> Along with several other cell lines, CHO cells can express very high levels
> of p-glycoprotein, and this actively pumps indo-1 out of the cells. The
> solution is to load in the presence of a pgp inhibitor such as 10-30 uM
> verapamil. We published an account of this problem in Cytometry last year.
That is all OK, but if one wants to use INDO-1 as calcium signal detector
(as it is mostly used for), the simultaneous use of verapamil (or another
calcium channel blocker) to block P-glycoprotein may not be the best
idea. I'd suggest reserpine (titrate first, starting from 1 microgram per
ml). It worked ok in our hands and did not affect calcium signal,
although it might be nasty if you want to culture the cells for a longer
time afterwards.
Jacek
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Jacek M. Witkowski
Department of Histology
Medical University of Gdansk, Poland.