They said studies in both animals and people suggest that the drug, sold widely under the name Tylenol and under many other brand names as well, might help stop the processes that lead to clogging of the arteries.
Many more studies would have to be done before doctors could start recommending that people take acetaminophen to prevent heart disease in the way that many now take small daily doses of aspirin, experts said. In large doses, acetaminophen can damage the liver.
But Dr. Addison Taylor of Baylor Medical School in Houston said he thinks acetaminophen might one day join a cocktail of drugs now used to treat heart disease. These include statins and other cholesterol-lowering drugs, medicines to control blood pressure, and blood thinners such as aspirin.
Taylor said he thinks acetaminophen may prevent the oxidation of fats, the first step they take toward becoming artery-clogging plaques.
Heart disease starts when fat floating in the blood becomes oxidized -- chemically altered in a process similar to metal rusting. Immune cells see these fat cells as bad and take them out of the blood by engulfing them and working their way out between the cells that make up the walls of the artery.
But these fattened immune cells are so big that they get caught in the little spaces between the vessel wall cells. As more and more get stuck in there, they build up what is known as a plaque or a lesion. These can block blood flow, or break off and cause a heart attack or stroke.
Taylor last year studied the effects of acetaminophen on people and found that it seemed to help prevent the oxidation of the fats in the first place.
Taylor said he needed to perform more basic experiments, so he turned to specially bred rabbits, favored by heart researchers because they develop clogged arteries very quickly when fed a high-fat diet.
Half the rabbits were given acetaminophen doses equivalent to the four grams a day recommended for people every day for 12 weeks.
Then the rabbits were killed and their arteries checked for the early layers of fat that are the first sign of disease.
"The rabbits that received acetaminophen had 50 percent less fatty streaking," Taylor told a meeting of the American Heart Association.
He said the acetaminophen affected two components of blood lipids that have been found in artery-clogging plaques.
"They do not appear to be affected by agents like the statins," he said. Now Taylor plans further studies.
"We need to know more about how this occurs, whether it is dose-dependent and whether it reverses the process," he said.
Taylor said he would like to study its effects in people at high risk of heart disease, such as smokers, people with high cholesterol and diabetics.
Edward Nelson of the McNeil Consumer Products unit of Johnson & Johnsn, which makes Tylenol, said the company helped pay for the research, along with the National Institutes of Health, in the hope that Tylenol can someday be marketed as a way to prevent heart disease.
"We are hoping to expand the indication based on future medical data," Nelson said.
By Maggie Fox, Health and Science Correspondent