A solvent for pCMBS within physiological pH range - (Feb/01/2007 )

Hi,

I need to add pCMBS to cells, therefore i need a non-toxic solvent which is within pH 7.0 -7.4. pCMBS does not dissolve in water. Sigma states to dissolve in NaOH but that increases to the pH to about 8.4 which is not healthy to my Namalwa cells. I have also tried DMSO and ethanol but i am worried these reagents may be too toxic for the cells. Hopefully someone can help me?

thanks in advance.

cheers,
nancy

---

are you going to bathe your cells in the solution or are you going to add the solution to the medium?

if you are adding to medium then the pH will be controlled enough that the naoh solution should have little effect on the pH in which your cells are living.

---

Hi mdfenko,

Thank you for your reply. I suspend my cells in an assay medium which consists of sucrose, KCl, Nacl and CaCl2. I would not not do it in medium (RPMI) as I am testing for proton expulsion and the medium would buffer any changes in pH. Since the pH range of these cells are different (due to the NaOH in which pCMBS is dissolved in) from my other test samples, i would unable to draw a proper comparison, thus my problem.

thank you,
nancy

---

will the pCMBS stay in solution if you were to adjust the pH of the naoh solution back to near neutral with hcl (of course, after solubilizing the pCMBS)?

on the other hand, small amounts of dmso should have little effect on your cells. you can control for any effect by treating the cells with the same amount of dmso as introduced with the pCMBS.

---

Yes, I had a DMSO control for the last experiment. I did a cell count with trypan blue exclusion after the experiment ~60 min and the cells didn't look healthy at all, though there were no significant difference in the cell numbers. I should look at the cells straight after the 20 min mark. The final concentration of DMSO in cells was 0.14%. It's a good idea to use HCl but this takes time and basically I am testing for proton extrusion in the first 5, 10 and 20 min after addition of specific reagents.

---

you could neutralize the solution with hcl before adding it to the cells.

---