Late sodium current in the node of Ranvier.

Voltage clamp experiments carried out on nodes of Ranvier of myelinated fibres of Rana esculenta showed that a small fractoon of sodium channels fail to inactivate. Thus during long lasting depolarizing pulses there is a small Na-current superimposed on the leakage and potassium currents. This late Na-current appears more marked in sensory fibres than in motor ones.