electrophysiology- intracellular solutions and miscellaneous

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blindwatchmaker's picture
electrophysiology- intracellular solutions and miscellaneous

How do people decide which intracellular solution to use? Why would you choose K+ based versu Na based? What are the best intracellular solutions for recording minis vs whole cell LTP etc.? Is there an intracellular solution that's best for switching between recording a cell's firing characteristics (current clamp mode) then going whole cell and recording minis? I'm trying to patch interneurons (blindpatch) so I need to be able to characterize them eletrophysiologically before recording minis-is this possible? The literature doesn't provide specifics and usually people use biocytin to backfill and then posthoc identify cells. I need the quickest way possible without posthoc identification using confocal. Are there other gudes for using multiclamp to do the current clamp and voltage clamp exp's besides the Axon guide? Can someone recommend literature or books that more specifically address intracellular solution composition logistics and switching between current clamp and voltage clamp for interneuron recordings? I don't have any training and have been pretty much teaching myself on the fly how to use this software and do these recordings. I've tried visualized patch but have found that I my cells are healthier with blind patch. Any tips for improving success rate for visualized patching (less positive pressure, less suction during attempted patching relavite to blindpatch etc?).

c.hill's picture
I am by no means an expert in

I am by no means an expert in this area but I can provide a little bit of advice.

K+ based intracellular solutions for patching neurons, rather than Na+ based, is fundamentally really important. Inside neurons there is high K+ and low Na+ concentrations, whereas outside neurons there is low K+ and high Na+ concentrations. Sometimes other cations are the principle ion in the solution - eg. caesium or barium - because they block some forms of transmission (from memory, GABAB or potassium channels - but don't quote me on that!).

It's also really important to consider whether you should use a chloride or gluconate based intracellular solution, which will depend on whether you'll be using voltage clamp or current clamp. In my mind at least, I consider chloride based intracellular solutions for voltage clamp and gluconate based solutions for current clamp - but there are exceptions! When recording mIPSCs I use a chloride based ICS but when recording mEPSCs I use a gluconate based ICS.

The information is out there in the literature, you just have to be patient and thorough. I searched Pubmed for papers on mEPSCs and mIPSCs and wrote down the composition of the ICS used. Sometimes there's a rationale for why they've used particular components, other times I've 'googled' it.