Abstract P175: Impairment of Autonomic Function Precedes Blood Pressure Elevation in Rat Model of Pre-eclampsia

Hypertensive disorders of pregnancy including pre-eclampsia affect about 5-7% of all pregnant women and can cause severe acute morbidity, long-term disability and death among mothers and babies. Impairment of heart rate variability predicts risk of cardiovascular disease and all cause mortality. In this study we investigated the hypothesis that impairment of the autonomic function at early time point during pregnancy precedes and may lead to the elevation of blood pressure. To test this hypothesis, blood pressure and heart rate were recorded under 2% isoflurane in 7 day pregnant rats generated via mating of the transgenic female rat containing the human angiotensinogen gene with the male transgenic containing human renin (hREN), the hAGTхhREN rat (TgA, n=8) which develop increased blood pressure, proteinuria and increased sensitivity to angiotensin II in the last half of gestation. The reverse mating of male containing the human angiotensinogen gene with the female transgenic containing human renin (TgR, n=8) which do not develop preeclampsia, and pregnant SD (n=8) rats at day 7 of gestation were used as controls. By the 7th day of pregnancy, TgA rats had significantly impaired heart rate variability measured as root of mean successive differences (rMSSD) compared to SD and TgR (2.39 ±0.3 ms vs. 3.4 ± 0.2 in SD or 3.4 ±0.1 in TgR) and impaired baroreflex sensitivity measured as HF alpha (1.2±0.3 ms/mmHg vs. 2.5±0.4, SD or 1.7±0.26, TgR) There was no difference in systolic arterial pressure or heart rate among the three groups at this time point but diastolic pressure was higher in TgA and TgR (91± 3.5 vs. 85±2.4 or vs. 75 ±2 mmHg in SD rats) Although the predictive value of impaired baroreflex and heart rate variability in preeclampsia development needs further investigation, our findings suggest that these changes at early pregnancy precede and may contribute to the significant rise in pressure in the last half of gestation in this rat model of pre-eclampsia which may have significant clinical implications.