Fig. 3.

Variety and stability of internal blocker affinity in hippocampal interneurons. A, I–Vcurves from two different interneurons, selected to show the extremes of inward and outward rectification, and an interneuron showing intermediate rectification. The fixed stoichiometry model (open circles) consisting of the weighted average of the two extremeI–V curves (80% outward + 20% inwardly rectifyingI–V curves) could fit the inward but not outward limb of the intermediate I–V curve. The Woodhull model [filled circles;K_D(0)/[polyamine] = 1.48,z(1 − δ) = 1.11] fit well over both inward and outward limbs of the curve. B, Stability of measured internal blocker affinity during the first 10 min after achieving whole-cell voltage clamp. Kainate currents were evoked every minute in neurons selected for initially high internal blocker affinity. Eachpoint represents the mean and SEM from three to nine cells. The hatched bar illustrates the time window for sampling neurons for the single-cell RT-PCR analysis. C, Direct comparison of rectification properties of AMPA receptors expressed by interneurons and oocytes. Each pointrepresents measurements from a different interneuron (n = 354) or oocyte (n = 170). Plots of data from the two cell types are superimposable except for the extreme GluR2-lacking recombinant receptors, which appear to be absent from the interneuron population.