[Sequential changes of vascular intimal ultrastructure in experimental cerebral vasospasm induced by oxyhemoglobin....

Organic changes of vessel wall may play an important role in the pathophysiology of vasospasm after subarachnoid hemorrhage. Sequential changes of intimal ultrastructure in experimental vasospasm induced oxyhemoglobin were investigated by scanning electron microscope. Thirty-four cats were used for this study. The basilar artery was exposed by transcervico-transclival approach. Oxyhemoglobin solution was applied under the arachnoid membrane around the artery in 16 cats at hourly intervals. Of 16 cats, 3 were sacrificed at 1 hour after the first application of the solution, 3 at 3 hours, 3 at 6 hours, 3 at 12 hours, 4 at 24 hours. Three sham-operated cats treated by artificial CSF were used as the control together with 5 untreated normal cats. All procedures were performed under aseptic condition. Perfusion fixation was done. The luminal surface and the cut surface made by freeze-fracture method were investigated by scanning electron microscope. As oxyhemoglobin solution, oxyhemoglobin-rich hemolysate was used and the concentration was 5.5 mM. By hourly application, continuous vasoconstriction of about 70% of the control diameter was obtained. In the control, the endothelial cell layer was flat. The elastic lamina had mild waving, and the luminal surface was smooth. In 1- and 3-hour groups, the elastic lamina was corrugated and the endothelial cells were protruded into the lumen in the depressed portion of corrugation. In 6- and 12-hour groups, degenerative changes of the endothelial cells, crater-formation and ballooning, were seen. Some blood-born cells adhered to the luminal surface in such cases. In 24-hour group, the changes of the endothelial cells became more remarkable.(ABSTRACT TRUNCATED AT 250 WORDS)