TABLE 2

Displacement of specific [³H]NECA binding by amiloride and HMA from wild-type human A_2AAR and point mutants D52A^2.50, S91A^3.39, W246A^6.48, N280A^7.45, N284A^7.49 transiently expressed on HEK293 cell membranes

Values are means ± S.E.M. of at least three separate assays performed in duplicate.

	[³H]NECA
	Amiloride		HMA
	IC₅₀	Change^a	IC₅₀	Change^a
	µM		µM
Wild type	16 ± 3	1.0	2.5 ± 0.4	1.0
D52A^2.50	175 ± 75***	11	35 ± 9***	14
S91A^3.39	13 ± 1.8	0.81	2.3 ± 0.6	0.92
W246A^6.48	2.7 ± 0.9***	0.17	0.43 ± 0.05***	0.17
N280A^7.45	10 ± 2	0.63	2.4 ± 0.6	1.0
N284A^7.49	5.9 ± 1.4	0.37	1.0 ± 0.3*	0.40

↵^a Change in fold over wild type.
Significantly different from wild type with *P < 0.05 or ***P < 0.001 (one-way analysis of variance with Dunnett’s posttest performed on corresponding pIC₅₀ values).