. Author manuscript; available in PMC: 2012 Aug 7.

Published in final edited form as: Handb Exp Pharmacol. 2009;(193):123–159. doi: 10.1007/978-3-540-89615-9_5

Table 2.

Binding affinities of monosubstituted adenosine derivatives (2-ether-substituted) at the human A₃AR expressed in CHO cells and at A₁ and A_2A ARs, and maximal A₃AR agonist effect

graphic file with name nihms-396515-t0031.jpg

Compound	Substitution R¹ =	pK_i at A₁AR^a	pK_i at A₂AAR^a	pK_i at A₃AR^a	%Activation, A₃AR^a
29	Cl	8.12	6.20	7.06	100
30		5.29	7.36	6.44	32
31		6.19	6.23	6.93	17
32		6.66	8.03	7.27	71
33		5.43	6.23	5.71	ND
34		6.28	7.21	6.51	72
35		6.66	7.75	6.85	1
36		6.54	7.19	6.98	91
37		5.32	7.57	6.76	0
38		<5	6.51	7.27	0

A₃AR binding experiments were performed with membranes prepared from adherent CHO cells stably transfected with cDNA encoding the human A₃AR, using as radioligand [¹²⁵I]N⁶-(4-amino-3-iodobenzyl)adenosine-5′-N-methyluronamide ([¹²⁵I]I–AB–MECA; 2000 Ci/mmol) at a final concentration of 0.5 nM, in Tris·HCl buffer (50 mM, pH 8.0) containing 10mM MgCl₂, 1mM EDTA. Nonspecific binding was determined using 10 μM Cl–IB–MECA. The mixtures were incubated at 25°C for 60 min. ND, not determined. Maximal A₃AR agonist effect is inhibition of forskolin-stimulated adenylate cyclase at 10 μMusing a reference value for Cl–IB–MECA of 100% (Gao et al. 2004)