[Endothelial function and spasm of the coronary artery]

The tone of isolated segments of human coronary arteries with manifestations of atherosclerotic lesions was increased by serotonin (10(-6) M) or prostaglandin F2 alpha (10(-6) M). Insignificant endothelium-dependent relaxation induced by bradikinin, calcium ionofore A-23187 or substance P was observed in several segments with marked (plaque) as well as macroscopically invisible sclerotic lesion. Segments of human coronary arteries without sclerotic damage demonstrated endothelium-dependent relaxation in response to activators of endothelial relaxation factor. Functional disturbance of coronary artery endothelium in endothelial relaxation factor production may be one of the causes of increased smooth muscle tonic contractions, responsible for coronary artery spasm underlying angina pectoris and myocardial infarction.