The discovery that nitrite improves blood flow through reduction to nitric oxide creates potential for new treatments for diverse conditions including hypertension, myocardial infarction, and peripheral vascular disease, according to an article published online on November 2 and to appear in print in the December issue of Nature Medicine.

In the current work, the American researchers found that nitrite, which is present in significant levels in blood, undergoes physiologic reduction to form the vasodilator nitric oxide through the action of deoxyhemoglobin.

"The importance of this work is that no one considered this molecule to have any significant function and it is relatively abundant in the blood stream," said Dr. Mark
Gladwin, senior author of the study. Nitrite levels had previously been shown to be low in patients with hypertension.

The collaborators studied 18 healthy volunteers who were enrolled in a physiological study. Sodium nitrite was infused into the brachial artery in the forearm to determine whether nitrite affects blood flow. They showed that blood flow increased by 175 percent.

"We saw a huge improvement in blood flow," said Gladwin. "Nitrite helps get more blood to regions of the body with low oxygen such as kidneys, the heart, the brain and muscles. This has potential as a new therapy that was previously overlooked. It's a powder sitting on the shelf and everyone has it."

However, he warned that nitrite at high concentrations can be toxic; clinical trials are underway at the National Institutes of Health, where the physiology study was conducted, to establish whether nitrite has clinical usefulness for various conditions.