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Biomedical subjects

B I Tkachenko

Publications and source records attributed to B I Tkachenko.

At least 55 records · Page 3Linked to original sources
PubMed1990

[The effectiveness of the joint action of vasodilator humoral stimuli on the arterial and venous vessels of the skeletal muscle].

Two pairs of stimuli: isoproterenol and histamine, and isoproterenol and papaverine, did not enhance the effect of their separate components on either arterial or venous vessels, the dilatory responses not exceeding the vascular responses to separate agents. However, if the vascular responses to an isolated component of the pairs differed, then the effect of a pair of stimuli was equal to a greater response from the responses to an isolated component. Venous vessels differed from arterial ones in that their response to a combined action of above substances was sharply reduced as compared to responses to isoproterenol.

Animals↗
PubMed1990

[Comparative characterization of reactions of skeletal muscle arterial and venous vessels to combined adrenergic effects].

In experiments with the constant blood flow perfusion of the cat calf muscle and combined actions of adrenalin and noradrenaline were tested as to the blood flow resistance changes of the arterial and venous blood vessels. Separately applied the catecholamines evoked vascular resistance changes practically similar in value; combined effects of catecholamines realized in greater increase of arterial than venous resistance. In contrast to arterial vessels supramaximal stimuli resulted in much lesser constrictive effect as compared with reaction of intramural veins to separately applied catecholamines. Greater doses of catecholamines being combined, stability of effector system of skeletal muscle veins is decreased as compared to arteries.

Animals↗
PubMed1990

[Character of arterial pressure changes under combined action of pressor and depressor agents].

It is shown in acute experiments in cats that byphasic arterial pressure changes occurred due to action of two heterodirectional and equivalent humoral stimuli. Magnitudes of both initial depressor and following pressor phases were authentically less than the ones due to separate action of those stimuli. It is noticed that the character of sum reaction depends neither on action mechanisms of vasoactive agents in the blood circulation system nor differences in the latent period of the effect of those drugs, but connected with intensiveness of stimuli. Predominance of depressor phase magnitude was shown to observe due to a rise of stimuli intensiveness down to complete disappearance of pressor reaction.

Acetylcholine↗
PubMed1990

[The capacitive function of the spleen during electrical stimulation of the structures of the ventral section of the medulla oblongata].

In acute experiments on cats under perfusion with constant blood expenditure of hemodynamically isolated spleen the authors studied the reactions of its vessels in the electrical stimulation of ventral brainstem. It was shown that the stimulation of the rostral zone of these structures increased vein outflow from the spleen. It was shown the deterioration of the parametres which characterize a capacitance function of the spleen by stimulation of a causal depressor zone of the brainstem by means of the current of threshold size and its increase by irritation of the brain structures with a 2 threshold current size. There have been made a supposition has been made about the participation of the pointed structures of the brain in the regulation of a vasomotion tonus of the spleen vessels.

Animals↗
PubMed1989

[Dependence of hypoxic changes in macro- and micro-hemodynamics on the activity of adrenoreceptors in the skeletal muscle in hypothermia].

Dependence of hypoxic changes of macro- and microcirculation on the activity of adrenergic receptors in the cooled organism was studied on decentralized shank of cat under perfusion with constant blood flow. After cooling of cat (to 30 degrees C) and blockade of alpha-adrenoreceptors hypoxic hypoxia (10% O2 in N2) caused (a) much greater reduction of precapillary resistance of shank, (b) more striking (by 3 times) increase of capillary filtration coefficient and (c) the increase of capillary pressure and postcapillary resistance in contrast to 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 blood vessels evoked by hypoxia under cooling.

Animals↗
PubMed1989

[Changes in the transsinusoidal fluid transfer in the cat liver during noradrenaline infusion].

The blood microcirculation and the lymph flow were studied in the cat hemodynamically isolated liver perfused under conditions of a regulated venous outflow and i.a. and intraportal administration of noradrenaline. An increase in the fluid transsinusoidal transfer revealed by the lymph flow acceleration in the liver, was determined by an increased hydrostatic pressure in the sinusoids at practically unaltered level of sinusoidal filtration. The above shifts were observed against the background of constriction of arterial, portal, venous and lymphatic vessels and of a decrease in capacitance of the liver vessels which were due to alpha-adrenocereptors excitation by noradrenaline.

Animals↗
PubMed1989

[The mechanism coupling adrenergic and cholinergic influences on the smooth musculature of the small intestine].

Experimental results, substantiating the idea of a specific mechanism for the activation of small-intestinal smooth muscle by the adrenergic system are summarized. This mechanism is realized via catecholamines affecting excitatory beta-adrenoreceptors located on cholinergic interneurones of the myenteric plexus. The excitatory beta-adrenoreceptors are shown to contribute to the realization of small-intestinal motor responses to acetylcholine, vagal stimulation and 5-hydroxytryptamine, histamine, bradykinin. The data obtained are an evidence of physiological significance of this specific adrenosensitive input of small-intestinal cholinergic neurones. The cholinergic neurones are shown to participate in producing small-intestinal responses to 5-hydroxytryptamine, histamine, bradykinin, the responses being, for this reason, dependent on the level of catecholamines, stimulating excitatory beta-adrenoreceptors. It is suggested that cholinergic neurones of the enteric nervous system are under double adrenergic control: a stimulating effect of catecholamines mediated by excitatory beta-adrenoreceptors is counteracted by an inhibitory effect of alpha-adrenoreceptor activation by sympathetic neuromediator noradrenaline.

