[Changes in gas composition of expired air during electric stimulation of the ventral medulla oblongata]. / Izmenenie gazovogo sostova vydykhaemogo vozdukha pri élektricheskoi stimuliatsii ventral'nykh otdelov prodolgovatogo mozga.

The experiments on urethane-anesthetized cats with the electrically stimulated ventral brain stem revealed that caudal ventral medulla at the depth of 1500 microns possesses structures whose electrical activation increases the level of carbon dioxide in arterial blood and in the end portion of expirate, on the one hand, and decreases the oxygen content in expirate and arterial blood, on the other hand.

[The organic macro- and microhemodynamics and the systemic circulation under the combined action of hypoxia and hypothermia]. / Organnaia makro- i mikrogemodinamika i sistemnoe krovoobrashchenie pri sochetannom deistvii gipoksii i gipotermii.

In regimen of the constant blood flow perfusion of shank and small intestine of cat combined effect of hypoxia (10% O2 in N2) and hypothermia (about 30 degrees C) involved a decrease in precapillary resistance, an increase in capillary filtration coefficient in both vascular regions, an increase in postcapillary resistance and in mean capillary pressure in the intestine, and their decrease in the shank. In hypothermia, the hypoxic stimulus induced insignificant shifts in all the parameters under study in both organs. Dependence of hypoxic changes of macro- and microhemodynamics on the activity of adrenergic receptors in the cooled organism was studied on decentralized shank of cat. After cooling of cat and blockade of alpha-adrenoreceptors hypoxic hypoxia caused much greater reduction of precapillary resistance of shank, more striking (by 3 times) increase of capillary filtration coefficient and the increase of capillary pressure and postcapillary resistance in contrast with their decrease to hypoxia under hypothermia before alpha-blockade. Beta-adrenoreceptor blockade had no influence on the changes of the resistance and exchange function of skeletal muscle (shank) blood vessels evoked by hypoxia under cooling. Systemic arterial pressure are diminished during hypoxia under the normothermic conditions of animals. Such kind shifts caused especially by the decreasing of the total peripheral resistance; cardiac output are small raised in this situation. But combined influence of hypoxia and hypothermia evoked the pressor shifts of the systemic arterial pressure because of less decrease of total peripheral resistance and more remarkable rise of cardiac output. Hypoxic stimulus caused both in normothermia and hypothermia conditions caused the rising of venous return.(ABSTRACT TRUNCATED AT 250 WORDS)

[Dependence of hypoxic changes in macro- and micro-hemodynamics on the activity of adrenoreceptors in the skeletal muscle in hypothermia]. / Zavisimost' gipoksicheskikh sdvigov makro- i mikrogemodinamiki ot aktivnosti adrenoretseptorov v skeletnoi myshtse okhlazhdennogo organizma.

Dependence of hypoxic changes of macro- and microcirculation on the activity of adrenergic receptors in the cooled organism was studied on decentralized shank of cat under perfusion with constant blood flow. After cooling of cat (to 30 degrees C) and blockade of alpha-adrenoreceptors hypoxic hypoxia (10% O2 in N2) caused (a) much greater reduction of precapillary resistance of shank, (b) more striking (by 3 times) increase of capillary filtration coefficient and (c) the increase of capillary pressure and postcapillary resistance in contrast to their decrease to hypoxia under hypothermia before alpha-blockade. Beta-adrenoreceptor blockade had no influence on the changes of the resistance and exchange function of skeletal muscle blood vessels evoked by hypoxia under cooling.

[Characteristics of conjugate functions of the vessels of skeletal muscles and intestines during separate and combined action of hypoxia and hypothermia on the body]. / Kharakteristika sopriazhennykh funktsii sosudov skeletnoi myshtsy i kishechnika pri razdel'nom i sochetannom deistvii gipoksii i gipotermii na organizm.

In regimen of the constant blood flow perfusion of skeletal muscles and intestine, hypoxia reduced precapillary resistance and increased the capillary filtration coefficient in both organs whereas postcapillary resistance and capillary pressure were reduced in the intestine and increased in the muscle. Hypothermia increased precapillary resistance in the intestine rather than in the muscle whereas the changes of the capillary filtration coefficient were contrary in both organs; postcapillary resistance and capillary pressure had a tendency to increase in the muscle whereas an increase in these parameters was quite evident in the intestine. Combined effect of hypoxia and hypothermia involved a decrease in precapillary resistance and distensibility of venous vessels, an increase in capillary filtration coefficient in both vascular regions, an increase in postcapillary resistance and in capillary pressure in the intestine, and their decrease in the muscle. In hypothermia (about 30 degrees C), the hypoxic stimulus induced insignificant shifts in all the parameters under study in both organs.

[Pre- and postcapillary resistance and transcapillary fluid exchange in the intestine under the effect of hypoxic and hypothermic stimuli in the body]. / Pre- i postkapilliarnoe soprotivlenie i transkapilliarnyi obmen zhidkosti v kishechnike pri deistvii gipoksicheskogo i gipotermicheskogo stimulov na organizm.

