Keywords: nonstochastic effects, ionising radiation, low doses, epithelium, renal tubules, cell death, ultrastructural pathology, low radiation, damaged cells, male rats, nephrocytes, radiation effects
Unusual cellular effects of small doses of radiation: a massive, persisting, dose-independent increase in yield of ultrastructural pathology in the rat nephrocyte population
Electron microscopy and optical tests were used to observe the occurrence of damaged cells in the epithelium of renal tubules in white non-breed male rats after being irradiated with gamma rays in doses of 0.25 and 1.5 Gy. The duration of the study was 6 months. The data obtained were analysed from the viewpoint of the phenomenon of 'nonstochastic effects of low doses', which had been discovered earlier in various unicellular organisms and in the studies of postradiation subcellular damage in the capillary endothelium in rats' myocardium. It was shown that even at a dose of 0.25 Gy, there is a sharp increase in the spontaneous death rate of nephrocytes associated with an increase in occurrence of relatively light, predominantly local ultrastructural defects. The effect did not increase with a six-fold increase in dose (up to 1.5 Gy). It was observed at an early stage after the exposure (12 hours) and affected almost all animals. It was persistent during the whole period of observation and was not associated with mitosis. These characteristics do not fit the general concept about the stochastic nature of radiation effects. At the same time, these effects correspond with the phenotype of the studied nonstochastic damage.