Abstract 66: Ascorbate Prevents Hypertension, Proteinuria and Concentric Hypertrophy by Balancing the Nitroso-redox System in a Model of Preeclampsia, the S-nitrosoglutathione Reductase (gsnor) Deficient Mice

Abstract

Introduction: Preeclampsia (PE), a leading cause of maternal and fetal mortality and morbidity, is characterized by increased levels of reactive oxygen species (ROS) and S-nitrosylated protein, and decreased levels of the antioxidant, ascorbate (Asc). Mice lacking S-nitrosoglutathione reductase (GSNOR –/– ), a denitrosylase that regulates protein S-nitrosylation, exhibit a PE-like phenotype including maternal hypertension, proteinuria, cardiac concentric hypertrophy and impaired placental vascularization. We hypothesize that the PE-like phenotype is mediated by nitroso-redox imbalance and nitrosative stress and can be rescued with ascorbate treatment. Methods: Pregnant GSNOR –/– and control (WT) mice (n=5-7) were provided drinking water ± Asc beginning at day 0.5 of gestation (E0.5). We determined blood pressure using a Millar catheter, relative wall thickness (RWT) by echocardiography, and placental vascularization by isolectin staining. Cardiomyocytes (CM) were isolated at late stage pregnancy (E17.5) and fluorescent dyes used to determine levels of ROS (2’7’-dichlorofluorescein), nitric oxide (NO, diaminofluorescin) and peroxynitrite (dihydrorhodamine 123). Results: Isolated CMs from pregnant GSNOR –/– hearts, exhibited elevated levels of ROS (2.48±0.39 vs. 1.58±0.18 ΔF/F 0 ), free NO (6.65±0.43 vs. 5.59±0.26 ΔF/F 0 ) and peroxynitrite (0.75±0.04 vs. 0.39±0.03 ΔF/F 0 ) compared to WT. These increases were prevented with Asc treatment (P<0.01), which completely rescued the PE phenotype in GSNOR –/– mothers, including hypertension (105±2 mmHg vs. 95± mmHg in Asc-treated, P<0.05), proteinuria (P<0.05) and RWT (0.56±0.04 vs. 0.45±0.03 in Asc-treated (P<0.05). Placental vascularization was also significantly improved with Asc treatment in GSNOR –/– mothers. Asc had no significant effect in WT mice. Conclusion: Our findings indicate that nitroso-redox imbalance and nitrosative stress contributes to PE in mice. Asc treatment balanced the nitroso-redox system and rescued the pathological phenotypes in GSNOR –/– mice, suggesting that it can be used therapeutically to treat or prevent preeclampsia.