New developments in the understanding of cerebral vasoregulation and vasospasm: the endothelin-nitric oxide network

Abstract

Endothelins, which are powerful vasoconstrictors, and nitric oxide, which is a powerful vasodilator, together form a balanced system that regulates blood flow in the brain and in other organs. Ongoing research may yield new drugs that act on this system to prevent or reverse cerebral vasospasm in subarachnoid hemorrhage and other conditions. Many compounds are involved in cerebral vasoregulation under physiologic and pathologic conditions; of these, endothelins and nitric oxide have attracted considerable attention over the last several years. Endothelins and nitric oxide differ in chemical structure and pharmacological properties: endothelins are potent vasoconstrictor peptides consisting of 21 amino acids; nitric oxide is a free radical with a half-life of only a few seconds and exerts powerful vasodilatory effects. Both are produced by a number of cell types in the brain and interact at various levels to profoundly influence cerebral vessel function.