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Biomedical subjects

N A Mal'tsev

Publications and source records attributed to N A Mal'tsev.

At least 19 recordsLinked to original sources
PubMed1996

[Corticosteroids limit the decrease in blood flow velocity in the microvessels of the gastric submucosal layer during stress in rats].

To evaluate the influence of stress and corticosteroids on blood flow velocity in gastric submucosal microvessels it was used intravital microfilming by means of a dark-field contact epiobjective. The plasma filled "gap" in the continuous erythrocyte flow were used as the markers to measure linear blood flow velocity. In unstressed rats the linear blood flow velocity was equal to 2.0 +/- 0.08 mm/sec (156 microvessels, 6.4 +/- 0.14 micron in diameter), calculated volume blood flow--(6.9 +/- 0.48) x 10(-5) microliters/sec. Stress (water immersion and restraint) led to a decrease of blood flow velocity in microvessels to more than double. A stress-induced decrease of blood flow velocity was more greater in rats with insufficient corticosteroid production. The linear velocity of blood flow of these rats was lowered to 0.6 +/- 0.06 mm/sec, volume blood flow to (1.6 +/- 0.21) x 10(-5) microliters/sec. Replacement corticosterone therapy increased the blood flow velocity. It was concluded that stress decreases blood flow in microvessels of gastric submucosa. The results revealed that glucocorticoids take part in normalization of blood flow of gastric microvessels during stress and this action can provide antiulcerogenic effect of corticosteroids which was shown by us previously.

Adrenal Cortex Hormones↗
PubMed1996

[The adaptation-protective effect of corticosteroids on the rat gastric mucosa and its mechanism].

The influence of stress-induced corticosteroid production on gastric ulceration, blood flow velocity in gastric microvessels and blood pressure was studied in rats. The role of plasma corticosteroids was investigated by means of blockade of the pituitary-adrenocortical system (PACS) and following corticosterone replacement therapy (400 mu/100 g b.w.). The blockade which was induced by Fi. hydrocortisone administration (7 days before stress, 30 mg/100 g b. w.) resulted in an insufficient corticosteroid production. To evaluate the influence of corticosteroids on blood flow velocity in gastric microvessels of muscular, submucosal and mucosal coats it was used intravital microfilming by means of a dark-field contact epiobjective. Stress (water immersion + restraint) induces an ulceration, a decrease in the systemic arterial blood pressure (3 h after stress onset) and a decrease in blood flow velocity in the gastric microvessels (3 h after stress onset). In rats with insufficient corticosteroid production stress-induced ulceration, a decrease in blood pressure and gastric blood velocity were more greater than in rats with intact PACS. Replacement corticosterone therapy corrected all parameters. The results revealed that antiulcerogenic effect of stress-induced glucocorticoid production is realised owing to normalisation of gastric blood supply which is provided by an increase in systemic blood pressure.

Adaptation, Physiological↗
PubMed1995

[The effect of stress and corticosteroids on the rate of blood flow in the microvessels of the gastric muscular coat of rats].

In order to evaluate the influence of stress and corticosteroids on blood flow velocity in microvessels of muscular coat of the stomach we applied intravital microfilming by means of a dark-field contact epiobjective. The plasma filled "gap" in the continuous erythrocyte flow were used as the markers to measure linear flow velocity. In unstressed rats the velocity was equal to 1.76 +/- 0.07 mm/sec (182 microvessels, 3.7-8.7 mu in diameter). Stress (water immersion and restraint) led to a decrease of blood flow velocity in microvessels to more than double. A stress-induced decrease of blood flow velocity was greater in rats with insufficient corticosteroid production. The velocity of blood flow in these rats was lowered to 0.62 +/- 0.04 mm/sec. Replacement corticosterone therapy increased the blood flow velocity. It was concluded that stress decreases blood flow in microvessels of muscular coat of the stomach as well as in microvessels of mucosa. The results revealed that glycocorticoids take part in normalisation of blood flow of gastric microvessels during stress.

Adrenal Cortex Hormones↗
PubMed1995

[The microcirculation in the cerebral cortex of rats at different stages of deep immersion hypothermia].

A 25-30 degrees C hypothermia significantly increased the capillary blood flow in the rat cerebral cortex. A deeper hypothermia (17-15 degrees C) led to a stable decrease in the blood flow up to initial level. Breathing ceased at this stage, the cardiac activity being evident for 30-40 minutes after this. Deep hypothermia also led to a reversible aggregation phenomenon which seemed not to hinder the blood flow.

Animals↗
PubMed1993

[The circadian rhythm of the formation of stress stomach ulcers in rats].

Areas of stress-induced gastric ulceration vary parallels with changes of corticosterone levels. The ulceration was greater in the morning during low basal corticosterone level than in the evening during high one. Adrenalectomy ceased the circadian basal rhythm of corticosterone and the rhythm of stress-induced ulceration. The decrease of ulceration in the evening seems to indicate an increase of the body adaptability resulting from the circadian corticosterone increase.

