Lab 2 Voltage clamp Notes

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MODELING Voltage Clamp in OpenCOR We want to model the Voltage Clamp experiment in COR, trying to reproduce the protocol that Hodgkin and Huxley used in their first measurement. We will export the data in Excel. The voltage clamp we’ll use is like this. We start from the resting potential Vhold, then performing a jump to the test potential and going back to holding potential. Vhold will be set at -75 mV, and then we’ll perform a jump of 10 mV, then 5 mV and approaching different levels of testing potential. We are interested in the activity of the neuron in the 20ms test. The typical response we are going to expect is an increase of the sodium conductance gNa. We are going to perform the experiment for Sodium. Remember that gNa (sodium conductance) is the current JNa divided by V-VNa : the driving force. We modified the model selecting. 50 ms is the time in which we hold the Vhold. 20 ms is the time we keep the testing potential. 50+20+50 = 120 ms full stimulation. The second modification will be the value for the Sodium current. We add commented line in the code, which is the Sodium current but set to zero. The same for Potassium. This will allow to switch between the measurement of Sodium and Potassium. We are preparing the code to simulate a full block of Potassium, leaving the Sodium channel open. Then we will switch the commented conductances obtaining the opposite effect. In the simulation section, in fact, in this first part you have the gK = 0, whereas gNa = 120. NOTE that the changes in the editing section are permanent. (they will apply always, unless you change them. SIMULATION We will progressively vary the Vtest, starting from -70, then -60, -55, -45, -40, -30, -20, -10, 0 and the last two +10 and +20. (it is similar to what HH did). We set the duration at…