Indirect Effect of X-lrradiation on Spleen Acid Deoxyribonuclease Activity1

As in previous studies, the CF-1 mouse, 10 to 14 weeks of age, was used. The apparatus was a 250-kv machine, 1 mm aluminum, 12 mm HVL copper filtration, target-to-tissue distance 75 cm. This provided a field that was homogeneous within 5 % over a diameter of 20 cm and a dose rate of 32 r/min. For irradiation of the whole mouse with the spleen exteriorized and shielded, the spleen was mobilized through an abdominal incision under anesthesia (0.075 mg of sodium pentobarbital i.p. per gram of body weight) without sacrificing any of the vessels supplying the spleen. The spleen was enclosed in a lead box, 7 mm thick, with a slot in its side, 3 x 10 mm, through which the pedicle extended. The spleen was wrapped in gauze wet with saline. After irradiation the spleen was replaced into the peritoneal cavity, and the incision was closed with wound clips. Unirradiated control animals were similarly operated and handled, except that they were not placed in the X-ray beam. Irradiated controls were also similarly prepared, but the spleen wrapped in gauze wet with saline was not shielded during X-irradiation.