Muscle sympathetic nerve activity and volume-regulating factors in healthy pregnant and nonpregnant women

Charkoudian, Nisha; Usselman, Charlotte W.; Skow, Rachel J.; Staab, Jeffery S.; Julian, Colleen G.; Stickland, Michael K.; Chari, Radha; Khurana, Rshmi; Davidge, Sandra T.; Davenport, Margie H.; Steinback, Craig D.

doi:10.1152/ajpheart.00312.2017

Cited by 20 publications

(14 citation statements)

References 38 publications

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“…Moreover, we found that they were strongly correlated with SNA. This is consistent with our recent work demonstrating a similar pattern in the third trimester of pregnancy (Charkoudian et al., ). Therefore, these findings suggest that during pregnancy, a complex mechanism underlying central sympathetic activation could be responsible for the observed increase in SNA.…”

Section: Discussionsupporting

confidence: 94%

Sympathetic neurovascular regulation during pregnancy: A longitudinal case series study

Reyes

Usselman

Skow

et al. 2018

Experimental Physiology

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The adaptations of sympathetic nerve activity (SNA) during pregnancy remain poorly understood. An increase in blood volume, cardiac output and SNA, with a concomitant drop in total peripheral resistance (TPR), suggest that during pregnancy there is a reduced transduction of SNA into TPR. Most of these findings have originated from cross-sectional studies; thus, we conducted a longitudinal assessment of SNA and TPR in two participants. Measurements were made before pregnancy (early follicular phase), on four occasions during pregnancy and at 2 months postpartum. Mean arterial pressure and cardiac output were used to calculate TPR. The SNA was measured using microneurography (peroneal nerve). There was a gestation-dependent increase in SNA burst frequency (r = 0.96, P = 0.009). Neurovascular transduction, however, decreased by 53% in both women. Sympathetic hyperactivity was reversed postpartum, whereas neurovascular transduction remained lower. These longitudinal data highlight the progressive sympatho-excitation of pregnancy, which is offset by a concurrent reduction in neurovascular transduction.

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Section: Discussionsupporting

confidence: 94%

Sympathetic neurovascular regulation during pregnancy: A longitudinal case series study

Reyes

Usselman

Skow

et al. 2018

Experimental Physiology

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“…As reported previously (Charkoudian et al . ; Jarvis et al . ), resting sympathetic burst frequency and burst incidence were higher in pregnant women compared to non‐pregnant women ( P < 0.05).…”

Section: Resultsmentioning

confidence: 99%

“…All of the women included in the analysis had taken part previously in other studies in our laboratory (Charkoudian et al . ) and all provided their informed written consent at the time of assessment. All assessments were conducted in the morning.…”

Section: Methodsmentioning

confidence: 99%

“…Data from 18 normotensive pregnant women and 18 normotensive non-pregnant women were analysed for the present study ( Table 1). All of the women included in the analysis had taken part previously in other studies in our laboratory (Charkoudian et al 2017) and all provided their informed written consent at the time of assessment. All assessments were conducted in the morning.…”

Section: Methodsmentioning

confidence: 99%

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Blunted sympathetic neurovascular transduction during normotensive pregnancy

