THE EFFECT OF N-G-MONOMETHYL-L-ARGININE ON BLADDER FUNCTION

Recent studies have demonstrated the presence of nitric oxide synthase (NO synthase) in lower urinary tract tissues, however, its role in th e detrusor is unclear. The current study was designed to determine if NO synthase inhibition alters detrusor activities, including micturiti on volume threshold, and inhibition of pelvic nerve-evoked contraction s by various stimuli. In naive, anesthetized adult cats, inhibition of pelvic nerve-evoked bladder contractions, induced by hypogastric nerv e stimulation or the intraarterial administration of NA, ATP, adenosin e, beta,gamma-methylene ATP and 2-methylthio ATP, was measured before and after inhibition of NO synthase. The micturition volume threshold was also measured before and after NO synthase inhibition. L-NMMA decr eased the micturition volume threshold by 38% (2 mg intravesical admin istration) or 80% (4 mg/kg i.a.). The magnitude of the micturition con tractions was modestly increased. These results, and information in th e literature, indicate that NO may play a role in the collection phase of the bladder cycle and any alteration of nitric oxide availability could induce or allow development of various bladder malfunctions, suc h as small bladder diseases, like interstitial cystitis.