Three-vessel middle cerebral artery occlusion model

In the search for a more reproducible focal ischemic stroke model in the rat, we systematically interrupted blood flow to the right middle cerebral artery (MCA) territory by transient ligation of the right MCA, and both right and left common carotid arteries (CCAs) in succession. The regional CBF in this model was examined by laser Doppler flowmetry and [14C] isopro-pyliodoamphetamine and [14C] iodoantipyrine autoradiographic comparison. The right MCA cortex sustained severe ischemia, with a regional blood flow reduction by 88-92%, whereas only very mild ischemia was noted (reduction of blood flow by 10-20%) outside the right MCA cortex. A ligation-time-dependent focal infarct was consistently noted in the cerebral cortex supplied by the right MCA. The characteristic changes of ischemic necrosis were limited to the cortex, sparing the subcortical structures. The mortality rate was very low (less than 2%). Occlusion of the right MCA alone or together with the right CCA did not consistently cause gross infarction. Permanent ligation of the right MCA and both CCAs had a high mortality. Results from this study showed that a more consistent cortical infarction in the right MCA territory with low mortality can be achieved by interruption of collateral circulation following the right MCA ligation.