The effects of fluoxetine (Prozac™) on the activity of human small-conductance calcium-activated potassium (SK) channels were investigated utilizing a functional fluorescence assay with bis-(1,3-dibutylbarbituric acid)trimethine oxonol (DiBAC4(3)). Fluoxetine blocked SK channels stably expressed in HEK 293 cells in a concentration-dependent manner displaying half-maximal inhibitory concentrations (IC50) of 9 μM for hSK1, 7 μM for hSK2 and 20 μM for hSK3. The block of hSK3 channels was confirmed by whole cell patch-clamp recordings of the recombinant cells and human TE 671 cells. Fluoxetine also inhibited [125I]apamin binding in a concentration-dependent manner displaying IC50 values of 63 μM for hSK1, 148 μM for hSK2 and 295 μM for hSK3. These results provide new information concerning the mechanism of therapeutic and/or side effects of one of the most widely used antidepressant drugs.
Terstappen, G., Pellacani, A., Aldegheri, L., Graziani, F., Carignani, C., Pula, G., & Virginio, C. (2003). The antidepressant fluoxetine blocks the human small conductance calcium-activated potassium channels SK1, SK2 and SK3. Neuroscience Letters, 346(1-2), 85-88. https://doi.org/10.1016/S0304-3940(03)00574-3