Protective effects of MnM2Py4P and Mn-salen against small bowel ischemia/reperfusion injury in rats using an in vivo and an ex vivo electron paramagnetic resonance technique with a spin probe

Background. Reperfusion of ischemic tissues results in the formation of toxic reactive oxygen species (ROS), such as superoxide anion, hydroxyl radicals, hydroperoxide, and peroxynitrite. ROS are potent oxidizing agents, capable of damaging cellular membranes by lipid peroxidation. In the present study, we applied an in vivo electron paramagnetic resonance (EPR)/spin probe and an ex vivo EPR technique to provide direct evidence of ROS following experimentally induced small bowel ischemia/reperfusion (I/R) injury. Materials and Methods. We used a rat model of small bowel I/R injury to explore the possibility that MnM2Py4P or Mn-salen can prevent the accumulation of ROS species following experimentally induced I/R injury. We examined the ability of MnM2Py4P and Mn-salen to scavenge radicals in living Sprague-Dawley (SD) rats using an in vivo and an ex vivo EPR technique with a spin probe. Results. The CP decay rates in the MnM2Py4P- and Mn-salen-treated rats were significantly higher than those in the untreated rats and almost equal to those in sham group rats. There were no significant differences between the MnM2Py4P-treated group and the Mn-salen-treated group. Superoxide scavenging activities (SSA) in the MnM2Py4P- and EUK-8-treated group were higher than those in the untreated group and almost equal to the sham group. Conclusion. The present study suggested that the protective effects of MnM2py4P and Mn-salen against small bowel IR injury were mediated by the inhibition of O-2, H2O2, and NO production.