The development of screening assays for the Ca_V1.2 channel has been challenging due to the tendency of Ca_V1.2 expressing cell lines to exhibit declining current levels (rundown) during the experiment^1,2. Here we report a robust Ca_V1.2 assay yielding high success rates, low rundown and reliable pharmacology.

• Pharmacology and current-voltage relationship in accordance with literature values
• Success rates up to 94%
• Stable currents with rundown as low as (1.2 ± 0.9)% per minute
• The CiPA protocol yields stable currents with rundown as low as (1 ± 1)% per minute

The voltage-sensitive L-type Ca²⁺-channel (LTCC) Ca_V1.2 is widely expressed in vascular smooth muscle tissue and the heart muscle^1-3. The opening of the channels leads to an increase of intracellular calcium, which acts as second messenger and thereby affects a variety of cellular processes⁴ including heart muscle contraction and neurotransmitter release. Ca_V1.2 is therefore an important target in e.g. safety pharmacology screening. The channels are known to require a large depolarization for their activation and once activated they display a long-lasting current flow, which typically can be blocked by low micromolar concentrations of e.g. dihydropyridines, phenylalkylamines and benzothiazepines^5,6.
In this study, currents from CHO-hCa_V1.2 were recorded on the high-throughput platform Qube 384 in multi-hole mode (10 patch holes per well) at both a customer’s site and at Sophion. Success rates, rundown, sealing properties and the pharmacological effects of two compounds were determined.

The voltage-sensitive L-type Ca²⁺-channel (LTCC) Ca_V1.2 is a crucial component for controlling intracellular activity and thereby essential in the cardiovascular and neuronal system. It is widely expressed in vascular smooth muscle tissue and the heart muscle. The opening of the channels leads to an increase of intracellular calcium, which act as second messenger, and thereby affects a variety of cellular processes including heart muscle contraction and Ca_V1.2 is therefore an important target in e.g. safety pharmacology screening. Ca_V1.2 channels are known to require a large depolarization for their activation and once activated they display a long-lasting current flow, which typically can be blocked by low micromolar concentrations of e.g. dihydropyridines, phenylalkylamines and benzothiazepines. In these studies, currents from HEK-hCa_V1.2 were recorded on the high-throughput platform Qube 384 in both single-hole and multi-hole mode. Success rates, IV characteristics and the pharmacological effects of three different compounds were determined.