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Nitric oxide may benefit damaged hearts

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9:14pm, October 18, 2004
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From New Orleans, at a meeting of the American Heart Association

A sudden cutoff of oxygen can kill heart tissue and cause a heart attack. Even when blood flow is restored, however, yet another round of damage can occur, this time due to cell-killing swelling and inflammation.

In a new study of mice, breathing low concentrations of nitric oxide for 24 hours after a heart attack decreased the amount of heart-tissue death and scarring by 29 percent.

The treatment also reduced the number and activity of inflammatory white blood cells infiltrating the animals' heart muscle, report Kyung-Han Lee and Anthony Rosenzweig of Massachusetts General Hospital in Boston. They have yet to ascertain whether the nitric oxide treatment actually improved heart function.

Nitric oxide has another advantage. It's known to dilate blood vessels, allowing more blood to flow through them. When inhaled, however, the gas doesn't reduce overall blood pressure.

This is encouraging because heart attack patients often suffer from abnormally low blood pressure, says Rosenzweig.

"This study suggests that a very nontoxic therapy can positively modulate the degree of heart injury after a heart attack," says Mark T. Gladwin of the National Institutes of Health in Bethesda, Md. Gladwin is investigating nitric oxide's potential for treating sickle cell anemia (SN: 1/29/00, p. 78: Available to subscribers at NO News).

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