(-)-Bicuculline methiodide

(-)-Bicuculline methiodide is the N-methylated water-soluble derivative of the widely-employed ionotropic GABA_A receptor antagonist Bicuculline. This quaternary amine derivative demonstrates similar GABA_A receptor interaction as with the parent compound, though (-)-Bicuculline methiodide shows less specificity for this receptor and some activity at other sites. (-)-Bicuculline methiodide is observed to block afterhyperpolarizations mediated by Ca²⁺-activated K⁺ channels in dopaminergic neurons, an action unobserved with Bicuculline and other GABA_A antagonists. This differential activity is most likely related to the quaternary nitrogen atom in (-)-Bicuculline methiodide. While still a useful tool for study alongside Bicuculline, this differential interaction is relevant and must be included in experiment design.