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 ∞ 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 ∞ 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. © 1995 John Wiley & Sons, Inc.