studied in the blood microcirculatory bed of the small intestine mesentery, spinal trapezoid muscle and eye ball conjunctiva at various stages of a prolonged fasting. With an increasing time of the experiment, a gradual undirected character of the changes in the microvessels is noted. After 3 days of fasting the changes in diameters of the microvessels, comparing to the control ones, have not any significant values in all the organs studied. After 6 days of fasting significant changes in diameters in all the links of the microcirculatory bed of the eye ball conjunctiva and in that of the spinal trapezoid muscle are observed. The microvascular changes are mostly pronounced on the 9th day of fasting. The maximal decrease of the microvessel diameters is noted in the eye ball conjunctiva, and the minimal--in the small intestine mesentery. The changes in the spinal trapezoid muscle are of intermediate character. The highest points of the structural lability gradient fall on the capillary and postcapillary-venular links of the blood microcirculatory bed.     

Structure and function of the microcirculatory bed in the preserved heart]

The morphological analysis of the state of the heart during hypertermal perfusion with different conservants reveals clear dependence of the microcirculation and the activity of the heart upon the type of the conservant. Perfusion with a salt solution and hemodilution is accompanied by pronounced disorders in microcirculation and unsatisfactory parameters of the cardiac activity. Conservation with cryoprecipitated plasma is characterized by comparatively less microcirculatory disorders, but fails to give a reliable safety of the heart. When using medium 199, changes in microcirculation were found to be minimal and parameters of cardiac activity were satisfactory. In the complex of non-specific changes in microcirculatory vessels the maximum structural lability was revealed in blood capillaries and vessels of the postcapillary-venular link.     

The effect of a 3-hydroxypyridine-class antioxidant on disorders of the microcirculatory system in experimental dyslipoproteinemia and its alimentary correction

The effect of antioxidant (AO) of the 3-hydroxypyridin class on microcirculatory system (MC) disorders of rabbits with dyslipoproteinemia (DLP) and its alimentary correction (the standard ration--9 months) was studied. Aorta, the intestinal mesentery microcirculatory bed, the microvessels adrenergic innervation, erythrocyte morphology were examined. The various lipoprotein fractions and lipid peroxidation (LP) products were studied in venous blood. After AO including into atherogenic diet (ATD) the lipid homeostasis disorders, the LP activation, MC disturbances, anomalous erythrocyte form appearance and atherosclerosis changes in aorta were less pronounced. Under the AO influence when DLP was corrected the initial level of lipid metabolism and LP restored, the MC disorders and the atherosclerosis changes in aorta regressed in a shorter period of time. The interrelation was observed between the DLP level, the structural and functional MC disorders and the extent of aorta atherosclerosis. Thus, DLP and LP correction at the early stages of pathological process can lead to the disappearance of MC disorders, what seems important for the prevention of atherosclerosis. The role of the LP activation in MC disorders in DLP and mexidol effect on them, especially in complex with DLP correction were evaluated.     

Disorders in blood rheological properties in the post-resuscitation period after the agonal state

It has been discovered in experiments on anesthetized dogs that the early postresuscitation period following agony after a two-hour hypovolemic hypotension was characterized by pronounced disturbances of blood rheological properties: blood viscosity was significantly increased as compared with initial values under the shift rate 1.34 s-1; the limit of blood fluidity was twice as increased. Insignificantly changed was the magnitude of hematocrit following the recovery of the blood volume. Infusion of polyglucin (20-25 ml/kg) promptly after the blood volume recovery and on the first day after it (10 ml/kg) decreased the hematocrit magnitude to 0.26 l/l (days 5-7) but did not make blood fluidity return to normal. A significant increase of blood viscosity and fluidity could be observed for 1-3 months after resuscitation, the hematocrit magnitude being equal to 0.55 l/l instead of 0.47 l/l in an initial state (P less than 0.005).     

Mechanism of circulatory disorders in animals irradiated at high doses

Some data are reported on pathoanatomical changes, a status of the microcirculatory channel and the coagulogram of animals affected by high doses of ionizing radiation. The signs of disseminated intravascular blood coagulation have been revealed. The authors discuss the relationship between clinical manifestations with coagulopathy development and circulatory disturbances during intestinal and cerebral forms of acute radiation sickness.     

