| Assay Method Information | |
| | Automated patch clamp (Tonic Block) |
| Description: | Test Protocol for Determining the Potency of Compounds on Nav1.2 and Nav1.6 Subtypes of Voltage-Gated Sodium Ion Channels Expressed in Mammalian CellsCell culture procedures: Chinese hamster ovary (CHO) cells were stably transfected with the cDNA sequence of either the human SCN2A or SCN8A genes to create hNav1.2 or hNav1.6 cells respectively. The cell lines were cultured in Ham's F-12 medium supplemented with 10% fetal bovine serum and antibiotics in a tissue incubator at 37° C. under a humidified air/CO2 mixture (95/5 v/v). On the day of the experiment, cells were washed twice with Hank's balanced salt solution, treated with trypsin, and resuspended in fresh culture media at a density of 4−6×106 cells in 20 ml. Immediately before placing in the IonWorks Quattro instrument, cells were washed in Hank's balanced salt solution to remove culture medium and re-suspended in 3 ml of Hank's balanced salt solution. Automated patch clamp recordings of cells using the IonWorks Quattro Instrument: The assay used a 384 microwell plate, which enabled 20 compounds to be studied at four different concentrations in quadruplicate as well as allowing a vehicle control group and a positive control group using mexiletine at 8 different concentrations. Cells were added to the wells of the Population Patch Clamp planar electrode using a 48-channel pipettor in a volume of 6 μL, per well. After 5 minutes incubation at ambient temperature with compounds or vehicle, membrane currents were recorded using the patch clamp amplifier. Block of hNav1.2 or hNav1.6 channels was measured using a stimulus voltage pattern as shown in FIG. 1. The pulse pattern was repeated twice, before and after compound addition and peak current amplitudes were measured at TP1 to measure Tonic Block.Data analysis: Data acquisition and analyses were carried out using the IonWorks Quattro system operation software which uses an algorithm to correct data for leak currents. Concentration-response curves were fitted by non-linear least squares regression allowing calculation of an IC50 value (μM), being the concentration of the compound producing half-maximal inhibition. |
| Affinity data for this assay | |
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