Comparative pharmacology of human adenosine receptor subtypes – characterization of stably transfected receptors in CHO cells

摘要: Four adenosine receptor subtypes of the family G protein-coupled receptors, designated A1, A2A, A2B and A3 are currently known. In this study all human were stably transfected into Chinese hamster ovary (CHO) cells in order to be able their pharmacological profile an identical cellular background utilizing radioligand binding studies (A1, A3) or adenylyl cyclase activity assays (A2B). The A1 subtype showed typical with 2-chloro-N6-cyclopentyladenosine (CCPA) as agonist highest affinity a marked stereoselectivity for N6-phenylisopropyladenosine (PIA) diastereomers. competition antagonist biphasic curves observed agonists. presence GTP receptors converted single low state indicating functional coupling endogenous proteins. For A2A CGS 21680 (2-[p-(2-carboxyethyl)phenylethylamino]-5'-N-ethylcarboxamidoadeno sine) N-ethylcarboxamidoadenosine (NECA) found most potent agonists followed by R- S-PIA minor stereoselectivity. relative potencies could only tested measurement receptor-stimulated activity. NECA was EC50-value 2.3 microM whereas other compounds active at concentrations high micromolar range. Inhibition NECA-stimulated identified xanthine amino congener (XAC; 8-[4-[[[[(2-aminoethyl)amino]-carbonyl]methyl]oxy]phenyl]-1,3-dipropylxa nthine) subtype. characterized nonselective [3H]NECA. N6-benzyl substituted derivatives adenosine-5'-N-methyluronamide (MECA) turned out notion xanthine-insensitivity should dropped least xanthines submicromolar found. Overall, characteristics similar species some species-specific characteristics. we present first time comparative pharmacology known subtypes. CHO provide such characterization. These valuable systems further characterization specific development new ligands.