CHEMBL5733942

BIOLOGICAL ASSAY: Prokineticin receptor 1 (PKR1) antagonists may be functionally assessed by measurement of change in intracellular calcium levels induced by Gq mediated increase in inositol triphosphate (IP3) levels. The ability of a compound to block the intracellular release of calcium mediated by PK1 in RBL2H3 cells expressing human PKR1 receptors is determined as a measure of the compound's antagonist activity in vitro.Approximately 10,000 cells per assay well are seeded in normal culture medium in a 384 well plate (Corning). Twenty-four hours after seeding, the cells are loaded with a calcium sensitive fluorescent dye by replacing the culture medium with assay buffer (1× Hanks buffered saline, 25 mM HEPES, 0.1% w/v fatty acid free BSA (bovine serum albumin), pH 7.4) containing 1 mM probenecid and 1× Calcium 5 Reagent (Molecular Devices). Cells are incubated at 37° C. for 1 hour to allow for dye uptake.To test for antagonist activity, test compounds at a final concentration range between 0.32 nM-10 μM (diluted in assay buffer) are added to the assay wells and allowed to incubate for 10 minutes prior to stimulation with PK1. After incubation with test compounds the assay plate is placed in a FLIPR Tetra (Molecular Devices) and PK1 (diluted in assay buffer) is added at the determined EC80 concentration (final). Ligand-dependent changes in intracellular calcium levels are determined by measuring changes in fluorescence of the dye at 525 nM following excitation at 485 nM. Readings from wells that do not contain antagonist enable percentage inhibition curves to be plotted using 4-parameter fit algorithm and IC50 values are calculated for each test compound.