Perforated Patch Problem

[Matthew Ireland]

Dominic-Luc Webb molmed <domweb at mbox.ki.se> wrote in message news:<Pine.GSO.4.33.0109081702570.14848-100000 at mbox.ki.se>...
> On 3 Sep 2001, Matthew Ireland wrote:
> 
>    > Dear Colleagues
>    >
>    > Currently I am using perforated patch on neurons within the CNS.
>    > Recently, I have been experinceing a problem when I try to perforate a
>    > neuron, instead of a full perforation as you would expect, it only
>    > results in a partial perforation.
> 
> 
> Not sure what a partial perforation is. Are you in fact getting
> a proper seal? I suppose the ampB could go bad, or it could
> leak out of the pipette and permeabilize the cells as well.
> Are you back filling a small volume of the ampB into a large
> volume of ampB-free buffer in the pipette?
> 
> 
> Cheers,

I am backfilling the electrode with an AmpB free solution and I'm
forming normal seals.

What I'm seeing, is instead of a normal perforation (ie. within 5
mins, around 15pF & 10mOhms), I see a small change in the whole cell
capacitance (4pF) that remains that way for the duration of the
experiment.

I don&#8217;t think the AmpB is leaking out of the electrode. 

With thanks
Matthew