The Effect of Whole-Body X-Irradiation on the Distribution of Acid Deoxyribonuclease and β-Galactosidase in Subcellular Fractions of Rat Spleen

Abstract

The distribution of acid DNase activity in spleen subcellular fractions of rats given 700 r of whole-body x irradiation was determined 16 and 64 hours postirradiation and compared to that in pair-fed controls. In the controls, the percentage distribution in nuclei, mitochondria, microsomes, and supernatant fraction was 25.8%, 30.6%, 10.7%, and 32.5%, respectively. Sixteen hours after irradiation this had changed to 15.9%, 26.9%, 13.1%, and 44.2% for the same fractions, respectively. There was no further significant change at 64 hours. Considerable increases in specific acid DNase activity were measured in the homogenate and all fractions 16 hours postirradiation; smaller changes were observed at 64 hours. At 16 hours postirradiation, evidence was obtained for a small net increase (14.5%) in total spleen DNase activity, compared to that in controls, and it was suggested that this increase might be caused by either increased enzyme synthesis or increased susceptibility of spleen lysosomes from irradiated animals to breakage during isolation and assay. In spleen of control animals, 67% of the BETA -galactosidase activity was found in the supernatant fraction, and 700 r of whole-body x irradiation did not significantly alter the distribution of this enzyme in subcellular fractions at either 16 or 64 hoursmore » postirradiation.« less