Fig. 8.
Tonic activation of GABAA receptors does not change voltage threshold. Action potentials were evoked every 10 s for 2 min, then 1 μM muscimol was applied for 2 min, and finally washed out for 1 min. Pipette chloride was standard low chloride concentration to facilitate detection of effects on threshold. A1: representative action potentials in the absence (black), presence (red), and washout (blue) of 1 μM muscimol. Inset: rising part of the phase plot, with voltage threshold indicated by the horizontal line at 10 mV/ms. A2: time course of voltage threshold change with time under the various experimental conditions. Same color codes as in A1. A3: time course of input resistance (Rm). The example shows 1 of the larger changes observed. B and C: average values for thresholds (B) and input resistance (C) for each condition (n = 10 cells).