Figure 2. Effect of nitrous oxide on the amplitude of the evoked population spike recorded in the CA1 region of rat hippocampal slices. Slices received 50% nitrous oxide and 45% oxygen for 30 min (solid line) and then were aerated with 95% oxygen (n = 5). This is described as experimental series 1 in the methods section. Slices treated with 50% nitrogen and 45% oxygen for 30 min (dashed line) were not significantly different from the nitrous oxide-treated slices (n = 8). There was no hypoxic period in these experiments; the oxygen concentration was the same in both groups throughout the experiment, and 5% carbon dioxide was present in all gas mixtures. The x axis shows the time after slice preparation and the percentage of oxygen in the gas mixture. Values shown are the mean +/- SEM.