Effects of acute myocardial ischaemia on platelet aggregation in the coronary sinus and aorta in dogs.

The effect of an acute myocardial ischaemia on circulating platelet aggregates (CPA) in the coronary sinus and aorta was studied in open chest dogs. Even before induction of myocardial ischaemia significantly more CPA were found in the coronary sinus than in the aorta. Acute myocardial ischaemia produced by a non-thrombotic coronary artery occlusion increased CPA in coronary sinus, but not in aorta. Administration of acetylsalicylic acid (ASA) reduced the extent of the myocardial ischaemia as evidenced by reduced ST-segment elevations in epicardial ECG. Before induction of myocardial ischaemia, ASA significantly reduced CPA in coronary sinus, but no significant effect was observed during myocardial ischaemia. In the aorta no effect of ASA on CPA was found.