Induction of nitric oxide synthase in rat intestine and its association with tissue injury

Induction of a calcium-independent nitric oxide synthase (NOS) has been detected in the rat small intestine and colon, 3–5 h following endotoxin (3 mg kg⁻¹ i.v.). This was associated with an increase in vascular permeability to plasma protein in jejunum and colon, and both induction of NOS and vascular leakage were inhibited by pretreatment with dexamethasone (1 mg kg⁻¹ s.c.). Induction of colonic NOS was also detected in a TNB colitis model, 24 h after challenge. Thus, increased NO synthesis may be involved in the microvascular and mucosal injury associated with inflammatory diseases of the gut.