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. 2014 Mar 5;34(10):3719–3732. doi: 10.1523/JNEUROSCI.4206-13.2014

Figure 6.

Figure 6.

Axonal Kv7 channels maintain resting membrane potential stability. A, Left, Schematic drawing of the drug application (red) and recording pipette arrangement (black). In this example, XE-991 was focally applied to the AIS. Right, Example voltage recordings before (gray) and after XE-991 application (red) locally to the AIS (right top) or in the bath (right bottom) show an augmentation of the ADP. Calibration: 10 ms, 10 mV. B, Line and scatter plots of the individual data reveal an increase in the ADP after local XE-991 application to the AIS (n = 6) or global block in the bath (n = 18). C, Population data of the resting membrane potential change for the different locations and solutions. HEPES, Control solution without XE-991 to the AIS; Dend, XE-991 to the dendrite; AIS, XE-991 to the axon initial segment; Node, XE-991 to the node; AIS + first node, XE-991 to the AIS and node; Bath, XE-991 in the bath; AIS + TTX, XE-991 to the axon initial segment in the presence of 1 μm TTX. **p < 0.001, *p < 0.05. Data represent the mean ± SEM. Inset, Focal AIS application of XE-991 depolarized the resting membrane potential. Calibration: 1 mV, 1 min. D, Example of a recording in which 20 μm XE-991 caused spontaneous firing. A 20 min period before washout was blanked for clarity. Calibration: 4 min, 10 mV. E, Summary data for the 17 experiments in which 10–20 μm was focally applied to the AIS. Washout was tested in three experiments. F, Power spectrum of the spontaneous action potential firing rate during AIS Kv7 channel block. Action potential frequencies ranged between ∼4 and 38 Hz (n = 6). Calibration: 0.1 s, 10 mV. G, After local XE-991 application to the AIS blocking the persistent sodium current by bath application of 5 μm riluzole decreased the ADP (left). Calibration: 10 mV, 10 ms. Population data for the changes of the ADP area during XE-991 application to the AIS and in the presence of riluzole (right). The XE-991 data is the same as in B. H, Recording in which XE-991 puffing to the AIS caused spontaneous firing and application of 5 μm riluzole abolished the spontaneous APs. Gaps in the recording are blanked for clarity. Calibration: 2 min, 20 mV.