In 1980 Furchgott and Zawadzki described the phenomenon of endothelium dependent relaxation¹ and identified a novel labile relaxant factor later identified as nitric oxide. A few years earlier John Vane and colleagues² had identified prostacyclin as a potent antiplatelet agent released from endothelial cells. Together these findings stimulated a huge increase in clinical research in vascular mechanisms and endothelial function. Twenty years on it is time to take …