A glass of red may keep arteries loose. (Astronomy).

Wine dissolves behavioral inhibitions, but a biochemical inhibition may underlie some of red wine's benefits to the heart.

Moderate intake of alcoholic beverages reduces a person's risk of heart disease. Some studies have suggested that red wine has an added benefit. If true, what makes reds special?

A clue comes from endothelin-1 (ET-1), a chemical produced by cells in the walls of blood vessels. High concentrations of ET-1 can constrict blood vessels, a condition that can contribute to heart disease.

Roger Corder and his colleagues at Queen Mary, University of London, set out to test whether drinking red wine might inhibit ET-1 production. They added various amounts of alcohol-free extracts of red wine to cows' blood vessel cells. The more extract the cells received, the less ET-1 they released.

The trend could result from compounds called polyphenols. Red-grape juice, which has some of the same polyphenols that red wine does, had a less dramatic effect on ET-1. White and rose wines, which have relatively few of these polyphenols, had no effect, the scientists report in the Dec. 20/27, 2001 NATURE.

The research suggests a benefit specific to red wine, says Peter Ganz of Brigham and Women's Hospital in Boston. That's "an important part of the puzzle" about what might make this drink especially good for the heart, he says. --B.H.