INHIBITORY EFFECTS OF HEPARIN, ASPIRIN AND KETANSERIN ON CORONARY-ARTERY VASOCONSTRICTION AFTER ARTERIAL BALLOON INJURY IN HYPERCHOLESTEROLEMIC MINIATURE PIGS

Objectives. The present study aimed to clarify the effects of heparin, aspirin and ketanserin on coronary artery vasoconstriction after arte rial balloon injury. Background. The mechanisms of coronary artery vas oconstriction after coronary angioplasty are not well understood. Meth ods. After being fed a cholesterol-rich diet for 1 month, 71 Gottingen miniature pigs were randomly allotted to five groups: 16 pigs with no pretreatment (group A); 21 pigs pretreated with heparin, 3,000 U (gro up B); 13 pigs pretreated with aspirin, 50 mg/day orally for 2 days (g roup C); 11 pigs pretreated with ketanserin, 1 mg/kg body weight (grou p D); 10 pigs pretreated with aspirin, 50 mg/day for 2 days, heparin, 6,000 U and ketanserin, 1 mg/kg (group E). After this pretreatment, th e left anterior descending or the left circumflex coronary artery, or both, was denuded by a 2F balloon catheter. Results. The coronary vaso constriction at the injured sites reached a peak level 6 min after the arterial injury and subsided within 30 min. The coronary vasoconstric tion at the injured site 6 min after arterial injury was 56 +/- 5% in group A, which was significantly greater than that in group B (28 +/- 6%, p < 0.01), group C (25 +/- 5%, p < 0.01), group D (26 +/- 7%, p < 0.01) or group E (24 +/- 5%, p < 0.01), whereas there was no significa nt difference in the coronary vasoconstriction among the latter four g roups. Conclusions. These results suggest that serotonin released from aggregating platelets plays a major part in the platelet-dependent co ronary artery vasoconstriction after arterial injury.