Ex vivo biomechanical properties of the female urethra in a rat model of birth trauma

Rachelle L. Prantil, Ron J. Jankowski, Yasuhiro Kaiho, William C. De Groat, Michael B. Chancellor, Naoki Yoshimura, David A. Vorp

Research output: Contribution to journalArticlepeer-review

22 Citations (Scopus)

Abstract

Stress urinary incontinence (SUI) is the involuntary release of urine during sudden increases in abdominal pressures. SUI is common in women after vaginal delivery or pelvic trauma and may alter the biomechanical properties of the urethra. Thus we hypothesize that injury due to vaginal distension (VD) decreases urethral basal tone and passive stiffness. This study aimed to assess the biomechanical properties of the urethra after VD in the baseline state, where basal muscle tone and extracellular matrix (ECM) are present, and in the passive state, where inactive muscle and ECM are present. Female rat urethras were isolated in a rat model of acute SUI induced by simulated birth trauma. Our established ex vivo system was utilized, wherein we applied intraluminal static pressures ranging from 0 to 20 mmHg. Outer diameter was measured via a laser micrometer. Measurements were recorded via computer. Urethral thickness was assessed histologically. Stress-strain responses of the urethra were altered by VD. Quantification of biomechanical parameters indicated that VD decreased baseline stiffness. The passive peak incremental elastic modulus of the distal segment in VD urethras was less than for controls (1.84 ± 0.67 vs. 1.19 ± 0.70 × 106 dyne/cm2, respectively; P = 0.016). An increase was noted in passive lowpressure compliance values in proximal VD urethras compared with controls (9.44 ± 2.43 vs. 4.62 ± 0.60 mmHg-1, respectively; P = 0.04). Biomechanical analyses suggest that VD alters urethral basal tone, proximal urethral compliance, and distal stiffness. Lack of basal smooth muscle tone, in combination with these changes in the proximal and distal urethra, may contribute to SUI induced by VD.

Original languageEnglish
Pages (from-to)F1229-F1237
JournalAmerican Journal of Physiology - Renal Physiology
Volume292
Issue number4
DOIs
Publication statusPublished - 2007 Apr

Keywords

  • Collagen
  • Sphincter
  • Stress urinary incontinence

ASJC Scopus subject areas

  • Physiology
  • Urology

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