Fig. 1.

Influence of substrate identity on the degree of inhibition of organic cation transporter 2 (OCT2)-mediated transport. The 3 test substrates were metformin (12 µM), cimetidine (30 nM), and 1-methyl-4-phenylpyridinium (MPP; 12 nM). Each point represents the average of 30-s uptakes of substrate (expressed as %control uptake) from 2 experiments (each measured in triplicate), measured in the presence and absence (control) of a 20 µM concentration of 1 of 150 to 200 structurally distinct test inhibitors. The resulting inhibitory profiles are presented as 3 paired comparisons: inhibition of metformin transport versus inhibition of cimetidine transport (A), metformin transport vs. MPP transport (B), and cimetidine transport vs. MPP transport (C). The lines of unity are represented by dashed red lines (modified from Ref. 85).