A Method for Recording Urethral Pressure Profiles in Female Rats

Shengfei Xu,Lei Xu,Guanghui Du,Biao Chen,Huibing Tan,Xiaohui Li,Michael Bader

doi:10.1371/journal.pone.0140851

Abstract

AimsUrethral pressure profile (UPP) and leak-point pressure (LPP) measurements as well as external urethral sphincter (EUS) electromyography (EMG) and videourodynamic analyses are the primary methods for evaluating urethral function in humans. However, UPP recording in female rats, a widely used animal model, is challenging due to their small body sizes. This study reports a novel method for recording UPP in female rats.Materials and MethodsSeventeen anesthetized female rats were studied. LPP data for 14 rats were included. The other 3 rats were excluded because of death or abnormal urogenital organs. UPP curves were recorded using a modified water-perfusion catheter system, with the lateral hole facing the 3-, 6-, 9-, and 12-o’clock positions in a randomized sequence. LPP, functional urethral length (FUL) and maximum urethral closure pressure (MUCP) were analyzed.ResultsThe mean LPP was 64.39 ± 20.29 cm H2O. The mean FUL and MUCP values at the 3-, 6-, 9-, and 12-o’clock positions were 12.90 ± 1.20, 16.70 ± 1.95, 13.90 ± 2.42, and 11.60 ± 0.97 mm, respectively, and 38.70 ± 11.85, 33.90 ± 11.82, 37.40 ± 11.95, and 71.90 ± 23.01 cm H2O, respectively. The FUL at the 6-o’clock position and MUCP at the 12-o’clock position were significantly greater than those at the other 3 positions. The FUL and MUCP of repeated UPP recordings were not significantly different than those of the first recordings.ConclusionsUPP recording using a modified method based on a water-perfusion catheter system is feasible and replicable in female rats. It produces UPP curves that sensitively and appreciably reflect detailed pressure changes at different points within the urethra and thus provides opportunity to evaluate urethral structures, especially the urethral sphincter, in detail. These results may enhance the utility of female rat models in research of urinary sphincter mechanisms.

Highlights

Due to their ready availability, female rats are widely used for investigations of lower urinary tract functions and the pathophysiology of certain common clinical entities, such as urinary incontinence, urinary sphincter injury, and bladder outlet obstruction, as well as for the development of new therapeutic modalities [1,2,3,4,5,6]
Urethral pressure profile (UPP) recording using a modified method based on a water-perfusion catheter system is feasible and replicable in female rats
It produces UPP curves that sensitively and appreciably reflect detailed pressure changes at different points within the urethra and provides opportunity to evaluate urethral structures, especially the urethral sphincter, in detail. These results may enhance the utility of female rat models in research of urinary sphincter mechanisms

Summary

Introduction

Due to their ready availability, female rats are widely used for investigations of lower urinary tract functions and the pathophysiology of certain common clinical entities, such as urinary incontinence, urinary sphincter injury, and bladder outlet obstruction, as well as for the development of new therapeutic modalities [1,2,3,4,5,6]. Urethral pressure profile (UPP) and leak-point pressure (LPP) assessments as well as external urethral sphincter (EUS) electromyography (EMG), and videourodynamic analyses are the primary methods for evaluating urethral function in humans [7,8,9,10,11,12]. While LPP measurement via suprapubic catheterization and EUS-EMG with surgically implanted electrodes are well-established and generally accepted methods for use in rats, recording UPP in this animal is challenging due to its small body size [1,2,3,4,5,6,10,11]. To the best of our knowledge, only one previous study has record UPP curves in female rats, and it was conducted with a 1.4 Fr. Mikro-Tip catheter pressure transducer by Walters and colleagues in 2006 [13]. The latest research progress was made by a German group, who used a novel micro-tip catheter to record UPP in female minipigs [14]

Results

Discussion

Conclusion