This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Omega-3 fatty acids from fish oils are known to reduce the risk for heart attacks, but the precise mechanisms by which they do this are not clear. One of the earliest know effects of fish oils (first seen in Eskimos) was prolonged bleeding times. Bleeding times are mostly influenced by how well the blood platelets aggregate at a site of injury. Drugs like aspirin inhibit platelet function, making the blood less likely to clot, and (to a point) this is a good thing -- it reduces the risk for blood-clot based heart attack. (Of course, too much platelet inhibition can lead to hemorrhage, not a good thing). We know how aspirin inhibits platelet function, but how do omega-3 fatty acids do it? What are the molecular mechanisms by which they operate, and what happens if you give fish oils and aspirin TOGETHER? This project will address these questions. We will recruit 10 healthy subjects and then do a panel of platelet tests in four settings: at baseline, one day after taking an aspirin tablet, after 4 weeks of taking fish oils, and after taking one aspirin tablet while on fish oil.