High Throughput Pharmacology of Cardiac L-Type Ca2+ Channels: Stable Recordings of CaV1.2 on a Highly Parallel Automated Patch Clamp System

The new paradigm in cardiac drug safety screening, the Comprehensive In-vitro Proarrhythmia Assay (CiPA) initiative, is being introduced to provide a more complete assessment of proarrythmic risk by evaluating and implementing currently available high throughput methods. An important part of this is an extension of the electrophysiological evaluation beyond hERG to include other cardiac channels such as NaV1.5, CaV1.2, KV-LQT1 and Kir2.1 (1, 2).A typical difficulty when performing patch clamp measurements of ion channels is the spontaneous loss of current amplitude over time, a phenomenon described as run-down. This phenomenon is particularly pronounced in CaV1.2 channels which dramatically impairs stable recordings and thus reliable pharmacological assessment, especially in the study of slow or use-dependent compounds.Nanion's SyncroPatch 384PE offers a high throughput gigaseal platform which records from up to 384/768 experiments at the same time. It does not only allow for high quality recordings with reliable pharmacology, but also for a more detailed biophyiscal characterization of an ion channel protein. A temperature control feature supports measurements at physiological temperatures. Our results show very stable recordings of CaV1.2 over an extended period of time (> 25 min.) that permits for cumulative compound application. Furthermore, we demonstrate CaV1.2 activation from different states that discriminates state- and use-dependent drug effects. Our assay development demonstrates how accurate pharmacology and high-throughput recordings of even difficult targets like CaV1.2 can be achieved in a reproducible and reliable manner with the SyncroPatch 384PE.