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Microneurography

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https://www.readbyqxmd.com/read/29070505/inter-individual-variability-in-muscle-sympathetic-responses-to-static-handgrip-in-young-men-evidence-for-sympathetic-responder-types
#1
Anthony V Incognito, Connor J Doherty, Jordan B Lee, Matthew J Burns, Philip J Millar
Negative and positive muscle sympathetic nerve activity (MSNA) responders have been observed during mental stress. We hypothesized that similar MSNA response patterns could be identified during the first minute of static handgrip and contribute to the inter-individual variability throughout exercise. Supine measurements of multi-unit MSNA (microneurography) and continuous blood pressure (Finometer) were recorded in 29 young healthy men during the first (HG1) and second (HG2) minute of static handgrip (30% maximal voluntary contraction) and subsequent post-exercise circulatory occlusion (PECO)...
October 25, 2017: American Journal of Physiology. Regulatory, Integrative and Comparative Physiology
https://www.readbyqxmd.com/read/29057701/the-relationship-between-the-sensory-responses-to-ankle-joint-loading-and-corticomotor-excitability
#2
Alan R Needle, Jochen Baumeister, William B Farquhar, Jody L Greaney, Jill S Higginson, Thomas W Kaminski, C Buz Swanik
PURPOSE: Maintaining joint stability is dependent on the ability of the nervous system to prepare for, sense, and react to potentially injuries loads. In attempts to understand the neurophysiologic mechanisms underlying joint stability, this afferent and efferent activity has been quantified separately at the cortical, segmental, and peripheral levels using various electrophysiologic techniques in vivo. However, no studies have attempted to quantify sensory and motor activation at multiple levels of the nervous system in a single subset, in order to understand potential adaptations for optimizing joint stability...
October 23, 2017: International Journal of Neuroscience
https://www.readbyqxmd.com/read/29040222/neurovascular-response-during-exercise-and-mental-stress-in-anabolic-steroid-users
#3
Rafael Armani Porello, Marcelo Rodrigues Dos Santos, Francis Ribeiro de Souza, Guilherme Wesley Peixoto da Fonseca, Ana Luiza Carrari Sayegh, Tiago Franco de Oliveira, César Abreu Akiho, Maurício Yonamine, Rosa Maria Rodrigues Pereira, Carlos Eduardo Negrão, Maria-Janieire de Nazaré Nunes Alves
PURPOSE: Increased resting muscle sympathetic nerve activity (MSNA) and lower forearm blood flow (FBF) were observed in young men who use anabolic androgenic steroids (AAS). However, the response of MSNA and FBF in AAS users triggered by muscle mechanoreflex and central command has never been tested. Additionally, we evaluated the blood pressure (BP) and heart rate (HR) responses during these maneuvers. METHODS: Nineteen AAS users (AASU) aged 31±6 yr and 18 AAS nonusers (AASNU) aged 29±4 yr were recruited...
October 16, 2017: Medicine and Science in Sports and Exercise
https://www.readbyqxmd.com/read/28939650/muscle-sympathetic-nerve-responses-to-passive-and-active-one-legged-cycling-insight-into-the-contributions-of-central-command
#4
Connor J Doherty, Anthony V Incognito, Karambir Notay, Matthew J Burns, Joshua T Slysz, Jeremy D Seed, Massimo Nardone, Jamie F Burr, Philip J Millar
The contribution of central command to the peripheral vasoconstrictor response during exercise has been investigated using primarily handgrip exercise. The purpose of the present study was to compare muscle sympathetic nerve activity (MSNA) responses during passive (involuntary) and active (voluntary) zeroload cycling to gain insight into the effects of central command on sympathetic outflow during dynamic exercise. Hemodynamic measurements and contralateral leg MSNA (microneurography) were collected in eighteen young healthy participants at rest and during 2 minutes of passive and active zeroload one-legged cycling...
September 22, 2017: American Journal of Physiology. Heart and Circulatory Physiology
https://www.readbyqxmd.com/read/28912362/sympathetic-function-during-whole-body-cooling-is-altered-in-hypertensive-adults
#5
Jody L Greaney, W Larry Kenney, Lacy M Alexander
During moderate cold exposure, cardiovascular-related morbidity and mortality increase disproportionately in hypertensive adults (HTN); however, the mechanisms underlying this association are not well defined. We hypothesized that whole-body cold stress would evoke exaggerated increases in blood pressure (BP) and muscle sympathetic nerve activity (MSNA) in HTN compared to normotensive adults (NTN) and that sympathetic baroreflex function would be altered during cooling in HTN. MSNA (peroneal microneurography) and beat-to-beat BP (Finometer) were measured continuously in 10 NTN (6M/4W; age 53±3 yrs; resting BP 125±3/79±1 mmHg) and 13 HTN (7M/6W; age 58±2 yrs; resting BP 146±5/88±2 mmHg) during whole-body cooling-induced reductions in mean skin temperature (Tsk; water-perfused suit) from 34...
