Nitric oxide gas is important in regulating blood vessel dilation, and consequently, blood flow. This gas is continuously produced by endothelial cells, which line the blood vessels. This study will examine whether nitrite, a molecule that normally circulates in the blood stream, can also dilate blood vessels. The results of this study may be valuable in developing treatments for people with conditions associated with impaired endothelial production of nitric oxide, including high blood pressure, high blood cholesterol, diabetes, estrogen deficiency, and others.