[Effect of the potential antiparkinsonian agent adamantane derivative on ion channels of NMDA glutamate receptors].

Interaction of a new potential antiparkinsonian drug, N-(2-adamantyl)hexamethyleneimine hydrochloride (A-7), with NMDA channels in acutely isolated rat hippocampal neuron culture was studied by the whole-cell patch-clamp technique. The currents through the NMDA channels were excited by aspartate (Asp) application in a magnesium-free glycine-containing (3 microM) medium. It was found that A-7 produced a concentration-dependent (IC50 = 11.8 +/- 0.6 microM) NMDA channel blocking. The blocking rate increased with the A-7 concentration, whereas the unblocking was concentration-independent. The degree of blocking was independent of the Asp concentration, but was markedly increased by hyperpolarization of the cell membrane. After Asp washout, A-7 remained trapped in the channel by the activation gate. The channel was unblocked upon the next Asp application. These data is evidence that the antiparkinsonian effect of A-7 is related to the NMDA-channel-blocking activity of the drug.