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A study was made of the radioprotective and therapeutic effect of potassium orotate on rats subjected to whole-body gamma-irradiated with doses of 11, 9 and 4 Gy. The preparation exerted a radioprotective action when administered intraperitoneally 60 min before irradiation as was estimated with a reference to the survival rate and leukocyte level in the peripheral blood. Fron the analysis of the peripheral blood consumption it was inferred that potassium orotate weakened the radiation damage and enhanced the recovery processes during the postirradiation period.

Using the method of electrophoresis in agar gel of superhelical plasmid DNA, which served as a substrate for determining endonuclease activity, the authors showed that the same radiation dose influenced in a different way the activity of acid and alkaline DNAases in rat blood serum. At early times (3-6 h) following irradiation, the activity of acid nucleases increased whereas that of alkaline DNAases decreased.

During the first hours following nonuniform gamma-irradiation (the nonuniformity coefficient was 3:1 and 5:1 with a dose change along the axis directed cranio-caudally and caudo-cranially), endonuclease activity (pH 5.75) in the blood serum increased with the dose which was estimated with a reference to total utilization of the substrate. Supercoiled plasmid DNA served as the substrate. The transformation of a supercoiled form of plasmid DNA into an open circular form was the criterion of estimation of nuclease activity. It was shown that the increase in the nuclease activity correlated with the increase in the nonuniformity coefficient.