Fig. 4.

Superoxide radical imaging in ischemic brain. Representative photographs showing the production of O₂⁻ by the presence of oxidized HEt in cortex (left), hippocampal CA₁(middle), and CA₃ (right) subregions. As previously observed by Kondo et al. (1997a), O₂⁻ production was demonstrated under normal physiological conditions by oxidized HEt signals appearing as small particles in the cytosol, suggesting possible mitochondrial production of O₂⁻ (A–C). At 1 hr after ischemia and reperfusion, the diffuse cytosolic oxidized HEt signal was observed in cortical cells (D). Although a high background could be observed, the cytosolic signals were not increased in the hippocampal CA₁(E) and CA₃ (F) subregions. At 1 d after ischemia, the diffuse cytosolic signals attenuated to preischemic levels in cortical cells except for endothelial cells (G). However, the marked diffuse cytosolic signal remained in the hippocampal CA₁subregion (H) but not in the CA₃ subregion (I). The diffuse signal was not found at 3 d after ischemia (J–L). Scale bar, 200 μm (lower magnification); 20 μm (higher magnification).