re: Indo-1 in CHO cells

Michael Fox (MFox@vines.ColoState.EDU)
Mon, 6 Nov 95 9:59:49 MST

Regarding the loading of CHO cells with indo-1, this is indeed a problem. We
isolated a CHO mutant that stains very well with indo-1 but otherwise has
very similar properties to normal CHO cells. This was published in Cytometry
17:33-38, 1994. The poor staining by CHO cells is related to drug efflux,
and is the same reason they stain poorly with Hoechst dyes. We found that
the mutants had about the same level of p-glycoprotein (as measured with
antibody C219) as the wild-type CHO cells, so the p-glycoprotein levels did
not seem to explain the higher level of staining in the mutants. It is
likely that another drug efflux pathway is involved. As David Hedley points
out, verapamil can be used to increase the staining with indo-1, but since
verapamil is a calcium channel blocker, one should be careful with it use
when studying calcium changes in cells.

Mike Fox
Colorado State University


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