[Effect of memantine on membrane properties and postsynaptic potentials in neurons of Aplysia californica].

The effect of 1,3-dimethyl-5-aminoadamantane (DMAA, D-145, memantine, Memantine) in the concentration range of 10(-6) to 10(-3) mol/l was investigated on membrane properties and synaptic transmission by the current or voltage clamp method on neurons in the visceral ganglion of Aplysia california. In the lower range (concentrations 10(-6) to 10(-5) mol/l) the substance increases the speed of voltage changes during the course of the action potential, increases spontaneous synaptic activity, and induces a slight membrane depolarization. With increasing concentration the effects reverse in that slope of action potential is slowed and synaptic transmission delayed or blocked. At the RC-R15 synapse, isolated from its interneuron, 10(-5) mol/l DMAA evokes spontaneously and regularly firing EPSPs; 10(-3) mol/l blocks both, spontaneous activity, and its responsiveness to electrical stimulation.