TABLE 2.

Antagonistic Effects of Tyrosine Derivatives on Function of Human P2X₇ Receptors Expressed in HEK293 Cells^a

Compound	Structure R1R2R3	% Inhibition of ATP-induced K releasea
1 (KN-62)		85 ± 9	(13)
3	IqIqH	14 ± 12	(3)
4	IqIqB	77 ± 24	(3)
5	QuQuH	5± 9	(3)
6	QuQuB	61 ± 30	(3)
7	IqQuB	37 ± 21	(5)
8	FQuB	34 ± 28	(3)
9	HQuB	1± 1	(3)
10	EQuB	5± 7	(3)
11	ZQuB	53 ± 23	(4)
12	BzQuB	13 ± 8	(3)
13	MsQuB	4± 4	(3)
14	BsQuB	8± 3	(3)
15	TsQuB	32 ± 16	(3)
16	MoQuB	26 ± 20	(4)
17	NQuB	16 ± 2	(3)
18	NbQuB	0	(1)
19	ZHB	0	(1)
20	ZMsB	0	(1)
21	ZBsB	59 ± 14	(3)
22	ZTsB	71 ± 30	(3)
23	ZMoB	62 ± 15	(3)
24	ZNB	25 ± 15	(3)
25	ZNbB	43 ± 16	(4)
26	ZIqB	43	(1)
27	ZZB	1	(1)
28	ZBzB	47 ± 21	(3)
29	ZEB	0	(1)
30	ZAB	0	(1)
31	ZPB	4	(1)
32	ZBsTs	0	(1)
33	ZBsMs	0	(1)
34	ZBsBs	0	(1)
35	ZBsMo	0	(1)
36	ZBsN	0	(1)
37	ZBsNb	0	(1)
38	ZBsZ	48 ± 29	(3)
39	ZBsE	24 ± 11	(3)
40	ZBsBz	78 ± 22	(3)
41	ZIqBz	85 ± 10	(3)
42	ZBsA	0	(1)
43	ZBsP	0	(1)
44	ZBnB	45	(1)
45	BBnBc	14 ± 18	(3)
46	BBsB	6	(1)
47	BBnBbc	0± 0	(3)
48	ZBnZbc	8± 7	(3)
49	BBnBbc	4± 3	(3)
50	ZBnBb	0	(1)

^aAll experiments were performed using adherent HEK293 cells stably transfected with cDNA encoding the human P2X₇ receptor. Adherent cells on 12-well polylysine-coated plates were incubated at 37°C in 1 ml physiological salt solution (125 mM NaCl, 5 mM KCl, 1 mM MgCl₂, 1.5 mM CaCl₂, 25 mM NaHEPES (pH 7.5), 10 mM D-glucose, 1 mg/ml BSA). Antagonists (3 µM final concentration) were added from 1,000× stock solutions dissolved in DMSO. Cells were preincubated with antagonists for 15 min prior stimulation for 10 min with 3 mM ATP (final concentration). Reactions were terminated by rapid aspiration of the extracellular medium in each well. The adherent cells in each well were then extracted overnight with 1 ml 10% HNO₃ and the K⁺ content in the extracts was assayed by atomic absorbance spectrophotometry. Duplicate or triplicate wells were run for all test conditions in each separate experiment and the measured K⁺ contents were averaged. Antagonist function was measured by the percent inhibition of the K⁺ release triggered by 3 mM ATP in paired cells in the absence of antagonist. Data points represent the mean ± SD values obtained; the number of separate experiments is indicated in parentheses. 4, MRS 2306; 6, MRS 2300; 11, MRS 2317; 21, MRS 2328; 22, MRS 2326; 23, MRS 2329; 28, MRS 2333; 38, MRS 2359; 40, MRS 2361; 41, MRS 2409.

^b47 = N^α-methyl derivative of 45. 48 = N^α-methyl derivative. 49 = D-isomer of 45. 50 = Boc-ethylene diamine (instead of Boc-piperazine) derivative of 44.

^cNo inhibition detected at 30 µM.