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As it was shown by us earlier, side population (SP) cells are more resistant to the low-LET radiation than the other part of mouse melanoma B16 cells (Matchuk et al., 2012). The aim of our research was finding some mechanisms of radioresistance, therefore we analyzed SP and nonSP cell cycle distribution, spontaneous and radiation induced DNA double-strand breaks (number of γH2AX foci) and intracellular NO concentration. The results indicate that SP cells have significantly less DNA double-strand breaks after irradiation at dose of 3 Gy than nonSP cells (24.4 vs 40.3, accordingly, P < 0.05 Mann-Whitney Ucriterion). SP cells are more quiescent compared to nonSP G1/G0 fraction is 85 vs 39%, accordingly, P < 0.01 Mann-Whitney U criterion). Most nonSP cells reside in S, G2/M phases (61%), believed to be rather radiosensitive. Thus, the difference of SP and nonSP cells radiosensitivity can be partly explained by peculiarities of cell cycle distribution. NO concentration is 1.5 times higher in SP than nonSP cells (P < 0.05 Mann-Whitney U criterion); since it is known that NO inhibits apoptosis, being one of the mechanisms of genetic stability maintenance, greater number of spontaneous DNA double-strand breaks in SP cells is unsurprising (P < 0.05 Mann-Whitney U criterion). The above-listed results explain considerably the higher resistance of SP cells to the action of low-LET radiation in comparison with other melanoma B16 cells. Further study of this question can become the basis for development of tools to target SP cells and, ultimately, more effective cancer treatment.

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The results of radiative and of chemical monitoring show definite contamination of this zone by 90Sr and toxic metals. The essential local contaminations of geosystems (up to 2.3 x 10(4) Bk/kg of soil) require in environmental condition assessment at biocenosis level. Biotesting found the increase of metallothioneines levels in kidney (up to 15.63 microg/g of tissue) and liver (up to 19.22 microg/g of tissue) of rodents inhabited in the region of RWS placing as compared with the control group (3.51 and 4.44 microg/g of tissue accordingly). Besides, the decrease of total quantity of leucocytes (by 14.5% as compared with the control group) and absolute quantity all forms of them in animal blood were noted. It was assumed the increase of protein--MT is the result of complex influence by ionizing radiation and toxic metals.

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In chronic experiments on conscious and quiet rats norepinephrine, isoproterenol, ether, hexenal and ketamine narcosis decreased the cerebral fraction of cardiac output but increased transcapillary filtration in tissues of rubidium chloride and blood supply in the capacitive part of blood vessels. The changes produced by pyroxan, obsidan and ornid in the same conditions were insignificant. A decrease of the cerebral fraction of cardiac output, an increase of transcapillary filtration of rubidium in the brain tissues and regional blood supply took place under the action of pyroxan, obsidan and ornid in experiments with immobilization of rats.

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Regional changes of circulation after injection of pirroxan, obsidan and ornid depended on functional state of rats. The differences were significant in systemic hemodynamic and regional changes of resistive, transcapillary exchange and the blood volume function of the circulation.

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The content of aldosterone (A) was studied in rat adrenal glands, blood plasma and peripheral tissues--in the myocardium, skeletal muscles, thymus and liver--1 h after the administration of alpha-adrenergic stimulator noradrenaline and beta-adrenergic stimulator isoprenaline and after simultaneous administration of alpha- and beta-blockers and a sympatholytic agent (pyrroxan, propranolol and bretylium tosylate respectively). Adrenergic stimulation did not change the level of A in the adrenal glands, raised its blood concentration and, to a greater extent, its level in the peripheral tissues. A marked increase in the blood concentration of A resulted from isoprenaline and its accumulation in tissues--from noradrenaline. A decrease in the level of adrenergic activity considerably lowered the A content in the adrenal glands, blood plasma and peripheral tissues excluding the myocardium where this value was higher than in the blood.

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The muscle and adrenal fractions of cardiac output increased after injection of isoproterenol. The relative blood flow increase in skeletal muscles was accompanied with the increase in regional by-pass blood flow. The latter or reduction in the vessel permeability were found in the lungs. The cardiac output fractions decreased in extensive areas of skin, brain, myocardium, internal organs of hepatic portal vein, kidneys, testicles. The signs of the blood flow increase were found in the brain, myocardium, liver. The relative blood volume decreased in the majority of internal organs and tissues while increasing in the liver.

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Inhalation of diethyl ether and intraperitoneal injection of hexenal in doses that provide a surgical state of anesthesia are accompanied by changes in the regional tone of the resistive blood vessels as well as by those in the ratio between the nutritive and shunting fractions of the blood flow in organs and tissues. The increase in the rate and enlargement of the area of transcapillary metabolism in the brain and myocardium (notwithstanding the decrease of the total blood flow in these organs) by means of the increased shunting fractions of the blood flow in vast skin and skeletal muscle areas are considered to be the most important events. Diethyl ether and hexenal cause different changes in the hepatic and renal hemodynamics.

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Emotional stress was stimulated by placing rats in a tight cage (moderate stress) or fixing them rigidly on a bench (marked stress) for 1 hour. In moderate emotional stress, the coronary fraction of cardiac output and effective myocardial blood supply declined considerably. Marked emotional stress caused a similar reduction in the cardiac output coronary fraction, whereas effective myocardial blood supply was not reduced, but, on the contrary, tended to increase. The decrease in coronary fraction was not related to adrenergic effects. Marked emotional stress provoked regional changes in the resistance, microcirculatory and capacity components of the vascular bed, an adaptation to enable effective myocardial blood supply and enhance cardiac activity. It was accompanied with kallikrein-kinin activation.

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A preliminary pharmacological desympathization (pirroxan, obzidan, ornid) decreased blood pressure, heart rate, cardiac output, and increased total vascular resistance in immobilized rats. The fraction of cardiac output decreased in lung (bronchial blood flow), liver and myocardium and increased in other organs and tissues. Relative blood supply increased in expansive regions of the skin, muscles and splanchnic organs but decreased in the liver. Opposite changes of transcapillary permeability were found in vascular regions of the skin and skeletal muscles as well as in splanchnic organs.

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The methods of radioactive detection and external radiometry were used to study the distribution of blood in cats and rats during 24 hours after heart arrest. Labeled albumins (131I) and erythrocytes (51Cr) were used as blood indicators. The animals after death were stored in a horizontal or, in some tests, in vertical position at room temperature. The activity was measured in the horizontal and sagittal planes in strictly defined sites (30 altogether) or by scanning of the entire body within 3-5 min after circulation arrest as well as at 5 and 24 hours. No significant changes in distribution of plasma and erythrocytes during 24 hours postmortem in the horizontal position were shown to occur, while in the vertical position there was an insignificant increase of the blood content in the lower part of the body.

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The main characteristics of systemic hemodynamics and relative changes in the blood content, blood flow and uptake of intravenous 86Rb in several tens of organs, tissues and parts of the body were examined in rat experiments 6 days after ligation of the common bile duct. This made it possible to appraise the resistive, capacitance and capillary constituents of the general peripheral vascular resistance. In this case the fractions of cardiac discharge diminished in a number of the internal organs of the abdomen and increased in muscle and bone tissues of the chest. The signs of extensive venodilation were defined, with these signs being the least remarkable in the liver and lungs. Transcapillary permeability for 86Rb substantially increased in the organs of the splanchic area and in the lungs.

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