Blockade of the mitochondrial permeability transition pore diminishes infarct size in the rat after transient middle cerebral artery occlusion. 
The mitochondrial permeability transition pore is an inducer of cell death.  During the reperfusion phase after cerebral ischemia, calcium accumulates in mitochondria, and a burst of free radical formation occurs, conditions that favor the activation of the mitochondrial permeability transition pore.  Here the authors demonstrate that a blocker of the mitochondrial permeability transition pore, the nonimmunosuppressive cyclosporin A analogue N-methyl-Val-4-cyclosporin A (10 mg/kg intraperitoneally), administered during reperfusion and at 24 hours of reperfusion, diminishes infarct size in a rat model of transient focal ischemia of 2 hours' duration.  The mitochondrial permeability transition pore may be an important target for drugs against stroke.