醫(yī)學(xué)補充閱讀:中風(fēng)患者腦細(xì)胞死亡之謎

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important new research identifies how brain cells die during a stroke
    medical research council (mrc) scientists, in collaboration with colleagues from british and italian universities, have unveiled a mechanism that causes the death of brain cells (neurons) in stroke. the discovery may help explain why some therapy approaches for stroke have been unsuccessful and identifies potential research avenues for the development of new treatments for stroke and other degenerative brain diseases.
    stroke is a consequence of an abrupt interruption of blood flow to the brain. when the blood supply stops, the nerve cells that are directly deprived of oxygen quickly die and release the chemicals that they use to communicate with each other. one of these neurotransmitters - glutamate - spreads to surrounding cells and sets off a process called excitotoxicity, causing much more widespread cell death. glutamate triggers a flood of calcium ions into the cells and, for reasons not previously understood, the level of calcium continues to rise and this kills the neurons.
    the new research, carried out at the mrc's toxicology unit in leicester, studied the mechanism of calcium overload in neurons after reduction in blood supply to areas of the rat brain. the initial flood of calcium activates enzymes called calpains, which break down the proteins in the cell membrane that normally pump calcium out of the cell.