Maintaining a balance between the intracellular and extracellular ionic concentrations at the postsynaptic terminal is critical to normal neuronal function.
During brain ischemia, glutamate is released in excess from the presynaptic terminal, leading to the uncontrollable opening of the glutamate receptors, including the NMDA and AMPA receptors, which allows for an excessive influx of Ca2+ into the intracellular environment.