Placental growth factor blunts uterine artery responses to angiotensin II

Changes in maternal serum concentration of placental growth factor (PlGF) and vascular response to intravascular infusion of Angiotensin II (Ang II) follow a bell-shaped curve pattern during gestation. This study evaluates the effects of PlGF and soluble vascular endothelial growth factor receptor-1 (sFlt-1) on responses of human uterine arteries (UA) to Ang II.

Experimental.

Baylor College of Medicine and Texas Children's Hospital-Pavilion for Women.

Uterine arteries samples (n = 14) were obtained from normotensive women undergoing caesarean hysterectomy at ≥32 weeks.

Uterine arteries rings were incubated with (1) Krebs solution; (2) PlGF at 1.45, 14.5, and 500 pg/ml; (3) sFlt-1 at 2 ng/ml; and (4) a combination of sFlt-1, and PlGF. Dose-contraction responses to Ang II were determined in UA rings incubated in the above-mentioned conditions. Responses were also measured in presence of L-NAME or inhibitors of endothelium-derived hyperpolarising factor: apamine and charybdotoxin. The t-test was used for comparisons.

Changes in vascular reactivity of UA rings.

PlGF blunted (P = 0.03) and sFlt-1 increased (P <0.01) the UA maximum responses to Ang II. A combination of sFlt-1 and PlGF blunted UA responses to Ang II (P < 0.05). l-NAME, apamine, and charybdotoxin reversed the relaxation effects of PlGF on UA responses to Ang II (P < 0.05).

PlGF contributes to the blunted vascular response to Angiotensin II during normotensive pregnancies and sFlt-1 appears to attenuate this effect. PlGF and sFlt-1 may contribute to the regulation of vascular tone during pregnancy by altering the vascular response to Angiotensin II.

Baylor College of Medicine.

Placental growth factor and soluble vascular endothelial growth factor receptor-1 modulate the uterine artery response to Angiotensin II in normotensive pregnant women.