Fig. 4.
Weak base competition between two P-gp inhibitors and compounds that increase lysosomal pH in KB-3–1 cells. (A) Two weak bases, tamoxifen and chloroquine, decrease the cellular accumulation of [3H]tariquidar (1 nM) from cells. Data represent mean ± SD (n = 3 observations). (B) Reduction in accumulation of the fluorescent weak base LysoTracker Red in cellular lysosomes by increasing concentrations of tariquidar and DCPQ assessed by confocal microscopy. Fluorescent staining shows the lysosomes (red, LysoTracker Red 10 nM) and the nuclei (blue, Hoechst 33342 8 μM).