Several authors working on spinal cord acute whole-mount prep (or acute slice prep) add c.a. 1.5 mM MgSO4 to their Standard ACSF . The use of 1.0-1.5 mM MgCl2 is instead mostly widespread amongst authors working on other parts of the CNS (and what I tipically used so far in cortex, hippocampus cerebellum, brainstem...).
Given that in all other ingredients recipes are equal, is there a particular reason to add MgSO4 to spinal cord-ACSF rather than MgCl2... or is this just (as I guess) a sort of "founder effect" applied to ACSF recipes?
Apart for Magnesium (see above), with Standard ACSF I mean c.a. 125 NaCl, 2.5 KCl, 2 CaCl2, 1.2 Na2HPO4, 10 Glucose 26 NaHCO3, c.a. 300 mOsm, pH7.4 with CO2/O2 (small variations according to each author).
Thanks in advance for your Kind suggestions and contributions!
I don't know much about spinal cord preparations, but at least to my eye your "founder effect" hypothesis seems plausible. I'd probably go with MgCl2 because why not. It won't change Cl- concentration, so shouldn't mess with inhibition. There's no SO4 in real ACSF. You seem to be buffering it by PO4 and carbonate... It's tempting to say "go with Cl2", but again, I'm not a spinal person.
In our lab, we perform patch-clamp in the hippocampus and cortex either in MgSO4- or MgCl2-containing ACSF and we do not observe any difference in the quality of recordings.
Best, Hristo
I usually add MgCl2 (instead of CaCl2) when I want to decrease Ca concentration to prevent tissue damage while I am cutting or making slices. Otherwise I have MgSo4 in my ACSF as default. (I record in hypothalamus and retina). In my opinion you should calculate your ECl when you add MgCl2 and if the ECl is in a range that does not affect your result for exmple GABAergic or glycinergic activity, Ca activated potassium (or chloride) channels then no matter if you have MgCl2 or MgSo4.
If your treatment included in aCSF does not include heavy metal ions like Cd2+, Ni+ etc you can you both MgCl2 and MgSO4 as your Mg2+ source. However once you plan to include those, to prevent precipitation (The solution becomes foggy), you need to avoid SO4, PhO4 in your aCSF. That is why some one simply use MgCl2, HPEPs in aCSF instead of SO4 or PhO4 and bicarbonate as Mg or pH buffer source/agent.
I regularly cut spinal and brainstem sections with vibratome for electrophysiology. I have tried both and have not noticed any significant difference. I guess 2 mM difference in Cl- concentration will not make a significant difference. I personally prefer MgCl2.
cheers, Refik
@Xinhuai Liu
Would you mind giving us the final concentration of each component you use in your aCSF, considering no heavy metal analysis?
Thank you very much!
please find one example of intracellular solution for whole cell recording, this is one EGTA as calcium buffer and gluconate based solution. You will note a bit differene in different paper.
I hope this will help you a bit, and good luck for your experiments.
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