Effects of the nootropics piracetam and GVS-111 on voltage-dependent ion channels of neuronal membranes

Abstract

The effect of two nootropics, piracetam and N-phenylacetyI-L-prolylglycine ethyl ester , is studied by measuring high-threshold K+ and Ca 2 § currents in isolated snail neurons using a two-microelectrode patch-clamp technique. Piracetam and GVS-111 are shown to reduce the amplitude of both the K § and the Ca 2 § (to a lesser extent) current. The threshold concentrations for GVS-111 and piracetam are 10-9-10 .8 M and 1-5• -4 M, respectively. It is assumed that the antiamnestic effect of the nootropics is partially mediated by a blockade of ion channels of the neuronal membrane. Key Words: high-threshold Ca 2 § channels; high-threshold K § channels; nootropic drugs; snail neuronsNumerous biochemical and electrophysiological effects of nootropics of the piracetam family suggest numerous targets of their action [10,12]. Voltage-dependent ion channels of the neuronal membrane responsible for the generation of nerve impulses can presumably be counted among these targets. This assumption is based on the positive therapeutic effect of ion channel antagonists in cognitive disorders [12]. In light of this it is obviously very important to study the effect of nootropics on ion channel conductance. However, little is known about the effect of the drugs on ion currents in the neuronal membrane, there just being a few contradictory reports on the effect of piracetam nootropics on Ca 2 § channels. Both inhibitory [8,9,16]