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Biomedical subjects

B I Tkachenko

Publications and source records attributed to B I Tkachenko.

At least 91 records · Page 5Linked to original sources
PubMed1986

[Systemic hemodynamic shifts in the arterial and venous portions of the vascular bed in hypoxia].

A reduction of total peripheral resistance is of a major importance for depressor shifts of arterial pressure in moderate hypoxia. The hypoxic stimulus induces a deficiency of increment in cardiac output shifts as compared with venous return. An increment of venous return and cardiac output suggests that the compensation for the depressor shifts induced with the lack of O2 in air and blood, occurs on account of flow induces of the circulation system.

Animals↗
PubMed1986

[Filtration-absorption function of the vessels of the small intestine in response to reflex effects].

The reflex activation of the cat intestine sympathetic nerves induced changes in capillary hydrostatic pressure depending on the perfusion regimen in the vascular bed: the pressure rose in stable blood expenditure and dropped in perfusion under constant pressure. The capillary filtration coefficient decreased in response to sympathetic effects, irrespective of the blood supply conditions.

Animals↗
PubMed1985

[Effect of somatostatin on the myoelectrical activity of the stomach and small intestine in conscious dogs and rabbits].

In chronic experiments on dogs and rabbits, i.v. administration of somatostatin (3.3 to 330.0 ng/kg) exerted activating effects in resting and in hunger upon the myoelectrical activity of stomach, duodenum, small intestine and ileum whereas in the course of digestion the effects were inhibitory. Somatostatin exerted mainly an inhibitory effect on the myoelectrical activity of stomach and small intestine in rabbits. Possible mechanisms of the somatostatin effect upon the contractile activity of the stomach and duodenum smooth muscles are discussed.

Action Potentials↗
PubMed1985

[Resistance, exchange and capacitance vessels of the skeletal musculature in acute hypoxic hypoxia].

In cats under conditions of autoperfusion of hemodynamically isolated m. gastrocnemius, acute hypoxia (10% O2 in nitrogen) increased the precapillary and decreased the postcapillary resistance, reduced the capillary hydrostatic pressure and induced shifts of the capillary filtration coefficient (CFC) by 30% on the average. In cross-circulation performed for analysis of the neurogenic component in the vascular responses, analogous changes of the above parameters were revealed, the CFC decreasing, however. In denervated vascular bed of the m. gastrocnemius, the acute hypoxia decreased the precapillary and increased the postcapillary resistance, the hydrostatic pressure and the CFC increasing. In decentralized vessels of skeletal muscle, hypoxia induced prevalence of filtration while absorption of fluid prevailed in perfusion of the preparation with donor's arterial blood and in recipient's hypoxia.

Acute Disease↗
PubMed1985

[Neurogenic changes in filtration-absorptive ratios in skeletal muscle vessels].

In cats, the volumometry of extracorporeally circulating blood revealed that the character of changes of the capillary hydrostatic pressure in the hindlimb skeletal muscles occurring in response to stimulation of the lumbar sympathetic string, virtually depends on the mode of perfusion: under constant blood flow the capillary pressure increased while in perfusion under constant pressure it decreased. The capillary filtration coefficient (CFC) increased in response to stimulation of sympathetic efferents irrespective of the mode of vascular bed perfusion. The mechanisms of the above changes of the capillary hydrostatic pressure are considered from the standpoint of participation of hemodynamic factors and active shifts of pre-and postcapillary pressure. Possible role of the change of the vascular bed permeability and activation of beta-adrenoreceptors in the mechanism of the capillary filtration coefficient increase, is discussed.

Absorption↗
PubMed1984

[Resistive, capacitive and metabolic functions of the vessels of the small intestine in acute hypoxic hypoxia].

In acute experiments on cats, under conditions of autoperfusion of the small intestine vessels, acute hypoxic hypoxia led to a ahort-term increase of the precapillary resistance and a stable decrease of the postcapillary one, to a decrease of capillary hydrostatic pressure and absorption of fluid from the interstitial space into the blood with an increase of the axchange surface. The mechanisms of above vascular and filtration-absorbent changes in the intestine during hypoxia, are discussed.

Absorption↗
PubMed1983

[Stretching of the veins of skeletal muscles following changes in the level of hydrostatic venous pressure].

