Assay Method Information

Assay Name:  Ca Flux Activity Assay
Description:  The 5-HT3 antagonist activity of the compounds of the invention was determined by measuring the ability of the compounds to inhibit the calcium flux activity of 3HT3a receptor expressed in HEK-293T cells. HEK-293T cells were transfected with the 5-HT3a expression construct using Xtreme Gene 9 (Roche) in 150 mm tissue culture treated plates and incubated for 24 hours at 37° C. Cells were then split and plated at a density of 60K cells/well in poly-lysine coated, black 96-well plates with clear bottoms (BD BioSciences) and incubated overnight at 37° C. Growth media was removed and cells loaded with 200 μL calcium indicator dye in HBSS containing 20 mM HEPES (Calcium 5 Assay kit, Molecular Devices) and incubated at 37° C. for 1 hour. While cells were incubating, the 10× antagonist and agonist/antagonist addition plates were made. For 10× antagonist plate: half log serial dilutions (final concentrations range from 10^−7 through 10^−10 with the bottom well a negative, no ligand control) were made from test compounds in DMSO at a 1000× concentration and then diluted to 10× in HBSS/20 mM HEPES. For addition plate: 5HT was diluted to 100× in HBSS/20 mM HEPES (final concentration in the assay−216 nM) and 15 μL was added to each well of the addition plate, 15 μL of 10× compound was also added to the addition plate, and finally 120 μL of HBSS/20 mM HEPES (for a total of 150 μL). Cells were then removed from the incubator and equilibrated to room temperature for 10 minutes, then 22.5 μL of 10× test compounds were added in triplicate to the plates and incubated at room temperature for 10 minutes (Tropisetron was used as a positive control in every assay). Test plate and addition plate were loaded into the FlexStation III (Molecular Devices), and using the fluidics, 22.5 μL compound additions were made (at t=~17 seconds), and fluorescence was measured for 90 seconds, reading every 2.2 seconds.
Affinity data for this assay
 

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