A great deal of attention has focused on three key mechanisms. Scientists have identified many drugs that can interfere with these links and thereby protect brain cells from these chemical processes. Some of these drugs are in clinical trials and more are still in the laboratory stage of testing. Calcium is normally maintained at low levels inside brain cells and at high levels in the surrounding fluids. During injury too much calcium enters cells, causing them to swell, stop working properly, and eventually burst.
Calcium enters the cell through channels, or doors, opened by excitatory amino acids.
Excitatory amino acids help brain cells communicate. Normally they are tightly regulated within a brain cell and only released in small amounts. When a brain cell dies, the entire quantity of these chemicals is released at once. They open calcium channels in other cells and keep them open too long. Free radicals are extremely destructive molecules that are unneeded byproducts of normal metabolism.