PubMed Health⌕ Search

Biomedical subjects

N A Slepchuk

Publications and source records attributed to N A Slepchuk.

At least 19 recordsLinked to original sources
PubMed1999

[Decrease in the lower limit of the rat brain vital activity by the physiological method].

The brain temperature, at which the cessation of the lung respiration occurs in the cooled animals, can be named the lower temperature limit of the brain functional competence, since at this temperature the spontaneous respiration is not restored on its own, and without special artificial undertakings the animals perish. In this study upon the total cooling of the rat bodies their lung respiration stopped completely as the temperature of the medulla oblongata in the region of the respiratory center decreased to 18.18 +/- 0.17 degrees C. This occurred simultaneously with an abrupt decrease in the heart rate and in the arterial blood pressure (AP) to 42 +/- 1 mm Hg. Upon an isolated cooling of the rat head the heart rate and AP were maintained at a comparatively high level. Under such conditions the lung respiration did not stop even as the temperature of the medulla oblongata decreased to 17.23 +/- 0.25 degrees C. It retained rhythmicallity, a particular rate, and a comparatively high amplitude. It is suggested that an intensive blood supply of the cooled brain decreases the lower temperature limit of its vital activity.

Animals↗
PubMed1995

[The effect of an elevation in the brain temperature of rats on respiration during immersion hypothermia].

After deep general hypothermia with arrest of breathing at 9-10 degrees C, the brain was rewarmed up to reappearance of breathing at 20.96 +/- 0.27 degrees C in white rats. The breathing became increased and regular only at 23.85 +/- 0.41 degrees C. The data obtained suggest that the cause of hypothermic arrest of breathing involves a direct effect of low temperature upon bulbar centres of the brain.

Animals↗
PubMed1992

[The temperature changes in different organs during immersion hypothermia].

Precise thermometry of the brain, liver, rectum, muscles and skin surface was performed in white rats in conditions of immersion of the body in water with the temperature 1 degree C. Breathing arrested within 15-18 min after immersion, their brain temperature being 16.7-18.2 degrees C, liver temperature 12.7-15.2 degrees C, rectum--10.4-15.5 degrees C, muscle 8.3-12.0 degrees C, skin surface--1.6-5.0 degrees C.

Animals↗
PubMed1992

[The temperature gradient values in the skin and their significance for thermoregulation].

The ambient temperature decrease from 32-35 degrees C to 15-17 degrees C was shown to increase the temperature gradient between the skin surface and its deep layers (2-3 mm from the surface) from 0.13 +/- 0.1 degrees C to 1.29 +/- 0.13 degrees C in humans. Considering the localisation of thermoreceptors in different skin layers, such a considerable gradient can be measured by the thermoregulation system and serve for determination of direction and intensity of heat flow across the skin.

Body Temperature↗
PubMed1991

[The coefficient of the useful action of muscle work in standard physical loading].

The efficiency coefficient of muscular work in 120 kg standard physical load, mean skin temperature, the ear canal's temperature, sweating, heart rate and oxygen consumption were measured in swimmers and field athletes as well as in control subjects not involved in sports. The coefficient was 25.2 +/- 0.7% in swimmers, 27.8 +/- 0.8% in field athletes, and 14.5 +/- 0.6% in control subjects. The efficiency coefficient can be used for estimation of training condition in sportsmen.

Adolescent↗
PubMed1990

[The specific characteristics of thermoregulation in athletes in different specialties].

Skin temperature in 10 sites, the temperature of the body "nucleus", sweating during physical loads in training were recorded in sportsmen of different specialization in different ambient temperatures. The body temperature was studied in conditions of cooling (26 degrees C) in water for 10 min. The temperature of extremities skin (hand, foot) dropped mode dramatically in sportsmen-swimmers during cooling in water as compared with skiers, gymnasts and the control groups. During physical work of 250 Watt, the temperature in external auditory meatus and of skin was more increased in swimmers than in other subjects. The greatest differences were found in temperature of hand, foot and forehead skin. When tested by the PWC170 technique, the thermoregulatory tension was less in sportsmen than in control group. The efficiency coefficient of muscular work seems to be higher in sportsmen than in the subjects with one-year training.

Adaptation, Physiological↗
PubMed1989

[Correction of the thermal status of the human body in threatened overheating].

The correction of the human organism thermal state was performed by means of the heat withdrawal from different parts of the body in conditions of overheating in a thermal chamber at 38-39 degrees C. Three series of trials were carried out. The 1st series involved blowing air of 18-24 degrees C at the hands in amount of 54 l/min which improved the thermal state of the subjects. The 2nd series involved passing of water through pipes put over shanks and feet (1.5 l/min), the temperature of the pipes surface being 15-18 degrees C. The improvement of the thermal state was the same as in the former series. The 3rd series combined both ways of cooling and induced the sensation of "comfort" or "coolness" in the subjects. The temperature in external auditory canal, the average skin temperature and the average body temperature dropped.

