The Role of Cyclooxygenase Activity in the Endothelial Function of Hypertensive and Hypercholesterolemic Patients

A layer of cells called the endothelium line the walls of blood vessels. These cells produce substances that control the tone of blood vessels and thus control blood flow through the vessel. This regulating activity of the endothelium is dysfunctional in several diseases of the heart and blood vessels, including high blood pressure and high levels of cholesterol. Previous research has pointed toward a decrease in the action of nitric oxide (NO) as the cause of this abnormality. Nitric oxide is a substance produced by the cells of the endothelium that plays a role in the relaxation of blood vessels. In this project researchers plan to study blood flow through the blood vessels in patients forearms after receiving four different drugs: sodium nitroprusside, acetylcholine, L-NMMA, and aspirin. These four drugs act on the blood vessels of the forearm through different mechanisms. Acetylcholine and sodium nitroprusside are drugs that open the blood vessels of the forearm and increase blood flow through the vessel. L-NMMA is a drug that blocks production of nitric oxide (NO). Aspirin's role in controlling blood flow is unknown. Patients participating in this research study will not directly benefit from it. However, the study will contribute to researchers understanding of diseases of the blood vessels and heart.