36Chloride flux in synaptoneurosomes - Incubations were performed in rat corticohippocampal synaptoneurosomes as described in Methods. (A) 36Cl uptake under control conditions (“Ctr”), in the presence of 100 μM GABA (“GABA”), and in the presence of GABA plus bicuculline (“Bicu”, 100 μM), picrotoxin (“Picro”, 100 μM), or bilobalide (“Bilo”, 100 μM). Shown are data ± SEM from N=6-12 separate experiments run in triplicate. **, p<0.01 vs control (Ctr). ##, p<0.01 vs. GABA. (B) Inhibition of 36Cl flux induced by GABA (100 μM) in the presence of bilobalide. The IC50 for bilobalide was calculated from six individual experiments by non-linear regression (sigmoidal dose-response function) as 39 μM (confidence interval: 24-63 μM; R2=0.99).