Monday, August 3, 1998 Published at 20:25 GMT 21:25 UK
Scientists crack cocaine secret
Cocaine stimulates the cells to send out the wrong messages
Scientists have discovered how cocaine causes heart attacks and may be able to use the knowledge to develop an effective treatment.
Writing in the academic journal Circulation, German scientists say cocaine attacks the endothelium, a layer of cells that lines the inside of blood vessels.
Cocaine stimulates receptors in the cells to release large quantities of endothelin, a chemical that causes blood vessels to contract.
Excessive amounts of the chemical can make blood vessels constrict faster and tighter, thereby choking off blood supply to the heart.
"Not only will this provide 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.
"Cocaine seems to use the same pathways that are activated in the body's response to stress."
Blocking the effect
After identifying cocaine's effects on blood vessels, the researchers turned their attention to ways to block these effects.
By using two drugs that readily interact with cell receptors, the scientists stopped the cocaine-induced release of endothelin from cells.
Used in healthy cells unaffected by cocaine, the drugs haloperidol and ditolylguanidine did not show significant effects on reducing the release of endothelin.
But using haloperidol alone eliminated all effects of cocaine on endothelin release.
Ditolylguandine also was shown to significantly reduce the increased release of endothelin that is associated with cocaine.
Dr Arendt and his colleagues examined blood and urine samples of 12 cocaine-intoxicated people and 13 healthy non-users.
The endothelin levels in blood and urine were 3 to 3.5 times higher in people who had used cocaine when compared to the individuals who had not.
However Dr Arendt said other factors may be partially responsible for cocaine-related cardiovascular disease.
"All of the cocaine-intoxicated patients in our study had elevated endothelin levels, but they did not all have a heart attack or stroke," he says.
"That means other factors come into play. It is likely that the interaction between endothelin and other constricting chemicals causes prolonged constricting of the blood vessels in the heart and brain."