title: Endotoxin-induced ileal mucosal injury and nitric oxide dysregulation are temporally dissociated.
abstract: Despite recent investigations, the mechanisms responsible for intestinal epithelial injury during endotoxemia remain unclear. The present study tests the hypothesis that epithelial necrosis and/or apoptosis correlate with nitric oxide (NO) dysregulation in a nonischemic model of sepsis-induced ileal injury. To test this hypothesis, a well-established in situ, autoperfused, feline ileal preparation was employed. After endotoxin (lipopolysaccharide [LPS], 3 mg/ kg, intravenously; n = 9) or vehicle (control; n = 5) treatment, ileal segments were obtained at baseline, 2 and 4 h for simultaneous evaluations of cellular and mitochondrial ultrastructure, immunoprevalence of inducible nitric oxide synthase (iNOS) and 3-nitrotyrosine (a stable biomarker of peroxynitrite), and histochemical evidence of apoptosis. Epithelial necrosis was prominent by 2 h post-LPS, despite unaltered global ileal tissue oxygen content, blood volume, and blood flow. Significant evidence of apoptosis and increases in the immunoprevalence of iNOS and 3-nitrotyrosine were not evident until 4 h post-LPS. These results suggest that the early ileal mucosal necrosis may be due to LPS-induced activation of inflammatory pathways and/or microcirculatory disturbances, whereas NO dysregulation may participate in later events, including protein nitration and epithelial apoptosis.
authors.affiliation: Division of Pulmonary and Critical Care Medicine, Department of Internal Medicine, The Ohio State University Medical Center, Columbus, Ohio, USA. Crouser-1@medctr.osu.edu
authors.forename: E D
authors.initials: ED
authors.lastname: Crouser
authors.forename: M W
authors.initials: MW
authors.lastname: Julian
authors.forename: D M
authors.initials: DM
authors.lastname: Weinstein
authors.forename: R J
authors.initials: RJ
authors.lastname: Fahy
authors.forename: J A
authors.initials: JA
authors.lastname: Bauer
mesh_terms: D000818:Animals; D017209:Apoptosis; D002415:Cats; D007082:Ileum / Q000378:metabolism / Q000473:pathology* / Q000648:ultrastructure; D007150:Immunohistochemistry; D007413:Intestinal Mucosa / Q000378:metabolism / Q000473:pathology*; D008070:Lipopolysaccharides; D008297:Male; D008928:Mitochondria / Q000648:ultrastructure; D009102:Multiple Organ Failure / Q000209:etiology / Q000473:pathology / Q000503:physiopathology; D009336:Necrosis; D009569:Nitric Oxide / Q000502:physiology*; D019001:Nitric Oxide Synthase / Q000032:analysis; D052247:Nitric Oxide Synthase Type II; D010101:Oxygen Consumption; D018805:Sepsis / Q000150:complications / Q000378:metabolism / Q000473:pathology*; D014443:Tyrosine / Q000031:analogs & derivatives / Q000032:analysis
chemical_list: D008070:Lipopolysaccharides; D009569:Nitric Oxide; C002744:3-nitrotyrosine; D014443:Tyrosine; D019001:Nitric Oxide Synthase; D052247:Nitric Oxide Synthase Type II