Cerebrospinal fluid and serum from patients with inflammatory polyradiculoneuropathy have opposite effects on sodium channels.

The effects of cerebrospinal fluid (CSF) and serum from patients having Guillain-Barré syndrome (GBS) or chronic inflammatory demyelinating polyradiculoneuropathy (CIDP) on voltage-dependent Na+ channels were compared. Bathing human myoballs in CSF substantially reduced their Na+ currents (by > 40% with 8 of 10 patients) elicited at 1 Hz under whole-cell recording conditions. This was because, at the resting potential, more Na+ channels were inactivated (left-shift of the h infinity curve). CSF from patients with other neurological diseases (OND) produces a similar, but smaller, effect. In contrast, serum samples from the same GBS and OND patients caused an increase of the Na+ currents by reducing the number of Na+ channels inactivated at the resting potential. This right-shift of the h infinity curve is in part explained by the effect of serum albumin. We confirm that the CSF of most GBS and CIDP patients contains factors inhibiting voltage-dependent Na+ currents. There is no indication that such factors are effective in the serum of these patients.