Table 1.

Responses of receptors to pyrazines at a 10⁻² dilution

	Or2a	Or7a	Or13a	Or22c	Or24a	Or30a	Or33b	Or35a	Or42a	Or42b	Or45a	Or45b	Or47a	Or49a	Or59a	Or67b	Or74a	Or82a	Or85c	Or94a	Or94b
2-Ethylpyrazine	9 ± 1	56 ± 13	9 ± 5	5 ± 9	16 ± 9	13 ± 3	144 ± 9	18 ± 5	124 ± 10	24 ± 15	35 ± 5	12 ± 7	35 ± 9	10 ± 2	66 ± 12	60 ± 14	7 ± 5	−6 ± 8	9 ± 11	2 ± 8	8 ± 8
2-Ethyl-5(6)-methylpyrazine	14 ± 4	47 ± 12	22 ± 4	68 ± 7	44 ± 46	7 ± 5	123 ± 23	54 ± 11	114 ± 13	1 ± 9	51 ± 16	11 ± 11	41 ± 12	5 ± 5	79 ± 23	15 ± 4	6 ± 1	9 ± 5	26 ± 3	19 ± 5	9 ± 9
2-Acetyl-3-methylpyrazine	11 ± 4	8 ± 2	18 ± 1	18 ± 12	101 ± 28	7 ± 3	90 ± 20	25 ± 9	9 ± 5	3 ± 9	27 ± 12	41 ± 13	12 ± 5	4 ± 2	132 ± 13	24 ± 7	8 ± 5	3 ± 8	25 ± 21	12 ± 5	0 ± 0
2-Ethyl-3,5(or 6)-dimethylpyrazine	1 ± 2	4 ± 11	27 ± 4	3 ± 7	0 ± 4	1 ± 1	105 ± 23	2 ± 3	51 ± 10	0 ± 1	20 ± 5	0 ± 0	16 ± 15	2 ± 2	139 ± 14	2 ± 2	0 ± 2	13 ± 5	0 ± 12	17 ± 10	0 ± 0
2-Methoxypyrazine	10 ± 2	26 ± 10	−5 ± 2	48 ± 13	94 ± 28	55 ± 8	130 ± 14	11 ± 11	85 ± 20	28 ± 19	37 ± 10	11 ± 6	11 ± 11	1 ± 1	78 ± 15	83 ± 23	7 ± 5	−13 ± 5	8 ± 28	15 ± 14	11 ± 11
2-Ethyl-3-methylpyrazine	1 ± 5	11 ± 8	14 ± 2	2 ± 3	5 ± 3	0 ± 4	69 ± 14	10 ± 4	22 ± 4	3 ± 8	25 ± 5	2 ± 3	9 ± 4	1 ± 1	133 ± 21	7 ± 2	5 ± 1	2 ± 5	1 ± 3	22 ± 11	0 ± 0
2-Ethyl-3-methoxypyrazine	9 ± 2	19 ± 12	4 ± 7	−1 ± 7	3 ± 6	15 ± 7	−5 ± 4	4 ± 4	10 ± 2	10 ± 8	17 ± 4	5 ± 5	12 ± 5	17 ± 5	128 ± 19	1 ± 2	5 ± 4	17 ± 7	12 ± 11	64 ± 6	19 ± 16
2,3-Diethylpyrazine	7 ± 7	10 ± 11	18 ± 5	1 ± 5	9 ± 3	1 ± 1	5 ± 7	4 ± 4	32 ± 8	4 ± 14	21 ± 6	0 ± 0	4 ± 21	1 ± 1	134 ± 20	6 ± 5	6 ± 10	9 ± 4	5 ± 4	−4 ± 2	15 ± 15
2-Chloropyrazine	14 ± 10	50 ± 4	−7 ± 2	8 ± 1	11 ± 3	18 ± 17	127 ± 21	25 ± 16	80 ± 13	28 ± 7	62 ± 20	11 ± 7	19 ± 20	1 ± 1	19 ± 7	4 ± 3	17 ± 8	−14 ± 6	2 ± 21	16 ± 12	0 ± 0
2-Isobutyl-3-methoxypyrazine	28 ± 5	−5 ± 7	13 ± 11	0 ± 1	6 ± 4	3 ± 2	29 ± 17	21 ± 1	12 ± 5	4 ± 6	2 ± 7	0 ± 0	3 ± 11	1 ± 1	58 ± 13	1 ± 2	5 ± 7	0 ± 5	3 ± 3	0 ± 6	1 ± 1
