Increased Luminal Nitric Oxide in Inflammatory Bowel Disease as Shown with a Novel Minimally Invasive Method

Background: The production of nitric oxide (NO) is increased in ulcerative colitis, as shown by bioassays of NO synthase activity in mucosal biopsy specimens.We wanted to develop a less invasive method for measurement of NO directly in the rectum in patients with inflammatory bowel disease (IBD). Methods: We studied 10 patients with active ulcerative colitis, 6 with active Crohn's disease, 6 with non-active ulcerative colitis, and 24 controls without inflammation A tonometer balloon catheter was inserted in the rectum and inflated with 5 ml of NO-free air. After 15 min of incubation the sample was extracted, and the NO concentration was immediately analysed with a chemiluminescence technique. Results: Patients with active disease had greatly increased concentrations of NO in the rectum as compared with controls and patients with non-active disease. Conclusions: During inflammation in the large intestine increased amounts of NO are released from the mucosa. Measurements of NO directly in the rectum could be of help in further understanding the role of this gas in IBD. Moreover, it is tempting to speculate that this minimally invasive method could be clinically useful as a diagnostic tool and in monitoring the effect of therapy.