Potentiation of GABA-gated currents by diazepam, ocinaplon and DOV 315,090. Rat GABAA-Rs consisting of α1β2γ2S, α2β2γ2S, α3β2γ2S and α5β2γ2S subunits were expressed in Xenopus oocytes. Potentiation was determined using an EC10 concentration of GABA (~10 μM for α1β2γ2S, α2β2γ2S and α3β2γ2S; ~5 μM for the α5β2γ2S). Curves were calculated by normalizing values of relative currents obtained following administration of diazepam (○), ocinaplon (●) or DOV 315,090 (□) in the presence of GABA (from at least four oocytes harvested from at least two batches) to the value obtained following application of GABA. The dose-response curves of diazepam were fitted up to 3 μM. Higher concentrations (in parentheses) were excluded from the fit due to a decline in potentiation at higher concentrations. Smooth curves are calculated based on mean parameter values given in Table 2. Asterisks indicate fits for which the extrapolated Emax is more than 25% greater than the maximum potentiation observed at highest drug concentration.