Peculiar cellular mechanisms of effects of the low-dose ionizing radiation

In biological objects of different organization, peculiar, non-mutational cell changes have been revealed, which, unlike the known changes, might be responsible for development of the tissue, organ, and organism disturbances after low-dose loads. Myocardium capillary endothelium have been examined ultrastructurally in 236 rats irradiated in a dose 0.5 Gy as well as (to characterize the effect) in doses of 2.25 and 4.5 Gy. Similarly 28 intact control animals were studied. Already of the lowest dose, 0.5 Gy, has been established to produce an increasing appearance of damaged cells with signs of oedema, partial cytolysis of cytoplasmic structures and isolated damage of mitochondria. All these kinds of changes were also observed in control, but much less frequency. These changes fully develop already after the relatively small doses of ionizing radiation, are of a massive character and are practically irreversible. This effect is manifested as a steady rise in the probability of the cell injury and death as compared with the spontaneous level and can be considered a new setup of the cell homeostasis. (author)