Fig. 5.

Inhibition of labeled substrate (atenolol, metformin, or MPP) uptake in hMATE2-K-expressing CHO cells by chloroquine (A), hydroxychloroquine (B), quinacrine (C), cetylpyridinium (D), and miramistin (E). Two min uptakes (pH 7.4) of ∼15 nM [³H]MPP, 150 nM [³H]atenolol, or 10 µM [¹⁴C]metformin were measured in the presence of increasing concentrations of each inhibitor . Each point is the mean (±S.D.) of results determined in three or more separate experiments (see Table 1 for a summary of results). The bar graph (H) compares inhibitor constants (IC₅₀) generated against the three substrates (atenolol, metformin, or MPP) for each of the inhibitors. *Indicates a difference between MPP & atenolol significant at the level of P < 0.05.