Age dependency of [ 3 H]-ouabain binding, 45 Ca 2? eflux and its magnetosensitivity in rats' brain cortex and heart muscle tissues were studied. Curves of dose-dependent [ 3 H]-ouabain binding consisted of three components with different affinities (10 -7 -10 -4 M (a 1 ); 10 -9 -10 -7 M (a 2 ); and 10 -11 -10 -9 M (a 3 )). These curves were also characterized by different dose-dependent kinetics. [ 3 H]-ouabain binding with a 3 receptors in brain cortex and heart muscle tissues of young and adult animals had a dose-dependent character, while that in old ones had a doseindependent character. A 0.2 T static magnetic field (SMF) exposure had modulation effect on ouabain binding with a 1 , a 2 and a 3 receptors in young rats, while in adult ones, only a 3 receptors were magnetosensitive. In old animals, SMF exposure had no significant effect on ouabain binding with a 3 receptors in brain cortex, while in heart muscle, it had inhibitory effect on it. Age-dependent effect of ouabain impact on 45 Ca 2? efflux showed that all concentrations of ouabain lead to inhibitory effect in young animals' brain cortex and heart muscle (with the exception of 10 -10 and 10 -6 M), while in old ones, it had activation effect as compared with data received without ouabain. SMF exposure in young animals had activation effect on 45 Ca 2? efflux from brain cortex and heart muscle in data without ouabain, and in old rats, 45 Ca 2? efflux from brain cortex was magnetic insensitive. In old animals, SMF increased 45 Ca 2? efflux even after extra low concentration of ouabain. It is suggested that a 3 receptors having a crucial role in the regulation of Na ? /Ca 2? exchange serve as age-dependent magnetosensors of excitable cells.

Non thermal (NT) effect of direct radiation 4 Hz-modulated 90-160 GHz of Millimeter Waves (MMW) and preliminary MMW-treated physiological solution (PS) influence were studied on snail isolated neuron, rat's brain tissue hydration and skin penetration. It was shown that the 4 Hz-modulated low intensity 90-160 GHz MMW direct radiation and MMW-treated PS leads to on single neuron shrinkage, skin and brain tissue dehydration. On the basis of obtained data it was suggested that the cell bathing aqua medium serve as a target through which the NT effect of MMW on cell hydration is realized. The MMW-induced brain tissue dehydration can considering as consequence of MMW-induced skin water structural changes leading to unknown messenger formation able to modulate the brain cell hydration. The extrasensitivity of cell hydration to low intensity of MMW radiation allow to recommend cell hydration as a cellular marker for estimation of the NT biological effect of MMW on cells and organisms.

Neuronal dehydration and high [Ca 2+ ] i are essential hallmarks for age-dependent memory impairment. Na M ouabain-induced tissue hydration is due to cAMP-activated Ca 2+-ATPase in endoplasmic reticulum membrane leading to reversion of Na + /Ca 2+ exchange and elevation of endogenous H 2 O release in cytoplasm. This effect has age-dependent depressing character. Thus, the dysfunction of α 3 isoform-dependent intracellular signaling system could be considered as a primary mechanism for age-dependent neuronal dehydration.

Based on our previous finding that metabolically controlled cell hydration is sensitive to the changes of physicochemical properties of cell aqua medium, which take place upon the effect of weak physical signals, including microwaves with non-thermal intensity (NT MW), it has been hypothesized that cell aqua medium serves as a primary target for NT MW effect on brain tissue. To elucidate the nature of the metabolic pathway through which the effect of NT MW-induced changes of physicochemical properties of cell aqua medium modulate cell hydration, the effects of intraperitoneal (IP) injection of PS treated by NT MW on brain tissue hydration, 45 Ca 2+ uptake, ] i), it is considered as a potential factor leading to the brain functional impairment, especially when brain metabolic activity is depressed (e.g. during aging).

Age-dependent effect of Static Magnetic Field (SMF) on rats in a condition of active and inactive Na(+)/K(+) pump was studied for comparison of brain tissues hydration state changes and magnetic sensitivity. Influence of 15 min 0, 2 Tesla (T) SMF on brain tissue hydration of three aged groups of male albino rats was studied. Tyrode's physiological solution and 10(-4) M ouabain was used for intraperitoneal injections. For animal immobilization, the liquid nitrogen was used and the definition of tissue water content was performed by tissue drying method. Initial water content in brain tissues of young animals is significantly higher than in those of adult and aged ones. SMF exposure leads to decrease of water content in brain tissues of young animals and increase in brain tissues of adult and aged ones. In case of ouabain-poisoned animals, SMF gives reversal effects on brain tissue's hydration both in young and aged animals, while no significant effect on adults is observed. It is suggested that initial state of tissue hydration could play a crucial role in animal age-dependent magnetic sensitivity and the main reason for this could be age-dependent dysfunction of Na(+)/K(+) pump.