Relaxing and Contracting Factors : Humana Press : 9780896031289 : 0896031284 : 24 Aug 1988 : It is an exciting task to be the editor of the first monograph covering a new area of the biomedical sciences. Since the first report in 1980 by Robert Furchgott and colleagues (see Chapter 1) of the evidence of endothelium-dependent relaxation in isolated arteries, there are ever­ increasing numbers of vascular physiologists and pharmacologists who are scraping away the endothelium to look into its role in cardiovascular con­ trol. And the more one looks, the more one discovers. Not only is the list of substances that can induce endothelium-dependent relaxations im­ pressively long, but these intriguing cells can also secrete vasoconstrictor substances. The ability of the endothelium to modulate the degree of con­ traction of the underlying smooth muscle is an ancestral property of the blood vessel wall, illustrating the logic of nature, since the endothelial cells are located in the best poss