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[Neuroscience] Gramicidin Perforated Patches and liquid function potentials

Bill via neur-sci%40net.bio.net (by connelly.bill from gmail.com)
Sat Oct 4 16:00:28 EST 2008


I may have already posted this, but it isn't showing up on google
groups, so I'm thinking there may have been a problem.

To get to the point I finally have got gramicidin perforated patching
working regularly (~30mOhms in 15 minutes) however all my cells appear
to be "resting" ~20mV more hyperpolarized than they do when I do whole-
cell recording using either a K-gluconate or KCl based pipette
solution. Does this make sense to anyone?

I presume this is something to do with the fact that during whole-cell
recordings the cell interior eventually becomes the same as your
pipette solution and hence there is no liquid junction potential (so
the added voltage which was 'bucked' out of the system when the
electrode was zeroed and the LJP was in force, and is added to your
recorded membrane potential)? However in perforated patch mode, you
have a difference situation, where different ions have different
mobilities, not only based on their mobilities in solution, but their
conductivity through the gramicidin pores? Or am I over analysing
stuff here?

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