[Characteristic of organism reactivity during repeated hypoxic exposures of rats varying in resistance to ionizing radiation].

Wistar rats were used in the experiment on correlation of radiation sensitivity of the organism with tolerance of repeated acute hypoxia. Experimental rats (n = 100) were numbered and "raised" to 11,200 m thrice before exposure to 8.0 Gy with a dose rate of 3.0 Gy/min. Tolerance of hypobaric hypoxia was determined by the time of pose reflex sustention (PRST) and recovery (PRRT), the PRST/PRRT ratio, and the body temperature drop. Lethal effect was taken as the measure of radiation sensitivity. Controls were 58 rats exposed to equal radiation conditions but without preliminary testing by hypoxia. Unlike radiation sensitive rats, during second testing PRST in the radiation resistant specimens increased against PRRT shortening after termination of decompression and lessening the load on adaptative reaction (lower level of hypoxic hypothermia). The conclusion is that the method of repeated hypoxic tests enables to feature individual tolerance and adaptation of organism to the non-radiation factor in specimens distinguished by resistance to ionizing radiation.