Copper-induced non-selective permeability changes in intracellularly perfused snail neurons.

The effect of extracellularly applied Cu2+ was studied on isolated intracellularly perfused Helix pomatia neurons. It was found that the Cu(2+)-activated current (ICu) is biphasic and composed of overlapping outward and inward components. The outward component of ICu is the result of a blockade by Cu2+ of the steady-state outward Cl- current. The inward component is assumed to flow through Ca(2+)-activated non-selective cationic channels. The washing-out procedure resulted in a large inward current (Iw), which was composed of transient and steady-state components. It is most likely that the activation of metabolic pumps is responsible for the transient component and the steady-state component is the result of increased neuronal membrane permeability for Cl-. Moreover, both ICu and Iw were highly Ca(2+)- and temperature-dependent processes. It is concluded that Cu2+ application resulted in complex permeability changes in the Helix pomatia neurons.