Animals↗
PubMed1989

[Joint functions of the gastrocnemius muscle's blood vessels in lesions of the ventral structures of the medulla oblongata].

Following bilateral electrolytic or chemical lesion of the neurons in rostral portion of the medulla oblongata ventral parts, a decrease in systemic arterial pressure, heart rate, precapillary resistance and perfusion pressure, postcapillary resistance and capillary hydrostatic pressure, was observed in the m. gastrocnemius vessels in cats, the capillary filtration coefficient increasing at that. Following chemical lesion of the neurons in caudal portion of the medulla oblongata ventral parts, a biphasic change of the AP and vascular resistance was observed in the m. gastrocnemius: their decrease within first 5 min was followed by their increase within next 120 min, the capillary filtration coefficient being decreased whereas capillary hydrostatic pressure increasing. No changes in the regional vascular capacity were found.

Animals↗
PubMed1989

[Interrelations of macro- and microhemodynamics and lymph outflow in the cat liver during stimulation of the hepatic nerves].

Sympathetic electric stimulation of the liver nerves increased hydrostatic pressure in sinusoids by 8-10% in cats. The sinusoidal filtration coefficient decreased, particularly at the stimulation frequency 10-20 Hz. No significant increase in the lymph outflow from the liver was revealed which suggested an absence of the fluid transfer from the sinusoids to extravascular space. The above changes occurred against the background of the constriction of arterial, portal and venous vessels, as well as a reduction of the liver capacity. Comparison of these shifts with analogous values in small intestine revealed that the microcirculation in excitation of sympathetic-adrenal system is more stable in liver than in small intestine.

Animals↗
PubMed1989

[The relation of lymph flow and microcirculation in the cat liver under the effect of serotonin and bradykinin].

In experiments on cats with hemodynamically isolated and perfused wider constant flow liver it was shown that intraarterial or intraportal infusion of serotonin and bradykinin increased a transinusoidal fluid fransher and lymph formation in the region. The elevated franshes walls of maintained mainly by an increase on the permeability of the walls of exchange microvessels. Differences were revealed in the achions of serofouri and bradykinin upon liver's arterial and portal vessels, the sensitivity of portal vein to the drugs being which lesser than of the live artery.

Animals↗
PubMed1989

[Dependence of the parameters of microcirculation and lymph flow in the liver on the value of venous pressure].

In experiments on cats the perfusion (at a constant flow and controlled venous outflow) of haemodynamic isolated liver was carried out. It was shown that at the levels of venous pressure in the liver 0, 2, and 4 mm Hg, the lymph flow (22.8 +/- 3.5, 41.8 +/- 5.7 and 57.6 +/- 8.6 mkl.min-1.100 g-1, respectively) was depended on the value of hydrostatic pressures in the sinusoids (1.4 +/- 0.1, 3.3 +/- 0.1, and 5.4 +/- 0.1 mm Hg, respectively) and did not depend on the value of sinusoidal filtration coefficient (0.421 +/- 0.029, 0.473 +/- 0.036, and 0.474 +/- 0.034 ml.min-1.mm Hg-1.100 g-1, respectively).

Animals↗
PubMed1989

[The effect of the ventral structures of the medulla oblongata on systemic arterial pressure and on the resistance and capacitance of the skeletal muscle vessels].

Following the isolation of ventral portions of the medulla oblongata from the dorsal ones and from the upper parts of the c. n. s. in cats, no changes were found in the initial level of systemic blood pressure, in perfusion pressure or in venous outflow in the m. gastrocnemius, vessels. Electrical stimulation of ventral portions of the lateral paragigantocellular nucleus under these conditions increased the systemic AP, regional vascular resistance and decreased the capacitance of the n. gastrocnemius' vessels, whereas after bilateral electrical coagulation of the nucleus the stimulation led to a stable and obvious decrease in the systemic AP and perfusion pressure in the muscle vessels. No changes of the regional vascular capacitance were noted. The significance of ventral structures of medulla oblongata in maintaining of initial AP level, formation of tonic neurogenic messages to arterial vessels of m. gastrocnemius and in actualization of the reflex neurogenic effects upon arterial and venous vessels of skeletal muscles, is discussed.

Animals↗
PubMed1988

[The participation of the structures of the ventral sections of the medulla oblongata in realizing vasomotor pressor reflexes].

In acute experiments on cats, under constant perfusion of tibial and small intestine vessels and after bilateral electrolytic lesion of ventral portions of the paragigantocellular nucleus a decrease of initial AP by 30-35%, perfusion pressure in tibial vessels by 30% was observed whereas the changes of AP in the small intestine vessel were insignificant. The occlusion of the common carotid artery or electrical stimulation of afferent fibers of brachial plexus exerted no effect, at that. Bilateral administration of L-glutamate into ventral portions of reticular nucleus increased the perfusion pressure in tibial vessels by 15% and in those of small intestine by 35%. Carotid sinus pressor reflex induced 1.5-fold shifts of systemic AP as compared with control values.

Animals↗