Why does a lack of energy turn into a flood of glutamate? · Grey Matter

Glutamate is cleared by transporters that use the sodium gradient, and that gradient is kept by the ATP-driven pump.

Why does a lack of energy turn into a flood of glutamate?

Glutamate is cleared by transporters that use the sodium gradient, and that gradient is kept by the ATP-driven pump. When ATP fails, the gradient runs down and the transporters slow, stop, and can even run in reverse, releasing glutamate from astrocytes and neurons. At the same time depolarised terminals open their calcium channels and release vesicles, adding more. The glutamate depolarises the neighbouring cells, which worsens their own energy deficit, so energy failure and excitation feed each other in a loop that spreads through tissue short of blood.