Optimization of a High-Throughput Assay for Calcium Channel Modulators on IonWorks Barracuda.

Voltage-gated calcium channels represent important drug targets. The implementation of higher throughput electrophysiology assays is necessary to characterize the interaction of test compounds with several conformational states of the channel, but has presented significant challenges. We report on the development of a high-throughput, automated electrophysiology assay for Cav2.2 on the IonWorks Barracuda™ platform. The assay provides an assessment of the potency of the test compound on the resting/closed and inactivated states of the channel in the same assay run. Inclusion of the heavy metal chelator 2,3-bis(sulfanyl)propane-1-sulfonate in the assay solutions improved the data quality by reversing a loss of current seen in wells directly above the ground electrodes. We hypothesize that the loss of current is caused by block of Cav2.2 currents by silver ions originating from the electrodes.