A STUDY OF THE NATURE OF THE EFFECTS OF X RAYS ON THE ACTIVITY OF TISSUE PROTEIN-ASES

Rats were given a whole-body x-ray dose of 600 r (series 1), a local dose of 600 r to the spleen with the rest of the body shielded with 3 mm lead (series 2), and a whole-body dose of 600 r with the spleen covered with 3 mm sheet lead (series 3). The mice were killed 5 minutes, 2, 24, 48, and 96 hours after the irradiation in order to determine the cell count in the spleen and liver, and to determine the proteolytic activity in the tissue by the rate of degradation on incubation in an acetate-phosphate buffer at a pH of 4.8 of a 1% casein solution. The build-up of tyrosine determined spectrophotometrically at a wavelength of 275 m mu was a measure of the proteolytic activity. The results show that the proteolytic activity of the spleen in whole-body irradiated animals is most pronounced 48 hours after the irradiation. Local irradiation of the spleen with the rest of the body shielded with lead does not result in an increase of proteolytic activity. There is a decrease in weight of the spleen during irradiation. The proteolytic activity of a liver extract after a whole- body irradiation reaches its maximummore » four days after the irradiation. The necrotic changes in the spleen are not related to its proteolytic activity. (TTT)« less