Fig. 2. Schematic illustration of protocol for experiment 2. O²and Iso: animals received saline intraperitoneally 1 h before each session of oxygen pretreatment and isoflurane pretreatment, respectively; DMTU+Iso and DMTU+O²: animals received the same volume of dimethylthiourea (DMTU, a free radical scavenger) intraperitoneally 1 h before each session of oxygen pretreatment and isoflurane pretreatment, respectively. All animals were subjected to spinal cord ischemia 24 h after the last pretreatment. MAC = minimum alveolar concentration.