Triplatin was incubated for 1 min with platelet-rich plasma (2 × 105/μl) followed by addition of collagen, U46619, and arachidonic acid, PMA, convulxin and ADP. Triplatin and agonist concentrations are indicated. In some experiments, platelets were treated with indometacin (50 μM) for 3 minuets before addition of the agonist. Typical experiments are shown (n = 3).