intra- and extracellular solution

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anja
anja's picture
intra- and extracellular solution

hi
i am looking for some litterature which says something about the composition of the intra- and extracellular solutions. i know the should resemble the true solutions, but can't you use different solutions depending on what you want to exam? and how do you know what to use?
thanks

Fraser Moss
Fraser Moss's picture
The simple answer is read

The simple answer is read scientfic papers that work on the same channels or that do the same /similar experiments that you do. Look at the composition of their solutions and see if they match your requirements.

Just ask yourself questions about the design of your experiments and tailor you solution appropriately. Here are some example questions.

What channel are you studying/ types of currents are you recording?

What is the major permeant ion and how much should I use to get approriate and recordable sized responses.

Do you want/need to use physiological compositions to do your experiment? Why?

Do you want low/no extracellular calcium or physiological Ca (1.8 mM)? Why?

Do you want to substitute your Ca for Ba to avoid activating some calcium dependent processes in the cell and to have higher calcium conductances?

How much EGTA should you use to buffer intracellular calcium?

Do you want high extracelular potassium or low extracelular postassium?

Do you need to substitute the Sodium for a non-permeant ion (e.g. NMDG)?

Do you need to substitute the Chloride for a non-permeant ion (e.g. gluconate)?

Will the current "run-down" and should I include ATP & GTP in the patch pipette.

What Buffer should I use to buffer the pH of the solutions (probably HEPES 10mM)?

Is the activity of the channel dependent on other divalent cations like Magnesium?

Are there other channels you need to block during recording by including drugs or certain ions?
e.g. Do you need to block poassium currents by using Cs in the pipette, or TEA in the Extracellular or Intracellular solution.

Do you need to block sodium channel with TTX or Calcium channel with dihydropiridines or conotoxins?