The effect of NG-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 the detrusor is unclear. The current study was designed to determine if NO synthase inhibition alters detrusor activities, including micturition volume threshold, and inhibition of pelvic nerve-evoked contractions by various stimuli. In naive, anesthetized adult cats, inhibition of pelvic nerve-evoked bladder contractions, induced by hypogastric nerve stimulation or the intraarterial administration of NA, ATP, adenosine, 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 decreased the micturition volume threshold by 38% (2 mg intravesical administration) or 80% (4 mg/kg i.a.). The magnitude of the micturition contractions was modestly increased. These results, and information in the 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, such as small bladder diseases, like interstitial cystitis.