Abstract P269: Circulating Factors in Response to Placental Ischemia Cause Vascular Endothelial Mitochondrial Oxidative Stress

Abstract

Introduction: Preeclampsia (PE) is associated with placental ischemia, new onset hypertension, oxidative stress and endothelial dysfunction. Factors linking placental ischemia with endothelial dysfunction and hypertension are not completely understood. Mitochondrial (mt) dysfunction (dys) is a major source of reactive oxygen species (ROS) and we have shown that placental ischemia causes oxidative stress in RUPP rats. We hypothesize that circulating factors in RUPP rats cause vascular endothelial mt dys and mt ROS as a contributor to endothelial dysfunction and hypertension during pregnancy. Methods: Female Sprague Dawley rats were dived into two groups; normal pregnant (NP) and RUPP rats. On gestational day (GD) 14, RUPP surgery was performed, GD18 carotid catheters were inserted, and GD19 conscious blood pressure (MAP) was measured. GD 19 placentas were collected and mitochondria were isolated for respiration and ROS measurements. Mt ROS was measured spectrophotometrically in HUVECs incubated with 10% serum from NP or RUPP rats using MitoSox Red. Results: MAP was elevated in RUPP (n=9) compared to NP rats (n=9) (122±2 vs. 104±2 mmHg, p<0.05). State 3 (313±16 vs 423±15 pmol/sec/mg, p<0.05) and maximal (244±13 vs 300±11 pmol/sec/mg, p<0.05) respiration rates were significantly reduced in placental mitochondria from RUPP (n=7) vs NP (n=8) rats. RUPP placental mitochondria show 35-fold increase in ROS production compared NP mitochondria (p<0.05). HUVECs incubated with RUPP (n=7) serum showed significantly increased ROS vs NP (n=7) serum (9±3 vs 3±1, % gated, p=0.05). Conclusion: Reduced placental mitochondrial respiration and increased mt ROS support the hypothesis that mt dys and mt ROS occurs in response to placental ischemia. Importantly, increased ROS from endothelial cells in response to RUPP serum indicate the importance of circulating factors to cause vascular mt dyst and mt ROS.