Voltage-gated currents recorded from the surface of the frog optic nerve

Macroscopic voltage-dependent currents were recorded from the surface of the intact optic nerve of Rana pipiens using the loose patch clamp technique. Depolarizing steps of more than 40 mV produced sodium-dependent TTX sensitive inward currents and a 4-AP and sodium sensitive fast outward current in addition to a slower outward current. Since the surface of the nerve is a glia limitans, it appears that the membranes of these astrocytes contain both voltage-sensitive sodium and potassium channels.