<prompt> Platelet aggregation is caused by?Nitrous oxideThromboxone A2AspirinPGE2  <response>: Ans. b. Thromboxone A2Ref: Robbins 9thpg 116-117Thromboxone A2 TXA2It is produced by activated platelets and has prothrombotic propertiesIt is an Arachidonic acid metabolite of COX pathwayFunctions: It is a potent platelet aggregator vasoconstrictorIts effect is neutralized by prostacyclin PGI2 