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Biomedical subjects

V I Kuznetsov

Publications and source records attributed to V I Kuznetsov.

At least 73 records · Page 4Linked to original sources
PubMedDate not supplied

[Action of microwaves with different modulation frequencies and exposure times on GABA receptor concentration in the cerebral cortex of rats].

The effect of 800 mHz microwaves of 0, 3, 5, 7, 16, and 30 Hz modulation on GABA receptor concentration in rat brain cortex has been investigated. Irradiation of the whole body at a modulation frequency of 16 Hz readily decreases the GABA receptor concentration. Irradiation at other modulation frequencies is ineffective. Irradiation of the whole body modulated at 16 Hz with various exposure times (5, 15 and 60 min) has revealed the highest effect at 5 min, while at a longer exposure the effect decreases.

Animals↗
PubMedDate not supplied

[The role of cholinergic regulation and stabilization of myocardial structures in the adaptive protection of the heart].

It was found that rat immobilization in small-size cages leb to physiological changes. On day 1 it was a stress-reaction that resulted in decreases of the fibrillation threshold and arrhythmia resistance. On day 5 it was an increase in the vagal tone that caused noticeable atropine-relieved bradycardia. The fibrillation level returned to the baseline. Heart resistance to ischemic and reperfusion arrhythmias increased drastically as compared to the control level. On day 15 the vagal effect declined to reach the baseline; in spite of this heart tolerance to reperfusion arrhythmias further increased. This was followed by enhanced resistance of isolated hearts of the adapted animals to the reperfusion paradox and tonic concentrations of epinephrine and Ca2+, which indicated the formation of the phenomenon of adaptation stabilization of cardiac structures. After termination of the 5-day stressogenic exposure the cholinergic stress-limiting protection of the heart disappeared rapidly, i. e. within 12 hours. The protective effect of the adaptation stabilization phenomenon, which developed during 15 days of the stressogenic exposure, proved to be more stable and persisted during 15 days after its cessation. It is concluded that, based on the coordination of short-term central and long-term cellular mechanisms, the animal body develops optimal adaptation that emerges rapidly and persists for an adequately long period of time. The step-by-step replacement of central mechanisms with cellular ones provides high reliability and efficiency of the protection of the heart and the entire body from extended environmental effects.

Acetylcholine↗
PubMedDate not supplied

[Contractile function and some parameters of energy metabolism of the myocardium in the process of adaptation to the effect of moderate continuous stress].

Experiments were conducted on rats to study the dynamics of changes of the heart contractile function (CF) and some indices of myocardial energy metabolism during adaptation to moderate continuous 15-day stress. After 24 hours of stress a complex of shifts typical of an acute stress syndrome (mobilization of CF, reduction of the content of glycogen and creatine phosphate, increase of phosphorylase activity) was recorded. After 5 days of stress the absolute CF value reduced, particularly at rest (doubled), as a consequence of which the relative values of the maximally developing CF on the 5th second of an isometric load induced by compression of the aorta were 1.5 times those in the controls. The content of glycogen and creatine phosphate and the activity of phosphorylase were reduced by 25-30%. After 15 days the CF and the values of myocardial energy metabolism were normalized. Exclusion of the vagal tonus by atropine on the 5th day of stress showed that the low level of CF and reduced phosphorylase activity are not consequent upon heart exhaustion but are regulatory mechanisms.

Adaptation, Physiological↗
PubMedDate not supplied

[Effect of ions on determination of 3',5'-AMP by the method of saturation].

The effects of La2+, Pb2+, Ba2+, Zn2+, Ca2+, Mg2+, Mn2+, NH+4 in concentrations of 10(-7), 10(-5), 10(-3) M were studied as applied to the protein binding of cyclic 3' : 5' = AMP. It is shown that Ba2+, La2+, Pb2+ increase the binding, while Zn2+ has no effect, and Mn2+, NH+4 decrease the binding of 3' : 5' = AMP. The effects of Ca2+ and Cd2+ were dependent on the concentration. The maximal binding in the presence of Ca2+ and Cd2+ was observed at a concentration of 10(-5) M and 10(-3) M, respectively. It is suggested that Mg2+ and Ca2+ take part in the regulation of cyclic AMP binding with proteinkinase in vivo.

