outward current at holding potential ( -80 mV)

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zang
zang's picture
outward current at holding potential ( -80 mV)

I tried to patch HEK cells (no transfected). My contidion is:

at room temerature
(K)i = 140 mM
(K)o = 4 mM
EK = -90 mV

At holding potential (-80 mV), most of times an inward holding current around -30 and -70 pA which seems to be reasonable (holding potential (-80 mV) > K reversal potential (-90 mV)).

But in some cells, I got an outward current around +20 pA.

How to interpret this outward current?
Thanks.

engstar
engstar's picture
the zero current potential of

the zero current potential of ur cell is dominated by Ek by also affected by other channels and the seal conductance. as long as the zero current potential is more positive than ur hold potential, there should be a negative holding current. Otherwise there should be a positive holding current, as in the case of very good seal.