1. Choose tutorial "Voltage Clamping a Patch"

  2. In patch parameters , set K+ conductance to 0.0 S / cm^2

  3. Under stimulus control click on Vclamp

  4. Set conditioning pulse to 10 ms , -90 mV

  5. Set testing level duration to 10 ms , step to -20 mV

  6. Set return level duration to 5 ms , -90 mV

  7. Under run control set total duration to 21 ms

image-20250218064009131

https://docs.google.com/spreadsheets/d/1dC1F_QDnCclecN0XUQRr_kBqovObZtBIxQI74e17IgU/edit?usp=sharing

  1. Use modifications of this pulse protocol to determine the midpoint of activation and the midpoint of inactivation for these Na+ channels.

    • Midpoint of Activation :

      image-20250218071545289

      • gmax0.08118785212 mS

      • so gmax2=0.0405939260622657 mS

      • the corresponding closest voltage value on the G / V thats around 0.04 is 0 mV !

      • so its already centered around the midpoint of activation at zero milli volts

    • Midpoint of InActivation :

      image-20250218074944856

      • gmax0.0138757406 mS

      • so gmax2=0.0069378702982972 mS

      • the corresponding closest voltage value on the G / V thats around 0.006937 is between 70 mV and 60 mV

  2. Convince your teammates that the data you collected from Study Guide 6 – Voltage Clamp , will suffice to determine the midpoint of activation.

    • study guid 6 and this study guide both produce normal sigmoidal curves for G / V plots.

    • so both should be fine to use

    • voltage clamp might be more accurate than having the dynamics of multiple pulses


  1. Set the K+ conductance back to the default value

  2. Set the Na+ conductance to 0.0 S / cm2

  1. Determine the voltage dependence of activation and inactivation for the K+ channels in this simulation

    • Midpoint of Activation :

      image-20250218081616101

      • gmax0.03456009159 mS

      • so gmax2=0.017280045795 mS

      • the corresponding closest voltage value on the G / V thats around 0.017 is 20 mV !

    • Midpoint of InActivation :

      image-20250218082555656

      • there is an asymptote on G / V curve around 75 mV , close to the potassium reversal potential

      • potassium channels don't really inactivate

  2. Convince your teammates that the data you collected from Study Guide 6 – Voltage Clamp , will suffice to determine the voltage dependence of activation

    • the voltage clamp data looked cleaner