Sigma ligands inhibit hERG current without decreasing hERG membrane expression or altering Sig1R-hERG association. A, effect of cell incubation with igmesine (IGM, 10 μm, 30 min) on hERG current density in shRD and shSig1R K562 cells. *, p < 0.002, Mann-Whitney. B, left panel, effect of with igmesine (IGM, 10 μm, 30 min) on hERG surface expression by flow cytometry in shRD K562 cells. Right panel, corresponding histogram. NS, not significant, Mann-Whitney. C, effect of HEK 293 cell incubation with igmesine (IGM, 10 μm, 30 min) on Sig1R-hERG association. Immunoprecipitation (IP) with an anti-c-Myc antibody of HEK 293 cell lysate proteins. Western blots (WB) were probed with anti-hERG (upper panel) or anti-Sig1R (lower panel) antibodies. The cells were transduced with hERG + cmycSig1R. Representative of three independent experiments. Ctrl, control.