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

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 :

     

     • $g_{\text{max}}\approx 0.08118785212mS$$g_{\text{max}}\approx 0.08118785212\ mS$

     • so $\frac{g_{\text{max}}}{2}=0.0405939260622657mS$$\frac{g_{\text{max}}}{2} = 0.0405939260622657\ mS$

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

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

   • Midpoint of InActivation :

     

     • $g_{\text{max}}\approx 0.0138757406mS$$g_{\text{max}}\approx 0.0138757406\ mS$

     • so $\frac{g_{\text{max}}}{2}=0.0069378702982972mS$$\frac{g_{\text{max}}}{2} = 0.0069378702982972\ mS$

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

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

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

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

   • Midpoint of Activation :

     

     • $g_{\text{max}}\approx 0.03456009159mS$$g_{\text{max}}\approx 0.03456009159\ mS$

     • so $\frac{g_{\text{max}}}{2}=0.017280045795mS$$\frac{g_{\text{max}}}{2} = 0.017280045795\ mS$

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

   • Midpoint of InActivation :

     

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

     • potassium channels don't really inactivate

4. 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