2-Acetyl-3-ethylpyrazine	2 ± 6	1 ± 5	11 ± 3	3 ± 5	1 ± 3	7 ± 6	−3 ± 4	7 ± 13	1 ± 3	5 ± 11	2 ± 4	0 ± 0	6 ± 4	2 ± 1	87 ± 22	1 ± 2	6 ± 7	7 ± 6	2 ± 3	13 ± 8	0 ± 0
2-Acetylpyrazine	0 ± 5	0 ± 20	5 ± 7	0 ± 10	0 ± 14	0 ± 3	17 ± 10	0 ± 13	46 ± 14	0 ± 0	−13 ± 12	0 ± 3	0 ± 9	0 ± 1	17 ± 9	0 ± 3	0 ± 13	0 ± 13	0 ± 5	0 ± 8	0 ± 2
5H-5-Methyl-6,7-dihydrocyclopenta	2 ± 4	8 ± 6	17 ± 4	−1 ± 8	5 ± 6	1 ± 1	77 ± 12	8 ± 2	23 ± 5	−6 ± 8	28 ± 14	9 ± 5	13 ± 3	0 ± 0	88 ± 20	5 ± 3	5 ± 3	1 ± 8	0 ± 6	18 ± 13	−2 ± 3
2-Methoxy-3-(1-methylpropyl)	15 ± 7	−1 ± 8	3 ± 3	1 ± 5	2 ± 5	3 ± 1	3 ± 4	4 ± 2	7 ± 3	3 ± 8	13 ± 4	1 ± 1	3 ± 10	3 ± 3	48 ± 21	0 ± 2	−1 ± 5	7 ± 10	6 ± 4	3 ± 6	0 ± 0
2,3,5-Trimethylpyrazine	9 ± 2	12 ± 3	23 ± 5	7 ± 5	30 ± 9	3 ± 1	89 ± 14	−6 ± 15	28 ± 7	4 ± 5	9 ± 2	6 ± 6	6 ± 5	3 ± 2	135 ± 13	8 ± 8	5 ± 5	4 ± 5	−8 ± 3	23 ± 9	9 ± 9
2-isobutyl-3-Methylpyrazine	15 ± 4	12 ± 9	15 ± 4	0 ± 4	1 ± 1	2 ± 0	60 ± 26	5 ± 4	3 ± 3	7 ± 12	34 ± 7	0 ± 0	8 ± 2	2 ± 2	13 ± 5	10 ± 6	7 ± 7	7 ± 5	1 ± 4	−9 ± 2	0 ± 0
2,6-Dimethylpyrazine	11 ± 5	12 ± 12	16 ± 54	4 ± 1	27 ± 6	11 ± 4	130 ± 13	5 ± 4	102 ± 19	18 ± 8	13 ± 11	9 ± 6	32 ± 15	7 ± 3	139 ± 14	20 ± 5	11 ± 6	5 ± 3	−5 ± 7	−7 ± 5	0 ± 0
2-Methoxy-3-methylpyrazine	0 ± 9	1 ± 2	2 ± 6	−4 ± 5	15 ± 8	8 ± 3	31 ± 11	8 ± 6	8 ± 4	−1 ± 12	15 ± 6	16 ± 15	16 ± 6	6 ± 6	155 ± 7	29 ± 9	5 ± 4	11 ± 9	−8 ± 5	44 ± 11	5 ± 5
2,3-Dimethylpyrazine	2 ± 1	6 ± 14	33 ± 2	5 ± 12	103 ± 20	10 ± 5	102 ± 20	−8 ± 6	24 ± 8	1 ± 3	19 ± 3	19 ± 11	17 ± 9	4 ± 4	126 ± 16	66 ± 12	4 ± 6	5 ± 1	−8 ± 4	33 ± 7	4 ± 5
2-Acetyl-3,5(or 6)-dimethylpyrazine	9 ± 6	2 ± 16	3 ± 3	0 ± 8	8 ± 4	3 ± 1	35 ± 16	−1 ± 20	10 ± 2	6 ± 5	16 ± 5	1 ± 1	6 ± 0	0 ± 2	68 ± 12	3 ± 5	6 ± 5	1 ± 3	1 ± 4	2 ± 5	−1 ± 4
2,5-Dimethylpyrazine	3 ± 3	31 ± 9	16 ± 7	38 ± 8	3 ± 2	31 ± 3	102 ± 33	10 ± 6	103 ± 11	16 ± 12	37 ± 3	1 ± 1	43 ± 11	14 ± 2	85 ± 7	19 ± 5	5 ± 6	−4 ± 8	−8 ± 3	69 ± 13	0 ± 0
