Repair during fractionated irradiation of the mouse bladder.

The capacity for repair of sublethal damage during fractionated irradiation of the mouse bladder has been measured. Graded doses of electrons were given as 1, 2, or 5 equal daily fractions. Two functional end points were used to assess bladder damage: (a) increased urination frequency and b) decreased bladder capacity. Repair of sublethal injury within 24 hours was found to be similar using both assays for bladder damage and was greater than the repair observed in mouse skin for a given dose per fraction. The possibility of a slower repair process occurring in bladder was investigated by giving two fractions in increasing overall times (from 24 hours to one month). No increased repair was observed with the longer time intervals; hence there was no evidence for slow repair in the bladder.