[Characterization of the antiinflammatory properties of methane inhalation during ischaemia-reperfusion]

Gastrointestinal methane generation has been demonstrated in various conditions, but it is not known whether it has any impact on the mammalian physiology or pathophysiology. Our aim was to characterize the effects of exogenous methane on the process of inflammatory events induced by reoxygenation in a canine model of ischemia-reperfusion.

Sodium pentobarbital-anesthetized inbred beagle dogs (n = 18) were randomly assigned to sham-operated or ischemia-reperfusion (I/R) groups. I/R was induced by occluding the superior mesenteric artery for 1 h, and the subsequent reperfusion was monitored for 3 h. For 5 min before reperfusion, the animals were mechanically ventilated with normoxic artificial air with or without 2.5% methane. The macrohemodynamics and small intestinal pCO2 gap changes were recorded and tissue superoxide and nitrotyrosine levels and myeloperoxidase activity changes were determined in intestinal biopsy samples. Structural mucosal damage was measured via light microscopy and HE staining.

Methane inhalation positively influenced the macrohemodynamic changes, significantly reduced the intestinal pCO2 gap changes and the magnitude of the tissue damage after reperfusion. Further, the intestinal myeloperoxidase activity, the superoxide and nitrotyrosine levels were reduced.

These data demonstrate the anti-inflammatory profile of methane. The study provides evidence that exogenous methane modulates leukocyte activation and affects key events of I/R-induced oxidative and nitrosative stress.