Low concentrations of potassium inhibit the Na-dependent [3H]glutamate binding to rat hippocampal membranes.

Potassium at low concentrations was found to inhibit the Na-dependent [3H]L-glutamate binding to rat hippocampal synaptic membranes. This inhibition was probably due to a competition between potassium and sodium at the ionic locus of the recognition site for glutamate of the uptake process. In addition, potassium inhibited the high-affinity [3H]L-glutamate uptake in hippocampal synaptosomes. These results provide an additional mechanism for the spreading of depression which accompanies seizure activity in the hippocampus.