Restoration of the functions of the respiratory center in rats after total cold paralysis.

White rats were cooled in water until respiratory arrest, which appeared at a brain temperature of 17.62 +/- 0.16 degrees C; animals were then removed from the water to a room at a temperature of 19-20 degrees C. Experimental animals were given 1 ml of 0.6% EDTA, which binds calcium ions, 1 min after the onset of respiratory arrest; controls received 1 ml of physiological saline. Electrical heaters were used to warm the medulla oblongata; respiratory recovery occurred at 6.0 +/- 0.3 min from the onset of respiratory arrest, when the medulla oblongata temperature was 18.62 +/- 0.15 degrees C. In controls, heating of the medulla oblongata to 18.84 +/- 0.17 degrees C did not restore respiration. EDTA bound calcium ions, facilitating transport of the excess quantities of these ions from the cell cytosol to the intercellular medium. Decreases in the cytosol calcium ion concentration to normal restored the normal regulation of metabolism in cells.

[Restoration of the respiratory center functions in rats after its complete cold-induced paralysis ]. / Vosstanovlenie funktsii dykhatel'nogo tsentra u krys posle ego polnogo kholodovogo paralicha.

White rats were cooled until cessation of their breathing (about 17.6 degrees C) and then transferred to a 19-20 degrees C room. The breathless rats were administered EDTA (experimental group) and saline (control groups). Within 6 min., warming of the brain stem to 18.6 degrees C caused restoration of breathing in experimental rats whereas the control rats remained breathless. The EDTA binds calcium ions in the cells' cytosol and thus restores the normal regulation of metabolism in the brain cells.

[Effect of Na2H2EDTA on the viability of rats' organism during hypothermia]. / Vliianie Na2H2EDTA na zhiznesposobnost' organizma krys pri gipotermii.

Effects of C-binding Na2H2EDTA (disodium salt of ethylene diamine tetraacetic acid) on the thermal control function of muscles and respiration in anesthetized rats of the Wistar strain cooled up to deep hypothermia were studied. Experiments were performed with the use of two cooling models, i.e. in water (10 +/- 0.2 degrees C) and air (-5 +/- 1 degrees C). Intravenous injection of 1 cm3 of the 0.6% Na2H2EDTA solution at 0.25 ml/min. was made first at the brain T = 24.0 +/- 0.4 degrees C and repeated at the brain T = 20.1 +/- 0.3 degrees C. Five to six minutes following injection the electrical myoactivity and respiration rate and amplitude grew up. The control experiments with injection of physiological solution were with null results. Injection of Na2H2EDTA reduced the thermal viability lower range as concluded from the drop of no-breathing temperature threshold and increase in tolerance period till respiration standstill by 10-15 min. It is supposed that physiological functions paralyzed by continuous cooling can be recovered by reducing active calcium in blood with intravenous Na2H2EDTA. This opens up brand new vistas for application of calcium-binding substances to assist overcooled organism.

[Effect of calcium ion level in blood on physiological functions in rat subjected to immersion hypothermia]. / Vliianie kontsentratsii ionov kal'tsiia v krovi na fiziologicheskie funktsii krys pri immersionnoi gipotermii.

I.v. administration of disodium salt of the ethylenediamine tetra-acetic acid to continuously immersed white rats intensified the rats' amplitude and rate of the respiration movement. I.v. administration of calcium chloride to the cooled rats diminished by 11.3% the respiration movement amplitude and by 20.7%--the muscles electrical activity. The findings confirm important role of the calcium ions in infringement of physiological functions under conditions of hypothermia.

[Decrease in the lower limit of the rat brain vital activity by the physiological method]. / Snizhenie nizhnei temperaturnoi granitsy zhiznedeiatel'nosti mozga krys fiziologicheskim metodom.

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.

[The maximal duration of respiratory arrest during hypothermia in white rats which it is possible to reverse by an increase in brain temperature]. / Maksimal'naia dlitel'nost' ostanovki dykhaniia pri gipotermii u belykh krys, pri kotoroi vozmozhno ego vosstanovlenie s pomoshch'iu povysheniia temperatury mozga.

Animals were cooled to 9-10 C, and the maximal reversible respiration arrest lasted 3.5 min. Irreversibility of the respiration arrest lasting longer than 3.5 min. seems to be due to the fact that increasing the brain temperature induces a discrepancy between the oxygen demand of the tissues and its contents which would lead to a brain hypoxia and its death.

[The effect of an elevation in the brain temperature of rats on respiration during immersion hypothermia]. / Vliianie povysheniia temperatury mozga krys na dykhanie pri immersionnoi gipotermii.

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.

[The temperature of different body organs in white rats being cooled in water and in the recovery period]. / Temperatura razlichnykh organov tela u belykh krys pri okhlazhdenii v vode i v vosstanovitel'nyi period.

In water cooling of white rats down to rectal temperature 17.37 +/- 0.03 degrees C, the temperature of the liver decreased by 1.13 +/- 0.03 degrees C more than in the brain. However, during independent recovery from the hypothermia, the liver temperature reached a higher value earlier than in other organs. This can be of importance for heating the organism.

[The temperature changes in different organs during immersion hypothermia]. / Temperaturnye izmeneniia v razlichnykh organakh pri immersionnoi gipotermii.

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.

[The temperature gradient values in the skin and their significance for thermoregulation]. / Velichiny temperaturnykh gradientov v kozhe i ikh znachenie dlia termoreguliatsii.

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.

[The coefficient of the useful action of muscle work in standard physical loading]. / Koéffitsient poleznogo deistviia myshechnoi raboty pri standartnoi fizicheskoi nagruzke.

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.

[The specific characteristics of thermoregulation in athletes in different specialties]. / Spetsificheskie osobennosti termoreguliatsii u sportsmenov razlichnoi spetsializatsii.

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.

[Correction of the thermal status of the human body in threatened overheating]. / Korrektsiia teplovogo sostoianiia organizma cheloveka pri ugroze peregrevaniia.

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.

[Temperature sensitivity of the hypothalamus as affected by an increase in the heat content of the body]. / Temperaturnaia chuvstvitel'nost' gipotalamusa pri povyshenii teplosoderzhania organizma.

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.

[Effect of increasing the heat content of the body on the temperature of the skin surface and various regions of the body underling it]. / Vliianie povysheniia teplosoderzhaniia organizma na temperaturu na poverkhnosti kozhi i pod nei v razlichnykh uchastkakh tela.

Artificial heating of the body (127.3 +/- 6.9 cal/kg) increased cutaneous temperature and subcutaneous one on the nose by 0.38 +/- 0.09 degrees and 0.38 +/- 0.10 degrees C, resp.; on the back - by 0.16 +/- 0.05 degrees and 0.18 +/- 0.05 degrees C, resp.; on the abdomen - by 0.19 +/- 0.04 degrees and 0.21 +/- 0.03 degrees C, resp.

[Temperature gradients in the skin and heat loss in various environmental temperatures]. / Temperaturnye gradienty v kozhe i teplootdacha pri razlichnoi okrazhaiushchei temperature.

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).