Fig. 5.

A: effect of increasing metformin concentration on the rate of organic cation transporter 2 (OCT2)-mediated [³H]1-methyl-4-phenylpyridinium (MPP; 6 nM) transport. MPP uptakes were based on 30-s net accumulation [uncorrected for accumulation in wild-type (WT) Chinese hamster ovary (CHO) cells). Each point is the mean ± SE of uptakes (normalized to accumulation measured in the absence of metformin) determined in three separate experiments (each the average of 6 wells in a 96-well plate). The line was fit to the data using Eq. 3. B: effect of increasing MPP concentration on the rate of OCT2-mediated [¹⁴C]metformin (12 µM) transport. Metformin uptakes were based on 30-s net accumulation (uncorrected for accumulation in WT CHO cells). Each point is mean ± SE of uptakes (normalized to accumulation measured in the absence of MPP) determined in five separate experiments (each the average of 6 wells in a 96-well plate). The line was fit to the data using Eq. 3.