| Assay Method Information | |
| | Cell-Based Assay |
| Description: | Compounds were tested on human Nav1.7 (hNav1.7) expressed stably in 293 cells, which have no endogenous sodium channels. Two forms of whole-cell patch-clamp assays were used. In both, peak current through Nav1.7 was evoked by a depolarizing voltage pulse, and currents were monitored as a function of time in response to exposure to several different concentrations of drug. Automated electrophysiology uses the PatchXpress 7000A system. Up to sixteen cells at a time were voltage-clamped in parallel, and the steady-state voltage dependence of inactivation was determined experimentally for each cell. For each cell, fractional inactivation was set at 20%, and peak current through Nav1.7 as a function of time was measured in response to increasing concentrations of test compound. Manual electrophysiology refers to conventional whole-cell patch-clamping (Hamill et al., 1981). After formation of the whole-cell clamp, cells were lifted off the bottom of the dish with the patch pipette and positioned directly in front of an array of glass microperfusion tubes each with internal diameter about 250 microns, with individual compound concentrations flowing from each tube. Current as a function of time in response to increasing drug concentrations was measured with Nav1.7 fully in the resting state (holding voltage set to −140 mV) and on the same cells with the holding voltage set to produce about 20% inactivation. Compounds were not applied for a prespecified time, but for as long as required to achieve a stable level of block. |
| Affinity data for this assay | |
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