The effect of valproate (VPA) on Na+ currents (INa), was studied by means of voltage clamp recordings using whole-cell patch clamp configuration in 21 acutely dissociated neocortical neurons. Concentrations of VPA up to 200 μM failed to induce any detectable decrease in fast INa (I(Naf)), but the persistent fraction (I(NAP)) was significantly reduced by low VPA concentrations (10-30 μM), corresponding to the lower values of the 'therapeutic' range in epileptic patients. Since it is known that I(NaP) critically regulates the firing properties of pyramidal neurons, it is suggested that the anticonvulsant effectiveness of VPA is mainly due to its effect on I(Nap).
- Sodium current
- Voltage clamp
ASJC Scopus subject areas
- Clinical Neurology
- Pediatrics, Perinatology, and Child Health