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Biomedical subjects

I V Sergeev

Publications and source records attributed to I V Sergeev.

At least 19 recordsLinked to original sources
PubMed1995

[The dependence of ortho- and antiorthostatic hemodynamic reactions on the initial (controllable) tonus of the arterial vessels in rats].

Ortho- and antiorthostatic responses of the hemodynamics were compared by numerous parameters in anesthetised rats. In particular, in antiorthostatism the decrease of diastolic pressure as well as systolic one was greater at a lower initial arterial pressure. The data obtained suggest that, in orthostasis, the constrictor vascular compensatory responses are mainly revealed at a high initial arterial pressure. This mechanism of the compensation is less obvious in antiorthostatism.

Angiotensin II↗
PubMed1994

[The influence of baroreceptor reflexes on the effects of rapid changes in blood volume in rats].

The effect of suppression of the sinocarotid and cardioaortal areas on systemic pressor responses were studied during fast administration of fluid. The data obtained does not corroborate the traditional ideas of the universal buffer role of the baroreflexes in regulation of arterial pressure under live conditions of formation of systemic pressor responses as the suppression of the baroreceptor areas tells not on the increment of the pressor responses but either suppresses them or preserves them intact.

Animals↗
PubMed1994

[The relationship of systemic pressor reactions to the initial (spontaneous) blood pressure level].

Relative responses of the systolic and diastolic pressure to polyglukine and mesatone administration were found to be more obvious in anesthetised rats with initial blood pressure less than 100 mm Hg. A reverse linear correlation was found between the above parameters at the high level of connexion for both agents. Exclusion of sinocarotid or cardioaortic areas did not affect the dependence of the responses to measatone on the initial blood pressure, whereas such a dependence was found for polyglukine at intact baroreceptors.

Adrenergic alpha-Agonists↗
PubMed1993

[The systemic vascular reactions during different methods of assessing the hydraulic resistance of the vascular system].

The ratio of the resistance shifts as estimated by the pressure under conditions of stabilised expenditure, in respect to the resistance shifts as estimated by the blood flow, was for the electrical stimulation of a somatic nerve and occlusion of the carotid artery 1:3.3; for the noradrenaline administrations--from 1:3 to 1:3.5; for the papaverine administrations--from 1:2.2 to 1:3.6. In the perfusion with established pressure the vasomotor responses were devoid of the baroreflectory control whereas in perfusion with constant blood volume the conditions for stimulation of baroreceptors with altered pressure were preserved.

Animals↗
PubMed1993

[Postural systemic vascular reactions].

Changes of hydraulic resistance of the vascular system were studied under conditions of stabilised blood expenditure in response to ortho- and antiorthostatic effects. The first type effects involved an increase in the resistance whereas the antiorthostasis decreased the resistance. Both ways of estimation of vascular responses are discussed from the standpoint of conditions for baroreflex control of vasomotor responses.

Animals↗
PubMed1991

[An analysis of the baroreflex influences on the systemic hemodynamics in head-down tilt].

In acute experiments on cats, the effect of carotid sinus' baroreceptors on systemic hemodynamics, was studied in antiorthostasis. Head-down tilt of the animals 15-45 degrees increased the arterial pressure and cardiac output whereas the heart rate and total peripheral resistance were decreased. The tests with decreasing the arterial pressure yielded analogous results. Exclusion of baroreceptors of the carotid sinus did not affect the initial shifts in the group with increasing arterial pressure. Whereas in the group with decreasing arterial pressure the same procedure reversed the reaction.

Animals↗
PubMed1991

[Expediency of performing duodenojejunostomy in chronic duodenal obstruction].

The article discusses treatment of 30 patients with chronic duodenal obstruction by means of an operation for duodenojejunostomy. Three variants of subcolonic duodenojejunostomy were used. The best drainage function of longitudinal duodenojejunostomy is noted. The postoperative results were poor in 40% of patients. The operation was repeated in 11 patients. The duodenum was excluded. The results of the second operations were satisfactory. Duodenojejunostomy is poorly effective in the treatment of duodenostasis. Exclusion of the duodenum from passage produced more favorable results in respect of function.

Adolescent↗
PubMed1990

[The effect of the initial vascular tonus on the development of compensatory constrictor reactions in orthostatic exposures].

