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muscle sympathetic nerve activity

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https://www.readbyqxmd.com/read/29412776/50-years-of-microneurography-learning-the-language-of-the-peripheral-sympathetic-nervous-system-in-humans
#1
J Kevin Shoemaker, Mark B Badrov, Stephen A Klassen, Paul J Fadel
As a primary component of homeostasis, the sympathetic nervous system enables rapid adjustments to stress through its ability to communicate messages among organs and cause targeted and graded end organ responses. Key in this communication model is the pattern of neural signals emanating from the central to peripheral components of the sympathetic nervous system. But what is the communication strategy employed in peripheral sympathetic nerve activity (SNA)? Can we develop and interpret the system of coding in SNA that improves our understanding of the neural control of the circulation? In 1968, Hagbarth and Vallbo reported the first use of microneurographic methods to record sympathetic discharges in peripheral nerves of conscious humans, allowing quantification of SNA at rest and sympathetic responsiveness to physiological stressors in health and disease...
February 7, 2018: Journal of Neurophysiology
https://www.readbyqxmd.com/read/29411383/vasoconstrictor-stimulus-determines-the-functional-contribution-of-myoendothelial-feedback-to-mesenteric-arterial-tone
#2
R Wei, S E Lunn, R Tam, S L Gust, B Classen, P M Kerr, F Plane
Constriction of isolated resistance arteries in response to α1 -adrenoceptor agonists is limited by reciprocal engagement of inhibitory endothelial mechanisms via myoendothelial feedback. In the current model of feedback, agonist stimulation of smooth muscle cells results in localized InsP3 -dependent Ca2+ transients that activate endothelial IKCa channels. The subsequent hyperpolarization of the endothelial membrane potential then feeds back to the smooth muscle to limit further reductions in vessel diameter...
February 7, 2018: Journal of Physiology
https://www.readbyqxmd.com/read/29405505/sympathetic-vasomotor-activity-during-dynamic-exercise-with-resistive-breathing-sex-differences-and-the-nerve-to-show-it
#3
Ken D O'Halloran
Respiratory muscle metaboreflexes exert substantial influence over cardiorespiratory and autonomic control, exemplified during heavy dynamic exercise in health, and in obstructive airways disease even at rest. This article is protected by copyright. All rights reserved.
February 5, 2018: Experimental Physiology
https://www.readbyqxmd.com/read/29395374/effects-of-weight-changes-in-the-autonomic-nervous-system-a%C3%A2-systematic-review-and-meta-analysis
#4
João Costa, André Moreira, Pedro Moreira, Luís Delgado, Diana Silva
BACKGROUND: Obesity has been linked to autonomic dysfunction, which is thought to be one of the main contributors for hypertension, cardiac remodelling and death. Exercise and diet-based weight loss are the mainstay therapy for obesity, but there is a paucity of data regarding the effect of weight changes in autonomic nervous system (ANS) activity. OBJECTIVE: To describe the impact of weight changes in autonomic nervous system. METHODS: A systematic literature search of four biomedical databases was performed evaluating effects of weight changes, thorough diet and/or exercise-based interventions, in the following ANS outcomes: heart rate variability, namely low frequency (LF)/high frequency (HF) ratio (LF/HF ratio), normalized units of LF (LFnu) and HF (HFnu), muscle sympathetic nerve activity (MSNA), noradrenaline spillover rate (NA-SR), standard deviation of normal-to-normal intervals (SDNN), root mean square of successive differences (RMSSD), baroreflex sensitivity and pupillometry...
January 9, 2018: Clinical Nutrition: Official Journal of the European Society of Parenteral and Enteral Nutrition
https://www.readbyqxmd.com/read/29388357/airway-obstruction-produces-widespread-sympathoexcitation-role-of-hypoxia-carotid-chemoreceptors-and-nts-neurotransmission
#5
Caroline B Ferreira, Sergio L Cravo, Sean D Stocker
Obstructive sleep apnea (OSA) is the most common respiratory disturbance of sleep and is closely associated to cardiovascular diseases. In humans, apnea increases respiratory effort and elevates muscle sympathetic nerve activity (SNA), but the primary stimulus for the SNA activation has not been identified. We recently developed a model of apnea in rodents using acute airway obstruction. In this study, we employed this model to test whether the elevation in SNA was mediated by hypoxia, carotid chemoreceptors, or neurotransmission in the nucleus tractus solitarius (NTS)...
