Facilitation of voltage-gated ion channels in frog neuroglia by nerve impulses

The functions of glial cells in the nervous system are not well defined, with the exception of myelin production by oligodendrocytes, uptake of amino-acid synaptic transmitters, and a contribution to extracellular potassium homeostasis. Neuroglia have receptors for neurotransmitters which may be involved in neuron-glia interactions. Recent studies have demonstrated voltage-gated ion channels in glial membranes. In a study of the optic nerve of the frog, small areas of the surface were examined with the loose patch-clamp method, and voltage-gated Na+ and K+ channels, presumably located in the membranes of the astrocytes forming the glia limitans, were identified. We now report that nerve impulses in the axons of the frog optic nerve transiently alter the properties of the voltage-dependent membrane channels of the surface glial cells (astrocytes), a demonstration of a new form of neuron-glia interaction.