Dose-rate dependent effects of ionizing radiation on vascular reactivity.

This study was designed to investigate the dose-rate dependent effects of ionising radiation on endothelium- and NO-mediated reactivity of aorta and coronary vessels. Rats were exposed to acute ((137)Cs, 9 x 10(-4) Gy s(-1), 18 min) and chronic ((137)Cs, 2.8 x 10(-7) Gy s(-1), 41 days) radiation in 1 Gy dose.

[Systemic approach to radiobiological studies].

The principles of information theory were applied for analysis of radiobiological effects. The perception of ionizing radiations as a signal enables living organism to discern their benefits or harm, to react to absolute and relatively small deviations, to keep the logic and chronicle of events, to use the former experience for reacting in presence, to forecast consequences. The systemic analysis of organism's response to ionizing radiations allows explaining the peculiarities of effects of different absorbed doses, hormesis, apoptosis, remote consequences and other post-radiation effects.

[The effect of small doses of ionizing radiation on the physico-chemical characteristics of the membranes of peripheral blood lymphocytes of rats].

The fluorescence probe method was used for investigating the physical state of a total lipid phase of a bi-layer and an annular (near-protein) zone of the membrane lipids of lymphocytes in a peripheral blood of rats on the 10th day after a whole-body acute and chronic gamma-exposure to doses of 0.25, 0.5, and 1.

[The aspects of adenylate cyclase activity regulation in myocardium cell membranes during hypokinesia].

Nonstimulated and isoproterenol, GTF, GITF, NaF stimulated activities of the adenylate cyclase in sarcolemma in white rats' myocardium was studied after two weeks of hypokinesia. As was established, in restrained animals the sensitivity of adenylate cyclase to the specified agents was increased and transition to the bimodal GTF regulation took place. It is hypothesised that involvement of membrane-bound Gi-proteins in the adrenergic effects on cardiomyocytes is one of mechanisms of the cardiotropic effects of restraint and heart distresses.

[Modifying effect of incorporated 137Cs on the mechanism of adrenergic control of myocardial contraction].

Incorporated 137Cs (absorbed dose of 0.26 Gy) causes decrease of myocardial's contractile function and inotropic response to beta-adrenagonists effect, isoproterenol-stimulated adenylate cyclase activity and beta-adrenoreceptors affinity. Adrenergic effects, mediated by alpha-adrenergic structures on heart contractile function, on the contrary, become stronger, that is due to the increase of the receptors' density on sarcolemma surface.

[Structural state of the cardiomyocyte sarcolemma in animals of different ages].

Cardiomyocyte plasmalemma membranes of adult (12 months) and old (24-26 months) rats have been studied. Ageing is accompanied with an essential decrease of the content of the membrane protein SH-groups. We have found an increase in the fraction of strongly immobilized spin-labeled SH-groups, a decrease in that of unsaturated lipids, as well as an increase in that of lysophosphatidylcholine in old rats membranes.

[Structural and functional changes in the synaptic membranes of the brain during aging].

Below 37 degrees the mobility of lipids in rat brain synaptic membranes evaluated by the spin probe method is higher in old (24-26 months) than in young (5-6 months) animals. The number of ouabain receptors in membranes increases with age, while maximum rate and Km values are not changed. The relation between structural state of membrane and properties of ouabain binding centers is discussed.

[Age changes of structural state of synaptic membranes of brain].

In the brain synaptic membranes from old rats (24-26 months) in comparison with the mature ones (6-7 months) an increase was shown in disintegration rate with DDS Na, mobility of 5-, 16-doxyl-stearate spin probes and in thermosensitivity of acetylcholinesterase. The total number of SH-groups decreased. While protein composition remained constant lysophosphatidylcholine and saturated fatty acid content in old animals increased.