Adrenalectomy↗
PubMed1992

[A quantitative analysis of primate motor activity in a situation of delayed spatial choice. The individual behavioral reactions].

Speed of movements in food getting responses of baboons, total time of the response, trajectories of the movements and other parameters revealed obvious changes during formation of conditioned activity. The data obtained suggest that many quantitative characteristics of the primate motor activity are specifically related to various aspects of complex behavioral responses.

Animals↗
PubMed1992

[An analysis of the joint activities of primates in a situation of delayed spatial choice].

A leader-dominant baboon of a couple took practically all the food in the situation of spatial delayed choice. The subdominant baboon managed to get some food, too, using fast changes of behavioral tactics during the experimental session. The obvious negative state of the subdominant baboon resulted in a severe neurotic breakdown. Long delays in the experimental scheme enabled the subdominant to get up to 50% of the food reinforcement due to the dominant baboons mistakes. The role of changes in the tactics of the monkeys is discussed.

Animals↗
PubMed1991

[Changes in the blood flow velocity in the capillaries of the rat cerebral cortex in acute massive blood loss].

A statistically significant drop in the blood flow velocity in capillaries of the rat cerebral cortex occurred in 50-60% loss of the blood volume: from 1.32 +/- 0.1 mm/sec to 0.2-0.8 mm/sec even in 30-40% loss, resp. A more massive blood loss (50-60%) decreased the blood flow velocity with no subsequent restoration. Aggregates of elements were formed in the capillaries with subsequent hemostasis in this part of the vessel.

Acute Disease↗
PubMed1990

[Separate flows of erythrocytes with different degrees of oxygenation in the venous vessels].

Having studied the structure of the blood flow in pial microvessels of the rat brain, the blood flow in venules was shown to consist of separate erythrocyte flows divided by the plasma layers Visualisation of these flows is facilitated after isovolume hemodilution until the 20-25% hematocrit. The blood flows in the same microvessel were found to differ from each other essentially by the oxygen tension level and by the velocity of their transition.

Animals↗
PubMed1985

[Hyperemia in capillaries of the gastrocnemius muscle following stretching].

Microcine-tv-study of the isolated m. gastrocnemius' capillaries in 9 anesthetized cats determined the blood flow mean velocity as 0.73 +/- 0.12 mm/s with a considerable dispersion for 216 capillaries (variation coefficient = 120-160%). The temporal dispersion of velocities in a single capillary was insignificant (variation coefficient about 45%). Longitudinal stretch of the muscle for 1-2 cm decelerated the capillary blood flow up to its complete arrest. After 1-min stretch, the blood flow velocity increased by 0.30 +/- 0.06 mm/s in 148 capillaries; decreased by 0.22 +/- 0.07 mm/s in 35 capillaries and remained the same in 5 capillaries. Apart from this, 4 capillaries initially invisible, became apparent. Average data for capillaries corresponded to those of macro-experiments. Responses of individual capillaries seem to be unrelated to initial velocity of their location within the net, if only absolute values of velocities are to be analysed.

Animals↗
PubMed1985

[Topography and hydrodynamic heterogeneity in the terminal bed of the vessels of the gastrocnemius muscle of the cat].

The cine-TV technique acided to reconstruct the in vivo pattern of the vascular bed surface in the m. gastrocnemius of anesthetized cats. Existence of microvascular elements (modules) was confirmed as regularly repeated every 400-500 mus along the muscular fibers. A module includes transversal (oblique) precapillary arteriole and postcapillary venule interconnected with 3-12 parallel capillaries. Mean blood velocity in the capillaries was initially 0.73 +/- 0.12 mm/sec and during postelongation hyperemia it was 0.91 +/- 0.13 mm/sec, the velocity being slower in distal capillaries. This diversity was reduced in postelongation hyperemia. Mathematical modelling of blood flow distribution over different types of modules showed the blood flow velocity in the capillaries to depend on the ratio: total resistance of incoming and outgoing vessels against the resistance of the capillary part. Along with diminishing of the ratio, the diversity of perfusion must also diminish which has been corroborated in the course of experiments.

Animals↗
PubMed1982

[Microcirculation in the liver in normal blood oxygenation and hypoxemia].

Vital contact microscopy and microfilming were used to measure the blood flow velocity in hepatic sinusoids 11 +/- 1 microns in diameter. The white blood cells moving in the axis stream of the red cells were used as the markers to measure linear flow velocity. In normoxia it was equal to 0.29 +/- 0.01 mm/sec and the volumetric flow rate in a liver sinusoid as calculated from this value was about 1.65 . 10(-3) microliters/min. Breathing with the mixture of nitrogen and 7% oxygen evoked a decrease of arterial blood pressure down to 80-70 torr and oxygen tension in a. femoralis and v. porta down to 45 +/- 3 torr and 18 +/- 3 torr, resp., as compared with 77 +/- 3 and 41 +/- 2 torr in normoxia. The mean sinusoidal blood flow velocity increased by nearly 12% only (p less than 0.01). This suggests that the increased oxygen extraction is the main compensatory mechanism in liver tissue hypoxia.

Animals↗