February 2018: Physiological Reports
https://www.readbyqxmd.com/read/29378730/evidence-for-pressure-independent-sympathetic-modulation-of-central-pulse-wave-velocity
#6
Massimo Nardone, Anthony V Incognito, Philip J Millar
BACKGROUND: Whether the sympathetic nervous system can directly alter central aortic stiffness remains controversial, mainly because of the difficulty in experimentally augmenting peripheral vasoconstrictor activity without changing blood pressure. METHODS AND RESULTS: To address this limitation, we utilized low-level cardiopulmonary baroreflex loading and unloading shown previously to alter sympathetic outflow without evoking parallel hemodynamic modulation. Blood pressure and carotid-femoral aortic pulse wave velocity (cf-PWV) were measured in 32 healthy participants (24±2 years; women: n=15) before and during 12-minute applications of low-level lower body negative pressure; -7 mm Hg) and lower body positive pressure; +7 mm Hg), applied in a random order...
January 29, 2018: Journal of the American Heart Association
https://www.readbyqxmd.com/read/29374335/renal-sympathetic-nerve-activity-after-catheter-based-renal-denervation
#7
Linn C Dobrowolski, Daan W Eeftinck Schattenkerk, C T Paul Krediet, Peter M Van Brussel, Liffert Vogt, Frederike J Bemelman, Jim A Reekers, Bert-Jan H Van Den Born, Hein J Verberne
BACKGROUND: Catheter-based renal sympathetic denervation (RDN) has been considered a potential treatment for therapy resistant hypertension (RHT). However, in a randomized placebo-controlled trial, RDN did not lead to a substantial blood pressure (BP) reduction. We hypothesized that variation in the reported RDN efficacy might be explained by incomplete nerve disruption as assessed by renal 123I-meta-iodobenzylguanidine (123I-mIBG) scintigraphy. METHODS: In 21 RHT patients (median age 60 years), we performed 123I-mIBG scintigraphy before and 6 weeks after RDN...
January 26, 2018: EJNMMI Research
https://www.readbyqxmd.com/read/29359025/cardiac-autonomic-neuropathy-risk-factors-diagnosis-and-treatment
#8
REVIEW
Victoria A Serhiyenko, Alexandr A Serhiyenko
Cardiac autonomic neuropathy (CAN) is a serious complication of diabetes mellitus (DM) that is strongly associated with approximately five-fold increased risk of cardiovascular mortality. CAN manifests in a spectrum of things, ranging from resting tachycardia and fixed heart rate (HR) to development of "silent" myocardial infarction. Clinical correlates or risk markers for CAN are age, DM duration, glycemic control, hypertension, and dyslipidemia (DLP), development of other microvascular complications...
January 15, 2018: World Journal of Diabetes
https://www.readbyqxmd.com/read/29357474/the-influence-of-acute-elevations-in-plasma-osmolality-and-serum-sodium-on-sympathetic-outflow-and-blood-pressure-responses-to-exercise
#9
Michael S Brian, Evan L Matthews, Joseph Charles Watso, Matthew Charles Babcock, Megan M Wenner, William C Rose, Sean D Stocker, William B Farquhar
Elevated plasma osmolality (pOsm) has been shown to increase resting sympathetic nerve activity in animals and humans. The following study tested the hypothesis that increases in pOsm and serum sodium (sNa+) would exaggerate muscle sympathetic nerve activity (MSNA) and blood pressure (BP) responses to handgrip (HG) exercise and post-exercise ischemia (PEI). BP and MSNA were measured during HG followed by PEI before and after a 23-min hypertonic saline infusion (HSI-3% NaCl). Eighteen participants (age 23{plus minus}1 yrs; BMI 24{plus minus}1 kg·(m2)-1) completed the protocol; pOsm and sNa increased from pre- to post-HSI (285{plus minus}1 to 291{plus minus}1 mOsm·kg H2O-1; 138...
December 13, 2017: Journal of Neurophysiology
https://www.readbyqxmd.com/read/29357457/neck-movement-but-not-neck-position-modulates-skin-sympathetic-nerve-activity-supplying-the-lower-limbs-of-humans
#10
Philip S Bolton, Elie Hammam, Vaughan G Macefield
We previously showed that dynamic, but not static, neck displacement modulates muscle sympathetic nerve activity (MSNA) to lower limbs of humans. However, it is not known whether dynamic neck displacement modulates skin sympathetic nerve activity (SSNA). Tungsten microelectrodes inserted into the common peroneal nerve were used to record SSNA in 5 female and 4 male subjects lying supine on a table that fixed their head in space but allowed trapezoidal ramp (8.1 {plus minus} 1.20/s) and hold (17.50 for 53s) or sinusoidal (350 peak-to-peak at 0...
