title: Changes in bladder contractility and compliance due to urethral obstruction: a longitudinal followup of guinea pigs.
abstract: OBJECTIVE
  We established the longitudinal changes in bladder contractility and compliance as a result of urethral obstruction using a guinea pig model.
  
  
  METHODS
  Obstruction was induced in guinea pigs by a silver ring around the urethra. Urodynamic studies were performed longitudinally in individual animals. Bladder contractility and compliance were calculated from the measured bladder pressure and urine flow rate.
  
  
  RESULTS
  Bladder contractility developed in distinct phases. It reached a maximum 200% increase after an average of 3.25 weeks concomitant with an almost 2-fold increase in urethral resistance, remained 150% to 200% increased during weeks 4 to 7 and then decreased to starting levels again, while urethral resistance remained almost 2-fold increased. Bladder compliance decreased by 80% during the first 3 weeks and continued to decrease to 5% of its original value after 10 to 11 weeks.
  
  
  CONCLUSIONS
  Our data indicate that as a result of obstruction bladder function passes through a specific sequence of stages, including first a compensatory increase in contractility, then a stabilization phase and finally a decompensation state. In contrast bladder compliance shows a continuous decrease. The data suggest that for assessing how far a bladder has deteriorated due to obstruction a combination of functional and structural data may be warranted.
authors.affiliation: Departments of Paediatric Urology and Urodynamics, Erasmus Medical Centre, Rotterdam, The Netherlands.
authors.forename: D J
authors.initials: DJ
authors.lastname: Kok
authors.forename: K P
authors.initials: KP
authors.lastname: Wolffenbuttel
authors.forename: J P
authors.initials: JP
authors.lastname: Minekus
authors.forename: R
authors.initials: R
authors.lastname: van Mastrigt
authors.forename: J M
authors.initials: JM
authors.lastname: Nijman
mesh_terms: D000818:Animals; D004195:Disease Models, Animal; D005500:Follow-Up Studies; D006168:Guinea Pigs; D008297:Male; D009119:Muscle Contraction; D009130:Muscle, Smooth / Q000503:physiopathology*; D014524:Urethral Obstruction / Q000503:physiopathology*; D001743:Urinary Bladder / Q000503:physiopathology; D014563:Urodynamics