ABSTRACT 332

Abstract

Background and aims: Ischemia induces significant changes in macro- and microcirculatory reperfusion. Reperfusion may influence the lesion size. Aims: The aim of this work was to describe the reperfusion phase in a juvenile stroke model and comparing it to a neonatal stroke model. Methods: Ischemia was induced in Wistar P7 and/or P14 rats by electrocoagulation of the left middle cerebral artery followed by a transient (50 min) occlusion of both common carotids under 1% isoflurane anesthesia. The macrocirculation was evaluated by transcranial Doppler imaging in both carotids. The microcirculation was evaluated by cortical tissue perfusion using Laser Speckle Contrast Doppler Imaging. Results: In the P14 rat, immediate and almost complete re-flow was observed in both carotids. Cortical tissue reperfusion was also immediate and blood flow returns to baseline as early as the first minute. In the P7 rat, a progressive and incomplete reperfusion was depicted in the carotids. A significantly lower flow was measured in the contralateral carotid as compared to the ipsilateral one. Both ipsilateral and contralateral gradual reperfusion was correlated with reduced cortical tissue blood flow and reduced cortical mitochondrial respiratory function. Conclusions: The macrocirculation and microcirculation were faster in a juvenile stroke model than in a neonatal stroke model. Differences observed with young stroke models are in favor of physiologic processes changing during development as evidenced by increase cortical vessel branching and endothelial cell proliferation during the two first weeks of life.