Diurnal variation of soluble E- and P-selectin, and intercellular adhesion molecule-1 in patients with and without coronary artery disease

BACKGROUND: The more frequent onset of acute coronary syndromes (ACS) in the morning has been known for a long time. Diurnal changes of fibrinolysis such as lower activity of tissue plasminogen activator and higher activity of plasminogen activator inhibitor-1 (PAI-1) in the morning has been demonstrated previously and correspond with the manifestation of ACS. Less is known about the diurnal variation of soluble adhesion molecules as markers of endothelial or platelet activity in patients with coronary artery disease (CAD). PATIENTS AND METHODS: 80 patients with a history of myocardial infarction and/or chest pain with positive exercise testing admitted for elective coronary angiography were studied. 10 had normal findings on coronary angiography (control group), 70 patients had at least one or more stenoses >/=50% of the diameter of an epicardial vessel. None of the patients suffered from acute inflammation, connective or tumor disease. Blood samples were drawn at 7:00 a.m. and at 7:00 p.m. at rest and plasma concentration of soluble P-selectin (sP-selectin), E-selectin (sE-selectin), intercellular adhesion molecule-1 (sICAM-1) and acute-phase proteins were measured by ELISA. RESULTS: In both groups, no diurnal variation was found in sE-selectin and sICAM-1. sP-selectin levels were significantly higher in the evening (CAD group: 149.8 +/- 54.5 vs. 172.2 +/- 68.8 ng/ml, p < 0.001; control: 148.7 +/- 75.5 vs. 187.5 +/- 96.3 ng/ml, p = 0.001, Wilcoxon test). CONCLUSION: We have demonstrated diurnal variation of sP-selectin in patients with CAD. We conclude that high sP-selectin values in the evening represent the shed forms of the morning membrane-bound P-selectin.