whole cell patch clamp: just like a "Q"

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zhangxu04
zhangxu04's picture
whole cell patch clamp: just like a "Q"

first: when pipette touch cell, I can see a increase of the resistance, but at the same time the baseline whobble greatly. I orignally think I press the cell too much, but even I slightly move the pipette onto the cell, the baseline also wobble greatly. can you teach me how this happen ?

 second: it need too long to establish the G ohm seal seal, about 5 minutes or even more. I think this is not correct.I do not know why

third: mostly, this is the most distriuting point. I can not eatablish  G ohm seal, always about 40-50M ohm, then seal stop increasing. I further  sucked, but  not increase of seal, still about 40-50M ohm. at this moment,  I find there is much of cell membrane-likes in the pipiette. when I lift up the pipette, there left a relative long and thin "tail" on the brim of cell  (just like "Q" as you imaging).  more strongly suck, more lone of this type of tail, but the seal can not increase.

I have check my system, not air leak.

so please help me.

The FFM
The FFM's picture
to help you i need to know

to help you i need to know first what the resistance of your pipette tip is before you patch, when it is just dipped in the ECF.

Also what is the inner diameter of the tips after you have pulled the glass?

What are the compositions of your extracellular and intracellular solutions?

What type of cells are you trying to patch?

zhangxu04
zhangxu04's picture
ok

ok

resistance of my pipette tip is about 3M ohm.  I did not measure the inner diameter og the tip.

I am tring to patch 293 cell line. I meet someone also have similar problem when patching the 293 cell line.

Internal Pipette solution

mM     Compound        

 
110     K-gluconate          
20        KCl                          
1          MgCl2.6H2O         
5          EGTA                  
5          MgATP                      
10        HEPES              

the extracellular solution is standard HBSS solution

hoping you can help me. this make me very bad.