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Biomedical subjects

B I Tkachenko

Publications and source records attributed to B I Tkachenko.

At least 109 records · Page 6Linked to original sources
PubMed1980

[Changes in systemic hemodynamics caused by intra-arterial and intravenous autoperfusion of small blood volumes].

Changes of general peripheral resistance in response to autoperfusion both prior to and after blockade of alpha- and beta-adrenoreceptors depended on its initial level: at a relatively low initial value autoperfusion increased the vascular resistance whereas at high value decreased it. During maximal shifts of hemodynamic parameters the venous return prevailed over the cardiac output. The pressor effect was practically unrelated to the way of blood administration.

Animals↗
PubMed1980

[Capacitive vascular reactions of the skeletal musculature before and after adrenoreceptor blockade].

In acute experiments on cats under autoperfusion of the denervated shank vessels with a constant blood volume, injection of noradrenaline into the perfusate could either decrease or increase vascular capacitance. The character and magnitude of reaction depended on the initial level of venous pressure: in pressure 10--15 Hg the decrease was predominant, whereas in pressure 0 and 25 mm Hg--the increase of vascular capacitance occurred. Under blockade of beta-adrenoreceptors with propranolol the dependence of the character of changes in shank vessels capacitance remained the same. Under dihydroergotoxin blockade of alpha-adrenoreceptors, noradrenaline produced only an insignificant increase of the vascular capacitance.

Animals↗
PubMed1979

[Hemodynamic structure of pressor reactions to vasoactive substances].

In cats, similar changes of the blood pressure had different hemodynamic structures under the influence of catecholamines or angiotensin. Adrenalin was able to evoke a pressor response by means to either caridac or vascular factor. In the former case, the increase in the cardiac output was induced both by an increasing blood flow towards the heart and by an additive outflow of the blood from the minor to the major circulation; in the latter case, the increase in the general peripheral resistance entailed a decrease in the cardiac output in spite of the augmentation of the venous return which determined a delay of the blood in the minor circulation. The latter variant of interrelationships among hemodynamic parameters can occur under the influence of noradrenaline as well. A combined similarly rendered participation of the cardiac and the vascular factors in the increasing the blood pressure occurs under the influence of angiotensin and sometimes of noradrenaline. The participation of cardiac output in the pressor response may depend on hemodynamic shifts in the minor circulation which either limit or facilitate, or leave unchanged the rate of increment of the cardiac output.

Angiotensin II↗
PubMed1978

[Reactions of the microcirculatory bed of cat mesentery during exposure to heat].

The TV-microscopy in cats revealed that, by the 30th minute of 2-hr overheating, the arterioles are dilated and venules constricted. In the course of raise of body temperature from 36 degrees to 40 degrees C, the number of dilatory and constrictory responses of venules remains the same while the number of arteriole dilatory responses diminishes and of constrictory responses increases. At 40 degrees C of body temperature, the number of dilatory responses of the mesenteric arterioles and venules makes about 20--30% while the number of constrictory responses--70--80%. The extent of dilation of arterioles and venules increases with the heating while the extent of constriction, having achieved a certain level, starts to diminish. The greatest responses occurred in the microvessels with initial diameter 60 and more microns. The responses of microvessels with a lesser diameter could be different. The data obtained using hexonium, dihydroergotoxin, inderal, atropin, dezeril, methyamide, and tavegil, suggest participation of adrenergic and histamingergic substances in vasomotor responses of the microvessels to the hyperthermia.

Animals↗
PubMed1978

[Relationship between central and peripheral mechanisms in regulating capacitance vessels].

In acute experiments on cats, responses of the resistance and capacitance vessels of the spleen and hindlimbs to local electric stimulation of the medulla oblongata, of the sympathetic nerves, and pressor reflexes during different pressure of the venous outflow, were studied. No structures were revealed which could selectively affect the capacitance vessels. The bulbar structures affected both the resistance and the capacitance vessels. The reflex responses aof the pre- and post-capillary portions of the vascular bed could be different, the transmural pressure being one of the factors for dilatory responses of the capacitance vessels. The different responses of the capacitance vessels could occur on account of both local and central mechanisms, their participation, however, being unequal.

