title: Impaired contractility of the circular striated urethral sphincter muscle may contribute to stress urinary incontinence in female zucker fatty rats.
abstract: OBJECTIVE
  Obesity 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.
  
  
  METHODS
  Ten Zucker Fatty (ZF) (ZUC-Leprfa185) and 10 Zucker Lean (ZL) (ZUC-Leprfa186) 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 70 mA were applied at frequency of 5 Hz for 5 min. Caffeine-containing Krebs' solution was administrated to contract the urethra until the contraction began to reach a plateau for 10 min. We performed immunofluorescence staining of the urethra after the experiment was finished.
  
  
  RESULTS
  Compared 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).
  
  
  CONCLUSIONS
  This 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.
authors: Faculty of Medicine, Department of Urology, Kaohsiung Medical University Hospital, College of Medicine, Kaohsiung Medical University, Kaohsiung, Taiwan.|Knuppe Molecular Urology Laboratory, Department of Urology, School of Medicine, University of California, San Francisco, California.
authors: Yung-Chin
authors: YC
authors: Lee
authors: Knuppe Molecular Urology Laboratory, Department of Urology, School of Medicine, University of California, San Francisco, California.
authors: Guiting
authors: G
authors: Lin
authors: Knuppe Molecular Urology Laboratory, Department of Urology, School of Medicine, University of California, San Francisco, California.
authors: Guifang
authors: G
authors: Wang
authors: Knuppe Molecular Urology Laboratory, Department of Urology, School of Medicine, University of California, San Francisco, California.
authors: Amanda
authors: A
authors: Reed-Maldonado
authors: Knuppe Molecular Urology Laboratory, Department of Urology, School of Medicine, University of California, San Francisco, California.|Department of Urology, The First Hospital of Jilin University, Jilin, China.
authors: Zhihua
authors: Z
authors: Lu
authors: Knuppe Molecular Urology Laboratory, Department of Urology, School of Medicine, University of California, San Francisco, California.
authors: Lin
authors: L
authors: Wang
authors: Knuppe Molecular Urology Laboratory, Department of Urology, School of Medicine, University of California, San Francisco, California.
authors: Lia
authors: L
authors: Banie
authors: Knuppe Molecular Urology Laboratory, Department of Urology, School of Medicine, University of California, San Francisco, California.
authors: Tom F
authors: TF
authors: Lue
mesh_terms: D000818:Animals; D004558:Electric Stimulation; D005260:Female; D009119:Muscle Contraction / Q000502:physiology*; D018482:Muscle, Skeletal / Q000503:physiopathology*; D009765:Obesity / Q000503:physiopathology; D051381:Rats; D011924:Rats, Zucker; D014521:Urethra / Q000503:physiopathology*; D001743:Urinary Bladder / Q000503:physiopathology*; D014550:Urinary Incontinence, Stress / Q000503:physiopathology*
keywords: electrical field stimulation; female rats; obesity; organ bath; urethral sphincter