Tomoda, Y; Kikkawa, F; Kurauchi, O; Kondo, I; Itakura, A; Goto, K; Ohno, Y; Mizutani, S; Kuno, N
Abstract:
The hydrolysis of bradykinin (BK) by human placental subcellular fractions andpregnancy sera was studied in the presence of inhibitors by measuring aminoacids liberated from BK by high-performance liquid chromatography. The effectsof the inhibitors DL-2- mercaptomethyl-3-guanidinoethylthiopropionic acid(MGTA, for kininase I), phosphoramidon (for endopeptidase 24.11) and captopriland rentiapril (for angiotensin-converting enzyme [ACE, kininaseII]) suggested the essential roles of the above three proteases in BKdegradation: among the three proteases, kininase I and endopeptidase 24.11appeared to be the most important in kininase action in the placentamicrosomes, whereas kininase I and ACE appeared to be the most important inkininase action in the placental cytosol, lysosome and pregnancy serum.Measurements of BK concentrations in the umbilical arterial blood, umbilicalvenous blood and maternal plasma revealed higher concentrations in the motherthan in the fetus. The present data suggest that degradation of BK in theplacenta and pregnancy serum might contribute to the gradient of BK betweenmother and fetus.