I'm a newcomer in the patch clamp technique. I'm using HEK293 cells with stabily expressed voltage gated potassium channels. For a recent experiment I have to do cell attached patches with the Axopatch 200B, but somehow I recognized something strange. Every time I do a cell attached patch after a good seal my cell looks to shrink and after five minutes I completely lose the seal. I thought that the problem might be the osmolarity so I adjusted the pipette solution and external solution to ~300 mmol/kg, but the problem stll remains. I can also not see some vibrations or small movements in the whole system, unless they are really small...I testes my cells on another set up with Multiclamp700B and there the seal remained stable longer than 30 minutes and the cells didn't change their shapes. Also the problem can not be the pipettes, since in both set ups I used the same.
Do you know a solution for this problem?