( )-Bicuculline is a competitive antagonist of gamma-aminobutyric acid type A (GABA A) receptors frequently employed as a pharmacological tool to elucidate the functional roles of inhibitory neurotransmission mediated by GABA A By antagonizing GABA binding this compound prevents chloride ion influx leading to reductions in neuronal inhibitory postsynaptic potentials (IPSPs) Additionally ( )-Bicuculline blocks small conductance calcium-activated potassium (SK) channels affecting neuronal excitability and firing patterns It is commonly utilized in electrophysiological studies such as patch-clamp or extracellular recordings to investigate synaptic transmission neuroplasticity mechanisms and epileptic activity models ( )-Bicuculline inhibits GABA A receptors with an IC 50 typically reported in the low micromolar range (approximately 2 5 M)