Fig. 7.

Kinetics of organic cation transporter 2 (OCT2)-mediated metformin transport determined in the absence (black circles with line) and presence (red circles with line) of 3 μM of unlabeled 1-methyl-4-phenylpyridinium (MPP). Rates of transport were determined from the time courses of net metformin accumulation (see Figs. 1 and 3). Each point is the average of OCT2-mediated transport (uncorrected the first-order component of substrate accumulation; see Fig. 4) determined in five separate experiments. Dashed lines show the OCT2-mediated kinetic profiles determined using Eq. 2. B: Eadie-Hofstee transformation of the data shown in A.