Thepericardial fluid of patients with coronary artery disease trigger substantialarterial contractions in isolated carotid arteries of rats, which are mediatedprimarily by ET-1.40 Our resultsshowed both the presence of an ACE isoform in the pericardial fluid, and, for thefirst time, the immunolocalization of that protein in parietal pericardialmesothelial cells, suggesting that the parietal pericardial mesothelial layer is onepossible source of the pericardial fluid ACE. This evidence concerns the gene ACE and coronary artery disorder.