Fig. 5
Dose-response curves for NECA, CGS21680 and compounds 1–6 in either the A1R and GPA1/Gαi1/2, A2AR and GPA1/ Gαs, or the A2BR (with GPA1/Gαs expressed in yeast strains). The efficacy of the compounds (1–6) was measured against A3R in CHO-K1-A3R cells. Reporter gene activity in yeast was determined using β-galactosidase assays, after 16-hours stimulation with either: NECA (a), CGS21680 (b) compound 1 (c), compound 2 (d), compound 3 (e), compound 4 (f), compound 5 (g), compound 6 (h), whereas cAMP inhibition was determined when in CHO-K1-A3R cells which were co-stimulated with each of the compounds 1–6 and 1 µM Forskolin. In general, the triazoloquinazolines 1–5 exhibited agonistic activity against the adenosine receptor sub-types, with compounds 1–3 being selective A2AR agonists. The data is represented as either percentage of the response obtained upon stimulating each receptor (A1R, A2AR, or A2BR) with NECA stimulation, or as a percentage response relative to 100 µM Forskolin simulation in the A3R ± SEM of 4–6 individual replicates