increase in electrode resistance
rsn_ at _comcast.net
Sun Mar 28 10:15:59 EST 2004
On Sun, 28 Mar 2004 15:00:25 +0100, usenet at out-of-phase.de (Christian
>r norman <rsn_ at _comcast.net> wrote:
>> om an increased probability of picking up floating
>> particles). It is even more important to obtain a seal rapidly when
>> the pipette solution contains peptides or proteins, as they tend to
>> cover the pipette tip..."
>> The same glass using in sharp microelectrode will have the same
>> ability to pick up proteins, something in ample supply inside a cell.
>I understood that statement from "Single Channel Recording" differently.
> I don't think that proteins and peptides will clog the pipette
>(consider the size of a patch pipette and the size of proteins). I think
>the problem here is more that a thin layer of proteins will lower the
>capability of the patch pipette to form a gigaseal, as it hinders the
>direct interaction of glass and membrane.
Of course you are right with patch clamp electrodes that have
relatively large tips. The problem, though, is that proteins do tend
to stick to glass. A coating of very small particles or individual
molecules will interfere with the seal, not clog the tip. However, an
intracellular microelectrode may have a tip opening in the tens of
nanometer size range and sticking it into a cell can easily break of
"chunks" of material.of a size that can occlude the tip.
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