IMPAIRMENT OF ANTIPLATELET-AGGREGATING ACTIVITY OF ENDOTHELIAL-CELLS AFTER EXPERIMENTAL SUBARACHNOID HEMORRHAGE

Background and Purpose: Serial changes of anti-platelet-aggregating ac tivity in the endothelial cells after experimental subarachnoid hemorr hage were studied in 30 feline two-hemorrhage models. Methods: One hou r 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 art ery to activate circulating platelets. Immediately after ADP infusion, the basilar artery was fixed by intra-arterial perfusion with 1.5% gl utaraldehyde in 0.1 mol/L phosphate buffer and was removed. The lumina l surface was examined under a scanning electron microscope. Results: One hour after subarachnoid hemorrhage, no platelets adhered or aggreg ated on the luminal surface. However, 4 to 7 days after subarachnoid h emorrhage, many platelets were observed adhering or aggregating on the luminal surface. Conclusions: These findings suggest the impairment o f anti-platelet-aggregating activity of endothelial cells after subara chnoid hemorrhage. This impairment may be involved in inducing cerebra l ischemia during cerebral vasospasm by causing platelet adhesion and aggregation.