The Effects of brain ischemia induced by bilateral carotid artery occlusion on microcirculation of the cerebral cortex of mongolian gerbil

ABSTRACT

BACKGROUND AND PURPOSE: The present study was carried out to investigate transient arteriolar vasospasm following reperfusion in the gerbil as an ischemic model and relationship between vasospasm and the changes of morphologic, physiologic and regional blood flow. METHODS: The transient arteriolar vasospasm was observed under the microscope. All gerbils were perfusion fixed and ischemic neuronal damage was checked in the CA1 subfield of the dorsal hippocampus. Metabolic parameters were serially measured during the occlusion and after recirculation, and cerebral blood flow was measured with a laser Doppler flowmetry. RESULTS: 1. Among the 18 gerbils with BCAO(bilateral carotid artery occlusion) for 2 minutes, 8 gerbils showed vasospasm after reopening, namely post-ischemic vasospasm, and 10 gerbils did not show vasospasm. 2. In all animals, metabolic parameters showed decreased PaCO2 and high pH just after the occlusion but increased PaCO2 and lowered pH following the recirculation. BCAO caused marked increase in systemic blood pressure but it returned to preischemic levels following the recirculation. 3. In all animals, BCAO caused marked decrease of cerebral blood flow compared to preischemic levels immediately following the occlusion but it returned to preischemic levels following the recirculation. And it took some longer the onset and duration of the transient increase in blood volume after reopening in the animals with vasospasm than those without vasospasm. 4. There was no morphological neuronal damage in the hippocampal CA1 subfield, at 1, 3, 7 days following 2-minute ischemic insult. CONCLUSION: The present study confirmed that BCAO in gerbils resulted in forebrain ischemia caused transient cortical vasospasm in the gerbil. But there was no close relationship between vasospasm and the changes of morphologic, physiologic and regional blood flow.