No. Transcellular ion transport function and paracellular permeability of solute transport are differentially regulated. The TEER measurement method is less sensitive especially in leakier cell monlayers and changes in paracellular leakage are size and charge dependent. There was a paper years ago that showed why one should use both solute flux and TEER for cell monolayers of low barrier function. We successively poked increasing numbers of holes in a cell monolayer through the filter with a dissecting needle and measured TEER and mannitol flux. While one hole caused marked increase in mannitol permeability, TEER was hardly affected. You should calibrate your system by using methods to open the tight junctions, e.g., Ca/Mg-free PBS +/- EDTA or concns of cytochalasin D,

No,

Four major questions to ask yourself that might explain what your seeing!

1- Did anyone in your lab run any LDH assay (cytotoxicity test) or a WST-1assay ( cell viability test )  for your compound at the same different concentrations that you are investigating in ECs? 

2- How long was your experiment?Preferably for a transport study to not exceed 2 hrs. In my experience, I have noticed a significant drop in the TEER values at 4hrs, only when we used serum-free media, and no TEER value change when we used fully supplemented media for the cells.

3- Depending on the TEER instrument that you are using, from my experience, You have to wait until everything reaches room temperature because reading will differ by 2-3 % if the TEER was read at slightly different temperatures. But if your using the instrument automatically measures the TEER values for you at every minute then just forget this point.

4- What was the material of both: the insert membrane and the coating matrix that you coated the insert for your experiment? I would recommend a polycarbonate membrane, and that you coat the inserts with human collagen before seeding the cells. We tested different material of inserts and ready to use ( pre-coated inserts, and we found that polycarbonate inserts where the best ( the only disadvantage we can't image the growing cells after seeding them), and human collagen was the best, as it exceeded all the pre-coated inserts.

I hope these points shed some light for you,

Good luck,

Sana

Dear Thomas,

Thank you very much for your comment. Would you please give the title of the paper that you are referring to?

Thanks.

Dear Sana,

Appreciated your comment. Actually, I did the viability test on my compounds. I am using polycarbonate inserts and Yes, I faced the problem of inconsistent TEER reading due to temperature variability. I am going to consider point number two.

Thank you.

Dr. Raub, could you please provide me the papers that you mentioned? thank you