The Catabolism of Nucleic Acids in the Rat

Summary

³H-thymidine was injected into rats three days before x- or sham-irradiation. Alterations in synthesis and replacement of DNA after irradiation were estimated on the basis of the changes in specific activity of DNA one to three days after exposure. Urinary β-amino isobutyric acid was also isolated in order to gain insight into radiation-induced changes of the specific activity in the precursor pools of DNA. On the third day the specific activity of DNA was lower in spleen and thymus and higher in the intestine of x-irradiated animals than that of sham-irradiated animals. The specific activity of β-amino isobutyric acid was somewhat higher on the first day and lower on the second and third day after x-irradiation than that of sham-irradiated rats. The significance of these findings in terms of inhibition of DNA-synthesis, alterations in DNA replacement and destruction of cells is discussed.