CORRELATION BE TWEEN ENDOTHELIAL INJURY AND CEREBRAL VASOSPASM FOLLOWING A DOUBLE SUBARACHNOID HEMORRHAGE IN THE RAT

While a wide array of pathological changes occur in cerebral arteries following subarachnoid hemorrhage (SAH), the most consistent is endothelial damage. Since the endothelium normally modulates reflexes that influence vascular tone, any damage to it may represent a significant contributor to cerebral vasospasm following SAH. This experimental study investigates the correlation between endothelial injury of rat basilar (BA) and middle cerebral arteries (MCA) and vasospasm following a double SAH. Animals were divided into three groups of control (nonsurgical-noninjected), saline-injected, and blood-injected rats. Rats in the blood-injected group were injected with two 0.3 mL doses of autologous blood into the subarachnoid space at intervals of 72 hours. Rats were killed at different time intervals to study the time course of endothelial injury along with vasospasm following the second SAH with scanning electron microscopy and image analysis system, respectively. Cerebral arteries exposed to blood demonstrated severe pathological alterations during acute (30 min. to 2 hrs.) and chronic (48 hrs.) periods of time post second SAH. Concurrent with endothelial injury, there was widening of inter-endothelial tight junctions. Morphometric evaluation revealed severe arterial constriction starting at 30 min. (p<0.01) and again at 48 hrs. (p<0.05) post second SAH. The correlation between the time course of ultrastructural alteration of endothelial cells with arterial constriction provides further morphological contribution to the major complication of SAH-cerebral vasospasm.