Under orthostatic actions, a decrease in cardiac output, systolic and diastolic pressure (the decrease of the latters being lesser by half) and an increase in total peripheral resistance occurred in cats. A decrease in the coronary blood flow only occurred at large angles of the inclination (45 and 60 degrees). The data obtained suggest compensatory vasoconstrictory responses to orthostasis. Against the background of an increased initial vascular tone (angiotensin administration), no significant changes occurred under orthostasis in diastolic pressure, peripheral resistance or coronary blood flow. The decrease in cardiac output and systolic pressure was the same as before the administration. Against the background of a decreased vascular tone (papaverin administration), orthostatic tests induced a slight increase in the depression of arterial pressure and a decrease in the cardiac output shifts. No significant decrease in peripheral resistance occurred except at the angles of 45 and 60 degrees. A decrease in the coronary blood flow only occurred at the inclination of 30 and 45 degrees. The data obtained suggest that vasomotor responses to orthostasis depend on the value of initial vascular tone.

Adaptation, Physiological↗
PubMed1990

[The participation of cardiac, vascular and coronary components in the shaping of cardiovascular reactions to head-down tilt exposures].

An increase in venous flow to the heart due to the 15-45 degrees head-down inclination of the cat, induced a drop in arterial pressure combined mostly with an increased cardiac output and changes of coronary blood flow. The character and obviousness of the responses did not depend on the inclination angle. Initial level of arterial pressure was found to be significant for subsequent responses to the antiorthostatism: the pressure increased at a low initial level and decreased at a high one.

Animals↗
PubMed1989

[The interrelations of arterial pressure, cardiac output and coronary blood flow during orthostatic reactions].

The influence of hypotension induced with orthostasis, upon cardiac output and coronary flow was studied in anesthetized cats. The body tilt to 15-60 degrees lowered the mean arterial pressure parallel with reduction of cardiac output. Under the tilt up to 30 degrees and 60 degrees, a significant difference was found in decrease of systolic but not diastolic pressures. The degree of cardiac output reduction was two-fold greater than the degree of diastolic pressure reduction. The findings suggest a participation of vascular constrictor responses in the forming of orthostatic reactions. The coronary flow decrease only began with the tilt up to 30 degrees. Its extent did not depend on the intensity of hypotension being, probably, the result of the reduction of the heart work.

Animals↗
PubMed1989

[The role of adrenergic innervation in distributing systemic and coronary fractions of left ventricular output under increased pressure in the ascending aorta].

The significance of neurogenic influences upon the distribution of systemic and coronary fraction during rise of aortic pressure by step occlusion of ascending aorta was studied in anesthetized cats. Under elevation of aortic pressure up to 60 mm Hg the increase in systemic fraction and less pronounced rise of coronary fraction were observed. When aortic pressure elevation was more than 60 mm Hg commensurable increase of both fractions occurred. Under beta-adrenoreceptor blockade elevation of aortic pressure more than 60 mm Hg evoked the significant increase in systemic fraction and reduction in coronary fraction.

Adrenergic Fibers↗
PubMed1988

[An analysis of the shifts in the heart pump function during pressure changes in the initial portion of the aorta].

External occlusion at the beginning of aorta induced different shifts of the cardiac output systemic fraction in different degrees of the AP raise. Various mechanisms of the changes in the left ventricle output were found to depend upon the degree of the AP raise in the aorta. An increase of systemic fraction in 1 to 60 mm Hg raise of the AP was due to changes in contractile activity of the myocardium, whereas in 61 to 90 mm Hg raise it was due to an increase in terminal diastolic pressure. If the AP increment exceeded 100 mm Hg a decrease of the systemic fraction occurred.

Animals↗
PubMed1987

[The ratio of systemic and coronary fractions of left ventricular output in reflex pressor reactions].

In acute experiments the participation of coronary and systemic fractions was studied during suppression of the carotid sinus baroreceptors by the occlusion of the carotid arteries and stimulation of the tibial nerve afferent fibers. In most tests systemic fraction was reduced in carotid arteries occlusion and increased in tibial nerve stimulation. The coronary fraction was always increased. The cardiac output (the sum of systemic and coronary fractions) was steady with blood pressure increase by 20 to 70%. The role of coronary fraction in the mechanism of homeometric regulation of the heart is discussed.

Afferent Pathways↗