Experiments with laboratory mice using the food produced in the areas contaminated with radiation have manifested that significant accumulation of 137Cs and concurrent external irradiation of the animals’ organisms cause various types of cytogenetic injuries: structural (primarily reciprocatory translocations) and genom (tetra-, hex-, onto- and higher level ploids). While the frequency of chromosomal aberrations in somatic cells increases together with the dose burden, this relationship is absent in sexual cells. Males have manifested the most pronounced cytogenetic effects (R.I. Goncharova, N.I. Ryabokon, 1995). It is believed that the difference in the pattern of dose-effect curves based on the frequency of chromosomal aberrations in somatic and immature sexual cells can be explained by a number of causes, including dose differences in the induction of reparative systems of sexual and somatic cells.

 

The effect of small doses of ionizing radiation upon the organism is explained by a number of researchers (A.H. Ejdus, 1996) from the point of view of the theory of non-specific responses of cells to the damaging effect. The theory is based on the principles of non-specific regulation of the activity of enzymes by low-molecular substances and compartmentalization of low-molecular substances in the cells. The result is that each portion of the cells maintains a low enough concentration of those substances which would strongly inhibit the evolving reactions of fermentation, while elevated concentrations in other compartments are adapted to the enzymes localized in them due to the differences in the concentration of effective control of various enzyme-ligand couples within the above range of non-specific regulation. According to this mechanism, it is enough to reduce the concentration of low-molecular components by reducing a portion of them using an external agent to destroy the integrity or permeability of the plasmatic membrane in order to stimulate the activity of some enzymes.

 

Small doses of radiation (I cGr) increase the adaptation response of the organism and only significantly higher doses intensify the inhibiting effect of reverse compartmentalization of cellular substrates due to the damage of the function of intracellular membranes.

 

V.A. Vetukh and V.N. Malakhovsky (1991) assume that dose dependencies in the appearance of a number of genetic disorders admit a linear threshold-free dependence. The effect of ionizing radiation upon the phospholipid layers of the membranes of erythrocytes lead to structural and conformation modifications of the latter due to intensified mobility and reduced degree of ordering (V.I. Dreval, 1993).

 

The surface charge of membranes changes, the viscosity of lipids reduces without any substantial modification of the structure of membrane proteins (V.I. Dreval, 1993).

 

Variations of the concentration of phospholipids in the membranes of mitochondrias of the fetus' and motherts liver have been registered after a single-time exposure to one and two Gy doses of ionizing radiation (I.A. Shirinova et al., 1992).

 

The above modifications of lipid-protein interactions persists until the 50th- 100th day after exposure (G.G. Egutkin et al, 1993), meanwhile pronounced modifications of membrane lipids are observed during the initial 50 days after exposure, the level of cholesterol increases, the relative concentrations of linoleic, arachidonic and other non-saturated fatty acids, the concentration of phospholipids reduce (G.G. Egutkin et al, 1993).

 

The damage of membranes, specifically inhibition of membrane enzymes Na+-, K- ATP-ase, Mg ATP-ase may be induced by irradiated solutions of sugars (I.P. Edimecheva et al., 1992).

 

Damage of the brain tissues is attributed to the toxic effect of a highly reactive nitrogen oxide (NO) appearing already during the first minutes after irradiation (V.L. Sharygin et al., 1994).