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

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.