Endothelin-1 acts in cerebral arteries from the adventitial but not from the luminal side

The in vivo vasoconstrictor effect of endothelin-1 (ET-1) was investigated on feline and canine basilar arteries. The basilar artery caliber was angiographically measured after either vertebral artery perfusion or asternal injection of the peptide. In both cats and dogs, ET-1 (5-S500 pmol) induced a dose-dependent basilar artery contraction in vivo when applied intracisternally. The vasoconstriction was extremely long lasting; no significant recovery of vessel caliber was observed up to 12 h after injection. In contrast, bolus injection of ET-1 up to 3 nmol into the vertebral artery had no appreciable effect on the basilar artery caliber. These observations suggest that ET-1 acts in cerebral vessels from the adventitial but not from the luminal side, possibly due to the presence of the blood-brain barrier. The long-lasting nature of the ET-1-induced constriction of the cerebral arteries in vivo suggests that the peptide might be involved in the pathogenesis of cerebral vasospasm.