(-)-Bicuculline methiodide

(-)-Bicuculline methiodide is the N-methylated water-soluble derivative of the widely-employed ionotropic GABAA receptor antagonist (+)-Bicuculline. This prototypic, competitive GABAA receptor antagonist displaces GABA from the agonist binding site to prevent receptor activation. It also acts as a negative allosteric inhibitor of channel opening to inhibit GABAA receptor activation by anaesthetic agents. Additionally it shows activity at SK calcium-activated potassium channels, nicotinic acetylcholine receptors and acetylcholinesterase. This compound reversibly and competitively blocks GABAA receptor mediated currents and is widely used to isolate glutamate receptor mediated EPSCs (excitatory postsynaptic potentials).