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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
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↗
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↗
PubMed1987

[Relation of systemic and coronary fractions of left ventricle output during administration of vasoactive substances].

Against the background of increased arterial pressure, administration of noradrenaline and adrenaline increased the systemic fraction of cardiac output in 53 and 59 per cent of cases, resp., and decreased it in the rest of tests. Administration of mesatone decreased the systemic fraction in 75 per cent of cases. The coronary fraction was invariably increased. The coronary to systemic fractions ratio revealed significance of one or another fraction for the left ventricle output. The group with a decreasing systemic fraction on administration of each substance revealed a hyperbolic relationship between the ratio an shifts of the left ventricle total output. Administration of noradrenaline and mesatone induced a transition from a reduction of the left ventricle total output to its enhancement at values of the ratio less than -1, whereas in case of adrenaline-at values less than -5. No interrelationship was found between the left ventricle total output and its coronary fraction and the arterial pressure increment induced with adrenaline and noradrenaline.

Animals↗
PubMed1986

[The role of the cardiac-pulmonary blood volume in the changes in left ventricle output during stimulation of the afferent fibers of somatic nerves].

Stimulation of tibial nerve afferent fibers has revealed heterogeneous shifts of left ventricular output, as well as pulmonary artery and posterior vena cava blood flow in anesthetized cats. Uniform changes in left ventricular output and pulmonary artery blood flow were noted in the majority of cases, with venous return most often exceeding pulmonary artery blood flow. beta-adrenoreceptor blockade failed to influence changes in pulmonary artery blood flow. It is concluded that the increase in pulmonary artery blood flow depends on the rise in venous return, but not on neurogenic influence upon the right ventricle. The reduction in left ventricular output is the result of decreased right ventricular outflow due to its overload caused by pulmonary vasoconstriction.

Afferent Pathways↗
PubMed1986

[Participation of the right chambers of the heart and pulmonary vessels in the development of changes in cardiac output during exclusion of the carotid sinus reflexogenic zone].

In 67% of tests, a decrease in the output from the cat left heart ventricle entailed a lessening of the lung artery blood flow, the latter being combined with an increased inflow to the right atrium in half of the cases. Suppression of beta-adrenoreceptors exerted no effect on the output from the right ventricle. Different factors are discussed affecting the lung artery blood flow and efficiency of the right ventricle in formation of shifts in the output from the left ventricle under occlusion of carotid arteries.

Animals↗