Animals↗
PubMed1978

Blood supply and O2 consumption of the small intestine in low flow.

Blood flow and O2 consumption of the small intestine were studied anaesthetized cats in two series of experiments. Two-step haemorrhagic shock was applied in the first one; the intestinal vascular bed was locally hypoperfused in the other. Resistance to blood flow decreased in both haemorrhage and hypoperfusion. Intestinal blood flow was 12.6 ml/min . 100 g in haemorrhage (blood pressure 60 mm Hg) and 13.3 ml/min . 100 g at 50% perfusion. O2 consumption was only slightly reduced (93% and 89% of the control, respectively). Decrease in resistance showed a similar character to the "autoregulatory escape" phenomenon. Two types of regulation of O2 supply took place during low flow. The first one tended to maintain O2 supply to the gut in the face of flow reduction; in the other O2 consumption depended upon blood upon blood flow. The lower was blood flow, the more dominant became the second mechanism.

Animals↗
PubMed1977

[Character of organ volume vessels during pressor reflexes].

In acute experiments on cats, responses of the resistance and capacity vessels of small intestine, spleen, kidneys, and m. gastrocnemius were studied during pressor sinocarotid reflex and electrical stimulation of the sciatic and brachial afferents. It was shown that, against the background of constrictory responses of the resistance vessels in these organs, both the constrictory and the dilatory responses of the capicitance vessels could occur or not. Correlation analysis revealed no dependence between the markedness and character of the capacitance vessel responses and the changes of the venous blood oxygenation during pressor reflexes. The regulatory mechanisms determining, different characters of the capacitance vessels during neurogenic effects and the methodical conditions revealing the true nature of changes occurring in the postcapillary bed, are discussed.

Animals↗
PubMed1977

[Comparative characteristics of changes in the diameters of microvessels and blood flow within them during systemic shifts in hemodynamics].

In anesthetized cats, with the aid of the method of television line single out, the diameters of mesenteric microvessels and their blood flow were studied. The diameter of the flow in arterioles and venules was shown to undergo greater changes than the diameter of the microvessels proper, although a close correlation was revealed between both parameters. The above differences of the changes of diameters are more obvious during dilatory responses. The changes depend on the initial caliber of the arterioles and venules.

Animals↗
PubMed1976

Relation of efferent impulse activity in splenic nerve to reflexly induced reactions of resistance and capacitance vessels to spleen.

Constrictory responses of splenic resistance vessels arising under pressor reflexes were abolished by hexonium (2 mg/kg) as well as the high amplitude (above 15 muV) impulses in sympathetic splenic nerves. Constrictory and dilatory responses of splenic capacitance vessels were preserved after administration of the same dose of hexonium and correlated as to the directivity with the changes of the low amplitude (15 muV and lower) impulsation in the splenic nerve.

Animals↗
PubMed1976

[Pressor reflexes and changes in sympathetic impulsation and the responses of intestinal and renal vessels].

In acute experiments on cats, the ganglio-blocking agent (hexonium 2 mg/kg) revealed no high-amplitude impulsation (over 15 mcV) in the branches of intestinal and kidney nerves. Simultaneously, no responses of the small intestine and kidney resistance vessels to constriction of the carotid arteries were observed. The constrictory and dilatory responses of the capacitance vessels in the same organs, after the above dose of the ganglioblocking agent, are preserved and correlated with the character of changes of the lowamplitude (equal to or lower than 15 mcV) impulsation persisting in the intestinal and kidney nerves. The post-ganglionar sympathetic fibers conducting high-amplitude discharges are suggested to be mainly responsible for the reflex responses of the resistance vessels, while the low-amplitude fibers--for responses of the capacitance vessels.

Animals↗