Membrane Stabilization and Protection of the Ischemic Brain

Abstract

If cerebral circulation is arrested, the oxidative metabolism and hence almost all ATP production will cease. The cells rapidly become depleted of ATP, and the energy requiring processes, mainly active ion transport, are arrested. The cells leak K⁺ and take up Na⁺, Cl^-, Ca²⁺ and water, and the membranes depolarize. This is the general scheme leading to the terminal stage of ischemic membrane failure. It is obeyed by all tissues subjected to acute ischemia, but the remarkable feature of the brain is the rapidity with which this occurs. Due to extreme leakiness of the cellular compartment in the brain, the state of terminal ischemic membrane failure is reached in a matter of minutes, while it may take hours or even days for the passive ion leak fluxed to come to a stop in other organs with tight membranes such a muscle, peripheral nerve, or erythrocytes.