In increase of pre- and postcapillary resistance due to hypothermia, hypoxia induced no considerable shifts in back-ground values of the organ hemodynamics in the cat small intestine preparations constantly perfused with own blood.

[Decrease in the effectiveness of a hypoxic stimulus during cooling of the vascular bed of an organ]. / Snizhenie éffektivnosti gipoksicheskogo stimula pri okhlazhdenii organnogo sosudistogo rusla.

Acute experiments on cats using perfusion of the innervated calf muscle and small intestinal vessels with self blood at a constant blood flow rate have established decreased sensitivity of vessels (cooled to 30 degrees C) to hypoxic stimulus effect (inhalation of 10% O2 in N2). The essence of the phenomenon consists in considerably smaller deviations of pre- and postcapillary resistance, capillary filtration coefficient, mean capillary pressure during simultaneous exposure to cold and hypoxia than during separate application of hypoxic or hypothermic stimuli. Organ distinctions in the degree and direction of changes in vascular resistance and metabolism have been observed.

[Changes in systemic hemodynamics during exposure of the cooled body to hypoxia]. / Izmeneniia sistemnoi gemodinamiki pri deistvii gipoksii na okhlazhdennyi organizm.

In cats with normal body temperature, hypoxia (10% O2 in nitrogen) induced depressor shifts of the arterial pressure due to a drop of the general peripheral resistance, whereas in cooling of the organism to +30 degrees C a slight increase of the arterial pressure occurred. Hypothermia was found to reduce the degree of increase in the venous return in response to a hypoxic stimulus.

[Systemic hemodynamic shifts in the arterial and venous portions of the vascular bed in hypoxia]. / Sistemnye gemodinamicheskie sdvigi v arterial'nom i venoznom otdelakh sosudistogo rusla pri gipoksii.

A reduction of total peripheral resistance is of a major importance for depressor shifts of arterial pressure in moderate hypoxia. The hypoxic stimulus induces a deficiency of increment in cardiac output shifts as compared with venous return. An increment of venous return and cardiac output suggests that the compensation for the depressor shifts induced with the lack of O2 in air and blood, occurs on account of flow induces of the circulation system.

[Capillary filtration coefficient and the distensibility of the venous vessels of the small intestine in the process of high-altitude adaptation]. / Koéffitsient kapilliarnoi fil'tratsii i rastiazhimost' venoznykh sosudov tonkogo kishechnika v protsesse vysokogornoi adaptasii.

In acute experiments on cats, the increase of capillary filtration coefficient and venous distensibility in small intestine was revealed after 3-5, 14-16 and 29-31 days of high altitude adaptation (The Pamirs, 3370 m above sea level), the changes being more obvious (by 78% and 45%, resp.) after 3-5 days in comparison with low altitude control. The effects of noradrenaline on the small intestine precapillary sphincters and venous distensibility were preserved at high altitude, whereas regional blockade of alpha- or beta-adrenoreceptors exerted no effect on the results. The increased capillary filtration coefficient seems to be of great importance in "struggle for oxygen" at high altitude hypoxia, and this obviously depends on the opening of preexisting capillaries.

[Adrenoreactivity of the vessels of the small intestine during adaptation to high altitude in the cat]. / Adrenoreaktivnost' sosudov tonkogo kishechnika u koshek v protsesse vysokogornoi adaptatsii.

Responses of the resistance and capacitance vessels of small intestine to adrenergic stimulation and blockade were studied in acute experiments on cats after 3-30 days of high altitude adaptation (the Pamirs, 3370 m). In comparison to control (Dushanbe, 830 m) constrictor responses of the resistance vessels to noradrenaline and adrenaline were significantly increases at high altitude, whereas the dilator responses to beta-stimulator propranolol were obviously reduced. Changes of venous blood outflow from small intestine in response to catecholamines at high altitude exceeded the control values. Pharmacological analysis suggests that the reactivity of alpha-adrenoreceptors of the small intestine resistance and capacitance vessels at high altitude was increased, whereas the beta-reactivity of the resistance vessels was reduced. Crucial shifts of the adrenoreactivity occurred after 3-5 and 14-16 days of the adaptation.

[Chemosensitive structures of the medulla oblongata participate in blood pressure regulation and belong to APUD-system]. / Uchastie khemochuvstvitel'nykh struktur prodolgovatogo mozga v reguliatsii arterial'nogo davleniia i ikh prinadlezhnost' k APID-sisteme.

It was shown in 25 experiments on anesthetized spontaneously breathing and immobilized artificially ventilated cats that the cooling of the intermediate chemosensitive area of the ventral surface of medulla oblongata to 20-22 degrees C is followed by depressor reaction that is more pronounced after preliminary occlusion of the sinocarotid and vagus nerves. Two types of apudocytes were revealed in this brain area with the use of the histochemical and immunohistochemical techniques. The first type cells are typically nervous and contain noradrenaline. The second type apudocytes adjacent to the microvascular wall showed melatonin and its precursors. It is assumed that the cells detected participate in the arterial pressure control.