JTS-653 blocks afferent nerve firing and attenuates bladder overactivity without affecting normal voiding function.

PURPOSE: We evaluated the role of TRPV1 in bladder overactivity based on afferent nerve firing and urodynamic parameters using the selective TRPV1 antagonist JTS-653. MATERIALS AND METHODS: We evaluated the effects of JTS-653 on the increased pelvic nerve discharge and intravesical pressure induced by intravesical infusion of 100 µM capsaicin in anesthetized rats. The effects of JTS-653 on the urodynamic parameters of bladder overactivity induced by intravesical infusion of 30 nM resiniferatoxin or 0.2% acetic acid, or on normal bladder activity were evaluated by cystometry in conscious rats. The effects of JTS-653 on carbachol induced contraction were investigated using bladder muscle strips. RESULTS: JTS-653 significantly suppressed the capsaicin induced increase in nerve discharge and intravesical pressure. Intravesical infusion of resiniferatoxin or acetic acid decreased the intercontraction interval and voided volume. JTS-653 significantly increased the intercontraction interval and voided volume in rats with resiniferatoxin or acetic acid induced bladder overactivity without affecting maximal voiding pressure. The antimuscarinic agent propiverine significantly decreased maximal voiding pressure but did not affect the intercontraction interval or voided volume in rats with acetic acid induced bladder overactivity. In normal rats JTS-653 showed no significant effects on the intercontraction interval, voided volume or maximal voiding pressure. JTS-653 did not affect carbachol induced contraction of the bladder muscle. CONCLUSIONS: Our findings suggest that TRPV1 is involved in bladder overactivity via afferent nerve activation but it is not associated with normal voiding function. A TRPV1 antagonist would be a useful drug for bladder overactivity with a different pharmacological profile than antimuscarinic agents.