• Aspirin and dipyridamole have been used to treat the thromboembolic complications of atherosclerosis. We studied the effects of these drugs on the rate of endothelial healing after a standard de-endothelializing injury of the thoracic aorta. Twenty-five rabbits received 13.5 mg/kg/day of aspirin and 15 mg/kg/day of dipyridamole one week before injury and for the period of endothelial regrowth. There were 25 control animals. Mean serum aspirin salicylate levels were 12 μg/dL at the time of injury and 15 μg/dL at death. Areas of endothelial regrowth were measured by Evans blue dye at 1, 4, 7, and 14 days after injury. The percentage of endothelial regrowth was measured by computor-assisted morphometry. Antiplatelet treatment retarded endothelial regrowth by 66% at four days, 22% at seven days, and 28% at 14 days. Antiplatelet drugs must be used cautiously, as re-endothelialization of injured arteries Is retarded.
(Arch Surg 1982;117:1459-1464)