COPPER-INDUCED NONSELECTIVE 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 Cu2+-activated current (I(Cu)) is biphasic and composed of overlapping outward and inward components. The outward component of I(Cu) is the result of a blockade by Cu2+ of the steady-state outward Cl- current. The inward component is assumed to flow through Ca2+-activated non-selective cationic channels. The washing-out procedure resulted in a large inward current (I(w)), 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 I(Cu) and I(w) were highly Ca2+- and temperature-dependent processes. It is concluded that Cu2+ application resulted in complex permeability changes in the Helix pomatia neurons.