Acute experiments in cats revealed that the integral venous compliance of m. gastrocnemius' could be represented by a graphic curve with ascending front, peak and descending front. These parts of the curve corresponded mainly to those ranges of the venous pressure values: (-10)-0 mm Hg; 0-(+10) mm Hg and (+10)-(+25) mm Hg, resp. The neurogenic component of venous tone in the skeletal muscles has no obvious effect on formation of venous compliance values in response to hydrostatic loads whereas increasing of this tone with noradrenaline or decreasing of it with papaverinum induced, resp., a decrease or an increase in the venous compliance.

Animals↗
PubMed1983

[Characteristics of vasomotor responses in the cat skeletal muscles and skin during heat stress].

In anesthetized cats, resistography and the volumometry of extracorporeal blood flow revealed that even the first stages of hyperthermia decreased the resistance and increased the compliance of the skin venous vessels, whereas an essential increase in the resistance of skeletal muscles' arterial vessels only occurred in marked hyperthermia. The compliance of skeletal muscles' venous vessels underwent no considerable changes in hyperthermia. The data obtained suggest a significant redistribution of the blood flow and blood volume among the skin and muscles vessels during heat stress. The observed differences in the rate of development of the above responses suggest participation of different mechanisms in their formation.

Animals↗
PubMed1982

[Comparative characteristics of the neurogenic reactions of capacitance vessels in organs of the peritoneal cavity and skeletal musculature].

Comparison of neurogenic reactions of accumulating vessels of the cat hindlimb, spleen and small intestine in conditions of continuous blood flow revealed that under pressure reflexes the accumulating vessels of small intestine actualize much greater part of the maximal neurogenic venoconstriction than vessels of skeletal muscles and spleen. Qualitative and quantitative differences of responses of the spleen and the hindlimb accumulating vessels evoked by electrostimulation of medulla oblongata were revealed.

Animals↗
PubMed1982

[Effect of high ambient temperature on regional redistribution of blood flow in the cat].

Supersound flowmetry revealed that the effect of heat (50 degrees C) involved an increase of the blood flow in skin vessels and its decrease in the vessels of small intestine and skeletal muscles. The blood flow resistance was diminished in skin vessels and increased in the vessels of small intestine and skeletal muscles. These shifts of the regional blood flow are due to the integral interaction of active and passive vascular responses. Specifics of the small intestine and skeletal muscle vessels' constrictory responses to hyperthermia suggest a difference in the mechanisms of their occurrence.

Animals↗
PubMed1982

[Characteristics of the central regulation of venous vessels].

In acute experiments on cats, the magnitude and type of responses of hindlimb accumulating vessels and of those responsible for pressure stabilization, to pressor reflexes were studied under normal conditions of the vasomotor center and after brain sections at different levels (decortication, decerebration, spinalization) as well as after occlusion of femoral or cava posterior vein. A considerable increase of arterial vessels responses to pressor reflexes occurred after decerebration at the intercollicular level whereas occlusion of the femoral or cava posterior veins led to a significant decrease of the responses. The reactions of venous vessels were constant owing to the specific features of their central regulation. Only efferent impulses to arterial part of the vascular bed seem to change under these conditions while modification of "venous" part of the efferent patterns occurred, probably, at the spinal cord level.

Afferent Pathways↗
PubMed1982

[Coefficient of capillary filtration in the skeletal muscles during changes of their hemodynamics].

In acute experiments on cats using the method of extracorporeal blood volumometry, the capillary filtration coefficient (CFC) in the skeletal muscle did not correlate with induced changes of arterial pressure (65-280 mm Hg), venous pressure (0-30 mm Hg) and the induced changes of the blood inflow (75-150%). A negative functional relationship was found between blood flow and CFC in the skeletal muscle in the blood flow was less than 75% of the initial level. This phenomenon is interpreted as a metabolic dilatation of the precapillary sphincters caused by limitation of the blood supply of the tissue under study.

Animals↗
PubMed1981

[Blood flow in the inferior vena cava measured by a Doppler ultrasound flowmeter in chronic experiments on cats].

Supercound Doppler's transducers indwelled in the cat v. cava posterior revealed that the higher blood flow values in chronic experiments as compared to acute ones were due to the effect of the chest suction action on the blood flow. The phasic changes of the venous blood flow occurring at resting and under various effects were related to respiration and heart activity, the respiratory component being more obvious than the cardiac one. A significant correlation existed between the mean value of the blood flow in the v. cava posterior and the respiratory changes of the blood flow amplitude.

Animals↗