Temporal Thresholds of Reperfusion in the Middle Cerebral Artery Occlusion Model in Rats.

In this study, the middle cerebral artery (MCA) of adult male Sprague-Dawley rats was occluded by the modified Koizumi method to determine the temporal thresholds of reperfusion for the treatment of cerebral embolism. Regional cerebral blood flow (rCBF) and pathological findings were measured at 1 and 2 h of ischemia and after 24 h and 7 days of reperfusion following 1 or 2 h of ischemia. rCBF was decreased the most (less than 10% of control CBF) in the parietal cortex (Pcor) and the lateral caudoputamen (Lcp) at both 1 and 2 h of ischemia. There was no significant difference in rCBF in these areas between the 2 ischemic groups. The 2 h ischemia group clearly showed infarction in the area perfused by the middle cerebral artery (including the Pcor and Lcp) after 24 h and 7 days of reperfusion, while the 1 h ischemia group showed only slight infarction. These findings suggest that temporal thresholds of reperfusion in this model exist between 1 and 2 h of ischemia, and that rCBF levels during ischemia and the duration of ischemia are the most important factors in producing brain infarction.