Objectives: An imbalance of vasoconstrictor and vasodilator substances in the placenta has been postulated in the pathogenesis of pregnancy-induced hypertension (PIH). There is however little information available on the kallikrein-kinin system (KKS) in women with PIH. The aim of this study therefore was to determine tissue kallikrein and kininogen levels and their distribution patterns in fetoplacental tissues from both normotensive pregnant (NTP) women and women with PIH.
Study design: The study group consisted of 24 women, 12 of whom had normal pregnancies, while 12 had PIH. Portions of amnion, chorion laeve, placental plate chorion, fetal placenta and maternal placenta were dissected from each freshly delivered placenta. Tissue kallikrein (total, active and inactive) and kininogen levels were estimated using a synthetic chromogenic substrate, S-2266 and an enzyme immunoassay, respectively. The data were analysed using Mann-Whitney U and Kruskal-Wallis tests.
Results: No significant differences were found for total, active and inactive tissue kallikrein levels in all fetoplacental tissues between both groups. However, kininogen levels were found to be significantly lower in chorion laeve, placental plate chorion, fetal placenta and maternal placenta from women with PIH when compared to those in similar tissues from NTP women.
Conclusion: These findings suggest the presence of an abnormality in the kallikrein-kinin system in the placentas of women with PIH, which requires further study.