Hi all of you ! Well, I am doing recordings of spontaneous EPSC for different projects, and I need to know if I can use a K-glu based internal solution (IS) to do that. I saw that this question was already asked several time but in my case I am not interested about the recording of the IPSCs, so I keep my potential to -65 mV. For one project, I am recording the spontaneous activity from neurons derived from stem-cells and I would like to characterize several properties in current-clamp also (that's why I am using a K-glu IS). For another project, I would like to know how the 5-HT affect the active and passive electrophysiological properties, as well as the spontaneous activity, so I should record all of those parameters from the same cells.
What do you suggest ? Can I use my K-Glu based solution or should I use a Cs based one ?
Thanks for your help !
Best,
Do you measure EPSC or EPSP? Under current-clamp conditions, one may record EPSPs (i.e., excitatory postsynaptic potentials).
When voltage-clamp mode is made, one might be hard to be distinguishable whole-cell recordings from cell-attached ones. Consequently, action currents would be mixed with EPSCs. Additionally, single-channel activity would influence EPSCs under voltage-clamp mode and EPSPs in current-clamp one.
Hi Noemie,
The K-gluconate internal is fine for recording sEPSCs at a holding potential near the typical resting membrane potential for your cell type. Just remember to make sure that the chloride reversal potential for your solutions is very close to -65 mV to avoid contamination with IPSCs. Alternatively change the holding a bit so that it equals the chloride reversal. And remember to take the aCSF/internal junction potential into consideration! ;)
Cheers!
Marcin
As Marcin said, KGluconate based internal solutions are fine for measuring spontaneous EPSCs around normal resting potentials. You really only need Cs if you are going to Voltage clamp the cell at very depolarized potentials. Depending on the exact cell and preparation, it can be hard to completely clamp the membrane at ECl though, so I would recommend blocking IPSCs pharmacologically (e.g. pictrotoxin, bicuculine, GABAzine, etc).
Thanks all of you for your answers which bring me a lot of advice and information. So I will keep the KGlu one for those experiments because I need to stay at -65 mV.
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