Ergometrine-induced arterial dilatation: an endothelium-mediated effect.

Ergometrine has generally been regarded as a vasoconstrictor and is used clinically to provoke coronary vasospasm in susceptible patients [3, 8, 9]. The ergometrine response appears however to be complex in that it can be biphasic, the constrictor response being preceded by an initial dilator response in experimental models [4]. The explanation for this is unknown, as is the underlying mechanism responsible for the clinical condition of coronary vasospasm. We have investigated this biphasic response in isolated artery preparations and shown that the dilator component is due to ergometrine-induced release of endothelium-derived relaxant factor (EDRF).