Analysis of Continence Reflexes by Dynamic Urethral Pressure Recordings in a Rat Sress Urinary Incontinence Model induced by Multiple Simulated Birth Traumas.

This study evaluated the real-time changes in urethral pressure during the storage phase using a rat model with stress urinary incontinence (SUI) induced by simulated multiple birth traumas, and investigated the relationship between urethral continence function and dynamic parameters associated with the changes in urethral pressure. Sprague-Dawley rats were divided into sham and 3-times vaginal distention (VD) groups. After transection of T8-9 spinal cord, simultaneous bladder and urethral pressure recordings were performed during intravesical pressure elevation. Then, urodynamic parameters such as leak point pressure (LPP), urethral baseline pressure (UBP), maximum urethral pressure (MUP), the MUP-UBP differential (dUP) during intravesical pressure elevation, the bladder pressure when urethral contraction begins (Puc), and the bladder pressure at bladder neck opening (Pno) were measured and compared. Compared with sham group, LPP, UBP, dUP, MUP, Puc, and Pno were significantly decreased in VD group. The pressure differences between LPP and Pno (LPP-Pno), and between LPP and UBP (LPP-UBP) were also significantly different in two groups. However, the difference values of LPP and MUP (LPP-MUP) or Pno and UBP (Pno-UBP) were not altered after VD. Our new methods of simultaneous recordings of dynamic changes in bladder and urethral pressures are useful to fully evaluate the functional alterations in the urethral continence function in the SUI model induced by multiple VD. Moreover, LPP-UBP values, which corresponds to Valsalva LPP (VLPP)-maximum urethral closure pressure (MUCP) in clinical urodynamics, would be useful to evaluate the impaired urethral continence function after simulated birth traumas in animal models.