Ischaemia at the frontoparietal cortex and lateral segment of the caudate putamen was achieved in all animals of the occlusion group by inserting a nylon thread through the extracranial carotid artery, ascending it up to anterior cerebral artery and occluding the origin of the middle cerebral artery. Reperfusion was accomplished by pulling the embolic thread out of the wound till resistance was felt. Neurological deficits were graded on the Bederson Scale. The level of lipid peroxidation was estimated by assay of major thiobarbituric add reactive malondialdehyde. Infarct size was determined by the lack of staining for mitochondrial dehydrogenase activity with tripehenyltetrazolium chloride.

In normal animals, the mean MDA level of the frontoparietal cortex and lateral segment of the caudate putamen was 4.82(+-0.68) nmol/gr tissue. The ischemic or reperfused area MDA levels were higher than the corresponding area of the contralateral hemisphere (p <0.05) or the normal and sham operated animals (p<0.03). MDA levels of the ischemic areas varied over time; values at the first hour were 20.2 % higher than at the second hour (p <0.02). MDA level, percent of infarction and neurological grade showed correlation in the occlusion group. Keywords : Cerebral ischaemia, free radicals, lipid peroxidation, rat