Barium↗
PubMedDate not supplied

[Contractile function of the heart in rats after chronic stress and thyroidin treatment].

We examined heart tolerance of rats, that had been exposed to two-month social stress, to acute overload caused by aortic coarctation and investigated physiological doses of thyroid hormones used to treat stress-induced tolerance changes. Cardiac contractility of rats adapted to chronic stress and exposed to overload was similar to that of controls and the functional maximum reached at the 5th second of aortic coarctation was 33-53% higher than that in the controls. However, tolerance of chronically adapted hearts measured by their ability to maintain increased contractility during 25 s aortic coarctation was 1.4-1.8 times lower. Thyroid hormones in physiological doses normalized tolerance of chronically stressed hearts to overload induced by aortic coarctation.

Adaptation, Physiological↗
PubMedDate not supplied

[Glycolysis activation, a decrease in the glycogen reserve and the absence of glucocorticoid control over the enzymes of carbohydrate metabolism in the liver of rats under prolonged hypokinetic stress].

The content of 11-oxycorticosteroids in blood plasma, the content of glycogen in the liver and the correlation of processes of glycolysis and gluconeogenesis in it (according to the activity of the key enzymes) were studied in rats in the course of chronic stress (on day 5, 15, 30, 45, and 60) induced by keeping the animals under conditions of severe hypokinesia. The 11-oxycorticosteroic content increased on the 5th, 45th, and 60th day of stress. On the 5th day processes of gluconeogenesis in the liver prevailed over processes of glycolysis, on the 60th day glycolysis prevailed over gluconeogenesis. On the 45th-60th days the content of glycogen in the liver reduces and the activity of the key enzymes becomes exempt from hormonal control.

11-Hydroxycorticosteroids↗
PubMedDate not supplied

[The functional status of the small intestine and lipid metabolism in diphyllobothriasis patients].

198 diphyllobothriasis patients have been examined before and 1-2, 4-6, 10-12 months after dehelminthization. The absorption of fats and carbohydrates by the small intestine was studied; total lipids, total phospholipids and their range in the serum were determined. Fucose content in the intestinal juice and the overnight portion of urine was determined for functional evaluation of the mucosal protective barrier. The studies revealed alterations in lipid and carbohydrate absorptions by the small intestine as well as that of the mucosal protective barrier in the gastroduodenal zone, and changes in lipid metabolic values.

Adolescent↗
PubMedDate not supplied

[Contractile function of the heart of guinea pigs after long-term continuous stress].

Guinea-pigs exposed to 60- and 100-day biosocial stress were used to examine the contractile function of the heart in the whole body and in an isolated state. A 60-day stress effect caused adaptation which included increases in the intensity of heart contractility and in its weight unit by 29% and 38%, respectively. Measurement of resistance of such an adapted heart to isometric load produced by a short-term aortic occlusion showed increases in maximal rates of its contraction and relaxation by 34-35%. After a 100-day stress-effect the strength and velocity of heart contraction and resistance to isometric load returned to normal; however, the intensity of the function of the weight unit increased by 27-32%. The effect of adaptation was also seen in an isolated heart: after a 100-day exposure the isolated hearts did not lose their ability to react to a greater preload according to Starling's law; moreover at the filling pressure 15 cm H2O their cardiac output increased by 50% as compared to the baseline. This observation suggests that the process of adaptation of guinea-pig hearts to chronic stress involves not only activation of central mechanisms of regulation but also enhancement of mechanisms of self-regulation but also enhancement of mechanisms of self-regulation.

Adaptation, Physiological↗