NaV1.5 sodium channel assays for preclinical safety studies
Why conduct a NaV1.5 sodium channel assay?
The voltage gated cardiac sodium ion channel NaV1.5, encoded by the SCN5A gene, is a key component for the initiation and transmission of this electrical signal throughout the heart. Its activation induces the depolarization of the cell membrane and initiates the rising phase of the action potential (dV/dtmax). When the NaV1.5 sodium channel cannot adequately conduct the electrical current across the cell membrane, this can result in a potentially fatal disorder called type 3 long QT syndrome (LQT3) or Brugada syndrome.
The NaV1.5 sodium channel & preclinical studies
At a preclinical stage, NaV1.5 sodium channel assays aim to identify potential inhibitory effects early in drug discovery. A number of clinically successful drugs have had the tendency to inhibit NaV1.5 sodium channel and to create 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 As a result, a large number of drugs have been withdrawn from the market or during late stage clinical trials due to cardiotoxic effects.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 sodium current has been shown to delay the depolarization process and lead to a reduction of cardiac conduction. This makes the human NaV1.5 sodium channel a major target for the cardiac safety assessment.
Mutation LQT3: Mutations in the SCN5A gene result in persistent depolarizing current throughout action potential duration causing the Long QT Syndrome 3 phenotype.
- Conventional manual Patch Clamp
- 3 or 4 increasing concentrations of assay compound tested independently
- Human Embryonic Kidney HEK-293 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 –30mV (pA)
- Amplitude of the base current at –110mV (pA)
- Inhibition of NaV1.5 peak current amplitude (%)
Typical effects of flecainide on NaV1.5 sodium currents recorded from HEK-293 cells
- ion current inhibition measurement
- IC50 value
Reference compounds or positive controls
Advice from our expert scientists
In order to confirm results during NaV1.5 sodium channel assays and the impact on cardiac conduction or ECG, PhysioStim recommends completing your NaV1.5 sodium channel assay with additional tests: