Dynamic changes of urodynamic parameters before and after intermittent hypoxia exposure in rats

Abstract

Objective To detect the dynamic changes of urodynamic parameters before and after intermittent hypoxia (IH) exposure in rats and evaluate the impact of IH on urodynamic assessment of bladder function. Methods Thirty female Sprague-Dawley (SD) rats aged 60 days and weighing 177±13 grams were selected. A piezometric catheter was inserted into bladder by suprapubic cystostomy and the dynamic changes of urodynamic parameters were detected before and after IH exposure. Bladder capacity (BC), voided volume (Vv), residual volume (RV), start-up voiding pressure (SVP), maximal voiding pressure (MVP), micturition time interval (MTI), detrusor instability (DI) and detrusor-sphincter collaborative (DSC) were recorded. Results Before IH, bladder capacity and voided volume were (0.67±0.29) ml and (0.52±0.23) ml respectively. After hypoxia, both significantly declined (0.52±0.18) ml and (0.29±0.13) ml respectively and two groups showed significant statistical differences (P 0.05); the maximal voiding pressure at pre-hypoxia decreased significantly post-hypoxia [(10.43±3.43) vs (5.77±1.91) mmHg] and the difference was significant (P<0.05); the micturition time interval pre-hypoxia decreased significantly post-hypoxia [(157.71±75.51) vs (84.30±38.21) sec] and the difference was significant (P<0.05). Only 1/10 developed detrusor instability contraction versus 6 after hypoxia. During bladder filling phase, 1/10 before hypoxia had detrusor-sphincter dyssynergia versus 2 after hypoxia; during voiding phase, 2/10 before hypoxia had detrusor-sphincter dyssynergia versus 3 after hypoxia. Conclusions After intermittent hypoxia exposure, urodynamic changes are manifested as reductions of bladder capacity, voided volume and maximal voiding pressure, increase of residual volume, shortening of micturition time interval shortened, detrusor instability and no significant change in start-up voiding pressure before and after hypoxia. And detrusor-sphincter dyssynergia is non-typical. Key words: Rats; Anoxia; Urodynamic