title: Development and changes with age of detrusor overactivity in spontaneous hypertensive rats as observed by simultaneous registrations of intravesical and intraabdominal pressures.
abstract: OBJECTIVE
  Overactive bladder is especially common in the elderly, although it is not regarded as a normal part of aging. Thus, we investigated how aging alters the cystometric and detrusor overactivity (DO) parameters and the density of nerve growth factor (NGF) in awake spontaneous hypertensive rats (SHRs) of different ages.
  
  
  METHODS
  Three age groups of 12- (n=5), 17- (n=6), and 21- (n=6) week-old SHRs (Oriental Bio Inc.) were used. A catheter was implanted into the bladder to record the intravesical pressure (IVP), and a balloon-fitted catheter was positioned in the abdominal cavity to record the intraabdominal pressure (IAP). Of the IVP elevations above 2 cm H(2)O, DO was defined as a rise in IVP without a simultaneous change in IAP and was counted during the filling phase. We measured the expression of NGF in the bladders by enzyme-linked immunosorbent assay.
  
  
  RESULTS
  Both the body and bladder weights significantly increased with age, but the normalized ratio between those was not changed. As for DO, none of the12-week-old rats showed DO, whereas the other groups did. DO increased significantly with age (P=0.0045 by Mantel-Haenszel trend test), although no significant differences were found in DO frequency or pressure between the 17- and 21-week-old age groups. NGF did not show any significant differences among the three groups.
  
  
  CONCLUSIONS
  Our results showed that SHRs begin to shows DO after a certain age, such as 12 weeks of age, and that the occurrence of DO has a close relationship with aging. However, NGF, which is known to be increased in the bladder wall of patients with overactive bladder, did not show any relationship with aging in this study.
authors.affiliation: Department of Urology, Inha University College of Medicine by BK 21 Project, Incheon, Korea.
authors.forename: Long-Hu
authors.initials: LH
authors.lastname: Jin
authors.forename: Hun-Jae
authors.initials: HJ
authors.lastname: Lee
authors.forename: Hwa-Yoan
authors.initials: HY
authors.lastname: Shin
authors.forename: Bo-Hwa
authors.initials: BH
authors.lastname: Choi
authors.forename: Sang-Min
authors.initials: SM
authors.lastname: Yoon
authors.forename: Chang-Shin
authors.initials: CS
authors.lastname: Park
authors.forename: Tack
authors.initials: T
authors.lastname: Lee