Impairment of anti-platelet-aggregating activity of endothelial cells after experimental subarachnoid hemorrhage

Serial changes of anti-platelet-aggregating activity in the endothelial cells after experimental subarachnoid hemorrhage were studied in 30 feline two-hemorrhage models. One hour or 2, 4, 7, or 14 days after mimic subarachnoid hemorrhage, ADP (40 mg/kg) was infused into the basilar artery via the right vertebral artery to activate circulating platelets. Immediately after ADP infusion, the basilar artery was fixed by intra-arterial perfusion with 1.5% glutaraldehyde in 0.1 mol/L phosphate buffer and was removed. The luminal surface was examined under a scanning electron microscope. One hour after subarachnoid hemorrhage, no platelets adhered or aggregated on the luminal surface. However, 4 to 7 days after subarachnoid hemorrhage, many platelets were observed adhering or aggregating on the luminal surface. These findings suggest the impairment of anti-platelet-aggregating activity of endothelial cells after subarachnoid hemorrhage. This impairment may be involved in inducing cerebral ischemia during cerebral vasospasm by causing platelet adhesion and aggregation.