During demyelination, what happens to the density of sodium channels at the inter-nodal membrane?

• A. There is an increase in sodium channels at inter-nodal membrane
• B. Sodium channels are absent entirely
• C. There are few sodium channels in inter-nodal membrane
• D. Sodium channels cluster at nodes of Ranvier during demyelination

Answer: (C)

In myelinated fibers, voltage-gated sodium channels are densely packed at the nodes of Ranvier to regenerate the action potential, while the internodal (inter-nodal) membrane has relatively few channels because the myelin sheath insulates and reduces current leaks. When demyelination occurs, the insulation is lost and conduction becomes impaired. The axon may attempt to compensate by redistributing channels toward exposed regions to support conduction, but the inter-nodal membrane itself does not become highly channel-rich; it remains comparatively sparse. Therefore, the density of sodium channels in the inter-nodal membrane stays low, meaning there are few sodium channels there.