I haven't patched a soma quite that small before (what is it?).
Cerebellar granule cells aren't much bigger, and I've patched them
before. Is it in a slice, or in a culture dish? And Layer V pyramidal
cell dendrites are that size too, and I've hit them.
My thoughts are: Use thick walled glass: more glass at the tip has got
to make a physically more stable seal, right? Use high resistance
electodes: chances are your cells will be high resistance and low
capacitance, so you should still get good voltage clamp even with an
uncompensated series resistance in the 20-40MOhm range. (and if you're
not doing voltage clamp then no problem). On that note, for whatever
reason, I have always found that in small cells, say your open tip
resistance is 5MOhm, then your whole-cell series resistance will be at
least 3x that, i.e. 15MOhm. With big cells I usually find it only goes
up by a couple of MOhms.
If you're tiny cells are anything like granule cells, and are still in
the slice, they will move around alot when you move your pipette up,
so once you're near your cell of choice, drop the positive pressure
down to low mouth pressure. and if possible approach from the side,
rather than from straigh down, as it is easier to tell when you are
just touching the cell (so it doesn't spring out of the way).
I don't know if those are any of the problems you are having, but
seeing as it was "urgent" I thought I'd try
On Apr 10, 7:34 am, "Wei Zhang" <zha... from stanford.edu> wrote:
> I am trying to record from tiny cells and urgently need to ask some
> technical questions. If you are experienced with tiny neurons (3-5 micro
> meter) and willing to help, I'd like to invite you for a cup of coffee to
> talk about it. Thanks.