Biomedical subjects
Publications and source records attributed to O A Kovalev.
Regional changes of circulation after injection of pirroxan, obsidan and ornid depended on functional state of rats. The differences were significant in systemic hemodynamic and regional changes of resistive, transcapillary exchange and the blood volume function of the circulation.
The muscle and adrenal fractions of cardiac output increased after injection of isoproterenol. The relative blood flow increase in skeletal muscles was accompanied with the increase in regional by-pass blood flow. The latter or reduction in the vessel permeability were found in the lungs. The cardiac output fractions decreased in extensive areas of skin, brain, myocardium, internal organs of hepatic portal vein, kidneys, testicles. The signs of the blood flow increase were found in the brain, myocardium, liver. The relative blood volume decreased in the majority of internal organs and tissues while increasing in the liver.
Emotional stress was stimulated by placing rats in a tight cage (moderate stress) or fixing them rigidly on a bench (marked stress) for 1 hour. In moderate emotional stress, the coronary fraction of cardiac output and effective myocardial blood supply declined considerably. Marked emotional stress caused a similar reduction in the cardiac output coronary fraction, whereas effective myocardial blood supply was not reduced, but, on the contrary, tended to increase. The decrease in coronary fraction was not related to adrenergic effects. Marked emotional stress provoked regional changes in the resistance, microcirculatory and capacity components of the vascular bed, an adaptation to enable effective myocardial blood supply and enhance cardiac activity. It was accompanied with kallikrein-kinin activation.
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The methods of radioactive detection and external radiometry were used to study the distribution of blood in cats and rats during 24 hours after heart arrest. Labeled albumins (131I) and erythrocytes (51Cr) were used as blood indicators. The animals after death were stored in a horizontal or, in some tests, in vertical position at room temperature. The activity was measured in the horizontal and sagittal planes in strictly defined sites (30 altogether) or by scanning of the entire body within 3-5 min after circulation arrest as well as at 5 and 24 hours. No significant changes in distribution of plasma and erythrocytes during 24 hours postmortem in the horizontal position were shown to occur, while in the vertical position there was an insignificant increase of the blood content in the lower part of the body.
A preliminary pharmacological desympathization (pirroxan, obzidan, ornid) decreased blood pressure, heart rate, cardiac output, and increased total vascular resistance in immobilized rats. The fraction of cardiac output decreased in lung (bronchial blood flow), liver and myocardium and increased in other organs and tissues. Relative blood supply increased in expansive regions of the skin, muscles and splanchnic organs but decreased in the liver. Opposite changes of transcapillary permeability were found in vascular regions of the skin and skeletal muscles as well as in splanchnic organs.
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The main characteristics of systemic hemodynamics and relative changes in the blood content, blood flow and uptake of intravenous 86Rb in several tens of organs, tissues and parts of the body were examined in rat experiments 6 days after ligation of the common bile duct. This made it possible to appraise the resistive, capacitance and capillary constituents of the general peripheral vascular resistance. In this case the fractions of cardiac discharge diminished in a number of the internal organs of the abdomen and increased in muscle and bone tissues of the chest. The signs of extensive venodilation were defined, with these signs being the least remarkable in the liver and lungs. Transcapillary permeability for 86Rb substantially increased in the organs of the splanchic area and in the lungs.
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The results of an experimental study of fluctuations in the relative content of blood in 15 internal organs on exposure of the intact organism to the effect of various factors are discussed. A total of 25 experimental series was conducted, with 14 animals used in each series. Four types of regional blood redistribution reactions were distinguished according to the changes in blood filling (in the brain, heart, liver, and other organs of the abdomen and true pelvis). In most cases these reactions are accepted as a sign of mobilization of the dynamic intravascular blood reserve from the large-capacity vessels, mainly of the abdominal organs and organs of the true pelvis, with or without the participation of the liver, and also as a sign of utilization of the "reserve" blood in organs and tissues experiencing functional stress. The results of correlative analysis bear evidence of the reciprocal character of fluctuations in the amount of blood during stress, in the brain, lungs, and heart on the one hand and in the organs of the abdomen and true pelvis on the other, and also testify to the autonomous character of changes in the amount of blood in the liver. The internal organs of the abdomen and true pelvis are not a functionally single vascular region.
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The authors studied regional redistribution of the blood in the experiments on 12 white male rats adapted to the experimental conditions. There were no postoperative complications in the laparotomy model. The main direction of the postoperative regional blood redistributions has been considered as one of the typical redistribution reactions associated with the mobilization of the intravascular blood reserve and its use in the organs with an intense function.
Regional redistributions of blood under height and drop of fever-heat were studied in rat experiments. Fever was induced by intravenous administration of leukocytic rabbit pyrogen as well as by intravenous injection of pyrogenal. The former factor produces more rapid and more significant temperature rise than the latter one. In all series of experiments multidimensional statistical analysis allowed one to reveal the effect conducive to a relative decrease in the blood content in the brain, myocardium, lungs, liver and to its increase in some abdominal organs, skin, muscle and bone tissues of the extremities, abdomen and pelvis. At the same time there emerged effects directed to blood redistribution mainly from organs and tissuesof the head, neck and chest to the liver.
Changes are described in relative contents of blood in tissues and organs, usable for evaluation of regional redistribution of blood caused by various factors influencing the organism. Despite specific characters of such changes, several basic types were identified which may represent several phases of a general nonspecfic reation, whose character varies in dependence on the actual degree of stimulation or lesion. In the first phase the relative contents of blood increase in the brain, heart, lungs, and in the muscle and bone tissues of the head, neck , and thorax. The second phase is characterized by increased blood content in the liver. In the third phase blood is mobilized from the liver and redistributed into tissues exposed to functional loads, with marked anaemization of the liver. In the fourth phase the regional redistribution becomes pathological. Experiments were made in male albino rats exposed to various stresses [blood loss, confinement in a tight box, treadmill running, various types of general anaesthesia, and others].
Unanesthetized rats put in the hermetic chamber breathed with a gas mixture containing 10.5% of oxygen in nitrogen during 30 and 60 min (moderate hypoxia), and 3.5% of oxygen in nitrogen for 30 min (severe hypoxia). The circulating blood volume increased in moderate hypoxia but was rather reduced in severe hypoxia. Mobilization of blood from the liver occurred in moderate hypoxia after 30 min, becoming less obvious after 60 min or in severe hypoxia. Redistribution of blood in the myocardium, skeletal muscles of the head and neck occurred in moderate hypoxia. Severe hypoxia led to depression of the regional circulating blod redistribution and the signs of pathological accumulation of the blood in the liver, small intestine, colon and testicles.