Fig. 1.

Cocaine and DA applications to a voltage-clamped hDAT oocyte evoke opposite changes in membrane current. Drug applications (solid bars) to oocytes voltage-clamped at −60 mV. A, An hDAT-expressing oocyte was initially superfused with 10 μm cocaine (Coc), which elicited a small outward current that slowly returned to baseline after 10 min of washout (flow rate 4 ml/min, chamber volume 0.5 ml). Superfusion of 20 μm DA induced an inward current that rapidly returned to baseline. Reapplication of cocaine caused an outward current comparable in magnitude and kinetics to that evoked by its initial application. B, No responses were evoked by drug application to a water-injected control oocyte.