Sympathetic Responses to Isometric Handgrip Exercise in Women following Preeclamptic Pregnancies

Abstract

Women who have had preeclamptic (PE) pregnancies are at increased risk for developing cardiovascular diseases later in life. One potential mechanism that may mediate this increased risk is sympathetic dysregulation. Indeed, there is evidence for elevated muscle sympathetic nerve activity (MSNA) both during and following PE pregnancies. Moreover, previously PE (PPE) women may demonstrate impaired MSNA responses during stress, although this has only been examined to a limited extent. Therefore, we tested the hypothesis that MSNA responses to isometric hand grip exercise (HG) would be greater in PPE women (n=6, age 31±6 years, BMI 29±5 kg/m2, 17±4 months postpartum) compared with women who had a healthy pregnancy (HP; n=8, age 29±2, BMI 25±4 kg/m2, 14±4 months postpartum). MSNA (peroneal nerve microneurography), mean arterial pressure (MAP; finger photoplethysmography), and total peripheral resistance (TPR; MAP/cardiac output), were assessed at baseline, during a 2‐min HG protocol, and during 2‐min post‐exercise circulatory occlusion (PECO). As previously reported, baseline MSNA was higher in PPE than HP (22±7 vs 13±5 bursts/min, P=0.01). Baseline MAP was not different between PPE and HP (94±11 vs 89±9 mmHg, P=0.23), nor was TPR (13±3 vs 13±2 mmHg/L/min, P=0.63). During HG, MSNA was greater in PPE than HP (24±8 vs 16±6 bursts/min, P=0.03), whereas MAP was not different between PPE and HP (95±12 vs 95±11 mmHg, P=0.99), nor was TPR (13±3 vs 14±2 mmHg/L/min, P=0.39). During PECO, no differences were observed between PPE and HP women in MSNA (26±8 vs 18±6 bursts/min, P=0.08), MAP (93±12 vs 96±12 mmHg, P=0.70), or TPR (12±3 vs 15±2 mmHg/L/min, P=0.18). These findings indicate that PPE women demonstrate exaggerated MSNA during isometric HG exercise relative to HP women, although the role of the metaboreflex in mediating this effect, as assessed using PECO, remains unclear. Importantly, these data also demonstrate that young PPE women were able to buffer the deleterious cardiovascular outcomes of elevated MSNA such that MAP and TPR outcomes were similar to age‐matched HP women during all conditions.