Molecular biological considerations in cerebral vasospasm following aneurysmal subarachnoid hemorrhage.

Chronic delayed cerebral vasospasm (CDCV) remains a serious and often fatal complication of aneurysmal subarachnoid hemorrhage (SAH). The current understanding of its fundamental mechanisms and molecular biological characterization is rudimentary. Two important vasoactive substances have been implicated in CDCV: endothelin-1 (ET-1) and nitric oxide (NO). A 21--amino acid vasoconstrictor peptide, ET-1 has generated interest as a possible important contributor to cerebral vasospasm on the basis of both clinical and experimental evidence suggesting abnormally enhanced production. Nitric oxide is a cell membrane--permeable free radical gas that accounts for the vasodilatory effect of endothelium-derived relaxation factor and is a physiological antagonist of ET-1. As with ET-1, abnormalities of NO production have been implicated in several pathological conditions including cerebral vasospasm. This brief report reviews some of the physiological and regulatory features of these two molecules and explores the possibility of their relationship to cerebral vasospasm.