Steinback

Fraser

Usselman

et al. 2019

The Journal of Physiology

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Key points Normotensive pregnancy is associated with elevated sympathetic nervous system activity yet normal or reduced blood pressure. It represents a unique period of apparent healthy sympathetic hyperactivity. The present study models the blood pressure and heart rate (ECG R–R interval) responses to fluctuations in sympathetic nervous system activity aiming to understand neurocardiovascular transduction. The reported data clearly demonstrate that transduction of sympathetic nervous system signalling to systemic cardiovascular outcomes is reduced in normotensive pregnancy. These data are important for understanding how blood pressure regulation adapts during normotensive pregnancy and set the foundation for exploring similar mechanisms in hypertensive pregnancies. Abstract Previously, we described sympathetic nervous system hyperactivity yet decreased blood pressure responses to stress in normotensive pregnancy. To address the hypothesis that pregnant women have blunted neurocardiovascular transduction we assessed the relationship between spontaneous bursts of sympathetic nerve activity (SNA) and fluctuations in mean arterial blood pressure and R–R interval. Resting SNA, blood pressure and ECG were obtained in pregnant (third trimester, n = 18) and non‐pregnant (n = 18) women matched for age and pre‐/non‐pregnant body mass index. Custom software modelled beat‐by‐beat pressure (photoplethysmography) and R–R interval in relation to sequences of SNA bursts and non‐bursts (peroneal microneurography). Sequences were grouped by the number of bursts and non‐bursts [singlets, doublets, triplets and quadruplet (four or more)] and mean blood pressure and R–R interval were tracked for 15 subsequent cardiac cycles. Similar sequences were overlaid and averaged. Peak mean pressure in relation to sequences of SNA was reduced in pregnant vs. non‐pregnant women (doublets: 1.6 ± 1.1 mmHg vs. 3.6 ± 3.1 mmHg, P < 0.05; triplets: 2.4 ± 1.2 mmHg vs. 3.4 ± 2.1 mmHg, P < 0.05; quadruplets: 3.0 ± 1.0 mmHg vs. 5.5 ± 3.7 mmHg, P < 0.05). The nadir R–R interval following burst sequences was also smaller in pregnant vs. non‐pregnant women (singlets: −0.01 ± 0.01 s vs. −0.04 ± 0.04 s, P < 0.05; doublets: −0.02 ± 0.03 s vs. −0.05 ± 0.04 s, P < 0.05; triplets: −0.02 ± 0.01 s vs. −0.07 ± 0.04 s, P < 0.05; quadruplets: −0.01 ± 0.01 s vs. −0.09 ± 0.09 s, P < 0.05). There were no differences between groups in the mean arterial pressure and R–R interval responses to non‐burst sequences. Our data clearly indicate blunted systemic neurocardiovascular transduction during normotensive pregnancy. We propose that blunted transduction is a positive adaptation protecting pregnant women from the cardiovascular consequences of sympathetic hyperactivity.

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“…MSNA was recorded via peroneal microneurography as previously described (Charkoudian et al 2017). Briefly, the raw sympathetic signal was rectified and integrated to produce a neurogram with a characteristic bursting pattern.…”

Section: Muscle Sympathetic Nerve Activitymentioning

confidence: 99%

The carotid chemoreceptor contributes to the elevated arterial stiffness and vasoconstrictor outflow in chronic obstructive pulmonary disease

Phillips

Steinback

Collins

et al. 2018

The Journal of Physiology

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Chronic obstructive pulmonary disease (COPD) patients have increased central arterial stiffness and muscle sympathetic nervous activity (MSNA), both of which contribute to cardiovascular (CV) dysfunction and increased CV risk. Previous work suggests that COPD patients have elevated carotid chemoreceptor (CC) activity/sensitivity, which may contribute to the elevated MSNA and arterial stiffness. Accordingly, the effect of CC inhibition on central arterial stiffness, MSNA and CV function at rest in COPD patients was examined in a randomized placebo-controlled study. Thirteen mild-moderate COPD patients (forced expired volume in 1 s (FEV ) predicted ± SD: 83 ± 18%) and 13 age- and risk-matched controls completed resting CV function measurements with either i.v. saline or i.v. dopamine (2 μg kg min ) while breathing normoxic or hyperoxic air (100% O ). On a separate day, a subset of COPD patients and controls completed MSNA measurements while breathing normoxic or hyperoxic air. Arterial stiffness was determined by pulse-wave velocity (PWV) and MSNA was measured by microneurography. Brachial blood flow was determined using Doppler ultrasound, cardiac output was estimated by impedance cardiography, and vascular conductance was calculated as flow/mean arterial pressure (MAP). CC inhibition with dopamine decreased central and peripheral PWV, and MAP (P < 0.05) while increasing vascular conductance in COPD. No change in CV function was observed with dopamine in controls. CC inhibition with hyperoxia decreased peripheral PWV and MSNA (P < 0.05) in COPD, while no change was observed in controls. CC inhibition decreased PWV and MSNA, and improved vascular conductance in COPD, suggesting that tonic CC activity is elevated at rest and contributes to the elevated arterial stiffness in COPD.

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Muscle sympathetic nerve activity and volume-regulating factors in healthy pregnant and nonpregnant women

Cited by 20 publications

References 38 publications

Sympathetic neurovascular regulation during pregnancy: A longitudinal case series study

Sympathetic neurovascular regulation during pregnancy: A longitudinal case series study

Blunted sympathetic neurovascular transduction during normotensive pregnancy

The carotid chemoreceptor contributes to the elevated arterial stiffness and vasoconstrictor outflow in chronic obstructive pulmonary disease

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