Selection of a control rat for conscious spontaneous hypertensive rats in studies of detrusor overactivity on the basis of measurement of intra-abdominal pressures.

Abstract

AIMS: We investigated which animal model is appropriate as a control for the spontaneous hypertensive rat (SHR) in studies of detrusor overactivity (DO). METHODS: Age-matched SHRs (n = 10), Wistar-Kyoto (WKY) rats (n = 9), Wistar-ST (Wistar) rats (n = 10), and Sprague-Dawley (SD) rats (n = 10) were studied. A balloon-fitted catheter was positioned in the abdominal cavity to record intra-abdominal pressure (IAP). Cystometric pressure- and volume-related parameters and DO-related ones during the filling phase were investigated. Of the intravesical pressure (IVP) rises above 2 cmH(2)O, DO was defined as a rise in IVP without a simultaneous change in IAP and was counted during the filling phase. RESULTS: Compared with SHRs, the WKY rats did not show a significant difference in pressure or volume parameters, but Wistar rats and SD rats showed a significant increase in volume parameters, such as bladder capacity, micturition volume, and micturition interval. Typical DO was seen in SHRs and WKY rats during the filling phase, but not in Wistar and SD rats. Furthermore, the frequency and increased amplitude of the DO were similar in WKY rats and SHRs. CONCLUSION: Although WKY rats are an appropriate control for SHRs in studies of hypertension, they may be inappropriate as controls in studies of DO, because they have inherent DO of similar frequency and amplitude as found in SHRs.