<prompt> Which among the following is a vasoconstrictor?HistaminePGI2BradykininTXA2  <response>: Ans. is d i.e., TXA2 Important mediators Vasodilatation Histamine, prostaglandins, prostacyclins, serotonin, Nitric oxide, bradykinin. Vasoconstriction Leukotrienes LTC4, D4, E4, Thromboxane A2. 