reversal potential of hERG

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lazy
lazy's picture
reversal potential of hERG

Hi
I am working with hERG channel at physiological temperature. Ko is 4 mM, and Ki is 140mM.

(1) With the condition that the LJP was not cancelled (LJP was added to the potential applied):
The reversal potential is in good accordance with theoretical value. But the activation threshold potential is rather negative (-70 mV) than the values in publications (-50 mV).

(2) With the condition that the LJP was cancelled (LJP was treated as zero):
The reversal potential is in good accordance with "thoretical value plus LJP". The activation threshold potential is also around -50 -40 mV which is in good accordance with the published values.

Also, I have checked, in several articles, the polarity of the tail current recorded at -80 mV (HP), sometimes outward, sometimes inward, sometimes zero. In my condition, it is outward when (1) indicating the reversal potential is more negative than the holding potential (actually, the theoretical reversal potential is more negative than the HP), but zero wehn (2), indicating that the reversal potential is closed to the HP.

Finally, I am not sure if I am doing correctly or not, or if my understanding is correct or not.
I apprecite if you help me.
Thanks. 

egovoru
egovoru's picture
 Dear Konstanz,

 Dear Konstanz,

You mentioned that background currents or leak can influence measurements of the reversal potential.

How can I estimate the extent of these influences and correct the results of Vrev measurements? I would be very grateful for your help with this problem.