Nitrosyl complex formation during endotoxin-induced injury in the rat small intestine

The objective of this study was to demonstrate nitric oxide (NO) production and determine its role in the rat small intestine following endotoxin treatment. By using electron paramagnetic resonance (EPR) spectroscopy, we were able to detect high concentrations of nitrosylated proteins in the small intestines of rats administered 1 mg/kg lipopolysaccharide (LPS) and sacrificed 6 h later. EPR spectra of non-heme and heme nitrosyl complexes were detected in the epithelium layer and intestinal wall. Only EPR spectra characteristic of nitrosyl hemoprotein complexes were detected in the luminal contents of these rats. LPS administration elevated the concentrations of intestinal lipid peroxidation biomarkers, thiobarbituric acid-reactive substances, and conjugated dienes. These changes were attenuated by NO synthase inhibitor treatment. We conclude that oxidants associated with NO formation were at least in part involved in the oxidation of tissue lipids. This process may be one of the mechanisms of intestinal injury induced by LPS.