Abstract 44: Restoration of Angiogenic Balance and Improved Endothelial Cell Function via Ampk Activation is Hypoxia and Ischemia Dependent in Trophoblast Cells and Pregnant Rats

Abstract

Previous studies indicate restoration of angiogenic balance lowers blood pressure and improves vascular endothelial cell function in several experimental models of preeclampsia. Stimulation of the adenosine monophosphate kinase (AMPK) pathway is known to increase VEGF expression. We hypothesized stimulation of AMPK with aminoimidazole carboxamide ribonucleotide (AICAR) would increase plasma VEGF, improve endothelial cell (EC) function and attenuate reduced uterine perfusion pressure (RUPP)-induced hypertension. RUPP was induced on day 14 of gestation (term=21), AMPK activation was stimulated in vivo by AICAR administered i.p. (50mg/kg) twice daily. Arterial pressure (AP) and tissues were collected on day 19. Human derived trophoblast cells were cultured in physiologic normoxic (8% O 2 ) and hypoxic (1.5% O 2 ) conditions. Angiogenic balance and EC function were assessed with an endothelial tube formation assay using human umbilical vascular endothelial cells (HUVEC) cultured for 8h with 5% serum from each treatment group. AICAR increased ( P <0.05) placental phosphorylation of AMPKα in RUPP+AICAR (0.33±0.06) compared to normal pregnant (NP), NP+A and RUPP rats (0.19±0.03 vs. 0.16±0.04 vs. 0.18±0.03). AICAR increased ( P <0.05) free plasma VEGF in the RUPP+AICAR (884±128 pg/ml) compared to NP+AICAR, NP and RUPP rats (708±179 vs. 843±52 vs. 420±75 pg/ml). EC function as assessed by tube formation was decreased by treatment with serum from RUPP vs . NP (25±2 vs. 51±7; tubes/frame; P <0.05) rats and this deficit was abrogated with serum from RUPP+AICAR rats (86±9 tubes/frame; P <0.05). RUPP hypertension was mitigated by AICAR infusion (NP 95±3; RUPP 123±2; NP+AICAR 104±3; RUPP+AICAR 101±5mmHg; P <0.05). Hypoxia increased ( P <0.05) VEGF secretion 30% by BeWo cells and this effect was augmented a further 60% ( P <0.05) by treatment with the AICAR mimetic metformin. AICAR increased levels of placental AMPK activation, increased free VEGF concentrations in plasma, restored endothelial cell function and reduced blood pressure RUPP rats but had no effect on these measures in NP control rats. These findings show AMPK activation and stimulation of VEGF with AICAR is ischemia/hypoxia dependent and may be useful for management of hypertension in pregnancy.