Fig. 3. Relations between duration of ischemic depolarization and neuronal damage. Rectangles and circles represent data for animals in the nitrous oxide group and nitrogen group, respectively. The logistic regression curves show close relations between duration of ischemic depolarization and neuronal damage (nitrous oxide group, line A : r 2= 0.64, P < 0.0001; nitrogen group, line B : r 2= 0.78, P < 0.0001). The 95% confidence intervals (shaded areas ) did not overlap from 4.96 to 8.44 min of duration of ischemic depolarization (*).