Action of argiotoxin636 on N-methyl-D-aspartate channels in cerebellar cells.

We investigated the mode of action of argiotoxin636 on isolated N-methyl-D-aspartate (NMDA) receptor channels in cultured cerebellar granule cells. We found that the toxin blocks NMDA channels by decreasing their opening probability and by inducing a flickering activity, in a voltage-dependent manner. Our results indicate that argiotoxin636 acts as an open-channel blocker and might therefore be a useful tool for studying the structure of glutamate-gated channels.