[Stimulating effect of partial cystectomy on regeneration of rat bladder urothelium and its significance for carcinogenesis (author's transl)].

Cell proliferation kinetics of the urinary bladder urothelium have been analyzed in a total of 218 female Wistar rats after partial cystectomy. After one-third resection of the bladder DNA synthesis started 15 h postoperatively in the bladder stump and reached its maximum at 25 h with a mean 3H-TdR index of 10.1%. In the area of resection the proliferative activity increased after 20 h and the highest 3H-TdR index was found to be 24.7% after 45 h. In the case of hemicystectomy the labeling index in the stump increased 15 h postoperatively and the highest 3H-T-dR index was determined at 20 h with 16.6%. The urothelial cells in the area of resection began to proliferate synchronously with those in the stump and the maximum of DNA synthesis was measured 35 h postoperatively with an 3H-TdR index of 24.2%. After 2 weeks the proliferative activity within the stump and operative region corresponded to that of the control urothelium. The basal cells showed absolutely the highest proliferative activity, the suprabasal cells exhibited on the other side the highest regenerative potential compared with the control urothelium. Partial cystectomy might possibly serve as an experimental model for testing low potential carcinogens, in the case where carcinogenic effects would be initiated, potentiated and accelerated via stimulation of the DNA synthesis.