biophysics - How to measure Na/K channel activation at the membrane level?

Assume that there are two different signals occurring on the ECG - during depolarization and repolarization in the standard ECG. I was advised not to use the standard ECG in measuring the exact electrical events during:

• stages 0-2


• 3-4

We can get data about the electric activity of neurons in vivo in Fig. 1 where some data about the electric activity of neurons is present. So my thought is that a similar technique could probably work with cardiomyocytes.

Fig. 1 Example of measurement for electric activity of neurons in vivo

I estimate that there is about 18% uncertainty when using the standard ECG because of the peak in the stage 1 (Gibbs phenomenon) and those two complete different phases.