Figure 3.

Effect of Ca²⁺ on PD169316- and β-PMA-induced inhibition of 5-HT uptake. Synaptosomes were treated with modified Krebs'-bicarbonate buffer to remove Ca²⁺ followed by incubation with PD169316 (10 μm) or β-PMA (1.0 μm) or PD169316 plus β-PMA for 30 min in the presence or absence of Ca²⁺ as described (see Materials and Methods). 5-HT uptake was measured using 20 nm labeled 5-HT for 3 min. Parallel assays were conducted in the presence of vehicle and 0.1 μm fluoxetine to define the effect of vehicle and SERT-specific uptake. The mean uptake values ± SEM from three independent experiments performed in triplicate are given. ^*p < 0.05 denotes significant changes compared with vehicle controls; ^#p < 0.01 denotes values significantly different from PD169316 or β-PMA alone in normal Ca²⁺-containing buffer (one-way ANOVA with Bonferroni post hoc analysis).