A model of embolic cerebral ischemia in the rat.

Experimental studies of embolic cerebral ischemia using the rat are limited by variability in the location, size, and frequency of lesions produced. A technique is described herein which improves the reliability of an established model. Eight male Sprague-Dawley rats underwent injection of the cervical internal carotid artery with 0.1 ml of 1-h-old fragmented autologous blood clot through an external carotid artery cannula. The pterygopalatine artery was ligated prior to embolization. At killing 2 h after embolization, clot was observed in the proximal middle cerebral and posterior cerebral arteries in all animals. Areas of reduced blood flow at 2 h postembolization were assessed by digital image processing of iodo-[14C]antipyrine autoradiographic images. No-flow and low-flow areas were measured for each of approximately 25 serial brain sections with a computerized bit-pad. Volumes were calculated and lesions localized by anatomical reconstructions. No animal sustained a hemorrhagic lesion. One animal sustained only a very small area of ischemia in the internal capsule. Of the remaining seven, all had large regions of ischemia in the middle cerebral distribution involving cortex and basal ganglia. Posterior cerebral involvement was observed in six of the seven animals as well. The contralateral hemisphere was unaffected. Volume values could be calculated for primary vascular distributions. Most variability occurred in the pattern of posterior cerebral involvement. The technique described produces a relatively consistent region of ischemia in the middle and posterior cerebral artery distributions in the rat and is a useful model for the study of cerebral ischemia.