Figure 4. Receptor isoforms respond differently to application of 3 mM of GABA for 50 s. (A) Agonist-evoked conductance (height of thick black bars minus baseline response) was recorded in the presence of saturating levels of GABA. Calibration bar represents 50 micro S for the first, second, and fourth representative examples and 12.5 micro S for the third. (B) Mean (+ SEM) residual response at the end of the 50-s challenge for each cell tested. Calculated as a percentage of its own conductance level at time zero. None of the pairwise comparisons attained significance (n = 5–7 per isoform, P > 0.05 using one-way analysis of variance).