ABSTRACT
The brain requires a constant supply of oxygen and nutrients through blood vessels for survival and normal function. It consumes about 20% of the total body oxygen consumption. Cerebrovascular insufciency, a form of cerebrovascular disease, caused by poor blood supply to the brain can lead to transient ischemic stroke (minstroke) or stroke. Stroke is the third leading cause of death in the USA, causing more than 150,000 deaths annually. Insufcient blood supply to the brain can occur by formation of clot (thrombosis) in the carotid artery that supplies blood to the brain, release of clot from another part of the body and lodged in the carotid artery, or by stenosis of the carotid artery. There are two major zones of ischemic injury referred to as core ischemic zones (necrosis of neurons and glia cells) and ischemic penumbra (surrounding ischemic area containing potentially viable neurons). The damage in the core ischemic zone is irreversible, whereas cells in the ischemic penumbra can regain function if blood circulation to the brain is restored before they become dead. When blood circulation to the brain is restored, reperfusion injury occurs that can aggravate damage caused by ischemia. The existence of ischemic penumbra provides an opportunity to rescue neurons and glia cells and thereby reduce the impact of ischemic/reperfusion injury on the brain functions. However, the window of time for rescuing neurons is very short.
