Nitric oxide and inflammatory bowel disease.

Nitric oxide (NO) is an important biological mediator with effects on homeo stasis, neurotransmission and immune function. Chronic inflammation of the intestinal mucosa in patients in ulcerative colitis and Crohn's disease has been reported to be associated with enhanced production of NO and nitric o xide synthase (NOS) activity. Whereas small amounts oi NO produced by endot helial constitutive calcium-dependent NOS may act to preserve intestinal mu cosa integrity, large amounts of NO synthesised by inducible calcium-indepe ndent NOS may play a key role in further aggravation of the inflammation an d may be associated with the development of intestinal mucosal injury and a mplification of immune response in patients with inflammatory bowel disease (IBD). In this article we review NO pathways, mechanisms of action, functi ons, regulation, immunogenetics and the role played in IBD. A deeper knowle dge of the NO physiopathology may allow new therapeutical approaches in IBD patients. In fact, the development of selective inhibitors of NOS isoforms could provide a novel therapeutic option in the management of IBD patients .