Endogenous substances and drugs that cause vasodilation are termed vasodilators. Mitral regurgitation may be treated medically with vasodilators, diuretics, digoxin, antiarrhythmics, and chronic anticoagulation. Such medical treatments include diuretics, vasodilators, and ACE inhibitors. Giving vasodilators such as nitroglycerin or calcium channel blockers is recommended. Vasodilators (such as nitroglycerin) increase the size of blood vessels, thereby decreasing arterial pressure. Intravenous administration of anticoagulants, vasodilators, and sympatholytics may be useful with massive doses. Additionally, PDE3 inhibitors act as vasodilators. This means administration of diuretics and vasodilators must be monitored carefully. ACE inhibitors are also vasodilators with both symptomatic and prognostic benefit. Prostaglandins are powerful, locally-acting vasodilators and inhibit the aggregation of blood platelets. The vasospasm responded readily to intra-arterial and intravenous vasodilators, such as tolazoline. Nitric oxide is one of the important vasodilators in blood vessels. Individuals with chronic MR can be treated with vasodilators as well to decrease afterload. The endothelium maintains vascular homeostasis through the release of active vasodilators. The latter is further converted to bradykinin, one of the most powerful vasodilators known.