December 27, 2017: Journal of Neurophysiology
https://www.readbyqxmd.com/read/29351473/sympathetically-mediated-cardiac-responses-to-isolated-muscle-metaboreflex-activation-following-exercise-are-modulated-by-body-position-in-humans
#11
André L Teixeira, Mauricio Daher, Mayara Souza, Plinio Santos Ramos, James P Fisher, Lauro C Vianna
Isolated muscle metaboreflex activation with post-handgrip exercise ischemia (PEI) increases sympathetic nerve activity and partially maintains the exercise-induced increase in blood pressure, but a smaller heart rate (HR) response occurs. The cardiopulmonary baroreceptors, mechanically sensitive receptors that respond to changes in central blood volume and pressure, are strongly associated with changes in body position and upon activation elicit reflex sympathoinhibition. Here, we tested the hypothesis that postural changes modulate the sympathetically-mediated cardiac response to PEI in humans...
December 15, 2017: American Journal of Physiology. Heart and Circulatory Physiology
https://www.readbyqxmd.com/read/29334157/elevated-sympathetic-vasomotor-outflow-in-response-to-increased-inspiratory-muscle-activity-during-exercise-is-less-in-young-women-compared-with-men
#12
Keisho Katayama, Joshua R Smith, Kanako Goto, Kaori Shimizu, Mitsuru Saito, Koji Ishida, Teruhiko Koike, Satoshi Iwase, Craig A Harms
We compared changes in muscle sympathetic nerve activity (MSNA) and cardiovascular variables during leg cycle exercise with increased inspiratory muscle resistance in men and women. We hypothesized that sympathetic vasomotor outflow during exercise with increased inspiratory resistance would be attenuated in young women compared with age-matched men. Eight women and seven men completed the study. The subjects performed two 10-min exercise bouts at 40% peak oxygen uptake using a cycle ergometer in a semirecumbent position [spontaneous breathing for 5 min and voluntary hyperventilation with or without inspiratory resistive breathing for 5 min (breathing frequency: 50 breaths min-1 with a 50% duty cycle, inspiratory resistance: 30% of maximal inspiratory pressure)]...
January 15, 2018: Experimental Physiology
https://www.readbyqxmd.com/read/29315576/the-metaboreflex-does-not-contribute-to-the-increase-in-muscle-sympathetic-nerve-activity-to-contracting-muscle-during-static-exercise-in-humans
#13
Daniel Boulton, Chloe E Taylor, Simon Green, Vaughan G Macefield
Both central command and metaboreflex inputs from contracting muscles increase muscle sympathetic nerve activity (MSNA) to non-contracting muscle during sustained isometric exercise. We recently showed that MSNA to contracting muscle also increases in an intensity-dependent manner, but whether this can be sustained by the metaboreflex is unknown. MSNA was recorded from the left common peroneal nerve and spikes of MSNA extracted. Eleven subjects performed a series of four-minute dorsiflexions of the left ankle at 10% of maximum voluntary contraction under three conditions: without ischaemia, with 6 min of post-exercise ischaemia and with ischaemia during and after exercise; these were repeated in the right leg...
January 8, 2018: Journal of Physiology
https://www.readbyqxmd.com/read/29283975/sympathetic-baroreceptor-regulation-during-hypoxic-hypotension-in-humans-new-insights
#14
Christophe Janssen, Guido Grassi, Dominique Laude, Philippe van de Borne
BACKGROUND: Baroreceptor activation by a continuous infusion of phenylephrine selectively abolishes the muscle sympathetic nerve activity (MSNA) response to hypoxia in humans. Baroreceptor deactivation enhances the MSNA rise during hypoxia in animals. Whether this is true in humans is unknown and was tested in the present study. METHODS: We assessed MSNA responses elicited by isocapnic hypoxia (10% O2 in N2) during baroreflex loading and unloading with phenylephrine and nitroprusside, respectively, in 19 healthy volunteers...
December 27, 2017: Journal of Hypertension
https://www.readbyqxmd.com/read/29220864/the-nature-of-catecholamine-containing-neurons-in-the-enteric-nervous-system-in-relationship-with-organogenesis-normal-human-anatomy-and-neurodegeneration
#15
G Natale, L Ryskalin, C L Busceti, F Biagioni, F Fornai
The gastrointestinal tract is provided with extrinsic and intrinsic innervation. The extrinsic innervation includes the classic vagal parasympathetic and sympathetic components, with afferent sensitive and efferent secretomotor fibers. The intrinsic innervations is represented by the enteric nervous system (ENS), which is recognized as a complex neural network controlling a variety of cell populations, including smooth muscle cells, mucosal secretory cells, endocrine cells, microvasculature, immune and inflammatory cells...
