Mucosal Muscarinic Receptors Enhance Bladder Activity In Cats With Feline Interstitial Cystitis

Main Category: Urology / Nephrology
Also Included In: Veterinary
Article Date: 05 Apr 2009 - 2:00 PDT

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UroToday.com - Domestic cats have been shown to have a syndrome called "feline interstitial cystitis" (FIC), which shares many characteristics seen in humans with IC. Bladder urothelium dysfunction is a factor contributing to IC symptomatology. The urothelium is a highly impermeable barrier that prevents toxic components in urine from crossing to muscle. It also acts as a sensory organ that responds to mechanical and chemical stimulation by releasing neurotransmitters, such as acetylcholine, ATP and nitric oxide. It is hypothesized that these factors can act on suburothelial afferent nerves and interstitial cells to modulate bladder activity during filling.

Ikeda and colleagues from Pittsburg, Pennsylvania and Columbus, Ohio note that in FIC cases, the urothelium has been shown to have decreased transepithelial resistance, and increased water and urea permeability compared to controls in response to hydrodistention. Barrier function is compromised, possibly leading to the sensitization of sensory nerves by irritants from urine crossing into the muscle layer. They examined the role of muscarinic receptor activation in full-thickness cross-sections of FIC and normal adult cat bladder strips with or without mucosa. Optical mapping of Ca2+ transients was done to measure the changes in fluorescence intensity induced by calcium entering the cell.

The authors had previously noted significant changes in urothelial barrier function, stretch mediated release of factors and purinergic receptor expression in bladders from cats with FIC. The current study they report extends these findings by demonstrating increased spontaneous Ca2+ activity present in the mucosal layer of the bladder of cats with FIC compared to that in normal adult controls. There was also a differential response to muscarinic activation between these bladders that depended on the presence of the mucosa.

They conclude that changes in the expression of sensitivity of mucosal muscarinic receptors may have a contributing role in IC symptoms.

Ikeda Y, Birder L, Buffington C, Roppolo J, Kanai

J Urol. 2009 Mar;181(3):1415-22
10.1016/j.juro.2008.10.138

Written by UroToday.com Contributing Editor Philip M. Hanno, MD, MPH

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