Assay Method Information

Assay Name:  High-Throughput Cav2.2/Kir2.3 T-Type Fluorescent Assay
Description:  Cells were plated in 384-well, clear-bottom, black-walled, poly-D-lysine coated plates (Becton Dickinson, Franklin Lake, N.J.) 2 days prior to use in the FLIPR assay. 100 μL of cells (1.4×106 cell/mL) containing doxycyline (Sigma-Aldrich, 1.5 μg/mL; to induce channel expression) were added to each well using a Multidrop (Thermo Scientific, Waltham, Mass.) and were maintained in 5% CO2 incubator at 37° C. On the morning of the assay, cells were transferred to a 5% CO2 incubator at 29° C. Cells can then be washed with a wash buffer containing (in mM): 118 NaCl, 18.4 HEPES, 11.7 D-glucose, 2 CaCl2, 0.5 MgSO4, 4.7 KCl, 1.2 KH2PO4, pH adjusted to 7.2 with NaOH. 4.4 μM of the fluorescent indicator dye, Fluo-4 (Invitrogen), prepared in pluronic acid (Sigma-Aldrich), were loaded into the wells and incubated for 45 minutes at 29° C. in 5% CO2. Cells were then rinsed with either a 2 mM KCl closed-state buffer (in mM: 138.5 NaCl, 10 HEPES, 10 D-glucose, 1 CaCl2, and 2 KCl, with the pH adjusted to 7.4 with NaOH) when performing the closed-state assay or 12.5 mM KCl inactivated-state buffer (in mM: 128 NaCl, 10 HEPES, 10 D-glucose, 1 CaCl2, and 12.5 mM KCl, with the pH adjusted to 7.4 with NaOH) when performing the inactivated-state assay. Concentration-dependent response curves were generated from 5 mM stock solutions prepared in DMSO (Sigma-Aldrich) and diluted in either the 2 mM KCl buffer or 12.5 mM KCl buffer and incubated for 20 minutes at 29° C. in 5% CO2. Calcium entry was evoked with an addition of 130 mM KCl stimulation buffer (in mM: 10.5 NaCl, 10 HEPES, 10 D-glucose, 1 CaCl2, and 130 KCl, with the pH adjusted to 7.4 with NaOH) for both the closed-state or inactivated-state assay. A change in the Fluo-4 fluorescence signal was assessed using FLIPRTETRA™ instrument (Molecular Devices, Sunnyvale, Calif.) for 3 minutes following the elevation of extracellular KCl using an illumination wavelength of 470-495 nm with emissions recorded at 515-575 nm.
Affinity data for this assay
 

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