FIG. 7.
Inhibition of Ih by isoflurane increases synaptic excitability in cortical neurons. A: effects on WT cortical pyramidal neurons of 40-Hz electrical stimulation delivered at a rate of 1 Hz to the superficial cortex under control conditions (left), in the presence of 0.15 mM isoflurane (middle), and following wash (right). (Spikes are truncated in this panel and in B.) B: an expanded view of 2 stimulus events under control conditions (blue) and during exposure to isoflurane (red); note the slight hyperpolarization and enhanced EPSP summation in isoflurane, when both events were associated with spike firing. C: quantification of data from this cell, illustrating the increased likelihood that the synaptic stimulation triggered a spike in the presence of isoflurane (as a percentage of all stimulation events in a 2-min epoch under the indicated conditions). These results are representative of those obtained in the 2 other cells studied with this protocol.