Immediate effects of continuous beta-irradiation to the kidneys

Renal response to irradiation was examined over the course of 24 h in an animal preparation of continuous renal irradiation. Continuous beta-irradiation to the renal parenchyma was carried out in C57Bl6 mice by application to the surface of both kidneys of a 32P-impregnated anion exchange resin yielding an initial beta surface dose of approximately 30 cGy/min and approximately 2.3 cGy/min at a 2 mm depth. This technique proved easily reproducible and highly effective in causing immediate renal damage. In a kinetic study, the blood urea nitrogen (BUN) values of 5 week old mice exposed to continuous renal irradiation rose significantly (2 h: 21 +/- 4; 4 h: 33 +/- 4; 6 h: 42 +/- 5; 16 h: 65 +/- 8; and 24 h: 62 +/- 5 mg%) while that of sham-operated animals (provided with a nonradioactive resin) remained below 17 mg% throughout the entire observation period. When mice of various ages were exposed to continuous renal irradiation over a 16 h period, the functional changes were shown to be inversely correlated with the age of the animals (BUN at 5 week: 65 +/- 8; 8 week: 51 +/- 6; and 11 week: 20 +/- 2 mg%). Thus, our results indicate that continuous beta-irradiation to the kidneys promptly causes severe age-related renal functional deficits. This novel approach may offer an alternative to the current methods of investigation of radiation-induced renal damage.