Regenerative The consequent change in Vm opens more m gates and augments the inward Nat current. As Vm approaches about 65 mV, the remaining m gates rapidly swing open in the fast Nat channels until virtually all the m gates are open Effective refractory period The h gates then remain closed until the cell has partially repolarized during phase 3, in this time the cell is in its effective refractory period, and it will not respond to further excitation Recovered from inactivation a+通道有三种状态,都是电压依赖性的: 备用(-90mV)→激活→失活The consequent change in Vm opens more m gates and augments the inward Na+ current. As Vm approaches about -65 mV, the remaining m gates rapidly swing open in the fast Na+ channels until virtually all the m gates are open Regenerative The h gates then remain closed until the cell has partially repolarized during phase 3, in this time the cell is in its effective refractory period, and it will not respond to further excitation. Effective refractory period Na+通道有三种状态，都是电压依赖性的： 备用 (-90 mV) → 激活 → 失活 Recovered from inactivation