Differential assay method for high molecular weight and low molecular weight kininogens.

Abstract

<h2>Abstract</h2> A differential assay method for high molecular weight (HMW) and low molecular weight (LMW) kininogens was developed. Plasma from human or rat was divided into three portions for the following purposes. For total kininogen, plasma was pretreated at pH 2.0 and bradykinin released by trypsin was separated and assayed on rat uterus. For HMW kininogen, plasma was incubated with glass powder in the presence of o-phenanthroline (a kininase inhibitor). The released bradykinin was separated and assayed. For LMW kininogen, plasma was incubated with glass powder in the absence of o-phenanthroline. The HMW kininogen-depleted plasma was treated in the same way as for the total kininogen assay. The HMW, LMW and total kininogen levels were as follows: 0.98 ± 0.05, 3.08 ± 0.09, 4.11 ± 0.10 for human and 0.96 ± 0.06, 0.94 ± 0.16, 1.93 ± 0.11 μg bradykinin equivalent/ml plasma for rat. From the results using heated human plasma (60°C, 1 hr), 10% of normal plasma was required to obtain full formation of kinin from HMW kininogen by 30 min incubation with this method.