Local researcher discovers hypertension-causing enzyme

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COLUMBIA - Obesity is a problem affecting one-third of American adults who are also at a higher risk for diabetes and cardiovascular diseases like hypertension. 

"Hypertension is a very serious problem with the obese population," said professor of medical pharmacology and physiology at the MU School of Medicine and lead researcher William Durante. 

Hypertension is caused when blood vessels are exposed to high pressure, which causes the heart to work harder to pump blood to the tissue. The disease can cause blood vessels to burst and kidney and organ failure. 

Durante led a study funded by the American Heart Association and the National Institutes of Health which identified the enzyme that is responsible for hypertension in obese individuals. 

The enzyme, arginase, is found primarily in the liver working to break down ammonia; however, the problem comes when the enzyme is found in blood. Arginase depletes blood and blood vessels of arginine, which is needed to produce nitric oxide. 

"Nitric oxide is a very important gas that's formed by arginine that dilates blood vessels and in turn lowers blood pressure," Durante said. 

The study was first conducted on obese rats. Scientists treated the first group with the amino acid L-arginine to replace what was being lost, while they gave the second group drugs to block the activity of arginase. In both circumstances, the treatments reversed hypertension in the obese rats. 

"We went on to show that if we could correct the deficiency of argenine in the animals, we could reduce their blood pressure," Durante said. 

Now, researchers said they can relate their findings to humans and work toward finding a way to prevent hypertension in obese patients.

"In this study we identified arginase as a critical mediator of hypertension. In future studies, we want to translate this finding to the clinic by developing drugs that can specifically block the activity of arginase, and this will treat either the development of hypertension in obese patients or normalize hypertension in obese patients," Durante said. 

Researchers also hope the findings may lead to new information and treatment options for obese patients with high blood pressure.