Application and Limitations of Awake Cystometry in Sprague-Dawley Rats with Partial Bladder Outlet Obstruction as a Model of Overactive Bladder or Obstruction

ABSTRACT

PURPOSE: Partial bladder outlet obstruction (PBOO) in rats leads to changes in bladder function, such as obstruction and detrusor overactivity (DO). The aim of our study was to observe factors essential for the objective descriptions of PBOO rats as an overactive bladder model as well as an obstruction model under awake cystometry. We also aimed to investigate the urodynamic effects of PBOO objectively in view of DO-related parameters as well as conventional pressure and volume-related parameters. MATERIALS AND METHODS: PBOO was produced in 10 female Sprague-Dawley rats by ligating the proximal urethra over a 0.9 mm metal rod; 10 sham-operated rats were used as controls. Intravesical pressure (IVP) was recorded via an open catheter in the bladder, and intraabdominal pressure (IAP) via an intraabdominal balloon catheter. Continuous cystometry was performed 2 weeks after the PBOO procedure. Conventional and newly developed DO-related urodynamic parameters were investigated. RESULTS: PBOO led to a significant increase in bladder weight. Three rats showed the picture of decompensated bladder and were excluded from the analysis. The obstructed group showed some increased pressure- and volume-related parameters. They showed a DO frequency of 1.5+/-0.3/min, but the sham group did not. CONCLUSIONS: Our results showed that bladder decompensation can happen after PBOO, and we need to describe those exclusions accurately in reports. In conscious PBOO rats, simultaneous registration of IAP and IVP is needed for accurate investigations of DO, because PBOO can lead to DO as well as bladder hypertrophy.