Hemodynamic responses to angiotensin-(1-7) in women in their third trimester of pregnancy

Abstract

Background: To understand the role of Angiotensin-(1-7) (Ang-(1-7)) in vasculature of pregnant women, we compared cardiac output (CO), total peripheral resistance (TPR) and forearm blood flow (FBF) responses to Ang-(1-7) infusion between normotensive pregnant women in their third trimester and healthy age matched non-pregnant women. The responses of skin microcirculation to Ang-(1-7) were tested in preeclamptic, normotensive pregnant and non-pregnant women. Responses to Angiotensin II (Ang II) were also determined. Methods: Non-invasive methods for systemic (bioimpedance and VascuMAP), FBF (venous occlusion strain gauge plethysmography), and skin (laser Doppler) hemodynamics assessments were used. Results: Compared to non-pregnant women, systemic infusion of Ang-(1-7) (2000 pmol/min) resulted in a greater increase in CO (9.4 ± 6.4 versus −3.3 ± 2.1%, n = 9–10) in normotensive pregnant women. Brachial local infusion of Ang-(1-7) had no effect on FBF in either group. In non-pregnant and normotensive pregnant women, local Ang II induced a dose-dependent decrease in FBF and increase in forearm resistance at 50 and 100 pmol/min (p < 0.05 versus corresponding baseline, n = 7–10). Following iontophoretic application of 5 mmol/l dose of Ang-(1-7), the change in skin flow was higher in normotensive pregnant versus preeclamptic women (182.5 ± 93 versus 15.76 ± 19.46%, n = 14–15). Skin flow was lower in normotensive pregnant versus preeclamptic women (−46.5 ± 48.7 versus 108.7 ± 49.1%, n = 14–15) following Ang II infusion at 1.0 pmol/min. Conclusion: In the third trimester of pregnancy, Ang-(1-7) induces alterations in CO and differentially regulates micro- and macro-circulations, depending on the dose. Dysregulation in skin vasculature may contribute to the development of vascular dysfunction and hypertension in preeclampsia.

• Angiotensin-(1-7)
• Noninvasive methods
• Pregnancy
• Regional (skin and brachial) blood flow

Acknowledgements

We would like to thank Karen Klein, M. A. for manuscript editing and Kristi Lanier, R. N., BSN, Cheryl Moorefield, R. N., and Courtney Gruver, R. N. for help with data analysis and measurements.