September 14, 2017: Journal of Applied Physiology
https://www.readbyqxmd.com/read/28887003/effects-of-acupuncture-at-the-st-36-point-on-muscle-sympathetic-nerve-activity-and-blood-pressure-in-normal-adults
#6
Kenichi Kimura, Kazuya Ishida, Noriyo Takahashi, Yasushi Toge, Fumihiro Tajima
The aim of the present study was to determine the effects of acupuncture on post-ganglionic muscle sympathetic nerve activity (MSNA) in humans. MSNA was measured in 8 healthy adult males by microneurography evaluation of the left peroneal nerve. Blood pressure (BP) and heart rate (HR) were simultaneously recorded. MSNA was evaluated as the burst rate, with total MSNA, BP and HR normalized to their respective baseline values. After 10min of rest in the supine position, acupuncture was applied to the right ST-36 point in the tibialis anterior muscle for 15min, with recovery then monitored over a 20-min period...
September 1, 2017: Autonomic Neuroscience: Basic & Clinical
https://www.readbyqxmd.com/read/28860174/ubc-nepal-expedition-acute-alterations-in-sympathetic-nervous-activity-do-not-influence-brachial-artery-endothelial-function-at-sea-level-and-high-altitude
#7
Michael M Tymko, Joshua C Tremblay, Craig D Steinback, Jonathan P Moore, Alex B Hansen, Alexander Patrician, Connor A Howe, Ryan L Hoiland, Daniel J Green, Philip N Ainslie
Evidence indicates that increases in sympathetic nervous activity (SNA), and acclimatization to high-altitude (HA), may reduce endothelial function as assessed by brachial artery flow-mediated dilatation (FMD); however, it is unclear whether such changes in FMD are due to direct vascular constraint, or consequential altered hemodynamics (e.g. shear stress) associated with increased SNA as a consequence of exposure to HA. We hypothesized that: 1) at rest, SNA would be elevated and FMD would be reduced at HA compared to sea-level (SL); and 2) at SL and HA, FMD would be reduced when SNA was acutely increased, and elevated when SNA was acutely decreased...
August 31, 2017: Journal of Applied Physiology
https://www.readbyqxmd.com/read/28816745/restoration-of-normal-sympathetic-neural-function-in-heart-failure-following-baroreflex-activation-therapy-final-43-month-study-report
#8
Raffaella Dell'Oro, Edoardo Gronda, Gino Seravalle, Giuseppe Costantino, Luca Alberti, Barbara Baronio, Tiziana Staine, Emilio Vanoli, Giuseppe Mancia, Guido Grassi
BACKGROUND: Baroreflex activation therapy (BAT) exerts in severe heart failure sympathoinhibitory effects, improving clinical variables and reducing hospitalization rate. The current follow-up study was aimed at determining the long-term effects of BAT, assessing whether BAT in heart failure allows to restore physiological levels of sympathetic function. METHODS: Seven patients out of the 11 heart failure patients aged 66.5 ± 3 years (mean ± SEM) in New York Heart Association Class III with left ventricular ejection fraction 40% or less and impaired functional capacity recruited in the study survived at the final follow-up (43...
August 14, 2017: Journal of Hypertension
https://www.readbyqxmd.com/read/28814736/emotions-alter-muscle-proprioceptive-coding-of-movements-in-humans
#9
Rochelle Ackerley, Jean-Marc Aimonetti, Edith Ribot-Ciscar
Emotions can evoke strong reactions that have profound influences, from gross changes in our internal environment to small fluctuations in facial muscles, and reveal our feelings overtly. Muscles contain proprioceptive afferents, informing us about our movements and regulating motor activities. Their firing reflects changes in muscle length, yet their sensitivity can be modified by the fusimotor system, as found in animals. In humans, the sensitivity of muscle afferents is modulated by cognitive processes, such as attention; however, it is unknown if emotional processes can modulate muscle feedback...
August 16, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28810724/sympathetic-nerve-traffic-and-blood-pressure-changes-after-bilateral-renal-denervation-in-resistant-hypertension-a-time-integrated-analysis
#10
Gino Seravalle, Graziella D'Arrigo, Giovanni Tripepi, Francesca Mallamaci, Gianmaria Brambilla, Giuseppe Mancia, Guido Grassi, Carmine Zoccali
Background: Renal denervation reduces blood pressure (BP) and sympathetic drive in experimental animal models, but the effect of this intervention on sympathetic activity in patients with treatment-resistant hypertension is still unclear. Methods: In an incident series of 29 patients with treatment-resistant hypertension, we performed serial measurements (n = 123) of muscle sympathetic nerve activity (MSNA, microneurography) and standardized BP measurements. Data were analysed by mixed linear modelling (MLM) and by regression analysis of time-integrated changes of both MSNA and synchronous, standardized (in-lab) BP measurements...
