Endotoxin-induced ileal mucosal injury and nitric oxide dysregulation are temporally dissociated.
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.
Crouser
E D
ED
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
Julian
M W
MW
Weinstein
D M
DM
Fahy
R J
RJ
Bauer
J A
JA
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
D008070:Lipopolysaccharides; D009569:Nitric Oxide; C002744:3-nitrotyrosine; D014443:Tyrosine; D019001:Nitric Oxide Synthase; D052247:Nitric Oxide Synthase Type II