| Assay Method Information | |
| | Screen Quest Fluo-8 No Wash Calcium Assay Kit |
| Description: | Ca2+ influx was measured in HEK-293 cells stably transfected with the receptor using Screen Quest Fluo-8 No Wash Calcium Assay Kit (AAt Bioquest ). Briefly, once inside the cells, the lipophilic blocking groups of Fluo-8 are cleaved by non-specific cell esterases, resulting in a negatively-charged fluorescent-dye that stays inside cells. Its fluorescence increases upon binding to calcium. When HEK-293/P2X7 cells were stimulated with BzATP, Ca2+ entered the cells and the fluorescence of Fluo-8 NW increaseed. The dye absorption spectrum was compatible with excitation at 488 nm by argon laser sources and its emission wavelength was in the range of 515-575 nm.To routinely test the compounds, HEK-293 cells stably transfected with rat P2X7R were seeded overnight in growth medium at 10000, 15000 or 20000 cells/well in 384-well plate, according to the level of response after thawing. 24 hours later, the medium was removed and the cells were pre-loaded at RT for 1 hour with 20 μL/w of Fluo-8 NW prepared in Tyrode 0.3 mM Ca2+/Mg2+-free. Compounds of the invention were tested at 8 concentrations (4 replicates for each concentration): 10-3.16-1-0.316-0.1-0.0316-0.01 and 0.00316 μM, in the same plate.Compounds were tested at FLIPRTETRA according to the following method: first injection at FLIPRTETRA of 10 μL of 3× test compound (in Tyrode's buffer 0.3 mM Ca2+/Mg2+-free+DMSO 0.5% final concentration) 5′ incubation second injection at FLIPRTETRA of 15 □L of 3× BzATP at ECK) (in Tyrode's buffer 0.3 mM Ca2+/Mg2+-free+BSA 0.0003% final concentration) Fluorescence recording for 3′Between one plate and the following, tips were extensively washed with water, then with 100% DMSO and finally with water to avoid carry-over inside the tips.The effect of the test compounds was measured as percent inhibition vs a reference antagonist and IC50 values were calculated accordingly. |
| Affinity data for this assay | |
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