Abstract A number of phenylsulfonamido derivatives have been synthesized and tested for their ability to inhibit: a) thromboxane A 2/prostaglandin H 2 (TXA2PGH2) mimetic (U46619)- induced guinea pig platelet aggregation; b) aortic ring contraction; and c) binding of a radioiodinated TXA2PGH2 mimetic (I-BOP) to platelets. In platelet, K d values ranged from 9 nM to> 50 μM. pK b values in aortic rings ranged from 7.63 to 3.66 and in platelets from ...