QUANTIFICATION OF DES-ARG(9)-BRADYKININ USING A CHEMILUMINESCENCE ENZYME-IMMUNOASSAY - APPLICATION TO ITS KINETIC PROFILE DURING PLASMA ACTIVATION

There is a renewed interest in the kininase I pathway of kinin metabol ism, because des-Arg(9)-bradykinin (des-Arg(9)-BK) and des-Arg(10)-Lys -BK are selective and potent agonists of the B-1 receptors, that are a pparently upregulated by tissue injury. We have developed a polyclonal rabbit antiserum against des-Arg(10)-Lys-BK. In a radioimmunoassay fo r des-Arg(10)-Lys-BK, this antiserum exhibited high specificity. Notab ly, native kinins with the C-terminal Arg residue, bradykinin (BK) and Lys-BK, did not cross-react to a significant extent, whereas des-Arg( 9)-BK and digoxygenin (DIG)-des-Arg(9)-BK exhibited a complete cross-r eactivity. The antibodies were used to set up a sensitive chemilumines cence enzyme immunoassay (CLEIA) using the DIG-anti-DIG system as inte rmediate for the revelation of the immune complexes. The detection lim it and the half-maximal saturation concentration for des-Arg(9)-BK wer e 27 and 1530 fmol/ml respectively. This assay, as well as another for BK quantification, have been applied in vitro to rabbit plasma activa ted by kaolin. The conversion of BK into des-Arg(9)-BK was generally e fficient, and the persistence and concentration of both peptides were increased in the presence of enalaprilat an inhibitor of the angiotens in converting enzyme (ACEI). Rabbits treated with bacterial lipopolysa ccharide exhibited an increase of plasma immunoreactive des-Arg(9)-BK that was potentiated in animals also treated with ACEI. This CLEIA for des-Arg(9)-BK is a new analytical tool applicable to analyze of the k ininase I metabolites of kinins in vitro and in vivo. Measurements of des-Arg(9)-BK may be useful indicators of the kallikrein-kinin system activation.