TABLE 2.

EC₅₀ values of methamphetamine and amphetamine for hOCT1 and hOCT2 determined by two-binding site fitting

The EC₅₀ values were obtained by fitting inhibition data in Fig. 1 and Supplemental Fig. 2 using eq. 2 described in Materials and Methods with the fit shown in Supplemental Fig. 3. The last column lists the P values obtained by comparing eqs. 1 and 2 with an extra sum-of-squares F test. Results represent mean ± S.D. of three independent experiments each run in triplicate.

Inhibitor	Two-Binding Site			Two-Binding versus One-Binding Site
	Transporter	EC50 Value
		High Affinity	Low Affinity
		μM	μM
Methamphetamine	hOCT1	5.29 ± 0.66	400 ± 229	P < 0.0001
	hOCT2	1.21 ± 0.19	58.2 ± 23.4	P < 0.0001
Amphetamine	hOCT1	NA	NA	P = 0.55
	hOCT2	0.72 ± 0.29	145 ± 104	P < 0.0001

NA, not applicable.