[Ascorbic acid radicals induced by the action of radiation in tissues from rat organs frozen at 77 K].

Subsequent annealing technique and computer assistant analysis of EPR spectra were used to isolate an asymmetric EPR signal Rs(g = 2,0051; delta H = 0.8 mT) from the EPR spectrum of rat spleen gamma-irradiated at 77 K. Radicals with the same EPR spectrum were registered in: 1) water solution of ascorbic acid (2.10(-2) M, pH 3.4) frozen and irradiated at 77 K and 2) water-glycerol solution of ascorbic acid (10(-2) M, pH 10.3) frozen rapidly at the moment of intensive autooxidation. These model experiments allow to conclude that Rs signal is caused by the radicals of semidehydroascorbic acid. Radiochemical yield of these radicals as well as of all the radicals induced by gamma radiation in the whole rat tissues were measured. The EPR signal (Rs) is equivalent to the well known "artifact" signal of lyophilized tissues. The explanation of the mechanism of the radicals formation taking place under annealing of the frozen and irradiated tissues was suggested.