INTERNODAL POTASSIUM CURRENTS CAN GENERATE ECTOPIC IMPULSES IN MAMMALIAN MYELINATED AXONS

Positive clinical symptoms can arise from ectopic action potentials in several disorders of myelinated axons. Here we report that an elevate d K+ concentration in the periaxonal, internodal space can cause inter nodal K+ currents to become excitatory, resulting in slow potential os cillations and associated bursts of ectopic spikes. Ectopic firing may therefore be favoured by conditions in which periaxonal K+ buffering is compromised.