Some short-term cell kinetic effects of ionizing radiation on mouse bladder urothelium.

Early morphological changes and the pattern of reactive proliferation of the hairless mouse urinary bladder urothelium after irradiation are reported. Groups of female hairless mice were anaesthetized with sodium pentobarbital and irradiated over the bladder region with 0, 10, 20 and 30 Gy. Control groups were sham-treated. Short-term cell kinetic changes were monitored using incorporation of tritiated thymidine and flow cytometry. Only minor radiation-induced alterations in the cell kinetic pattern were recorded, and no significant histomorphological changes were seen. However, a marked increase in the thymidine incorporation was seen in the control animals on the first day after anaesthesia. Radiation proctitis induced early deaths in the 30 Gy irradiated animals. The present results are in accordance with commonly accepted radiobiological theories, but not in agreement with results previously published by others.