Search PubMed⌕ Search

Biomedical subjects

B I Tkachenko

Publications and source records attributed to B I Tkachenko.

At least 19 recordsLinked to original sources
PubMed2001

Relationship between venous return and right-atrial pressure.

The dynamics and amplitude of changes in venous return and right atrial pressure (central venous pressure) in response to pressor stimuli were studied in acute experiments on cats. The increase in venous return was accompanied by either increase, or decrease in the central venous pressure. Thus, shifts in systemic venous return were not accompanied by simultaneous and co-directed changes in the central venous pressure. These findings suggest the absence of a direct relationship between these parameters.

Animals↗
PubMed2001

[Effect of negative intrathoracic pressure on venous return].

In acute experiments on cats and in observations made in human subjects, an increase of the negative intrathoracic pressure (NIP) leads to no significant changes of the venous return (VR) mean values. The peak values of the VR, however, increased and decreased more in inspiration and expiration following a deep breathing as compared with the normal breathing. The NIP seems to exert no direct effect upon the VR.

Animals↗
PubMed2001

[The constant level of the right atrial pressure and its role in the venous return characteristics].

Dynamics of the central venous pressure, superior and inferior v. cava flow and venous return following action of pressor stimuli were studied in acute experiments on anaesthetised mongrel cats with artificial lung ventilation and opened chest. The central venous pressure returned to the initial level faster as compared with the dynamics of superior and inferior v. cava flow and venous return. The superior v. cava blood flow increased more than that of inferior v. cava. The data suggest that the central venous pressure is controlled near the lower constant level.

Animals↗
PubMed1994

[The role of the ventral structures of the medulla oblongata in regulating the resistive functions of organ arterial vessels].

In the rostral part of medullary ventral areas (MVA) both the pace-maker neurons forming the tonic sympathetic activity, and the relay structures integrating the baroreceptor information on its way towards vascular areas, are located. The structures of the caudal portion of this cerebral area exert a depressing effect upon the activity of neuronal pools of the brain rostral part and modulate own baroreflexes. An obvious relationship was revealed between the character the extension of changes in the resistive function of the intestine and skeletal muscles' vessels, on the one hand, and the functional state of the MVA structures (excitation or inhibition), on the other hand.

Analysis of Variance↗
PubMed1993

[The effect of the structures of the ventral medulla oblongata on the hemodynamics and transcapillary fluid exchange in the lungs].

Pulmonary arteries and veins reacted by constriction to electric activation of rostrally located medulla oblongata ventral structures (lateral paragiant-cell nucleus area) in acute cat experiments. In contrast to this, electric stimulation of medulla oblongata caudal ventral structures induced dilatation of lesser circulation vessels. Counter-phase changes in parameters characterizing pulmonary microhemodynamics (capillary hydrostatic pressure, capillary filtration index) in response to electric stimulation of the studied brain structures permit a conclusion on the high homeostatic parameters of pulmonary microcirculation when maintaining ventilation perfusion relationships.

Acid-Base Equilibrium↗
PubMed1993

[The effect of changes in the blood flow and the level of arterial and venous pressures on the filtration-absorptive processes in the small intestine].

Under conditions of perfusion of the small intestine's vessels with constant volume of the auto-blood, stationary shifts of the arterial perfusion pressure by +/- 50 mm Hg and/or blood flow by +/- 50% of the initial level practically did not affect the size of the exchange surface of the organ's microvessel bed (the capillary filtration coefficient) or the average capillary pressure in artificially stabilised pressure of venous outflow at the level of 6 mm Hg. However, under conditions of normo-, hypo- and hypertone of the small vessels' smooth muscles, the shifts of the venous outflow pressure (from 0 to 24 mm Hg) increased the exchange surface of the microvessels and the average capillary pressure. The mechanisms of the shifts in microhemodynamics and transcapillary exchange of fluid are discussed.

Animals↗
PubMed1992

[Changes in gas composition of expired air during electric stimulation of the ventral medulla oblongata].

The experiments on urethane-anesthetized cats with the electrically stimulated ventral brain stem revealed that caudal ventral medulla at the depth of 1500 microns possesses structures whose electrical activation increases the level of carbon dioxide in arterial blood and in the end portion of expirate, on the one hand, and decreases the oxygen content in expirate and arterial blood, on the other hand.

Animals↗
PubMed1991

[The dependence of changes in the microhemodynamics and lymph formation in the liver on the level of the arterial and portal blood flows].

In cats, when perfusing hemodynamically isolated liver with a constant blood volume, an increasing of arterial as well as portal blood flows was shown to increase hydrostatic pressure in sinusoids and lymph production in the liver, whereas decreasing of the flows decreased these parameters. The above changes of the blood flows entailed various shifts of sinusoidal hydrostatic pressure and postsinusoidal resistance. When the volume blood flow in the liver artery increased, the coefficient of sinusoidal filtration increased too, whereas an increment of the blood flow in portal vein led to its diminishing. The resistance of liver artery and portal vein changed very little both in case of increasing and diminishing of the blood flow in these vessels.

Animals↗
PubMed1991

[The nature of the changes in the systemic hemodynamic parameters under the combined action of vasoactive substances].

The direction and obviousness of changes in systemic arterial and venous vascular beds occurring in combined action of two similarly acting pressor and depressor vasoactive drugs, were studied in acute experiments in cats. The changes of last and general peripheral resistance of vessels were greater under the action of the two drugs as compared to the effect of a single drug, and yet less obvious than their algebraic sum. The shifts in cardiac output and venous return were not greater than the most obvious response to a single drug. The same was true for the blood flow changes in v. v. cavae. Irrespective of the mechanism of action of vasoactive drugs and the direction of shifts of systemic AP, single and combined drugs increased the blood flow in the v. cava anterior whereas the v. cava posterior's blood flow changed in different directions.

Acetylcholine↗