Removal of urothelium affects bladder contractility and release of ATP but not release of NO in rat urinary bladder.
BACKGROUND
The objective of our work was to investigate both the contractile function and the release of ATP and NO from strips of bladder tissue after removal of the urothelium.


METHODS
The method of removal was a gentle swabbing motion rather than a sharp surgical cutting to separate the urothelium from the smooth muscle. The contractile response and ATP and NO release were measured in intact as well as on swabbed preparations. The removal of the urothelial layer was affirmed microscopically.


RESULTS
After the swabbing, the smaller contractions were evoked by electrical as well as by chemical stimulation (50 microM carbachol or 50 microM alpha, beta meATP). Electrical stimulation, carbachol and substance P (5 microM) evoked lower release of ATP in the swabbed strips than in intact strips. Although release of NO evoked by electrical stimulation or substance P was not changed, release of NO evoked by carbachol was significantly less in the swabbed preparations.


CONCLUSIONS
Since swabbing removes only the urothelium, the presence of the suburothelial layer may explain the difference between our findings and those of others who found an increase in contractility. Evoked release of ATP is reduced in swabbed strips, indicating that ATP derives solely from the urothelium. On the other hand, electrical stimulation and substance P evoke identical degrees of NO release in both intact and swabbed preparations, suggesting that NO can be released from the suburothelium. Conversely, carbachol-induced release of NO is lower in swabbed strips, implying that the cholinergic receptors (muscarinic or nicotinic) are located in the upper layer of the urothelium.
Munoz
Alvaro
A
Scott Department of Urology, Baylor College of Medicine, One Baylor Plaza, Houston, Texas, USA.
Gangitano
David A
DA
Smith
Christopher P
CP
Boone
Timothy B
TB
Somogyi
George T
GT
D000255:Adenosine Triphosphate / Q000378:metabolism*; D000818:Animals; D005260:Female; D009119:Muscle Contraction / Q000502:physiology*; D009130:Muscle, Smooth / Q000502:physiology*; D009569:Nitric Oxide / Q000502:physiology; D051381:Rats; D017207:Rats, Sprague-Dawley; D001743:Urinary Bladder / Q000502:physiology*; D019459:Urothelium / Q000502:physiology* / Q000601:surgery*
D009569:Nitric Oxide; D000255:Adenosine Triphosphate