The Effect of Whole-Body X-Irradiation on the Activity of Some Acid Hydrolases in Homogenates and Subcellular Fractions of Rat Spleen

Abstract

Recently the effects of total-body X-irradiation on the distribution of ribonuclease (RNase) in subcellular fractions prepared from rat spleen homogenates were described (1). It was reported that: (1) in animals exposed to 700 r, RNase specific activity increased twofold, as compared to control samples, 16 hours postirradiation, and returned to the control level 64 hours postirradiation; (2) total organ RNase activity increased 54% over the control level 16 hours postirradiation; and (3) 28% of the total RNase activity appeared in the supernatant fractions of control rat spleen homogenates, but 16 and 64 hours after irradiation this figure rose to 45% and 66%, respectively. Previously, Goutier-Pirotte and Thonnard (2) had observed that, 30 minutes after administering a dose of 800 r to rats, spleen homogenates contained 73% of the total deoxyribonuclease (DNase) activity in the supernatant fractions, whereas the value for the control preparations was only 43%. It was suggested (1) that the results observed with RNase could be explained by an increasing in vivo breakdown of lysosomal particles (3) after X-irradiation. With this in mind, it was considered of value to investigate other acid hydrolases-which characterize liver lysosomes-in spleen to determine if they would behave like RNase and DNase in animals given whole-body X-irradiation. The enzymes investigated were p-glucuronidase (P-G), acid phosphatase (Pase), and phosphoprotein phosphatase (PPase).