Mental stress and physical exercise increase platelet-dependent thrombin generation

Thrombin generation is an important factor in the pathogenesis of thromboge nic disorders and acute coronary syndromes. Increase in mental stress has b een associated with the initiation of the acute coronary syndromes, but the exact mechanism is not known. The present study examined the effects of ph ysical exercise and mental stress on platelet-dependent thrombin generation . Twelve healthy men (mean age 34.2 +/- 2.4 years) underwent a treadmill ex ercise test and a mental stress test by performing mental arithmetic. Plate let-dependent thrombin generation and plasma concentrations of catecholamin es, thrombin-antithrombin III complex (TAT), plasmin-alpha2 plasmin inhibit or complex (PIC), and plasminogen activator inhibitor-1 (PAI-1) were measur ed before, immediately after, and at 10 and 30min after stress. Thrombin ge neration increased significantly immediately after exercise, followed by ra pid normalization. Mental stress caused a significant increase in thrombin generation 10min after stress. While plasma concentrations of epinephrine, norepinephrine, and dopamine were elevated immediately after exercise. and rapidly returned to baseline, only plasma norepinephrine increased immediat ely after mental stress. TAT and PIC concentrations did increase immediatel y after exercise, however, PAI-1 remained unchanged. The increase in thromb in generation with exercise and mental stress was unaffected by treatment w ith 81 mg/day of aspirin of 7 days. However, it was inhibited by a single o ral 40-mg dose of metoprolol. Both exercise and mental stress cause an incr ease in platelet-dependent thrombin generation, which was suppressed by bet a -blocker therapy, but not by aspirin.