Effects of prostacyclin and indomethacin on experimental delayed cerebral vasospasm

Isolated canine basilar artery contracted by prostaglandin E2, hemoglobin, or serum was relaxed in a dose-dependent manner by the addition of 10(-8)M to 10(-6)M prostacyclin (PGI2), and was scarcely relaxed by 10(-9)M PGI2. In other studies, intravenous administration of PGI2 (25 or 75 ng/kg/min), indomethacin (4 mg/kg), or indomethacin (4 mg/kg) plus PGI2 (25 ng/kg/min) failed to reverse angiographic delayed vasospasm produced in vivo in the canine basilar artery by an intracisternal injection of blood. In addition, no significant increase occurred in mean values of regional cerebral blood flow (rCBF) with any treatments, and mean rCBF difference in dogs treated by PGI2 infusion at 25 ng/kg/min was 2.5 +/- 1.2 ml/100 gm/min and only significantly increased (p less than 0.01). Mean arterial blood pressure was significantly reduced by PGI2 infusion at 25 (p less than 0.05) or 75 ng/kg/min (p less than 0.005).