Adult↗
PubMed1987

[Temperature sensitivity of the hypothalamus as affected by an increase in the heat content of the body].

To obtain a vascular thermoregulatory response of the ear floor, the hypothalamus had to be heated by 0.59 +/- 0.03 degrees C. After preliminary intraperitoneal administration of subthreshold amount of heat (195.7 +/- 8.9 cal.) constituting 50.7 +/- 1.8% of the threshold (386.4 +/- 14.3 cal.) the hypothalamus had to be heated by 0.19 +/- 0.01 degree C only to obtain the same response in the animal. The change of own temperature sensitivity of the hypothalamus in increased heat contents of the organism might be an auxiliary mechanism for estimation of the heat contents changes by the organism.

Acclimatization↗
PubMed1981

[Temperature gradients in the skin and heat loss in various environmental temperatures].

Increase of the chamber temperature from 15 degrees to 30 degrees C induced a significant drop in the heat emission and in temperature gradients on the rabbit nose, back and abdomen skin (1.0--1.2 and 2.0--2.5 mm from the surface). The revealed reduction of the temperature gradient values is within limits of thermoreceptor sensitivity. One can assume that the thermoreceptors situated on different skin layers are able to measure the temperature gradients (i. e. the heat flows).

Animals↗
PubMed1979

[Role of changes in the body's heat content during the development of thermoregulatory responses].

Summation of temperature signals from different body parts was shown to occur in the temperature homeostasis maintenance, as revealed by the value delta to average . m . c, where delta to average--increment of the body average temperature, m--body mass, c--body specific heat. Raise of the rabbit heat condition by 245.9 +/- 35.8 cal/kg at ambient temperature 19-21 degrees C induces ear vasodilatation which is the thermoregulatory response aimed at the heat loss. Dropy of the rabbit heat condition by 266.9 +/- 21.5 cal/kg at ambient temperature 28-30 degrees C induces ear vasoconstriction. The heat condition seems to the object of regulation in the organism thermoregulation system.

Animals↗
PubMed1978

[Amplification factor in the thermoregulatory system at different environmental temperatures].

With the aid of a heater implanted into the hypothalamus, the temperature was raised in the medial preoptic area of the rabbit hypothalamus; Vasodilatation was observed at that in the helix and in the nose skin. The heat emanated during this response was measured with the aid of a dynamic biocalorimeter. The amplification coefficient in the thermoregulation system was calculated as the ratio: the heat emanated by the rabbit during the vascular thermoregulatory response--the heat introduced into the hypothalamus in the course of heating. At the temperature 20% in the calorimeter chamber, the amplification coefficient was 3.9+/-0.8, and at 24 degrees it was as high as 13.6+/-1.0.

Animals↗
PubMed1978

[Role of a decrease in the body's heat content on the thermoregulatory reaction of the vessels of the external ear].

At the constant ambient temperature 28--30 degrees C the rabbit ear vessels were dilated and their temperature was 34.8/0.1 degrees C. Administration of the 23--29 degrees water into the stomach entailed thermoregulatory constriction of the ear vessels within 15--25 min. The response occurred at various combinations of temperature changes in different parts of the body. The heat content of the rabbit body, as calculated by the blood temperature in the aorta arc, reduced by 266.3 +/- 26.2 cal/kg at the beginning of the response. The decrease in the organism heat content seems to serve as a signal for occurrence of a corresponding thermoregulatory response.

Animals↗
PubMed1977

[Thermoregulation in rats in a helium-oxygen environment].

Effects of 21% O2 + 79% He mixture at the normal pressure on temperature of different body areas, blood temperature, heat emission, heat production, and the muscle electrical activity were studied at ambient temperature 21-22 degrees C. Action of the mixture during 60 min increased the heat emission by 21%, heat production by 17%, muscle activity by 37%. In spite of this, the temperature decreased in hypothalamus, cerebral cortex, rectum, muscles, and under the skin, as well as the blood temperature in the aortic arch and in the v. cava anterior. The occurring increase in the heat production is insufficient for preventing the drop of the body temperature. The disturbance of thermoregulation in the helium-oxygen atmosphere seems to occur mainly because of the excessive increase in the heat emission.

Animals↗
PubMed1976

[Heat content of the body as a basic parameter of thermoregulation].

With the aid of thermometry and calorimetry, the role of the organism's heat degree for the vasomotor response of the ear skin was studied in the rabbit. The calorimetric temperature was constant (19-21 degrees C) throughout the experiment. The heat threshold varied from 86 cal/kg to 320 cal/kg, depending on the different initial heat degrees in the animal. The increase in the organism's heat degree is concluded to be the main mechanism for initiation of the heat loss responses.

Animals↗