Expression of Renin and Angiotensinogen Genes in Preeclamptic and Normal Human Placental Tissue

Abstract

Objective: We have quantitated renin activity and angiotensinogen and measured the expression of renin and angiotensinogen genes in placentas from normal and preeclamptic subjects to determine if tissue renin system parameters are elevated in preeclampsia.

Methods: Tissue renin activity and tissue levels of angiotensinogen were measured by enzymatic techniques, and renin and angiotensinogen mRNA were quantitated by blot hybrodization in placentae from young nulliparous black women with preeclampsia and normal controls.

Main Outcome: Placental ischemia is considered one of the etiological factors of preeclampsia. All components of the renin system are present in human placenta, and enhanced expression of this system may contribute to placental ischemia.

Results: Tissue active renin concentration was slightly elevated in preeclamptics (130 ± 20 ng Al/mg protein/h) versus controls (80 ± 20), but angiotensinogen levels did not differ. In preeclamptic placentae renin mRNA was also elevated (249 ± 35 versus 207 ± 42 arbitrary density units/jig total RNA), and angiotensinogen mRNA levels were the same as normal placentae. In normal, but not in preeclamptic placentae, a significant linear correlation was apparent between renin mRNA and total renin concentration (r = 0.87, p < 0.002).

Conclusions: Tissue renin systems may well contribute to the hypertension associated with pregnancy; however, larger study populations will be required to verify this.

Key Words:

• Placenta
• Preeclampsia
• Renin