CaV1.2 calcium channel assays for preclinical drug studies
Why conduct a CaV1.2 calcium channel assay?
The voltage gated cardiac calcium ion channel CaV1.2, encoded by the CACNA1C gene, is a key component of the shape of the plateau phase and is highly implicated in the repolarization process of the action potential. When the CaV1.2 calcium channel cannot adequately conduct electrical current across the cell membrane, this may result in undesirable cardiovascular side effects leading to life threatening arrythmias called Torsade de Pointe.
CaV1.2 calcium assays & preclinical studies
At a preclinical stage, CaV1.2 calcium channel assays aim to identify potential inhibitory effects early in the drug discovery process. A number of clinically successful drugs have had the tendency to inhibit the Cav1.2 calcium channel, entailing a concomitant risk of sudden death. As a result, a large number of drugs have been withdrawn from the market or during late stage clinical trials due to cardiotoxic effects.
What we measure
A pharmacological reduction of the calcium current has been shown to shorten the repolarization process and decrease the contractility. This makes the human CaV1.2 calcium channel a major target for the cardiac safety assessment.
Mutation LQT8: the gain-of-function mutation in the CACNA1C gene may result in a markedly prolonged action potential duration causing a rare congenital arrhythmia: the long QT syndrome LQT8 (Timothy syndrome).
- Conventional manual Patch Clamp
- 3 or 4 increasing concentrations of assay compound tested independently
- Chinese Hamster Ovary CHO cells
- 6 treated cells per concentration tested and 6 control cells (as basic design protocol but can be adapted)
- Amplitude of the peak current upon depolarization to 0 mV (pA)
- Amplitude of the base current at –80 mV (pA)
- Inhibition of CaV1.2 peak current amplitude (%)
Typical effects of nifedipine on CaV1.2 calcium currents recorded from CHO cells
- ion current inhibition measurement
- IC50 value
Reference compounds or positive controls
Advice from our expert scientists
In order to confirm results during Cav1.2 calcium channel assays and the impact on cardiac contractility or ECG, PhysioStim recommends completing your Cav1.2 calcium channel assay with additional tests: