838 Kang et al FIG. 2. Ratio of bladder weight to body weight (A) and compliance (B) in sham rats, rats with bladder outlet obstruction (BOO) for 1 week, and rats with BOO for 2 weeks. Rats with BOO showed significantly higher ratio of bladder weight to body weight than did sham rats. Compliance was significantly lower in rats at 1 week and higher in rats at 2 weeks compared with that in sham rats. Results are expressed as mean±SEM. NS: not significant, Obs: obstruction group. ap＜0.01, bp＜0.001 (unpaired Student’s t-test). FIG. 3. The pressure parameters in sham rats, rats with bladder outlet obstruction (BOO) for 1 week, and rats with BOO for 2 weeks. (A) Basal pressure by detrusor pressure (DP). (B) Threshold pressure by DP. (C) Maximal pressure by DP. Results are expressed as mean±standard error of the mean. NS: not significant, Obs: obstruction group. ap＜0.05, bp＜0.01 (unpaired Student’s t-test). 3. Parameters to investigate detrusor overactivity during the filling phase Whereas the sham group showed no DO during the filling phase, the other two groups did. DO was demonstrated in all rats in both BOO groups (100%). However, the 1 week BOO group did not differ significantly from the 2 week BOO group in DO frequency or DO pressure (Fig. 6). DISCUSSION Our study showed that after the partial BOO, the rat blad- ders showed some sequential changes in bladder function in view of pressure and volume parameters and showed de- compensation from the initial phase of 1 week after the sur- gery in view of the residual volume percentage. The decom- Korean J Urol 2011;52:835-841