Effect of endothelin-1 receptor antagonist BQ-123 on basilar artery diameter after subarachnoid hemorrhage (SAH) in rats.

Aim of the study was to quantify cerebral vasospasm in rats after subarachn oid hemorrhage (SAH) by morphometric examination of basilar artery and to e valuate the influence of endothelin receptor blocker BQ-123 on basilar arte ry constriction. The rat cisterna magna (CM) was cannulated and after 7 day s SAH was developed by administration of 100 mu l autologic, non-heparinize d blood to the CM. The sham subarachnoid hemorrhage was developed by intrac isternal administration of 100 mu l of artificial cerebrospinal fluid. Endo thelin receptor blocker BQ-123 was injected into the CM in a dose of 40nmol dilated in 50 mu l of cerebrospinal fluid 20 min, before SAH, and 24h and 48h after SAH. After perfusion fixation the brains were removed from the sk ull and histological preparations of basilar artery were done. The internal diameter and wall thickness of basilar arteries was measured by interactiv e morphometric method. The most severe vasospasm was found in rats after SA H. The presence of numerous infiltrations composed of neutrophils and macro phages correlated with advanced vasospasm (index of constriction 5 times lo wer than in normal), suggesting the role of other factors participating in the late phase of vasospasms after SAH. Administration of BQ-123 in the lat e phase after SAH caused the dilatation of basilar artery. Following the ad ministration of BQ-123 in the late phase (48h after SAH) the basilar artery dilated, its wall became thinner, and the number of leukocyte infiltration s in the subarachnoid space decreased compared to the values after SAH alon e.