Background
It has been noticed by our group [1] that p-chloroamphetamine (PCA)-induced SERT current ''deactivates'' slower upon removal of PCA from the external solution, when compared to the deactivation of serotonin (5-HT)-induced current. This was observed in stably transfected human embryonic kidney (HEK) cells as well as in Xenopus laevis oocytes injected with hSERT-RNA, for PCA/5-HT concentrations between 1 and 30 μM. Following the removal of higher concentrations of PCA (>30 μM) from the bath solution we witnessed an intriguing, but yet paradoxical current rise.