Pharmacological Studies on Chemical Protectors againt Radiation I. : Radiosensitivities of Mice against X-Irradiation

In order to establish the potency test for chemical radiation protectors, radiosensitivity of various strains of mice to X-ray irradiation was examined. The mice used were ddY, CF1, and CRF1 strainrs, and it was found that the survival rate 30 days after irradiation and the mean survival time were both effective indices of radiation injury. Since the variation in radiation dosage, and the strain and age of mice affected the radiosensitivity, optical conditions for biological assay of chemical radiation protectors were determined as follows. When using ddY strain mice, those of 4∼7 weeks of age should be used and given X-ray irradiation of 700R. With CRF1 strain mice, 600 R dose seems to be appropriate. In the case of CF1 strain mice, radiation dosage and variation in survival rate failed to show linearity and this strain of mice is considered to be unsuitable for this biological assay.