September 1, 2017: Archives Italiennes de Biologie
https://www.readbyqxmd.com/read/29212669/long-duration-bed-rest-modifies-sympathetic-neural-recruitment-strategies-in-males-and-females
#16
Stephen A Klassen, Steven De Abreu, Danielle K Greaves, Derek S Kimmerly, Philippe Arbeille, Pierre Denise, Richard L Hughson, Hervé Normand, J Kevin Shoemaker
To understand the impact of physical deconditioning with head-down tilt bed rest (HDBR) on the malleability of sympathetic discharge patterns, we studied a) baseline integrated muscle sympathetic nerve activity (MSNA; microneurography) from 13 females participating in the WISE-2005 60-day HDBR study (Female, retrospective analysis), b) integrated MSNA and multi-unit action potential (AP) analysis in 13 males (Male) performed on data collected at baseline and during physiological stress imposed by end-inspiratory apnea, in a new 60-day HDBR study, and c) a repeatability study (Control, n = 6, retrospective analysis, 4 weeks between tests)...
December 6, 2017: Journal of Applied Physiology
https://www.readbyqxmd.com/read/29207251/oral-contraceptives-modulate-the-muscle-metaboreflex-in-healthy-young-women
#17
Hanna R Parmar, Jasmin Sears, Yannick Molgat-Seon, Cara L McCulloch, Laura A McCracken, Courtney V Brown, Andrew William Sheel, Paolo B Dominelli
There are known sex-differences in blood pressure regulation. The differences are related to ovarian hormones that influence β-adrenergic receptors and the transduction of muscle sympathetic nerve activity. Oral contraceptives (OC) modulate the ovarian hormonal profile in women and therefore may alter the cardiovascular response. We questioned if OC would alter the absolute pressor response to static exercise and influence the day-to-day variability of the response. Healthy men (n=11) and women (n=19) completed a familiarization day and two experimental testing days...
December 5, 2017: Applied Physiology, Nutrition, and Metabolism, Physiologie Appliquée, Nutrition et Métabolisme
https://www.readbyqxmd.com/read/29206785/three-weeks-of-overload-training-increases-resting-muscle-sympathetic-activity
#18
Alexandra M Coates, Anthony V Incognito, Jeremy D Seed, Connor J Doherty, Philip J Millar, Jamie F Burr
PURPOSE: Overload training is hypothesized to alter autonomic regulation, though interpretations using indirect measures of heart rate variability are conflicting. The aim of the present study was to examine the effects of overload training on muscle sympathetic nerve activity (MSNA), a direct measure of central sympathetic outflow, in recreational endurance athletes. METHODS: Measurements of heart rate variability, cardiac baroreflex sensitivity (BRS), MSNA (microneurography), and sympathetic BRS were obtained in seventeen healthy triathletes and cyclists after 1-week of reduced training (baseline) and following 3-weeks of either regular (CON, n=7) or overload (OL, n=10) training...
December 2, 2017: Medicine and Science in Sports and Exercise
https://www.readbyqxmd.com/read/29203629/exaggerated-vasoconstriction-to-spontaneous-bursts-of-muscle-sympathetic-nerve-activity-in-healthy-young-black-men
#19
COMPARATIVE STUDY
Jennifer R Vranish, Seth W Holwerda, Benjamin E Young, Daniel P Credeur, Jordan C Patik, Thales C Barbosa, David M Keller, Paul J Fadel
Blacks have the highest prevalence of hypertension, putting them at greater risk of cardiovascular disease and death. Previous studies have reported that, relative to whites, healthy black men have augmented pressor responses to sympathoexcitatory stressors. Although important, these studies do not inform about the resting state and the influence of spontaneous changes in resting muscle sympathetic nerve activity (MSNA). Likewise, little is known about the transduction of MSNA into a vascular response at rest on a beat-to-beat basis...
January 2018: Hypertension
https://www.readbyqxmd.com/read/29185161/exercise-therapy-and-autonomic-function-in-heart-failure-patients-a-systematic-review-and-meta-analysis
#20
REVIEW
M J Pearson, N A Smart
A large body of evidence exists indicating that autonomic imbalance is characteristic of heart failure, with several parameters of autonomic function associated with adverse clinical outcomes. The aim of this systematic review and meta-analysis was to investigate the effects of exercise training on parameters of autonomic function in patients with heart failure and where possible quantify the size of the effect. We conducted database searches (PubMed, EMBASE and Cochrane Trials Register to 31 March 2017) for exercise-based rehabilitation trials in heart failure; using search terms, exercise training, autonomic function, heart rate recovery, heart rate variability and muscle sympathetic nerve activity...
November 29, 2017: Heart Failure Reviews
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