A role for nitric oxide (NO) in ulcerative colitis has been suggested
because mucosal NO synthase activity, measured by indirect assays, is
increased in this disorder. We directly measured luminal NO in the col
ons of twelve controls and six patients with active ulcerative colitis
. During colonoscopy, gas was aspirated from different parts of the co
lon and immediately analysed by a chemiluminescence technique. NO conc
entrations were more than 100 times higher in the patients than in the
controls. Luminal NO is rapidly and easily measurable and may be used
to monitor inflammatory bowel disease.