TABLE 4.

Potency for substrates and inhibitors in competing for [³H]WIN35,428 binding in hDAT mutants

Data were calculated as a percent of total [³H]WIN35,428 binding in the absence of competing substrate or inhibitor and analyzed by nonlinear regression. Data displayed in the table are IC₅₀ values with confidence intervals (CI) given within parenthesis. The number of experiments (n) is given under the ligand. Statistical significance was determined by an F-test by comparing fits in which selected values were constrained to be equal or were allowed to differ. The null hypothesis was that the best fit parameter for the value did not differ. A conclusion of statistical significance represents a rejection of the null hypothesis and indicates a difference between designated values. F-test values and degrees of freedom are given only in cases of statistical differences.

Ligands	IC50 (95% CI)
	Room Temperature			4°C
	hDAT	T62A-hDAT	T62D-hDAT	hDAT	T62A-hDAT	T62D-hDAT
	nM
Substrates
DA	1300	460**	11***	73††	17†††	10
(n = 3)	(75–2370)	(280–760)	(3.2–43)	(24–220)	(9–34)	(2.2–49)
		F1,30 = 8.176**	F1,30 = 37.92***	F1,30 = 15.21††	F1,30 = 43.45†††
AMPH	390	62**	8***	113†	16†	110
(RT, n = 3)	(200–750)	(32–120)	(4–15)	(60–220)	(6–38)	(4.9–4100)
(4°C, n = 6)		F1,30 = 11.93**	F1,30 = 63.33***	F1,30 = 5.380†	F1,30 = 5.513†
AMPH + 100 μM Zn2+				494‡	61‡‡	13
(n = 3)				(260–940)	(43–88)	(3–45)
				F1,30 = 7.108‡	F1,30 = 8.476‡‡
Inhibitors
Cocaine	222	205	46*	N.D.	N.D.	N.D.
(n = 3)	(120–410)	(98–430)	(16–130)
			F1,30 = 6.127*
Benztropine	63	99	160	N.D.	N.D.	N.D.
(n = 3)	(38–100)	(39–253)	(100–486)
GBR12935	50	125	113	N.D.	N.D.	N.D.
(n = 3)	(20–130)	(56–280)	(45–290)

N.D., not determined.

^*P < 0.05 compared with wild-type value.

^**P < 0.01 compared with wild-type value.

^***P < 0.001 compared with wild-type value.

^†P < 0.05 compared with values at RT.

^††P < 0.01 compared with values at RT.

^†††P < 0.001 compared with values at RT.

^‡P < 0.05 compared with values at 4°C.

^‡‡P < 0.01 compared with values at 4°C.