Abstract
The effects of repeated short episodes of focal ischemia at 30-minute intervals or a single equivalent long episode of focal ischemia on neuronal function and development of cerebral infarction were compared using somatosensory evoked potential (SEP) recording and 2, 3, 5-triphenyltetrazolium chloride staining in a cat model. Seventeen cats underwent transorbital occlusion of the middle cerebral artery (MCA), using one of three procedures: sham-operation; single 1-hour occlusion of the MCA, followed by 3 hours of recirculation; or three 20-minute occlusions of the MCA at 30-minute intervals, followed by 3 hours of recirculation. Two of six cats in the single long-term occlusion group showed recovery of SEP, whereas all six cats in the repeated short-term occlusion group showed recovery of SEP at 3 hours after recirculation. All six cats in the single long-term occlusion group had cerebral infarction of various sizes, but only one cat in the repeated short-term occlusion group developed infarction. Repeated short episodes of focal ischemia are relatively less damaging than a single equivalent long episode of focal ischemia, even if the reperfusion interval is extended to 30 minutes.
