Figure 4. Concentration dependence of actions of the mTFD‐MPPB enantiomers on GABA‐evoked currents .

The notch protocol was the same as that in Fig. 3. Current traces were normalized to peak current amplitudes elicited by 10 μm (A) or 10 mm (B) GABA to allow for visual comparison between different cells. The section of the current trace shown in green (right panel of B), where a brief enhancement occurs with R‐mTFD‐MPPB, is enlarged in the inset. The concentration dependence of the actions of R‐ and S‐mTFD‐MPPB on normalized current amplitudes elicited by 10 μm GABA or 10 mm GABA are shown in C and D, respectively. Data in those panels were fit to the Hill equation by assuming that maximum inhibition or enhancement is attainable. The IC₅₀ values are given in the text.