Effects of X radiation on the synthesis and the amount of nucleic acids in rat liver, brain, and thymus

Quantitative changes of nucleic acids and the incorporation of 3H thymidine and of 14C orotic acid into rat liver, brain and thymus have been investigated in vivo during 7 days after single X irradiation with 154.8 mC/kg (600 R). There were no marked changes in the brain. Changes in the liver were mostly insignificant. In the thymus as one of the radiosensitive organs, DNA and RNA were reduced during the whole experiment, while the synthesis of nucleic acids, especially of DNA, was inhibited for a limited period. The incorporation of radioactive precursors was gradually increasing to a maximum at 48 hours for RNA, and at 72 hours for DNA. The results confirm the dependence of the extent of damage on the proliferative activity of tissues, and suggest a correlation between DNA concentration and radiation effect. (author)