Endothelial Progenitor Cells and Risk Factors for Coronary Artery Disease

Study Summary

This study will measure and compare the levels of endothelial progenitor cells (EPCs) in the blood of people with and without risk factors for atherosclerosis (hardening of the arteries) to see if there is a relationship between these cells and cardiovascular risk factors such as smoking, high cholesterol level and high blood pressure. Healthy male volunteers between the ages of 21 and 55 years with and without heart disease risk factors may be eligible for this study. Candidates must have no evidence of coronary or peripheral vascular disease, proliferative retinopathy, or other chronic disease and no history of cancer, migraine-type headache, cluster headache, raised intraocular pressure, raised intracranial pressure, hyperthyroidism. Participants will undergo the following procedures at the NIH Clinical Center: * Medical history and physical examination * Blood tests to measure EPC level and various risk and growth factors * Brachial reactivity study - This ultrasound study tests how well the subject's arteries widen. The subject rests on a bed for 30 minutes. An ultrasound measuring device is placed over the artery just above the elbow. The size of the artery and blood flow through it are measured before and after inflating a pressure cuff around the forearm. The pressure cuff stops the flow of blood to the arm for a few minutes. After a 15-minute rest, the drug nitroglycerin is sprayed under the subject's tongue. Before the nitroglycerin spray and 3 minutes after it, the size of the artery and blood flow through it are measured again.