Another thing worth mentioning: Rh123 has been used to measure 2
different things, which seem sometimes to be confused (or at least
confusing) in the literature. When used to stain cells under
conditions that permit dye efflux (i.e. stain, wash, incubate @ 37o),
it can be used to measure activity of the MDR gene product
p-glycoprotein which actively pumps the dye from the cell. When used
at higher concentration, or under conditions where efflux is blocked,
Rh123 has been used to measure mitochondrial activity (since this
charged low molecular weight lipophilic dye preferentially binds to
mitochondria).
Albert D. Donnenberg, PhD
Associate Professor of Medicine