We examined the effects of aspirin on coronary hyperreactivity to autacoids after arterial balloon injury in miniature pigs. Coronary vasoconstriction induced by histamine and serotonin were examined angio-graphically before, 1 h, 1 week, and 1 month after balloon injury in 29 hypercholesterolemic miniature pigs. The animals were divided into three groups: Group A, no treatment (n = 16); group B, pretreated with aspirin 50 mg/day for 2 days before injury (n = 7); and group C, treated with aspirin 50 mg/day for 2 days before and 5 days after injury (7 days in all) (n = 6). In group A, coronary vasoconstriction induced by autacoids was significantly greater at the injured than at the noninjured site at all times examined (p < 0.01). Hyperconstriction induced by the autacoids 1 h after injury were significantly less in groups B and C than in group A (p < 0.01). Hyperconstriction induced by autacoids 1 week after injury were significantly less in group B than in group A (p < 0.01) and were significantly less in group C than in group A (p < 0.01) or group B (p < 0.05). Treatment with aspirin for 2 or 7 days had no effect on the constrictive responses at the injured site 1 month after injury or on those at the noninjured site at all times examined. These results suggest that plateletvessel wall interaction may play an important role in coronary hyperconstrictive responses to autacoids 1 h and 1 week after injury.
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