Figure 8. R‐mTFD‐MPPB slows channel deactivation but S‐mTFD‐MPPB has no effect .

A and B, representative currents elicited in a reverse notch protocol by (A) a 400 ms pulse of 10 μm GABA or (B) a 5 ms pulse of 10 mm GABA (black traces), in the presence or the absence of 46 μm S‐mTFD‐MPPB (red) or R‐mTFD‐MPPB (blue). Outside‐out patches were held in the presence of 46 μm mTFD‐MPPB enantiomers for 30 s prior to the co‐application of GABA. The currents were also allowed to deactivate in the continuing presence of barbiturate. Deactivation rates after GABA was withdrawn were obtained from either single (10 μm) or double exponential (10 mm) fits and are shown as scatter plots (C and D). Horizontal bars indicate mean ± SD. Control values were consistent with those of Scheller & Forman (2002). Significance level compared to control were determined by one‐way ANOVA with Tukey multiple comparison test and are denoted as ***P ≤ 0.0001 and *P < 0.05. The deactivation rate at 10 μm GABA fell 4.4 (± 2.1)‐fold from 12 ± 4.5 to 2.7 ± 0.8 s⁻¹ in the presence of 46 μm R‐mTFD‐MPPB. At 10 mm GABA, deactivation was bi‐exponential, and the faster rate fell 1.7 (± 0.9)‐fold from 42 ± 16 to 25 ± 9.5 s⁻¹ and the slower rate fell 3.6 (± 2.4)‐fold from10 ± 4.8 to 2.8 ± 1.3 s^–1 in the presence of R‐mTFD‐MPPB. Activation rates are given in the text.