Figure 4: Measurement of ROS in the heart by DHE fluorescence. (a) Representative confocal fluorescence images of cryopreserved LV sections from different groups stained with DHE. (b) Quantification of superoxide generation is indicated by DHE fluorescence, sivelestat decreased tissue ROS during reperfusion, as compared to hearts infused with L-NAME. This decrease was reversed when L-NAME was coinfused with sivelestat ( = 3–5 per group). n.s.: nonsignificant.