[Dynamic penumbra in a rat model of focal cerebral ischemia and reperfusion]

To identify the ischemic core and penumbra of variant ischemia and reperfusion period by the dark neuron method, observe them dynamically, and elicit the morphological character of ischemic pneumbra.

Total 72 male Wistar rats were randomly divided into the following groups: pseudo-surgical, blank-control, O24R0 (sustained ischemia for 24 hours), O4R24(ischemia for 4 hours and reperfused for 24 hours, the following may be deduced by analogy), O2R0, O2R0. 5, O2R2, O2R4, O2R8, O2R24, O2R48, O2R96. There were 6 rats in each group. Rats in experimental groups were suffered focal cerebral ischemia-reperfusion through a nylon suture method. After perfusion fixed, the brains were coronal sectioned and stained with HE, TB and acetum plumbi/silver nitrate. Sections were observed with light microscope and electron microscope. The area of ischemic core and penumbra was measured and analyzed with an image analysis system.

The penumbra expanded rapidly in a short period after reperfusion, and reach its apex when reperfused for 2 hours (P < 0.05). The penumbra was relatively stable during 4 to 48 hours reperfusion. There were many cell types in ischemic core and penumbra, the proportion of cells changed according to reperfusion time.

Reperfusion could aggravate cerebral edema and make the ischemic penumbra to expand during the first hours.