COMPARATIVE ACTION OF NEW HIGHLY POTENT BRADYKININ RECEPTOR ANTAGONISTS IN THE GUINEA-PIG TRACHEA

We investigated the effect of two new bradykinin receptor antagonists, D-Arg0[Hyp3,D-HypE(trans-propyl)7,OiC8]bradykinin (NPC 17731) and rgo [Hyp3,D-HypE(trans-thiophenyl)7,Oic8]bradykinin (NPC 17761) on [H-3]br adykinin binding and on bradykinin-induced contraction of the guinea-p ig trachea. Both of these compounds inhibited [H-3]bradykinin binding with an affinity similar to that of unlabelled bradykinin. NPC 17731 i nhibited bradykinin-induced contraction in a non-competitve manner, wh ereas NPC 17761 showed competitive antagonism. Therefore, NPC 17761 co uld contribute to the investigation of the bradykinin receptors in gui nea-pig airways.