Figure 9

The reduction of axonal VGSC function by steady depolarization signal may weaken axonal capability to produce spikes in response to fluctuated signals. Axonal VGSCs are inactivated by long-time steady depolarization pulses in two ways. A) shows dual recording at the soma and axonal bleb. B) The fluctuated pulse (FP) is injected into the axon to induce spikes, while the steady pulse (SP) is injected into the soma to indirectly inactivate axon VGSCs. C) FP is injected into the soma to induce the spikes, while SP is injected into the axon to directly inactivate axonal VGSCs. D) shows input–output curves for directly (open symbols) and indirectly (filled symbols) inactivating axonal VGSCs. Spike capability induced by the fluctuated pulse is more dominantly reduced by the direct inactivation of axonal VGSCs than the indirect inactivation of axonal VGSCs does (n = 7).