Block of ionic and gating currents in node of Ranvier with oenanthotoxin.

Oenanthotoxin (OETX) is known to induce convulsions and epileptic spikes in rat. It is shown that OETX reversibly blocks the action potential and the sodium, potassium and gating currents in frog myelinated nerve fibres. These observations suggest that the block of ionic currents by OETX is due to an immobilization of the channel gates with the channel in a closed configuration. Before complete block, it is shown that OETX differentially affects the sodium current and the charge movement and blocks to different extents the different ionic currents. The results are discussed by comparison with the effects of agents known to immobilize the gating particles and in relation to the pharmacological actions of the toxin on the central nervous system.