Exogenously applied palmitic acid blocks Bdel2 current inhibition by SP. HEK-M1 cells were transiently transfected with Bdel2, α₂δ-1, Ca_Vβ2a, and NK-1R. (A) Schematic representing preincubation of cells with 10 µM palmitic acid blocks free AA, released after stimulation of NK-1R, from occupying the inhibitory site. Enhancement site, not depicted. The two exogenous palmitic acids (magenta) are shown bound to the inner region of Bdel2, antagonizing AA from binding to the inhibitory sites. (B and C) Individual traces taken before and 2 min after application of 5 nM SP alone (B) or in the presence of 10 µM palmitic acid (C). (D) Summary of Bdel2 inhibition by SP in the presence of 10 µM palmitic acid (PA). *, P < 0.05 compared with current amplitude before SP (n = 7) or compared with the presence of palmitic acid alone (n = 6). **, P < 0.05; percent inhibition by SP compared with percent inhibition by palmitic acid + SP. Error bars represent SEM. Bars, 10 ms and 200 pA.