NEW DEVELOPMENTS IN THE UNDERSTANDING OF CEREBRAL VASOREGULATION AND VASOSPASM - THE ENDOTHELIN NITRIC-OXIDE NETWORK

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 vaso-spasm in subarachnoid hemorrhage and other conditions. KEY POINTS 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.