Changes in bladder function with time following cystostomy in rats

To investigate bladder function patterns following cystostomy and determine the best time window for cystometric evaluation of bladder function in conscious rats.

Cystostomy was performed in rats of the first seven groups; thereafter, cystometry was performed in the designed time interval. Noncystostomy rats of group 8 voided freely as control. Basal bladder pressure (P_ves.basal ), maximum bladder pressure (P_ves.max ), bladder threshold pressure (P_ves.thre ), voiding interval (VI), bladder contraction duration (CD), bladder compliance (ΔC), voided volume (VV), postvoiding residual urine (PVR), and bladder capacity (BC) were recorded and compared with cystostomy groups, with VV, PVR, BC compared with the control values. Bladders were collected after the urodynamic study for weighing, hematoxylin-eosin, and Masson staining to investigate pathological changes.

P_ves.basal , P_ves.max , and P_ves.thre trended downward, while BC, VI, VV, and ΔC trended upward on days 1 to 5 postcystostomy. BC and VV significantly decreased on days 1 to 3 postcystostomy compared with control values; on days 5 to 15 postcystostomy, P_ves.basal , P_ves.max , P_ves.thre , VI, VV, BC, and PVR were stable, and BC, VV, and PVR showed no significant differences from the control values. However, on day 21 postcystostomy, BC increased significantly compared with the controls. Bladder weight increased in the cystostomy groups compared with the controls. Pathological analysis showed severe acute bladder inflammation on days 1 to 3, mild inflammation on days 5 to 15, and increased collagen deposition in bladder tissue on day 21 postcystostomy.

Cystometric evaluation of bladder function in conscious rats is best performed on days 5 to 15 postcystostomy.