The role of nitric oxide in altering intestinal motility in lipopolysaccharide-injected rats : a morphological and functional assessment

Nitric oxide, a short-lived free radical and neurotransmitter, is responsible for decreased smooth muscle contractility in vitro. When in excess, NO can cause hypotension and is believed to mediate altered intestinal motility. Not enough evidence is available for morphological changes in gastrointestinal smooth muscle and its correlation with motility disorders caused by Escherichia coli-induced NO production. Male Lewis rats were treated with injections of 10 mg/kg LPS from E. coli with or without 12.5 mg/kg of NOS inhibitor, LNMMA. Eighteen to 24 hours following injection, duodenum, ileum, colon, liver, and spleen were harvested for histological analysis. Urine and fecal analysis assessed functional aspects in control and treatment groups. Muscularis externa measurements revealed significant increase in muscle thickness of LPS + LNMMA injected group compared to control and LPS group. However, the average values in control and LPS group were not significantly different. Fecal consistency was significant in all 3 groups. Mean urinary nitrite in the LPS group was 44 times higher than control and 52 times higher than the inhibitor-treated group.Department of Physiology and Health ScienceThesis (M.S.