Effect of Aspirin on Hemostatic and Vascular Function After Live Fire Fighting

The investigators hypothesize that 1. an acute treatment of low-dose aspirin will lead to a) decreased resting platelet activation, platelet aggregation, and clotting potential, b) increased fibrinolytic potential following fire fighting, c) no significant effect on endothelial function or arterial stiffness versus the placebo condition. 2. chronic treatment with low-dose aspirin will lead to a) decreased resting and fire fighting induced platelet activation, platelet aggregation, clotting potential, b) increased fibrinolytic potential, and c) increased endothelial function and decreased arterial stiffness in response to live fire fighting versus the placebo condition. 3. short-term fire fighting activity will result in: a) a reduction in arterial function (reduced endothelial function, increased augmentation index and an attenuated arterial stiffness response); b) a disruption in hemostasis that is characterized by an increase in platelet number and function, an increased coagulatory potential and altered fibrinolytic potential; and c) an elevation in procoagulatory cytokines, systemic inflammation, monokine chemoattractant protein, and matrix metalloproteinases.