Ultrastructural changes in the microcirculatory bed and filtration-reabsorption barrier of the kidney during temporary ischemia after unilateral nephrectomy

Ultrastructure of cellular elements of the microcirculatory bed and filtration-reabsorption barrier has been studied in 150 mature white rats, in which vascular fasciculus of the left kidney has been compressed for 30 min, 1-2 h with a subsequent restoration of the blood stream in the organ undergone ischemia on the 3rd, 7th, 14th, 30th, 60th, 180th, 360th days under conditions of the preliminarily right kidney nephrectomy. On the 3rd day after ischemia of the remained kidney for 30 min, structural components of the walls of the glomerular arterioles and those of the filtration-reabsorption barrier undergo certain ultrastructural changes, that with time elapsed (7, 14 days) gradually pass away, and amount of cells with hypertrophic processes increases. Ischemia for 1 h in the remained kidney with subsequent restoration of the blood stream on the 3rd, 7th days produces in the structures mentioned more pronounced destructive changes. During subsequent compensatory hypertrophy (the 30th, 60th days) of the remained kidney after its ischemia, in the microcirculatory bed elements and in the convoluted canal epitheliocytes intracellular regenerative and hyperplastic processes develop. However, ischemia for 2 h in the remained kidney produces severe destructive-necrotic phenomena in ultrastructure of the microcirculatory bed and of the filtration-reabsorption barrier.     

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.     

Effects of the calcium channel blocker flunarizine on the hemodynamics and oxygenation of tumor microvasculature.

Flunarizine is a diphenylpiperazine calcium entry blocker that has been shown previously to increase tumor blood flow and sensitivity to radiotherapy via reduction in the radiobiologically significant hypoxic fraction. Two mechanisms of action have been proposed previously (vasodilation, altered blood viscosity), but no studies have been performed to examine its mechanisms of action in vivo. Such information would be invaluable in determining the role of flunarizine in multimodality approaches to reduce tumor hypoxia. Fisher-344 rats bearing R3230Ac tumors transplanted into dorsal flap window chambers were used to examine microcirculatory changes after administration of flunarizine (1.0 mg/kg, iv). The drug increased the diameters of the microvasculature and red cell velocities specifically in central tumor regions (producing an average increase in vessel flow by a factor of 1.96), which was accompanied by an increase in perivascular pO2 of 12 mm Hg, on the average. The drug did not change the diameters of tumor "feeding" vessels, nor did it change vascular length densities. Thus the improvement in central tumor blood flow and oxygenation could not be attributed to dilation of feeding vessels. The oxygen-carrying capacity of the blood was not altered either since hemoglobin saturation (measured in vitro) and the hematocrits of the microvasculature were unchanged after drug administration. Therefore, by a process of elimination, the most likely explanation for the effect of the drug is modification of blood viscosity. Additional studies are under way in this laboratory to examine whether changes in viscosity occur after flunarizine administration.     

Interrelationship between the structure, microcirculation and tissue-vascular permeability of the liver after experimental toxic damage]

Biomicroscopic and morphological studies demonstrated that in experimental heliotrine affection of the liver there occurred very early and marked microcirculatory disturbances which preceded the parenchymal damage. With the further progress of the pathomorphological changes and chronization of the pathological process in the liver one of the leading roles was played by the advance of microcirculatory disturbances and of the tissue-vascular permeability leading to hypoxia of the hepatic tissue and derangement of the metabolic processes in the organ.     

Gastric microcirculatory change and development of acute gastric mucosal lesions (stress ulcer)

Concerning the pathogenesis of acute gastric mucosal lesions, gastric microcirculatory change has drawn attention as an important factor. In view of this fact, gastric mucosal blood flow and microvascular structure were investigated in normal and in burn stressed rats. Moreover, alterations in acid and pepsin activities in by morphological and biochemical procedures in order to evaluate the relationship between defensive and aggressive factors of the gastric mucosa. Gastric mucosal blood flow decreased significantly in early period after induction of stress (p less than 0.01). The incidence of ulceration showed a correlative relation with the decrease of mucosal blood flow. Reduction of blood flow in burn was due to opening of arteriovenular shunt and it appeared that this was responsible for mucosal ischemia and congestion. Following the decrease of blood flow, acid output was lower in stress than that in control. Finally, the results of these studies demonstrated the importance of defensive factors. The reduction of mucosal blood flow resulted in the sequence of events that led to formation of acute gastric mucosal lesion.     

Experimental study of the immunotherapy of burns

Experiments were conducted on rats. The influence of the serum of a burn convalescent on the toxic properties, the level of proteolytic enzymes activity, and morphological changes following burn were studied. After the burn the blood serum and the extracts of the organs acquired toxic properties; there was an increase in the activity of proteolytic enzymes, and marked morphological changes developed Administration of the serum of aburn convalescent promoted detoxication, diminished the activity of proteolytic enzymes distinctly, and decreased the morphological disturbances.     

