Bad luck with patching... any tips?

BilZ0r BilZ0r at TAKETHISOUThotmail.com
Thu Nov 25 23:54:44 EST 2004


So I've just started trying to patch cells and I'm not having much luck. 
I'm using spike2v5 basically as an ossilocope, with a time base of about 
5 seconds, as I pass a 5mV step down the pipette (around 3MOhms K-
gluconate). I manually drive into the CA1 pyramidal cell layer with 
positive pressure on. I first see a very transient drop in the current 
trace (I assume this is entering the slice, if I reverse the pressure 
here I always get nothing). If I keep driving in a bit I usually don't 
really see a drop in the current, but the current trace goes a bit wavey, 
occilating up and down. If I drop the pressure here I get a 15% drop in 
current, (maybe 30% of the time) and if I put on negative pressure the 
"seal" forms more.

But I don't get zero current, Maybe down to 40-30% of original... I start 
to see some capacatinces transients, but I can't get the current down to 
nothing, or go whole cell.

1) Is there any way to get a more definate signal when I approach a cell? 
Or is it always subtle?

2) Do you thing I should try and increase my pipette resistance? 

3) Any ideas on what I'm doing that makes it look live I've got a cell, 
but yet I can't go whole cell (or even really on cell)?


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