pipette Cl- concentration and junction potential

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NWZ
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pipette Cl- concentration and junction potential

We did inside-out and cell-attached rcording.

our method:
1. the refferentce electrode: Ag-AgCl wire inserted into agar containing 3MKCl.
2. the bath and pipette solutions are the same, containing (in mM) : potassium aspartate 140, EGTA 5, MgCl2 2 and Hepes 10, and pH adjusted to 7.4.
3. Smooth myocyte.
4. Amplifier:Pclamp 200A

Question:
1. May the junction potential at the interface berween Ag-AgCl wire and pipette solution change and influence clamp potential? Is that caused by the change of Cl- activity in the pipette solution  during recording?
2. We thought that becouse the single channel current is small and recorded in short time the change of the  junction potential  would be small and influence little. Is that right?
3. How to estimate the change of the junction potential at this inteface quantitively?
4. How to correct this junction potential?

Thanks every one