Figure 5.

Modulation of MTSEA-induced inactivation of S277C by fluoxetine, imipramine, cocaine, and ibogaine. Membranes from cells expressing S277C were treated for 15 min with 0.1 mm MTSEA in the presence of varying concentrations of cocaine, ibogaine, imipramine, or fluoxetine. After washing membranes free of MTSEA and inhibitors, residual binding activity was determined by incubation with [¹²⁵I]β-CIT as described in Materials and Methods. The concentration range of each inhibitor is presented relative to its IC₅₀ (x-axis). The typical experiment illustrated was repeated four times with similar results. Inset, Imipramine effect in the presence (filled circles) or absence (open circles) of Cl⁻. The IC₅₀ for imipramine was 0.4 ± 0.1 μm in the absence of Cl⁻ and 0.05 ± 0.02 μm in its presence. In the absence of imipramine, Cl⁻ had a minor effect, decreasing the IC₅₀ for MTSEA by only ∼30% (comparing NaCl with Na-isethionate).