Table 8

Binding affinity of agonists and antagonists at rat adenosine receptor subtypes (K _i values with 95% confidence intervals or ±S.E.M. in parentheses)

	A₁	A_2A	A₃	Reference
Agonists with unmodified ribose
R-PIA	1.2 (±0.16)	124 (±9)		—^8-a
	1.3 (1.1–1.6)	730 (690–770)		—^8-b
	0.51			—^8-c
			220 (±43)	—^8-d
			160 (±52)	—^8-e
S-PIA	49 (±2.4)	1,800 (±380)		—^8-a
	29			—^8-f
			920 (±310)	—^8-e
CPA	0.59 (±0.02)	460 (±15)		—^8-a
	0.8 (0.6–1.0)	2,000 (1,400–2,900)		—^8-b
			240 (±36)	—^8-e
CCPA	0.4 (0.2–0.7)	3,900 (2,500–4,700)		—^8-b
	0.23			—^8-c
			240 (±71)	—^8-e
ADAC	0.85 (±0.35)			—^8-w
2-Cl-adenosine	9.3 (±0.58)	63 (±7.5)		—^8-a
			1,900 (±900)	—^8-e
DPMA	140 (±23)	4.4 (±0.2)		—^8-u
			3,600 (±1,700)	—^8-e
(S)-ENBA	0.3 (±0.02)	1,400 (±150)		—^8-v
Agonists with 5′-modified ribose
NECA	6.3 (±0.52)	10 (±0.5)		—^8-a
	11 (7.0–17)	22 (20–25)		—^8-f
	3.7			—^8-c
			260 (±36)	—^8-d
CGS 21680	3100 (±470)	22 (±4.3)		—^8-g
			580 (±32)	—^8-e
HENECA	136 (95–195)	3.8 (1.5–9.9)		—^8-f
PENECA	698 (611–798)	120 (112–128)		—^8-h
PHPNECA	2.5 (2.2–2.9)	0.9 (0.7–1.3)		—^8-i
AB-MECA	430 (±45)	1,600 (±180)	14 (±3)	—^8-j
IB-MECA	54 (±5)	56 (±8)	1.1 (±0.3)	—^8-j
IAB-MECA	18 (±5)	200 (±84)	1.3 (±0.18)	—^8-j
Cl-IB-MECA	820 (±570)	470 (±370)	0.33 (±0.08)	—^8-k
Antagonists: xanthines
DPCPX	0.3	340		—^8-l
	0.18^8-150 (0.16–0.20)			—^8-l
			>10,000	—^8-e
XAC	2.8 (1.9–4.2)			—^8-m
	3.5	24		—^8-l
	4	50		—^8-n
			>100,000	—^8-o
MRS 1754	17 (±3.6)	610 (±290)		—^8-o
MSX-2	900 (±10)	8 (±3)		—^8-p
Theophylline	11,000	32,000		—^8-b
			>100,000	—^8-o
Antagonists: non-xanthines
CGS 15943	21 (±3.5)	3.3 (±1.8)		—^8-q
	22	3		—^8-n
	6.4 (6.2–6.6)	1.2 (1.1–1.3)		—^8-r
			>100,000	—^8-o
SCH 58261	120 (100–140)	2.3 (2.0–2.7)		—^8-r
ZM 241385	2,000 (1,500–2,700)	0.30 (0.10–0.95)	150,000 (87,000–210,000)	—^8-s
MRE 3008F20	>10,000	2,000 (±220)	>10,000	—^8-t

