Effects of exercise and ticlopidine on platelet function and prostanoids in patients with old myocardial infarction.

Twenty-eight subjects, 16 with old myocardial infarction (OMI) and a control group of 12, received ticlopidine 250 mg/day for 4 weeks. All subjects underwent the standard Bruce protocol exercise test before and after therapy. Blood was collected from a peripheral vein to study platelet function at pre-exercise (rest), peak exercise (end point), and 6 min post-exercise (recovery). Platelet count, platelet aggregatory response, plasma thromboxane B2 (TXB2), and 6-keto-PGF 1 alpha were measured by Coulter counter, aggregometry, and radioimmunoassay, respectively. The platelet count, aggregatory response (induced by ADP, adrenalin, and collagen) and the plasma concentration of TXB2 and 6-keto-PGF 1 alpha were not significantly affected by exercise in the OMI and control groups. Overall, there were no significant changes in exercise duration, heart rate, and blood pressure in both groups before or after ticlopidine treatment, with some minor exceptions. There were no significant changes in the peripheral blood profiles, the bleeding and coagulation times, the blood chemistry data, and the platelet counts between the groups before or after treatment. There was a significant decrease in collagen- and ADP-induced platelet aggregation in both groups after ticlopidine therapy. Prior to treatment, a higher plasma TXB2 concentration was noted in the OMI group during and after exercise; the difference was no longer statistically significant after ticlopidine therapy when both groups were compared. There was a significant reduction in the TXB2 levels in the OMI group after ticlopidine treatment despite exercise. Before therapy, plasma 6-keto-PGF 1 alpha was significantly elevated in the OMI group before or after exercise but was not statistically significant after ticlopidine treatment.(ABSTRACT TRUNCATED AT 250 WORDS)