Pyrazine	5 ± 8	52 ± 15	11 ± 2	−2 ± 8	21 ± 23	14 ± 3	36 ± 24	58 ± 2	26 ± 12	5 ± 10	5 ± 4	5 ± 4	2 ± 4	7 ± 5	−1 ± 3	57 ± 8	43 ± 2	−3 ± 1	−7 ± 2	−1 ± 4	0 ± 0
2,3,5,6-Tetramethylpyrazine	3 ± 6	4 ± 5	23 ± 3	1 ± 6	−12 ± 4	2 ± 1	119 ± 21	−4 ± 26	12 ± 5	8 ± 20	25 ± 12	4 ± 5	2 ± 6	1 ± 1	137 ± 13	6 ± 4	4 ± 11	10 ± 5	1 ± 6	9 ± 12	0 ± 0
2-Methylpyrazine	2 ± 6	57 ± 10	18 ± 8	5 ± 10	11 ± 4	25 ± 1	124 ± 11	−11 ± 32	102 ± 14	33 ± 20	21 ± 7	65 ± 13	19 ± 16	5 ± 3	73 ± 24	51 ± 12	11 ± 6	−6 ± 5	2 ± 19	10 ± 17	6 ± 6
Pyrazineethanethiol	4 ± 3	21 ± 20	6 ± 3	5 ± 7	7 ± 10	3 ± 1	−1 ± 3	7 ± 2	37 ± 11	2 ± 7	10 ± 12	7 ± 17	15 ± 6	4 ± 4	3 ± 3	29 ± 13	3 ± 6	2 ± 4	23 ± 9	4 ± 4	11 ± 11
Background	8 ± 7	13 ± 9	17 ± 6	9 ± 6	6 ± 5	5 ± 5	16 ± 10	4 ± 6	11 ± 7	2 ± 7	8 ± 4	1 ± 3	5 ± 5	1 ± 2	10 ± 6	3 ± 3	4 ± 5	8 ± 6	5 ± 5	15 ± 7	2 ± 4
Paraffin oil	4 ± 6	21 ± 7	13 ± 4	9 ± 6	8 ± 8	7 ± 5	16 ± 10	6 ± 9	12 ± 10	2 ± 3	13 ± 7	2 ± 2	3 ± 5	5 ± 6	12 ± 6	3 ± 2	9 ± 6	24 ± 21	5 ± 2	13 ± 8	1 ± 1
Water	7 ± 6	42 ± 27	15 ± 7	72 ± 22	29 ± 31	3 ± 4	9 ± 9	41 ± 24	20 ± 9	0 ± 0	77 ± 21	26 ± 60	18 ± 17	3 ± 3	8 ± 6	10 ± 10	32 ± 40	21 ± 21	47 ± 12	25 ± 13	3 ± 5

Values are mean spike rates ± SEM except background, which is mean spike rate ± SD. Odorant–receptor combinations were initially tested three times; combinations that yielded a mean response >20 or <0 spikes/s were then tested an additional three times; thus n = 3–6. For background values, n > 80. Background firing rates and the responses to the diluent alone were subtracted from the responses to pyrazines. Background firing rates were subtracted from the values shown for the diluents. 5H-5-Methyl-6, 7-dihydrocyclopenta, 5H-5-Methyl-6, 7-dihydrocyclopenta[b]pyrazine; 2-Methoxy-3-(1-methylpropyl), 2-methoxy-3-(1-methylpropyl)pyrazine.