↵8-150 Data from saturation experiments; where confidence limits are missing, they are within 0.15 log units.
↵8-a Bruns et al., 1986; brain membranes (A₁), striatum (A_2A); radioligands [³H]CHA (A₁), [³H]NECA (A_2A).
↵8-b Lohse et al., 1988; brain membranes (A₁), striatum (A_2A); radioligands [³H]PIA (A₁), [³H]NECA (A_2A).
↵8-c Klotz et al., 1991; brain membranes; radioligand [³H]DPCPX.
↵8-d Olah et al., 1994; transfected CHO cells; radioligand ¹²⁵I-AB-MECA.
↵8-e van Galen et al., 1994; transfected CHO cells; radioligand¹²⁵I-APNEA.
↵8-f Cristalli et al., 1992; brain membranes (A₁), striatum (A_2A); radioligands [³H]DPCPX (A₁), [³H]NECA (A_2A).
↵8-g Hutchison et al., 1989; rat brain; radioligands [³H]CHA (A₁), [³H]NECA (A_2A). Given are IC₅₀ values; based on the experimental conditionsK _i values should be about 0.5–0.7 and 0.9 times the IC₅₀ values for A₁ and A_2A, respectively.
↵8-h Cristalli et al., 1995; brain membranes (A₁), striatum (A_2A); radioligands [³H]CHA (A₁), [³H]CGS 21680 (A_2A).
↵8-i Camaioni et al., 1997; brain membranes (A₁), striatum (A_2A); radioligands [³H]CHA (A₁), [³H]CGS 21680 (A_2A).
↵8-j Gallo-Rodriguez et al., 1994; rat brain (A₁), rat striatum (A_2A), transfected CHO cells (A₃); radioligand [³H]PIA (A₁), [³H]CGS 21680 (A_2A), ¹²⁵I-AB-MECA (A₃).
↵8-k Kim et al., 1994; rat brain (A₁), rat striatum (A_2A), transfected CHO cells (A₃); radioligand [³H]PIA (A₁), [³H]CGS 21680 (A_2A),¹²⁵I-AB-MECA (A₃).
↵8-l Lohse et al., 1987; brain membranes (A₁), striatum (A_2A); radioligands [³H]PIA (A₁), [³H]NECA (A_2A).
↵8-m Jacobson et al., 1986; rat brain, radioligand [³H]XAC.
↵8-n Jarvis et al., 1989; rat brain; radioligands [³H]CHA (A₁), [³H]CGS 21680 (A_2A).
↵8-o Kim et al., 2000; transfected HEK 293 cells (A₁), rat striatum (A_2A); radioligands [³H]PIA (A₁), [³H]CGS 21680 (A_2A).
↵8-p Sauer et al., 2000; brain cortex (A₁), striatum (A_2A); radioligand [³H]CHA (A₁), [³H]CGS 21680 (A_2A).
↵8-q Williams et al., 1987; brain (A₁), striatum (A_2A); radioligands [³H]CHA (A₁), [³H]NECA (A_2A). Given are IC₅₀values; based on the experimental conditions K _ivalues should be about 0.5–0.7 and 0.9 times the IC₅₀values for A₁ and A_2A, respectively.
↵8-r Baraldi et al., 1994; rat brain (A₁), rat striatum (A_2A); radioligand [³H]CHA (A₁), [³H]CGS 21680 (A_2A).
↵8-s Poucher et al., 1995; brain cortex (A₁), PC 12 cells (A_2A), transfected CHO cells (A₃); radioligands [³H]PIA (A₁), [³H]NECA (A_2A) ¹²⁵I-AB-MECA (A₃). Given are IC₅₀ values; based on the experimental conditionsK _i values should be about 0.1, 0.2, and 0.5 times the IC₅₀ values for A₁, A_2A, and A₃, respectively.
↵8-t Varani et al., 2000; brain cortex (A₁), striatum (A_2A), transfected CHO cells (A₃); radioligands [³H]DPCPX (A₁), [³H]SCH 58261 (A_2A),¹²⁵I-AB-MECA (A₃).
↵8-u Bridges et al., 1988; brain (A₁), striatum (A_2A); radioligand [³H]CHA (A₁), [³H]NECA (A_2A); DPMA or PD 125944 is compound 16 in this paper.
↵8-v Trivedi et al., 1989; brain (A₁), striatum (A_2A); radioligand [³H]CHA (A₁), [³H]NECA (A_2A).
↵8-w Jacobson et al., 1987; brain (A₁), radioligand [³H]PIA (A₁).