Role of nitric oxide in gastrointestinal function and disease

In the digestive tract, nitric oxide (NO) is extensively distributed, from the mouth to the anus, not only in mammals but also in lower vertebrates and even in invertebrates. It is involved in splanchnic and systemic hemodynamics, in mucosal protection, in immune mechanisms, in hepatic function, in endocrine secretion and in several other roles. It is also involved in the organization of the peristalsis as an inhibitory non-adrenergic non-cholinergic neurotransmitter and relaxant of the smooth musculature. The abundant literature dealing with NO in hepato-gastro-enterology is reviewed and discussed in a pragmatic approach for the gastroenterologist, with emphasis on the involvement of NO in pathophysiology and in the perspective of future therapeutics.