Activation gating in HCN2 channels
Fig 5
Effect of cAMP on computed gating currents per channel and moved gating charges.
The gating currents per channel were computed with model 1n (no cAMP) or 1a (10 μM cAMP). The holding potential was set to 0 mV. (a) ON-gating currents at the voltages between -140 and -70 mV. The main effect of cAMP is to significantly accelerate both the rising and the decay phase of the gating current, resulting in an increase of the peak amplitude. (b) OFF-gating currents at -40 mV following voltage pulses indicated in (a) containing a fast and a slow component. Both components are decreased by cAMP. (c) Effect of cAMP on the total gating charge computed by integrating the gating currents for a voltage pulse of 1.5 s duration in the absence and presence of cAMP. The holding potential was set to 0 mV. The effect of the voltage-dependent transition C1→C1* is only minor.