title: Inhalation of methane preserves the epithelial barrier during ischemia and reperfusion in the rat small intestine.
abstract: Methane is part of the gaseous environment of the intestinal lumen. The purpose of this study was to elucidate the bioactivity of exogenous methane on the intestinal barrier function in an antigen-independent model of acute inflammation.
  
  
  
  Anesthetized rats underwent sham operation or 45-min occlusion of the superior mesenteric artery. A normoxic methane (2.2%)-air mixture was inhaled for 15 min at the end of ischemia and at the beginning of a 60-min or 180-min reperfusion. The integrity of the epithelial barrier of the ileum was assessed by determining the lumen-to-blood clearance of fluorescent dextran, while microvascular permeability changes were detected by the Evans blue technique. Tissue levels of superoxide, nitrotyrosine, myeloperoxidase, and endothelin-1 were measured, the superficial mucosal damage was visualized and quantified, and the serosal microcirculation and mesenteric flow was recorded. Erythrocyte deformability and aggregation were tested in vitro.
  
  
  
  Reperfusion significantly increased epithelial permeability, worsened macro- and microcirculation, increased the production of proinflammatory mediators, and resulted in a rapid loss of the epithelium. Exogenous normoxic methane inhalation maintained the superficial mucosal structure, decreased epithelial permeability, and improved local microcirculation, with a decrease in reactive oxygen and nitrogen species generation. Both the deformability and aggregation of erythrocytes improved with incubation of methane.
  
  
  
  Normoxic methane decreases the signs of oxidative and nitrosative stress, improves tissue microcirculation, and thus appears to modulate the ischemia-reperfusion-induced epithelial permeability changes. These findings suggest that the administration of exogenous methane may be a useful strategy for maintaining the integrity of the mucosa sustaining an oxido-reductive attack.
authors.affiliation: University of Szeged, Institute of Surgical Research, Szeged, Hungary.
authors.forename: András T
authors.initials: AT
authors.lastname: Mészáros
authors.affiliation: University of Szeged, Institute of Surgical Research, Szeged, Hungary.
authors.forename: Tamás
authors.initials: T
authors.lastname: Büki
authors.affiliation: University of Szeged, Institute of Surgical Research, Szeged, Hungary.
authors.forename: Borbála
authors.initials: B
authors.lastname: Fazekas
authors.affiliation: University of Szeged, Institute of Surgical Research, Szeged, Hungary.
authors.forename: Eszter
authors.initials: E
authors.lastname: Tuboly
authors.affiliation: University of Szeged, Institute of Surgical Research, Szeged, Hungary.
authors.forename: Kitti
authors.initials: K
authors.lastname: Horváth
authors.affiliation: University of Szeged, Institute of Surgical Research, Szeged, Hungary.
authors.forename: Marietta Z
authors.initials: MZ
authors.lastname: Poles
authors.affiliation: University of Szeged, Institute of Surgical Research, Szeged, Hungary.
authors.forename: Szilárd
authors.initials: S
authors.lastname: Szűcs
authors.affiliation: University of Szeged, Institute of Surgical Research, Szeged, Hungary.
authors.forename: Gabriella
authors.initials: G
authors.lastname: Varga
authors.affiliation: University of Szeged, Institute of Surgical Research, Szeged, Hungary.
authors.forename: József
authors.initials: J
authors.lastname: Kaszaki
authors.affiliation: University of Szeged, Institute of Surgical Research, Szeged, Hungary. Electronic address: boros.mihaly@med.u-szeged.hu.
authors.forename: Mihály
authors.initials: M
authors.lastname: Boros
mesh_terms: D000280:Administration, Inhalation; D000818:Animals; D002199:Capillary Permeability / Q000187:drug effects*; D004195:Disease Models, Animal; D019332:Endothelin-1 / Q000187:drug effects / Q000378:metabolism; D007082:Ileum / Q000187:drug effects* / Q000378:metabolism; D007150:Immunohistochemistry; D007413:Intestinal Mucosa / Q000187:drug effects* / Q000378:metabolism; D008297:Male; D017538:Mesenteric Artery, Superior / Q000601:surgery; D008697:Methane / Q000494:pharmacology*; D018384:Oxidative Stress / Q000187:drug effects; D009195:Peroxidase / Q000187:drug effects / Q000378:metabolism; D011897:Random Allocation; D051381:Rats; D017207:Rats, Sprague-Dawley; D012016:Reference Values; D015427:Reperfusion Injury / Q000188:drug therapy* / Q000473:pathology
chemical_list: D019332:Endothelin-1; D009195:Peroxidase; D008697:Methane