Figure 2

Effect of morphine on KCl-stimulted [³H]GABA release. The ratio of the integration of the peaks S2 over S1 was calculated for each elution profile. Morphine (0.1, 1 and 5 μM) and naloxone (10 μM) alone or together were perfused as described in figure 1 but naloxone perfusion was started one fraction earlier. Data represent averages ± SEM. Labels on the x-axis indicate concentration of drugs present during S2. Statistical difference was calculated using one-way ANOVA. The data indicates that 1 and 5 μM morphine caused a statistically significant 16% reduction of [³H]GABA release as compared to control (a) (p < 0.01). This effect of morphine was blocked by the antagonist naloxone (c) which had no effect on its own (b).