A photothrombotic ring stroke model in rats with or without late spontaneous reperfusion in the region at risk

This study aimed at developing a dual setup of the photothrombotic ring str oke model with or without late spontaneous reperfusion in the region at ris k and to explore the morphological consequences. The exposed crania of adul t male Wistar rats were subjected to a ring-shaped laser-irradiation beam ( o.d. 5.0 mm, 0.35 mm thick) for 2 min simultaneously with intravenous eryth rosin B (17 mg/kg) infusion. Transcardial carbon-black perfusion revealed t hat a laser intensity of 0.90 W/cm(2) resulted in late, that is, starting a t 72 h, spontaneous reperfusion, whereas the lowest laser intensity that pr oduced lack of reperfusion at 7 days post-irradiation was 1.84 W/cm(2). Las er-Doppler flowmetry showed prompt cortical cerebral blood flow (cCBF) redu ction both in the ring lesion and region at risk (12% and 25% of control va lues) after high-intensity irradiation; these reduced flow values were more rapid and pronounced than in the low-intensity irradiation setup as previo usly shown. The high- compared with low-intensity irradiation setup produce d more frequent occurrence of thrombi in the ring-lesion region and a large r ischemic cortical lesion with a more rapid pace of ischemic cellular chan ges in the ring-lesion region and the region at risk. The region at risk tr ansformed into pannecrosis in the high-intensity, but recovered morphologic ally in the low-intensity irradiation setup. This dual photothrombotic setu p with or without spontaneous reperfusion enables the study of events relat ed to ischemic cell survival or death in an anatomically predefined region at risk. (C) 1999 Elsevier Science B.V. All rights reserved.