Nucleic Acid Changes in Rat Spleen after Localized X-Irradiation

Abstract

In the previously reported investigation (1) the effect of whole-body X-radiation on the content and composition of rat tissue nucleic acids was described. When these experiments were undertaken, the possibility was considered that localized irradiation to the spleen might not produce the same effect as total-body exposure, since it has been demonstrated by a number of investigators (2-6) that lead shielding of various parts of the body affords protection against the effects of X-radiation. Histologic alterations in the spleen after localized X-radiation to this organ are considerably less severe than after an equivalent dose to the whole body (7). A parallel study was therefore begun in order to be able to compare the effect of localized irradiation to the spleen and whole-body exposure on the content and composition of rat spleen ribonucleic acid (RNA) and deoxypentosenucleic acid (DNA). While this work was in progress a report appeared by Petersen et al. (7) wherein it was found that the effect on rat spleen adenosinetriphosphatase (ATPase), 5-nucleotidase, and DNA content was considerably smaller after 800 r localized X-radiation to the spleen than after exposure of the whole body to the same dose of X-rays. The present report is concerned with the histological appearance, weight, nucleic acid content, and nucleic acid composition of rat spleen after 400 r X-radiation to the spleen only. Comparison is made with data on the spleen from the previous study (1); the changes observed were considerably smaller than after whole-body irradiation with the same dose of X-rays.