Determination of bradykinin in blood and bradykininogen in tissues

Abstract

The rat uterus preparation was used to determine bradykinin and bradykininogen in blood. The use of an internal standard has permitted the quantitative estimation of the amount of bradykinin in the unknown samples. The effects of histamine, serotonin, catecholamines, and UML 491 (methyl sergide) on the assay of this polypeptide were studied. The results indicate that histamine in higher concentrations makes the uterus preparation insensitive to bradykinin. Serotonin and catecholamines increase the response of the uterus preparation to this polypeptide, and this effect can be blocked by UML 491. Normal human blood was found to contain bradykinin in the range 0.001 to 0.004 μg/ml and bradykininogen in the range 6 to 8 μg/ml. Bradykininogen was determined in different tissues from five species. Heart tissue had the highest bradykininogen content followed by liver, kidney, and brain.