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Characterization of the human brain putative A 2B adenosine receptor expressed in Chinese hamster ovary (CHO.A 2B4 ) cells
Author(s) -
Alexander Stephen P.H.,
Cooper Jacqui,
Shine John,
Hill Stephen J.
Publication year - 1996
Publication title -
british journal of pharmacology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.432
H-Index - 211
eISSN - 1476-5381
pISSN - 0007-1188
DOI - 10.1111/j.1476-5381.1996.tb16035.x
Subject(s) - chinese hamster ovary cell , adenosine , adenosine receptor , cgs 21680 , medicine , endocrinology , agonist , adenosine a1 receptor , biology , stimulation , receptor , chemistry
1 An [ 3 H]‐adenine pre‐labelling methodology was employed to assay cyclic AMP generation by adenosine analogues in Chinese hamster ovary (CHO.A 2B4 ) cells, transfected with cDNA which has been proposed to code for the human brain A 2B adenosine receptor, and in guinea‐pig cerebral cortical slices. 2 Adenosine analogues showing the following rank order of potency in the CHO.A 2B4 cells (pD 2 value): 5′‐N‐ethylcarboxamidoadenosine (NECA, 5.91) > adenosine (5.69) > 2‐chloroadenosine (5.27) > N 6 ‐(2‐(4‐aminophenyl)‐ethylamino)adenosine (APNEA, 4.06). The purportedly A 2A ‐selective agonist, CGS 21680, failed to elicit a significant stimulation of cyclic AMP generation at concentrations up to 10 μ m in CHO.A 2B4 cells. In the guinea‐pig cerebral cortex, NECA was more potent than APNEA with pD 2 values of 5.91 and 4.60, respectively. 3 Of these agents, NECA was observed to exhibit the greatest intrinsic activity in CHO.A 2B4 cells (ca. 10 fold stimulation of cyclic AMP), while, in comparison, maximal responses to adenosine (32% NECA response), 2‐chloroadenosine (61%), and APNEA (73%) were reduced. 4 Antagonists of NECA‐evoked cyclic AMP generation showed the rank order of apparent affinity (apparent pA 2 value in CHO.A 2B4 cells: guinea‐pig cerebral cortex): XAC (7.89:7.46) > CGS 15943 (7.75:7.33) > DPCPX (7.16:6.91) > PD 115,199 (6.95:6.39) > 8FB‐PTP (6.52:6.55) > 3‐propylxanthine (4.63:4.59). 5 We conclude that, using the agents tested, the A 2B adenosine receptor cloned from human brain expressed in Chinese hamster ovary cells exhibits an identical pharmacological profile to native A 2B receptors in guinea‐pig brain.