TABLE 3

Kinetic parameters of methamphetamine and metabolites determined from modeling the data in Fig. 4 and Supplemental Fig. 4

Models were chosen based on examination of Eadie-Hofstee plots. Methamphetamine was fit to a standard Michaelis-Menten equation. Amphetamine uptake kinetics was fit to a biphasic Michaelis-Menten equation (eq. 5). p-OHMA hOCT1- and hOCT3-mediated transport were fit to a standard Michaelis-Menten equation. Sigmoidal kinetics of hOCT2-mediated p-OHMA transport was obtained by fitting transporter-mediated uptake to the Michaelis-Menten equation with a Hill slope (eq. 5) for the substrate concentration and half-maximal transport concentration (K_1/2 in place of K_m). Results represent mean ± S.D. of three independent experiments each run in triplicate.