Source: Reuters Pubdate: Wed, 5 Aug 1998 CHEMICAL HELPS COCAINE CAUSE HEART ATTACKS - STUDY WASHINGTON, Aug 4 (Reuters) - German scientists said on Tuesday they had found one reason why cocaine can cause a heart attack -- it causes production of excess amounts of a chemical that can choke off blood supply to the heart. Doctors know all too well that cocaine can overstimulate the heart and cause a heart attack. But they have not understood why -- or how to fight it. Writing in the journal Circulation, Dr. Rainer Arendt of the University of Munich and colleagues said they had pinned down one mechanism. They said cocaine attacks the endothelium, which is the layer of cells that lines the blood vessels. When attacked, these cells release a chemical known as endothelin, which causes blood vessels to contract. They tested the blood and urine of 12 people high on cocaine and 13 non-users. Levels of endothelin were three times higher in the cocaine users. Tests on pig cells showed that cocaine causes so much endothelin to be produced that blood vessels can eventually close off blood flow to the heart. "This finding opens the opportunity to develop powerful drugs to fight cocaine's effects," Arendt said in a statement. "Not only will this provide a needed help in the occasionally difficult medical therapy of treating cocaine-induced heart attack or stroke, but it may prove to be important in understanding stress-related heart attacks and cardiac arrests," he added. "Cocaine seems to use the same pathways that are activated in the body's response to stress." Arendt's team tested two drugs that might counteract the deadly effects of cocaine. They said the antipsychotic haloperidol, sold as Haldol, eliminated the effects and another drug, ditolylguandine, helped. - --- Checked-by: Mike Gogulski