Effect of coexpression of OCT1 on the actions of membrane-impermeable APDs in enhancing cell-surface D2R expression.
A, effect of coexpression of the OCT1 transporter on the concentration–response curves for amisulpride-mediated enhancement of cell-surface D2R expression. HEK293T cells transiently expressing FLAG-D2R, either alone or co-expressing the OCT1 transporter, were treated (24 h) with the indicated concentrations of amisulpride. The amisulpride-mediated enhancement (over vehicle) of cell-surface D2R was quantified by probing the intact cells with anti-FLAG antibody and is plotted as a percentage of the response at 10 μm, the maximum amisulpride concentration that was tested (mean ± S.E. (error bars), n = 15). The percentage of maximum response with OCT1 was significantly greater at all of the sub-10 μm concentrations of amisulpride tested (t test, p < 0.0001). B, effect of coexpression of the OCT1 transporter on the concentration–response curves for tiapride-mediated enhancement of cell-surface D2R expression. Concentration–response curves for tiapride-mediated enhancement of cell-surface D2R expression were generated and plotted as in A (mean ± S.E., n = 15–16).