David wrote:
> Hope you could help me help me with this question. I would like to
> know whether expression of a Na channel in HEK cells results in Na
> loading which may be affecting the results of an assay based on a
> membrane voltage dye.
> What is the best way to measure resting potential using e-phys and
> without going whole cell (ie not disrupting the intracellular salt
> concentration)?
> (i) Is it possible to measure the resting potential in cuurent clamp
> mode with sharp electrodes (0.01 to 0.1 uM tip diameter) and or are HEK
> cells too flat for this?
> (ii) Would a current clamp of an on-cell patch give me an accurate
> measurement of membrane voltage?
> (iii) Should I go whole cell but take the current -clamp measurement
> as quickly as possible (before the cell interior is dialyzed out)?
>> Thanks,
>> David
> Hi David:
I am far away of being an expert, but I would like to share with you my
suggestions about the question.
(i) A possible solution seems to me to try with sharp electrodes. If
not, perforated patch-clamp should be a good possibility to study. Just
ask here if you want to know about it, there're a lot of competent
people working with this configuration.
(ii) With cell-attached recordings the potential across the patch
pipette is dependent on the resting membrane potential, which cannot be
determined!!!
(iii) I would be also possible to read the liquid junction potential
(the potential between the bath and the pipette solutions) and then
corrected from the membrane potential recorded under whole-cell conditions.
I hope it helps.
Regards!
--
ÿþS
