BPS2026 – Advancing automated electrophysiology: Single-channel recordings in the cell-attached configuration

Automated patch clamp (APC) platforms have evolved substantially over the past 25 years and are now widely used to address diverse research questions in ion channel pharmacology and physiology. Nevertheless, applications of APC have largely been confined to whole-cell or perforated patch configurations, limiting their utility for investigating channel gating at the single-channel level. Here, we report the establishment of a single-channel recording assay on the QPatch II APC platform. An updated amplifier in this system, with approximately 10-fold lower noise variance than earlier amplifiers, permitted resolution of current steps down to 2 pA. Using this configuration, single-channel activity of recombinantly expressed large-conductance calcium-activated potassium (BK) channels was recorded in HEK293 cells under cell-attached conditions. Channel openings were detected under basal conditions, and open probability increased following addition of ionomycin to the external solution, consistent with calcium-dependent activation. The BK activator, hydrochlorothiazide (HCTZ) and the inhibitor tetraethylammonium (TEA) were used to characterize the channel pharmacologically. These results demonstrate the feasibility of performing single-channel assays in the cell-attached mode on an automated patch clamp system using mammalian cell lines. This advancement broadens the scope of APC technologies to include mechanistic studies of channel gating and pharmacology at the single-channel level.