Urodynamics in acetone-induced cystitis of anesthetized rats

We examined the bladder function of cystitis models induced by intravesical acetone instillation in urethane-anesthetized rats. Acetone (0.35 mi) at 1 0, 30, or 50% concentration or deionized water (sham-treatment) was instill ed into the bladder via the cannula which was inserted into the lumen. Acet one was withdrawn 90 sec after instillation and the bladder lumen was washe d with saline after 15 min. One hour later, the cystometrogram induced by t ransvesical infusion of saline (3.3 ml/hr) was measured. During cystometrog raphy of normal (non-treated) or sham-treated group, the time required to c ause micturition, reflecting bladder capacity, was 9.6 +/- 0.9 (n = 7) or 1 0.0 +/- 0.8 min (n = 6), respectively. In the 10% acetone-treated group, th e bladder capacity was similar to that in the normal or sham group. In the 30% acetone group, the time to micturition was 4.4 +/- 0.4 min (n = 7), ind icating decreased bladder capacity, although the micturition pressure and t he threshold pressure were not significantly different from those in the no rmal or sham group. However, in the 50% acetone group, the micturition refl ex disappeared. In isolated rat bladder strips, contractile responses to ca rbachol or electrical field stimulation in the sham and 30% acetone group w ere similar. While, both responses in isolated strips from the 50% acetone group were reduced. The degree of damage from degeneration and desquamation of epithelium and hemorrhage in the bladder tissue from the 30% acetone gr oup was less prominent than in the 50% acetone group. Additionally, some ti ssue from the 50% acetone group showed degeneration of muscle layer. The ef fects of three drugs were investigated in the 30% acetone group which showe d increased urinary frequency. Baclofen (100 mu g/kg, i.v.) and morphine (1 00 mu g/kg, i.v.) increased significantly the bladder capacity and the thre shold pressure. Atropine (10 mu g/kg, i.v.) decreased the micturition press ure. These results suggest that cystitis models induced by intravesical ins tillation of 30% acetone may be valuable for evaluating drugs for the treat ment of urinary frequency. (C) 1999 Wiley-Liss, Inc.