[The physiological characteristics of genetic predisposition to catalepsy in rats depending on the stage of selection].

Male rats with a genetic predisposition to cataleptic reactions revealed a reduced motor activity and a diminished activation of mineralocorticoid and testosterone synthesis in response to a mild stress as compared with the Wistar rats. The reactions, however, were exactly opposite in the Wistar rats with signs of cataleptic features. The data obtained suggest that, when creating genetic animal models of human diseases, the initial stages of breeding should correspond to early stages of the disease whereas advanced stages of breeding are similar to later, chronic phases of the disease.

[The sex and corticosteroid hormones of rats selected for estrous-cycle reaction to constant illumination].

Two substrains of rats selected for the high (ESTH) and low (ESTL) ability to develop permanent oestrus under constant illumination were produced. The concentration of estradiol, testosterone in blood and 11-OCS in blood and adrenals was studied in rats of the 29 th generation under normal day (14L : 10D) and constant illumination (CL). The concentration of estradiol in blood of control rats in proestrus was 61.

[The neurohormonal characteristics of rats selected for the duration of the passive defense reaction and for the threshold of neuromuscular excitability].

Two strains of rats, "genetic catalepsy" and "low-threshold", simulating some human psychopathological symptoms, were compared. Levels of brain monoamines and blood corticosterone and testosterone showed no common features in the strains studied. The levels of dopamine in amygdala and testosterone blood levels in rats of the two strains significantly deviated in opposite directions from corresponding controls.

[The circadian rhythm of the adrenal glucocorticoid function in female rats selected for the reaction of the estrous cycle to constant illumination].

Studies have been made of the circadian rhythms of a glucorticoid hormone, corticosterone, in the adrenals and blood serum in female Wistar rats from two substrains selected for high (ESTH) and low (ESTL) ability to develop permanent oestrus under constant illumination. Significant changes in parameters of the circadian rhythm of the hormone were observed in animals of the 26th generation of selection. Total alleviation of corticosterone rhythm in the blood was on observed in ESTL rats, while in ESTH animals maximum level of the hormone in the blood was shifted to the dark time.

[Modeling of unstable heat-mass air exchange in the lungs].

A mathematical model of the unsteady-state heat and mass exchange of expired air in the bronchial tree is suggested. The model includes heat and mass exchange between air and bronchial walls, and heat exchange between blood circulation and bronchial tree. A problem has been numerically solved as a unidimensional one in the quasi-steady-state formulation.

[Biosynthesis of corticosteroid hormones in the cortical areas of the rat adrenal during emotional stress combined with a salt load].

The experiments on male albino rats have shown that excessive salt uptake increases the functional sensitivity of the adrenal cortex to emotional stress (group fighting). Emotional stress in combination with a salt load induces a much greater increment in corticosterone and 18-oxy-11-deoxycorticosterone production by fascicular and glomerular adrenal zones through the activation of the pregnenolone pathway of hormonal biosynthesis. A relatively high aldosterone production was also retained.

[Effect of an antidiuretic hormone on the aldosterone level in the blood plasma of rats with chronic water load and limited sodium intake].

The concentration of aldosterone in blood plasma of rats with chronic water and restricted sodium chloride intake substantially rose after subcutaneous injection of the antidiuretic hormone pituitrin in physiological doses. No simultaneous increase in blood corticosterone was seen. The production of hormones by rat adrenals remained unchanged.

[Adrenal mineralocorticoid function in sodium deficit with adequate or excess water consumption].

Upon addition of 3H-progesterone to the incubation medium the in vitro aldosterone production by the capsular part of the adrenals increased in rats exposed to two-week restriction of sodium intake, while that of deoxycorticosterone and corticosterone declined. The specific activity of corticosteroids appreciably rose which could suggest a decrease in the intensity of pregnenolone production in the early stage of the biosynthesis. The peripheral plasma aldosterone level increased considerably.

[Corticosteroid biosynthesis in various water-salt dietary regimens].

The production of desoxycorticosterone, 18-hydroxy-desoxycorticosterone and corticosterone by the mouse adrenals increases in vitro whereas 18-hydroxy-corticosterone and/or aldosterone production falls to an uncertain level when the salt consumption rises from about 0.07 to 50 mekv per animal a day under conditions of water consumption ad libitum. Specific activity values of 3H-corticosteroids, being formed by the adrenal cortex capsule from 3H-progesterone, added to the incubated culture, decrease.

[Functional activity of the adrenal cortex and thymus of mice of strains AKR, C57BL/6, C3H/He and C3Hf].

The authors studied the relationship between the functional activity of the adrenal cortex before and after the ACTH administration and the thymus mass in AKR, C57BL/6, C3H/He, and C3Hf mice. Blood 11-OCS level of these mice proved to differ in accordance with the differences in the 11-OCS production by the adrenal glands. There was revealed no expected inverse correlative dependence between the basal blood glucocorticoid content and the thymus mass.

[Distribution of mineralocorticoid receptors in the kidney cells of rats with different levels of aldosterone in their bodies].

A metabolic method was applied to the study of the distribution of mineralocorticoid receptors in the kidney cells of rats at various aldosterone levels in the organism. A great number of binding sites of aldosterone in the cytoplasm and a low aldosterone-H3 binding by the nuclei of kidney cells was revealed in adrenalectomized rats, as well as in the animals kept under conditions of sodium load, when endogenous aldosterone was absent in the organism. A reduction of the number of binding sites in the cytoplasm and an increase of aldosterone-H3 binding in the nuclei was noted in the animals with a high content of the given hormone in the organism (sodium deficiency in food or aldosterone administration to the adrenalectomized animals).

[Binding of H3-aldosterone to cytoplasmic receptors of the kidney in various functional states of the organ target].

A study was made of the capacity of the cytoplasmic cell fraction of rat kidney to bind H3-aldosterone, depending on the level of Na uptake with food, and, consequently, on the intensity of aldosterone secretion by the adrenal glands. It was shown by Sketchard's method that there existed in the cytoplasmic fraction of the kidney cells of rats with a high and low level of aldosterone secretion two classes of receptors binding aldosterone with a different degree of affinity. The number of binding sites for aldosterone in the 1st class of receptors, more specific for mineralocorticoids in the animals with a low level of aldosterone secretion (Na loading), was double that in comparison with the animals with a high level of aldosterone (Na deficiency).