... active concentration of these dyes in the mitochondria results in quenching of their fluores-cence. On the other hand, it has been reported that,when the active uptake of rhodamine dyes into the mitochondria ... they arehydrophobic and negatively charged. A comparison of rhodamine uptake, in the presence and the absence of uncouplers, allows the estimation of the effect of intracellular binding on the ... byactive pumping of the dyes into the mitochondria, dyeuptake was measured routinely in the presence of the mitochondrial uncoupler, CCCP, The quantities of rhodamine 123, tetramethylrhodamine (TMR),...