Mohamed, M: Kallikrein-kinin system in fetoplacental tissues

The pathogenesis of pregnancy-induced hypertension (PIH) remains an enigma. However, an imbalance of vasoconstrictor and vasodilator substances in the placenta has been postulated in the pathogenesis of PIH. There is however little information available on the kallikrein-kinin system (KKS) in women with PIH. Therefore, this study determined tissue kallikrein and kininogen levels in fetoplacental tissues from both normotensive pregnant women and women with PIH. 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 from normotensive pregnant women. No significant differences were found for total, active and inactive tissue kallikrein levels in all fetoplacental tissues between both groups. These findings might indicate a lower level of kinin (a potent vasodilator) generation in fetoplacental tissues of women with PIH confirming the reported preponderance of vasoconstrictor activity. This study suggests the presence of an abnormality in the KKS in the placentas of women with PIH which may provide further understanding on the pathogenesis of this disease.