Intermittent catheterization limits rabbit bladder dysfunction in responseto partial outlet obstruction

Introduction: The initial response of the urinary bladder to outflow partia l obstruction consists of distension, followed by a rapid increase in mass and concomitant; functional adaptations. Subsequently, an indeterminate per iod of stabilized function and little increase in mass occurs (compensation ). Finally, bladder mass again progressively increases, accompanied by dele terious changes in bladder morphology, biochemistry and pharmacology, and p rogressive loss of function (decompensation). The reported study was design ed to determine whether limiting the level of bladder distension, using int ermittent catheterization (IntCath), could protect the bladder from decompe nsation. Materials and Methods: Sixteen male New Zealand White rabbits were separate d into 4 groups of 4 rabbits each: control, control with IntCath, obstructe d, and obstructed with IntCath. IntCath was performed with the animals unde r inhalation anesthesia. An 8 Fr. catheter was inserted through the urethra into the bladder every 8 hours and the urine drained. After 14 days of obs truction, bladders were removed from all rabbits; longitudinal strips were cut from the bladder body and suspended in individual organ baths. Contract ile responses to field stimulation (FS), KCl, ATP, and carbachol were measu red. Results: There were no significant differences between control rabbits and controls with IntCath in bladder weights, compliance, and contractile respo nses to all stimuli. Bladder weights of both obstructed groups increased si gnificantly compared to those of both control groups. Bladder weights of ob structed rabbits increased to a significantly greater extent than did those of obstructed rabbits with IntCath. Bladder compliance in the obstructed g roup was significantly lower than compliance in both control groups and in obstructed rabbits with IntCath. Both obstructed groups exhibited significa ntly decreased contractile responses to FS, ATP and KCl, compared to contro l groups. The response of the obstructed group with IntCath to FS and carba chol was significantly greater than the responses of the obstructed group w ithout IntCath. Conclusions: These findings show that limiting distension with IntCath redu ces the magnitudes of the increased bladder mass, the loss of bladder wall elasticity (compliance), and the impaired contractile responses which occur secondary to outflow obstruction.