Mucosal muscarinic receptors enhance bladder activity in cats with feline interstitial cystitis.

Abstract

PURPOSE: Interstitial cystitis is a chronic pelvic pain syndrome of which the origin and mechanisms involved remain unclear. In this study Ca(2+) transients in the bladder wall of domestic cats diagnosed with naturally occurring feline interstitial cystitis were examined. MATERIALS AND METHODS: Cross-sections of full-thickness bladder strips from normal cats and cats with feline interstitial cystitis were examined by optically mapping Ca(2+) transients and recording tension. Responses of Ca(2+) activity and detrusor contractions to pharmacological interventions were compared. In addition, pharmacological responses were compared in mucosa denuded preparations. RESULTS: Optical mapping showed that feline interstitial cystitis bladders had significantly more spontaneous Ca(2+) transients in the mucosal layer than control bladders. Optical mapping also demonstrated that feline interstitial cystitis bladders were hypersensitive to a low dose (50 nM) of the muscarinic receptor agonist arecaidine when the mucosal layer was intact. This hypersensitivity was markedly decreased in mucosa denuded bladder strips. CONCLUSIONS: In feline interstitial cystitis cat bladders there is increased Ca(2+) activity and sensitivity of muscarinic receptors in the mucosal layer, which can enhance smooth muscle spontaneous contractions.