AimObesity has been an independent risk factor for female stress urinary incontinence (SUI), the mechanism of this association remains unknown. The aim of this study is to validate the hypothesis that urethral dysfunction is a possible contributor to SUI in obese women.
MethodsTen Zucker Fatty (ZF) (ZUC-Lepr(fa) 185) and 10 Zucker Lean (ZL) (ZUC-Lepr(fa) 186) female rats at 12-week-old were used in this experiment. The urethral sphincter rings were harvested from the bladder neck through to the most proximal 2/3 regions. In the organ bath study, single pulses of electrical field stimulation (EFS) were applied. For the fatiguing stimulation, repeated multi-pulse EFS with 70mA were applied at frequency of 5Hz for 5min. Caffeine-containing Krebs" solution was administrated to contract the urethra until the contraction began to reach a plateau for 10min. We performed immunofluorescence staining of the urethra after the experiment was finished.
ResultsCompared to ZL controls, ZF rats had significantly impaired muscle contractile activity (MCA) (P<0.05). Also, ZF rats presented early fatiguing of MCA and had a significantly greater percentage of MCA decline from baseline in the fatiguing test (37.7% vs 25.6%, P<0.05). The plateau of maximal MCA induced by caffeine in ZF rats was significantly lower than ZL controls (0.22 vs 0.36, P<0.05).
ConclusionsThis novel study showed that obese female rats had significantly impaired contractile properties of striated urethral sphincter, suggesting urethral dysfunction could be an important contributor to SUI in obesity.
[1]Kaohsiung Med Univ, Kaohsiung Med Univ Hosp, Dept Urol, Coll Med,Fac Med, Kaohsiung, Taiwan.
[2]Univ Calif San Francisco, Sch Med, Dept Urol, Knuppe Mol Urol Lab, San Francisco, CA 94143 USA.
[3]Jilin Univ, Hosp 1, Dept Urol, Changchun, Jilin, Peoples R China.
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