Say NO to ET

The endothelial cells relase both relaxing [nitric oxide (NO), endothelium- derived hyperpolarizing factor (EDHF), prostacyclin] and contracting factor s [endoperoxides, thromboxane A(2), superoxide anions, endothelin-1 (ET)]. The production of ET is inhibited by NO. The latter also strongly opposes t he direct effects of the former on vascular smooth muscle. With aging and v ascular disease, the production of enothelial NO declines, and thus ET can be released, act and contribute to the symptoms. (C) 2000 Elsevier Science B.V. All rights reserved.