Effect of acquired tolerance to ischemia on focal infarction in gerbils.

The protective effect of prior ischemia on focal cerebral infarction produced by permanent middle cerebral artery (MCA) occlusion was studied in a gerbil model. Forebrain ischemia for 2 and 5 minutes at an interval of 48 hours was used as the prior ischemic insult. Forty-eight hours after the second forebrain ischemia, the MCA was occluded. Progression of ischemic change caused by the MCA occlusion was delayed in the early ischemic period in animals with prior ischemia, as compared to animals without prior ischemia. The mean infarct volume 24 hours after the MCA occlusion was the same in animals with and without prior ischemia. Ischemic tolerance was acquired in this model, but had no effect on the extent of infarction caused by permanent ischemia.