Urodynamic effects of intravesical resiniferatoxin and capsaicin in conscious rats with and without outflow obstruction

Abstract

Purpose: The urodynamic effects of intravesical resiniferatoxin and capsaicin were investigated in rats.

Materials and methods: Continuous cystometry was performed in conscious, female Sprague-Dawley rats with and without outflow obstruction.

Results: Intravesical instillation of resiniferatoxin facilitated micturition. The potency of the drug was approximately 1,000 times higher than that of capsaicin. Repeated instillations of resiniferatoxin for 6 consecutive days caused desensitization to resiniferatoxin. This was not found with repeated instillations of capsaicin. Capsaicin was also effective in rats with bladder hypertrophy, while resiniferatoxin was not.

Conclusions: The findings suggest that resiniferatoxin can induce desensitization of vanilloid receptor-mediated release of tachykinins in the rat urinary bladder and that intravesical resiniferatoxin would be an interesting alternative to intravesical capsaicin in the treatment of selected cases of bladder hypersensitivity/hyperactivity.