LOCALIZATION AND ALTERATION OF IMMUNOREACTIVE ENDOTHELIN-1 IN CANINE BASILAR ARTERIES FOLLOWING SUBARACHNOID HEMORRHAGE

Localization and alteration of the levels of immunoreactive endotheoin -1 (ir-ET-1) products of canine basilar artery were examined in a one- hemorrhage model. Subarachnoid hemorrhage (SAH) was induced by a singl e injection of autologous arterial blood into the cisterna magna. In S AH dogs, the endothelial cells on day 2 showed minimal changes such as rounding nuclei or edema, and these injuries progressed on days 4 to 6 from moderate changes with subendothelial edema to severe damage cha racterized by denudation. In these dogs, ir-ET-1 products on endotheli al cells were significantly enhanced and reached maximum levels on day 2 followed by gradual reduction on day 4 to 6. Although no significan t changes appeared on endothlial cells in untreated dogs and control d ogs on day 2 after the injection of saline, weak ir-ET-1 products were localized irregularly on those cells. However, ir-ET-1 levels on day 4 and 6 were significantly higher in SAH dogs than in untreated dogs. Cerebral arteries were covered with blood clots and a number of inflam matory cells had invaded the adventitia of basilar arteries, in additi on to sorrounding the clots. The number of inflammatory cells and the quantity of ir-ET-1 products in the adventitia achieved maximum levels on day 2, and decreased on day 4 to 6. Almost all the inflammatory ce lls were positive for anti-macrophage antibody. Thus, the levels of ir -ET-1 products on endothelial cells were enhanced with minimal injury on day 2 and gradually decreased with the progression of the injury, w hile those in the adventitia correlated well with the number of migrat ing into the adventitia. suggest that ET-1 is derived macrophages migr ating into well as endothelial cells, and is an important factor for v asospasm after SAH, not only in the early phase but also in the late s tages.