The dynamics of morphofunctional changes in the microcirculation of the pelvic extremity after modeling the chief stages of its replantation]

Under study was the effect of autotransplantation in its "pure form" upon the morpho-functional reconstruction and structural mechanisms of adaptation of the blood and lymphatic links of the microcirculatory bed of extremities during early postoperation period up to 10 days. The pathophysiological state of the extremity sufficiently close to its autotransplantation was obtained by means of circular transection of soft tissues of the medial third of the femur together with the nerves and deep collecting lymphatic vessels. It was found that after modeling the main stages of replantation in the fascia and periosteum of the operated extremity there developed a spasm of the arteriolar link and dilatation of the venular and lymphatic links of the microcirculatory bed. The areas of leukocytic infiltration with the phenomena of diapedesis and microhemorrhages were revealed along the course of postcapillaries and venules in the paravasal connective tissue. The amount of functioning arteriole-venular anastomoses was increased. Against the background of pronounced oedema of soft tissues of the operated extremity the venous pressure increased and the rate of the capillary bloodflow in the skin and muscles decreased. The above changes tend to be reduced by the 10th day after modelling the main stages of replantation of the extremity.     

Effect of lead and tetraethyl lead poisoning on the microcirculatory bed of the conjunctiva of the eye

The ultrastructure of the bulbar conjunctiva bioptates have been studied in 12 persons suffering from lead intoxication (saturnism), 2-from tetraethyl-lead (TEL) intoxication and 3-are practically healthy persons; they make the control group. In all the patients manifested disturbances in the microcirculatory bed of the bulbar conjunctiva are revealed, the general character being identical at saturnism and TEL-intoxication. The main changes are observed in the wall of the blood microvessels: destruction of the endothelial lining up to revealing the basal membrane with adhesion of the blood formed elements and their diapedesis. This results in disorders of vascular permeability, in edema of the perivascular space and in appearance of cells and cellular detritus in it. An essential role in morphogenesis of the vascular disturbances produced by intoxication play certain rheological imparements: sludge-syndrome and microthrombosis. They produce certain distrophic changes.     

The blood microcirculatory bed of the small intestine, liver and pancreas after resection of the stomach and small intestine

As demonstrate the experiments performed on dogs and rats, after surgical intervention to the stomach and small intestine, other organs of the digestive system experience an increased functional loading, that results in noticeable changes in the intraorganic blood vessels and the blood microcirculatory bed organs. The course of the compensatory processes occurs with a definite regularity--as stages. The first stage is characterized with a predominance of the pathological reactions over the compensatory ones, in the second stage certain compensatory possibilities of the organism are noted. In the third stage the compensatory-adaptive reactions prevail over the pathological processes in the blood vessels and blood microcirculatory bed.     

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).     

Morphologic indices of the rat heart after colchicine application to the vagus nerve

By means of the light optic and electron microscopic methods atrial ganglia, myocytes, vessels of the right cardiac chambers have been studied in rats 2 days--3 weeks after application of 100 mcg of colchicine on the right nervus vagus. Certain changes of the neural fibers have been described at the area of the application. In the myocardium the microcirculatory bed, focal edema and hypoxic alterations of the myocyte ultrastructure have been revealed. In the ventrical ganglia destruction of some terminals of the preganglionar fibers, chromatolysis and vacuolization of single neurocytes, as well as intraganglionar granule-containing cells have been found. The changes described take place for 7 days and they nearly completely disappear in 10 days. A suggestion is made that some phenomena, in particular, destruction of the preganglionar fibers and changes of the cardiac microcirculatory bed are connected with certain disturbances of the quick transport of substances in the nervus vagus fibers.     

Dynamics of microcirculatory system recovery in the post-stress period

Twenty-four-hour immobilization or electric stimulation for 6 h were used in rats as stressors. The first stressor caused more profound and protracted disturbances in the microcirculatory system. The recovery of the microcirculation occurred in 50% of animals by day 6 and in 100% by day 14 after immobilization. The terminal blood flow recovery after 6-hour electric stimulation was seen in a day. Vascular permeability after 24-hour immobilization returned to normal in 24 h, and after 6 h of electric stimulation in 6 h. This process correlated with the morphofunctional status of mast cells and was probably phasic in nature.