CHARACTERIZATION OF KININ RECEPTORS ON THE HUMAN ISOLATED UMBILICAL ARTERY

The aim of this study was to determine the kinin responses on human um bilical artery (HUA) and to characterise the kinin receptors present o n this tissue. The HUA was found to constrict in response to both the B-2 receptor agonist, bradykinin (BK), and the B-1 receptor agonist, d es-Arg(9)-BK. The presence of indomethacin (2.79 mu M) was found to ha ve no significant effect on the responses to BK and des-Arg(9)-BK. The presence of the B-2 receptor antagonist, HOE-140 (+2.79 mu M indometh acin), resulted in a concentration-related rightward displacement of t he concentration-effect curves to BK. The antagonism of the constricto r responses to BK by HOE-140 was found to be competitive (pA(2)=7.5). The responses to BK were not significantly affected by the B-1 recepto r antagonist des-Arg(9)(leu(8))BK. The presence of des-Arg(9)(leu(8))B K (+2.79 mu M indomethacin) resulted in a concentration-related rightw ard displacement of the concentration-effect curve to des-Arg(9)-BK. T he antagonism of the response to des-Arg(9)-BK by des-Arg(9)(leu(8))BK was found to be competitive (pA(2)=5.9). The responses to des-Arg(9)- BK were not significantly affected by HOE-140. The results of the pres ent study suggest that the products of the cyclooxygenase pathway are not involved in the kinin constrictor response on HUA and indicate the presence of B-1 and B-2 receptors on this tissue.