PhysioStim Sodium Channel assays

Sodium channel assays (NaV1.5) for preclinical safety studies

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.
Mutation LQT3: Mutations in the SCN5A gene result in persistent depolarizing current throughout action potential duration causing the Long QT Syndrome 3 phenotype.

Nav1.5 assay & 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.

What is shown ?

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.


  • Conventional manual Patch Clamp
  • 3 or 4 increasing concentrations of assay compound tested independently

Study model

  • Human Embryonic Kidney HEK-293 cells
  • 5 treated cells per concentration tested and 5 control cells (as basic design protocol but can be adapted)

Measured parameters

  • 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 (%)
  • ion current inhibition measurement
  • IC50 value

Stimulation protocol

Typical effects of flecainide on Nav1.5 sodium currents recorded from HEK-293 cells.

Ref­er­ence com­pounds or pos­i­tive con­trols

Reference CompoundsIC₅₀

Fle­caïnide1.5 µM

Quini­dine21.1 µM

Additional tests according to PhysioStim scientist’s expertise

Humans cardiomyocites

Human cardiomyocytes

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Isolated Perfused heart

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