Abstract
A group of 30 rabbits (22 with no pretreatment, 8 thrombocytopenic) were given 0.7mg/kg of sodium arachidonate (AA) within 4-5sec. into the right carotid artery. Thirty minutes later, Evans blue was injected. Another 12 rabbits were given 20mg/kg of ADP within 1 minute. One hour after injection, brains were observed histologically. Brains of 77% (17/22) of AA-injected rabbits showed irregular blue staining in the ipsilateral cerebral hemisphere. Extravasation of plasma substance was histologically observed in this area. Frequent platelet adhesion on the luminal wall was seen. Derangement of endothelial lining was apparent around the area to where platelets adhered. The changes were not observed in the opposite hemisphere or in the thrombocytopenic group. Sixty six percent (8/12) of ADP injected rabbits showed marked blue staining and edematous changes which were confined to the right cortex. Ipsilateral hemisphere was stained in 2 cases and 2 cases showed no changes. The ADP-injected group showed similar, but less pronounced histological changes. Platelet count was more marked and of longer duration in the AA group as compared to the ADP group. These vascular injuries may be related to the consumption of intra-vascular platelet aggregates. Activated platelets might play an important role in the genesis of vascular injury.
