030-AP-02

Further Testing May Determine Right Antioxidant Mix to Relieve Hypertension

Irvine, Calif., Feb. 13, 2002 -- High doses of vitamin E significantly reduced high blood pressure in rats with chronic kidney failure, a UCI College of Medicine study has found.

The study illustrates the key role a damaging process called oxidative stress plays in causing high blood pressure. It also shows how vitamin E and other antioxidants may provide new ways to treat high blood pressure, especially in patients with kidney disease. The study appears in the wake of new research that suggests kidney disease is much more prevalent than previously assumed.

Dr. Nick Vaziri, professor of medicine and chief of nephrology, and his colleagues found that rats with impaired kidneys produced high levels of free radicals, highly reactive chemicals known to cause damage to cells and sub-cellular molecules. Antioxidants like vitamin E reduced free radical levels and eased the high blood pressure that accompanied impaired kidney function. The study appears in the January 2002 issue of Hypertension.

"This study confirms earlier work showing that kidney failure results in accelerated production of free radicals and demonstrates the beneficial effect of antioxidants," Vaziri said. "We hope that future tests on humans will show how much antioxidants can be used to help ease high blood pressure and free radical production in kidney disease."

Vaziri's team found that rats which had most of their kidneys resected to simulate kidney failure had very high blood pressure (about 197 millimeters of mercury, compared to normal readings of 110 mm). Levels of free radicals were also much higher in the kidney-resected rats. At the same time, levels of nitric oxide, a naturally occurring chemical known for its ability to relax blood vessels and for its antioxidant properties, were nearly half the levels found in rats with normal kidney function.

In addition, the team found that high doses of vitamin E raised levels of nitric oxide to nearly normal levels and lowered the high blood pressure readings by about 30 mm of mercury, bringing average pressure down to about 162 mm.

"While vitamin E clearly does not completely eliminate high blood pressure in kidney disease, it does provide partial relief and helps restore levels of nitric oxide in the body," Vaziri said. "Future research, including studies on humans, should tell us what combinations of antioxidants may be the best mix for successfully treating blood pressure."

Vaziri and his team have spent years studying the various biochemical interactions that lead to kidney failure in an attempt to find better treatments for the disease. Dr. Madeleine Pahl, associate professor of medicine, recently received a grant from UCI's Samueli Center for Complementary and Alternative Medicine to study the effects of antioxidants on hospitalized patients undergoing dialysis for advanced kidney failure. The study, which will take place at UCI Medical Center in Orange, is undergoing university reviews necessary for research on human subjects.

More than 300,000 people are treated for severe kidney failure in the United States every year, a number that has doubled in the past 15 years and is expected to double again by 2010, according to the U.S. Public Health Service. Recent studies suggest that as many as 20 million Americans may have some degree of kidney disease, which can lead to kidney failure if not detected and treated in time.

Half of kidney failure cases are caused by diabetes; the rest are caused by high blood pressure, inflammation, inherited disorders and infections. Currently, there is no cure, but early treatment and management of health issues that lead to kidney failure can help stave off the disease.


Contact:
Andrew Porterfield
(949) 824-3969
amporter@uci.edu

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