Modification of the radiation response of the mouse kidney by misonidazole and WR-2721.

The radiation response of the mouse kidney has been assayed after a range of X ray doses given with or without the nitroimidazole misonidazole or the aminothiol WR-2721. Sensitization and protection of the kidney were investigated by comparing the X ray dose needed to achieve a particular level of injury in the presence or absence of the drug. Two functional assays and kidney weight at sacrifice were used to obtain dose response curves. Urine output and 51Chromium EDTA excretion were used as functional assays at 25 and 49 weeks after irradiation. They demonstrated no radio-sensitization by misonidazole with 1, 2 or 5 fractions of X rays. Significant radioprotection was seen when 400 mg kg 1 WR-2721 was given before single X ray doses (PF = 1.34). Similar radioprotection was observed when renal weight at 1 year after irradiation was used as the third assay of damage. These results confirm that the kidney responds as a well-oxygenated normal tissue with only a small protection being afforded against radiation injury by WR-2721.