The effects of sex and menstrual cycle phase on sympathetic action potential recruitment patterns during hypercapnic-hypoxic apnea

Coovadia, Yasmine; Shoemaker, J. Kevin; Usselman, Charlotte W.

doi:10.1016/j.autneu.2023.103093

Cited by 3 publications

(1 citation statement)

References 44 publications

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“…In response to strong sympathetic stimuli (maximal voluntary apnea), older individuals have a blunted rise in the firing probability of previously active action potentials (analogous to blunted rate-coding) coupled with attenuated recruitment of previously silent larger and faster conducting sympathetic action potential recruitment (analogous to blunted population-coding) relative to young participants [34]. Although sex differences were not investigated in their study, they are likely to exist, as work in young individuals has provided evidence that sex and the menstrual cycle impact sympathetic action potential recruitment patterns in a manner that is mediated, in part, by gonadal hormones [35].…”

Section: Changes With Agingmentioning

confidence: 97%

Sex Differences in Neurovascular Control: Implications for Obstructive Sleep Apnea

Bock,

Greenlund,

Somers

et al. 2023

IJMS

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Patients with obstructive sleep apnea (OSA) have a heightened risk of developing cardiovascular diseases, namely hypertension. While seminal evidence indicates a causal role for sympathetic nerve activity in the hypertensive phenotype commonly observed in patients with OSA, no studies have investigated potential sex differences in the sympathetic regulation of blood pressure in this population. Supporting this exploration are large-scale observational data, as well as controlled interventional studies in healthy adults, indicating that sleep disruption increases blood pressure to a greater extent in females relative to males. Furthermore, females with severe OSA demonstrate a more pronounced hypoxic burden (i.e., disease severity) during rapid eye movement sleep when sympathetic nerve activity is greatest. These findings would suggest that females are at greater risk for the hemodynamic consequences of OSA and related sleep disruption. Accordingly, the purpose of this review is three-fold: (1) to review the literature linking sympathetic nerve activity to hypertension in OSA, (2) to highlight recent experimental data supporting the hypothesis of sex differences in the regulation of sympathetic nerve activity in OSA, and (3) to discuss the potential sex differences in peripheral adrenergic signaling that may contribute to, or offset, cardiovascular risk in patients with OSA.

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Section: Changes With Agingmentioning

confidence: 97%

Sex Differences in Neurovascular Control: Implications for Obstructive Sleep Apnea

Bock,

Greenlund,

Somers

et al. 2023

IJMS

View full text Add to dashboard Cite

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Effects of biological sex and oral contraception on the sympathetic neurocirculatory adjustments to static handgrip exercise in humans

D’Souza,

Hissen,

Manabe

et al. 2023

American Journal of Physiology-Regulatory, Integrative and Comp

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Biological sex affects the neurocirculatory adjustments to fatiguing exercise. However, the effects of sex and oral contraceptive pills (OCPs) on sympathetic action potential (AP) emission patterns and the transduction of AP discharge into vasoconstriction during static handgrip (SHG) exercise remains unknown. We tested the hypothesis that males, and females using OCPs, would demonstrate larger increases in sympathetic activation and sympathetic vascular transduction compared to naturally menstruating females during SHG and post-exercise circulatory occlusion (PECO). Young males (n=14, 25[5] yr), females using OCPs (n=16, 24[6] yr), and naturally menstruating females (n=18, 26[4] yr) underwent assessments of multi-unit muscle sympathetic nerve activity (MSNA)/AP discharge patterns (microneurography), and femoral artery blood flow (ultrasound) during fatiguing SHG at 40% maximum voluntary contraction and 2-min PECO. Sympathetic vascular transduction was determined as the quotient of the change in leg vascular conductance (LVC) and MSNA/AP discharge. Males demonstrated greater increases in APs/burst ( P=0.028) and total AP clusters ( P=0.008) compared to naturally menstruating females only, but not those using OCPs during exercise. Sympathetic vascular transduction of MSNA burst amplitude, APs/burst, and total AP clusters was greater in males and females using OCPs compared to naturally menstruating females (range: P=0.004-0.044). In contrast, no group differences in AP discharge were observed during PECO (range: P=0.510-0.872), and AP discharge was not related to LVC during PECO (range: P=0.08-0.949). These data indicate that biological sex and OCP use impact the central generation of efferent AP discharge, as well as the transduction of these neuronal messages into peripheral vasoconstriction during static exercise.

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Interaction of simultaneous hypoxia and baroreflex loading on control of sympathetic action potential subpopulations

Boyes,

Klassen,

Baker

et al. 2024

Journal of Neurophysiology

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Efferent muscle sympathetic nerve activity (MSNA) is under tonic baroreflex control. The arterial baroreflex exerts the strongest influence over medium-sized sympathetic action potential (AP) subpopulations in efferent MSNA recordings. Prior work from multi-unit MSNA recordings has shown baroreflex loading selectively abolishes the sympathetic response to hypoxia. The purpose of the study was to examine baroreflex control over different-sized AP clusters and characterize the neural recruitment strategies of sympathetic AP subpopulations with baroreflex and combined baroreflex/chemoreflex ( i.e., hypoxia) activation. We loaded the arterial baroreceptors (intravenous phenylephrine) alone and in combination with systemic hypoxia (SpO2 80%) in 9 healthy young men. We extracted sympathetic APs using wavelet-based methodology and quantified baroreflex gain for individual AP clusters. AP baroreflex threshold gain was measured as the slope of the linear relationship between AP probability versus diastolic blood pressure for 10 normalized clusters. Baroreflex loading with phenylephrine decreased MSNA and AP firing compared to baseline (all P < 0.05). However, the phenylephrine-mediated decrease in AP firing was lost with concurrent hypoxia ( P = 0.384). Compared with baseline, baroreflex loading reduced medium sized AP cluster baroreflex threshold slope (condition P = 0.005) and discharge probability (condition P < 0.0001); these reductions from baseline were maintained during simultaneous hypoxia (both P < 0.05). Present findings indicate a key modulatory role of the baroreceptors on medium-sized APs in blood pressure regulation that withstands competing signals from peripheral chemoreflex activation.

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The effects of sex and menstrual cycle phase on sympathetic action potential recruitment patterns during hypercapnic-hypoxic apnea

Cited by 3 publications

References 44 publications

Sex Differences in Neurovascular Control: Implications for Obstructive Sleep Apnea

Sex Differences in Neurovascular Control: Implications for Obstructive Sleep Apnea

Effects of biological sex and oral contraception on the sympathetic neurocirculatory adjustments to static handgrip exercise in humans

Interaction of simultaneous hypoxia and baroreflex loading on control of sympathetic action potential subpopulations

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