Lab 05: Dietary Lipids in Health and Disease Aspirin for prevention/therapy of heart attacks:» Cyclooxygenases (COX 1 & 2) initiate synthesis of many eicosanoids invarious tissues» In platelets (cells in blood stream involved with clotting): the COX-1 activity gives TXA2o This promotes clotting, this is good so we don’t bleed to death after a small cut» In endothelial cells (blood vessel wall): COX-2 activity gives PGI2o Clotting is inhibited, this is good so clots don’t form and block blood flow » So, we want these 2 processes to be balanced » Aspirin may be prescribed to block both COX-1 and COX-2 (covalent bond, suicide inhibitor) » The endothelial cells have DNA, so they can make more COX-2 and overcome the block from aspirin » However, the platelets do not have a nucleus (no DNA), so no more COX-1 enzyme is made » So … balance shifted to less clotting and less chance of heart attackVegetable (seed) oils in the diet gives us lots of omega 6!o Example: arachidonic acid (20:4beta6) o When it is cleaved, it is converted into eicosanoidso In platelets it is made into TXA2 = platelet aggregationo In endothelial cells it is made into PGI2 = inhibits platelet aggregationSo: aspirin shifts balance towards less platelet aggregation, less clotting, less heart attacks Omega-3 analogs of arachidonic acid (fish oils, flaxseed) produce eicosanoidcousins that are better (less inflammatory, less pro-aggregating, less vasoconstrictive) Animal fats and tropical oils are high in saturated fatsVegetable oils are high in unsaturated fatsOmega 3 fatty acids are high in cold water fish oils and flaxseed