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


CONCLUSIONS
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.
The Hypertension & Vascular Research Center, Wake Forest School of Medicine , Winston-Salem, NC , USA .
Liliya M
LM
Yamaleyeva
David C
DC
Merrill
Thomas J
TJ
Ebert
Thomas L
TL
Smith
Heather L
HL
Mertz
K Bridget
KB
Brosnihan
D000328:Adult; D000803:Angiotensin I / Q000502:physiology*; D002302:Cardiac Output; D016022:Case-Control Studies; D005260:Female; D005542:Forearm / Q000098:blood supply; D006801:Humans; D008833:Microcirculation; D010446:Peptide Fragments / Q000502:physiology*; D011225:Pre-Eclampsia / Q000503:physiopathology; D011247:Pregnancy; D011263:Pregnancy Trimester, Third / Q000502:physiology*; D012039:Regional Blood Flow; D014655:Vascular Resistance; D055815:Young Adult
D010446:Peptide Fragments; D000803:Angiotensin I; C118790:angiotensin I (1-7)
Angiotensin-(1-7); Noninvasive methods; Pregnancy; Regional (skin and brachial) blood flow