The Vasodilator reference article from the English Wikipedia on 24-Apr-2004
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Vasodilator

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A vasodilator is a substance that causes blood vessels in the body to grow slightly wider by relaxing the smooth muscle in the vessel wall. This will reduce blood pressure (since there is more room for the blood) and might allow blood to flow around a clot. Several vasodilators are used as drugs.

Natural vasodilators and drugs that exploit them: