Rabbit anti-GIRK1 polyclonal, guinea pig anti-GIRK2 polyclonal and rabbit anti-GIRK3 polyclonal antibodies (Aguado et al., 2008) were used in this study. The detailed characterization of the antibodies targeting GIRK channel subunits has been described elsewhere (Aguado et al., 2008; Fernández-Alacid et al., 2009).