title: Possible role of nitric oxide in visceral hypersensitivity in patients with irritable bowel syndrome.
abstract: Visceral hypersensitivity is a consistent finding in a considerable proportion of patients with irritable bowel syndrome (IBS), and may provide a physiological basis for the development of IBS symptoms. In this study, we aimed to confirm the hypothesis that nitric oxide (NO) is involved in maintaining visceral hypersensitivity in IBS. Ten healthy volunteers (HV) and 12 IBS patients with documented hypersensitivity to rectal distension underwent a rectal barostat study. The effect of placebo and the specific NO synthase inhibitor NG -monomethyl-L-arginine (L-NMMA) on resting volume, rectal sensitivity to distension and rectal compliance was evaluated in a double-blind, randomized, cross-over fashion. NG -monomethyl-L-arginine did not alter resting volumes in HV or IBS patients. In HV, l-NMMA did not alter rectal sensory thresholds compared to placebo (45 +/- 3 and 46 +/- 3 mmHg, respectively). In contrast, L-NMMA significantly increased the threshold for discomfort/pain in IBS patients (placebo: 18 +/- 2, l-NMMA: 21 +/- 3 mmHg, P < 0.05). Rectal compliance was not affected by L-NMMA. Although NO does not seem to play a major role in normal rectal sensation or tone, we provide evidence that NO may be involved in the pathophysiology of visceral hypersensitivity in IBS.
authors.affiliation: Department of Gastroenterology and Hepatology, Academic Medical Centre, Amsterdam, The Netherlands.
authors.forename: S D
authors.initials: SD
authors.lastname: Kuiken
authors.forename: T K
authors.initials: TK
authors.lastname: Klooker
authors.forename: G N
authors.initials: GN
authors.lastname: Tytgat
authors.forename: A
authors.initials: A
authors.lastname: Lei
authors.forename: G E
authors.initials: GE
authors.lastname: Boeckxstaens
mesh_terms: D000328:Adult; D001794:Blood Pressure / Q000187:drug effects; D003187:Compliance / Q000187:drug effects; D004106:Dilatation; D004311:Double-Blind Method; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005260:Female; D006801:Humans; D006930:Hyperalgesia / Q000503:physiopathology*; D043183:Irritable Bowel Syndrome / Q000503:physiopathology*; D008297:Male; D009569:Nitric Oxide / Q000378:metabolism*; D017288:Pain Threshold / Q000502:physiology*; D012007:Rectum / Q000187:drug effects; D014781:Viscera / Q000187:drug effects / Q000502:physiology*; D019323:omega-N-Methylarginine / Q000494:pharmacology
chemical_list: D004791:Enzyme Inhibitors; D019323:omega-N-Methylarginine; D009569:Nitric Oxide