Figure 6.

Depression of FVs by isoflurane. A, (top) An extracellular recording under control conditions showing the FV is partially occluded by the larger EPSP. A, (lower) The FV was isolated with CNQX (8.6 μM) and APV (125 μM) to block AMPA/kainate and NMDA receptors, respectively. B, Partial block of a FV by 60 nM TTX (green trace). C, Isoflurane produced small reductions of FV amplitudes (blue traces). D, Concentration dependence of the depression of FV amplitudes by isoflurane. Data were normalized to control conditions in the absence of drug. Each point represents the mean of multiple experiments carried out in different slice preparations (n = 6 each data point), with standard deviations represented by the error bars. The dashed line is a least-squares fit to a Boltzmann relation with an EC₅₀ = ~12 vol % and a Hill coefficient of 2 (χ² = 2.5). All measurements were made following at least a 20 minute period for the perfusion system to equilibrate.