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Biomedical subjects

A Iu Iurov

Publications and source records attributed to A Iu Iurov.

At least 19 recordsLinked to original sources
PubMed2005

[Changes in the major circulation vessel capacity and their role in forming the venous return shifts under the effect of catecholamines].

The study relates to characteristics of the major circulation vessel capacity and their part in forming the venous return shifts under the effect of catecholamines. In anesthetized cats, using the developed technique of controlled experiment enabling to stabilize the blood flow in the circulation arterial segment, fulfilling of pressor responses to i. v. administration of noradrenaline, adrenaline was found to increase the venous return, on the average, by 40% by means of changes in the major circulation vessel capacity (its venous segment, mainly). About 5% of the blood volume seems to become mobilized in the animal organism.

Animals↗
PubMed2004

[Participation of the cava vein blood flow in forming the total venous return under influence of different modality stimuli on the circulation system].

Participation of the anterior and posterior veins cava in forming the total venous return under pressor and depressor effects, stimulation of depressing foci of the medulla's ventral part, enhancement of pulmonary ventilation, hypoxia, hypothermia, administration of acetylcholine, histamine, corinfar, was shown to depend on the blood flow shift direction in each of the veins cava, dynamics of shifts' development in time, and intensity of the stimulus. In systemic responses, the blood flow shifts in the vena cava anterior much contribute to the total venous return at the maximum of the systemic arterial pressure rise (r = 0.87) whereas contribution of the vena cava posterior is the greatest during a later occurring increase in the venous return (r = 0.84). Along with increase in the stimulus intensity the vena cava anterior's part in forming the venous return becomes more limited whereas that of the vena cava posterior is enhanced.

Animals↗
PubMed2002

[Comparative characteristics of systemic and pulmonary hemodynamics during changes in the heart preloading].

A greater degree of relative shifts in the systemic arterial pressure in enhancing the right heart pre-load as compared with its diminishing. A primary role of the compensation mechanisms of the enhanced systemic arterial pressure level. The main role in the compensation of integral shifts of the arterial pressure induced by changes in the heart pre-load was shown to belong to the vascular resistance both in the major and the minor circulation circles. An idea of a greater involvement of the capacity function of the vascular bed in the minor circulation circle as compared with that in the major circulation circle in systemic haemodynamic shifts in changes of the heart pre-load, has been advanced.

Animals↗
PubMed1998

[Correlation analysis of the venous return effect on the central venous pressure during transitional circulation processes].

A fully computerized control of systemic circulation based on negative bio-technical feedback between cardiovascular system and automated external control enabled one to allocate contribution of venous return in the shifts of the total central venous pressure in cats. Using adrenaline and noradrenaline administration, shifts in the venous return were shown to induce the main portion (over 50%) of the total central venous pressure changes. Correlation analysis revealed a highly significant (p < 0.01) linear correlation between the maximal shifts of these two parameters of the systemic circulation. The findings suggest a close connection between the venous return changes and central venous pressure during pressure responses in the systemic circulation.

Animals↗
PubMed1990

[The organic macro- and microhemodynamics and the systemic circulation under the combined action of hypoxia and hypothermia].

In regimen of the constant blood flow perfusion of shank and small intestine of cat combined effect of hypoxia (10% O2 in N2) and hypothermia (about 30 degrees C) involved a decrease in precapillary resistance, an increase in capillary filtration coefficient in both vascular regions, an increase in postcapillary resistance and in mean capillary pressure in the intestine, and their decrease in the shank. In hypothermia, the hypoxic stimulus induced insignificant shifts in all the parameters under study in both organs. Dependence of hypoxic changes of macro- and microhemodynamics on the activity of adrenergic receptors in the cooled organism was studied on decentralized shank of cat. After cooling of cat and blockade of alpha-adrenoreceptors hypoxic hypoxia caused much greater reduction of precapillary resistance of shank, more striking (by 3 times) increase of capillary filtration coefficient and the increase of capillary pressure and postcapillary resistance in contrast with their decrease to hypoxia under hypothermia before alpha-blockade. Beta-adrenoreceptor blockade had no influence on the changes of the resistance and exchange function of skeletal muscle (shank) blood vessels evoked by hypoxia under cooling. Systemic arterial pressure are diminished during hypoxia under the normothermic conditions of animals. Such kind shifts caused especially by the decreasing of the total peripheral resistance; cardiac output are small raised in this situation. But combined influence of hypoxia and hypothermia evoked the pressor shifts of the systemic arterial pressure because of less decrease of total peripheral resistance and more remarkable rise of cardiac output. Hypoxic stimulus caused both in normothermia and hypothermia conditions caused the rising of venous return.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1990

[The dependence of the hemodynamic shifts in the systemic arterial and venous vascular beds on the degree of change in the arterial pressure under the action of vasoactive substances].

The participation of hemodynamic parameters in formation of systemic pressor displacement due to action of norepinephrine and angiotensin was shown in acute experiments in cats. An arterial pressure rise by 15 +/- 2% and 25 +/- 3% depended on total peripheral resistance and cardiac output enhancement. The maximal arterial pressure rise only depended on total peripheral resistance increase. The reduction of venous return resulted from a decrease of the blood flow in v. cava posterior whereas the blood stream in v. cava anterior increased. Depressor actions of acetylcholine and histamine were enhanced owing to a fall in the vessels resistance.

Acetylcholine↗
PubMed1988

[Dynamic characteristics of the dependence of the venous return on changes in the volume of the circulating blood].

Changes of the venous return of blood to the right heart were studied in respect to changes in the total blood volume. The latters were coarsed by the automatical transfusions of blood, controlled by the feed-back loop. Dynamic components of the dependence under study were treated by the spectral analysis technique. The contribution of them to the mechanism of the shift in systemic circulation can prevail over known static approximations of this dependence.

Animals↗
PubMed1987

[Changes in systemic hemodynamics during exposure of the cooled body to hypoxia].

In cats with normal body temperature, hypoxia (10% O2 in nitrogen) induced depressor shifts of the arterial pressure due to a drop of the general peripheral resistance, whereas in cooling of the organism to +30 degrees C a slight increase of the arterial pressure occurred. Hypothermia was found to reduce the degree of increase in the venous return in response to a hypoxic stimulus.

Animals↗
PubMed1983

[Study of the role of the venous return in pressor changes in the systemic hemodynamics by the means of the automatic regulation of its value].

Feed-back experiments with catecholamine-induced pressor changes of arterial pressure (AP) aided to study possible contribution of the venous return changes in cats. Preliminary recorded changes were reproduced with the aid of electronic control of perfusion pump connected with extracorporeal reservoir and venous portion of vascular bed. The reproduced changes of venous return corresponded to those occurring under action of catecholamines. The same maximal increase of AP (by 50%) could be obtained by means of increasing the venous return either by 1/6 with adrenaline (A) or by 1/10 with noradrenaline (NA). Maintaining of the increased AP involves to a greater extent participation of the above parameters in systemic shifts; in response to A 1/2 and in response to NA 1/3 of the pressor response can be maintained by an increase in the venous return. The quantitative contribution of the vascular component (total peripheral resistance) to pressor shifts of AP under the catecholamines action is greater than that of the cardiac component, particularly in response to NA.

Animals↗