August 1, 2017: Nephrology, Dialysis, Transplantation
https://www.readbyqxmd.com/read/28807531/absent-cardiac-and-muscle-sympathetic-nerve-activities-involvement-in-ross-syndrome-a-follow-up-study
#11
E Fileccia, R Liguori, P Cortelli, V Donadio
PURPOSE: Ross syndrome (RS) is characterized by selective involvement of post-ganglionic skin sympathetic nerve fibres. We report a follow-up study in 4 patients to clarify whether in RS autonomic dysfunction spreads affecting also cardiovascular system. METHODS: The patients underwent cardiovascular reflexes (CVR) and microneurography recording of muscle sympathetic nerve activity (MSNA) for a follow-up mean period of 5years. RESULTS: CVR and MSNA were normal at baseline and unchanged over the follow-up...
August 9, 2017: Autonomic Neuroscience: Basic & Clinical
https://www.readbyqxmd.com/read/28772037/cardiac-and-peripheral-autonomic-control-in-restrictive-cardiomyopathy
#12
Ana Luiza C Sayegh, Marcelo R Dos Santos, Adriana O Sarmento, Francis R de Souza, Vera M C Salemi, Viviane T Hotta, Akothirene Cristhina D B Marques, Heidrum H Krämer, Ivani C Trombetta, Charles Mady, Maria Janieire de Nazaré Nunes Alves
AIMS: Autonomic dysfunction determines the advance of dilated cardiomyopathy (DCM) and is related to poor outcomes. However, this autonomic imbalance is unknown in patients with restrictive cardiomyopathy (RCM) even though they have similar symptoms and poor quality of life as DCM patients have. The aim of this study was to evaluate if autonomic and neurovascular controls were altered in RCM patients. METHODS AND RESULTS: Fifteen RCM patients, 10 DCM patients, and 10 healthy subjects were evaluated...
August 2017: ESC Heart Failure
https://www.readbyqxmd.com/read/28757109/the-effect-of-empagliflozin-on-muscle-sympathetic-nerve-activity-in-patients-with-type-ii-diabetes-mellitus
#13
Jens Jordan, Jens Tank, Karsten Heusser, Tim Heise, Christoph Wanner, Martina Heer, Sreeraj Macha, Michaela Mattheus, Søren S Lund, Hans J Woerle, Uli C Broedl
Inhibition of sodium glucose cotransporter 2 with empagliflozin results in caloric loss by increasing urinary glucose excretion and has a mild diuretic effect. Diuretic effects are usually associated with reflex-mediated increases in sympathetic tone, whereas caloric loss is associated with decreased sympathetic tone. In an open-label trial, muscle sympathetic nerve activity (MSNA) (burst frequency, burst incidence, and total MSNA) was assessed using microneurography performed off-treatment and on day 4 of treatment with empagliflozin 25 mg once daily in 22 metformin-treated patients with type II diabetes (mean [range] age 54 [40-65] years)...
September 2017: Journal of the American Society of Hypertension: JASH
https://www.readbyqxmd.com/read/28743633/an-intra-neural-microstimulation-system-for-ultra-high-field-magnetic-resonance-imaging-and-magnetoencephalography
#14
Paul M Glover, Roger H Watkins, George C O'Neill, Rochelle Ackerley, Rosa Sanchez-Panchuelo, Francis McGlone, Matthew J Brookes, Johan Wessberg, Susan T Francis
BACKGROUND: Intra-neural microstimulation (INMS) is a technique that allows the precise delivery of low-current electrical pulses into human peripheral nerves. Single unit INMS can be used to stimulate individual afferent nerve fibres during microneurography. Combining this with neuroimaging allows the unique monitoring of central nervous system activation in response to unitary, controlled tactile input, with functional magnetic resonance imaging (fMRI) providing exquisite spatial localisation of brain activity and magnetoencephalography (MEG) high temporal resolution...
October 1, 2017: Journal of Neuroscience Methods
https://www.readbyqxmd.com/read/28733092/exercise-training-to-reduce-sympathetic-nerve-activity-in-heart-failure-patients-a-systematic-review-and-meta-analysis
#15
REVIEW
María Javiera Saavedra, Fernando Romero, Jorge Roa, Iván Rodríguez-Núñez
OBJECTIVE: To determine the effects of exercise training on sympathetic nerve activity in heart failure patients. METHODS: A systematic review was performed. An electronic search of MEDLINE, ProQuest, SciELO, SPORTDiscus, Rehabilitation and Sport Medicine Source, Cumulative Index to Nursing and Allied Health Literature, Tripdatabase, Science Direct and PEDrO was performed from their inception to February 2017. Clinical trials and quasi-experimental studies were considered for primary article selection...
July 7, 2017: Brazilian Journal of Physical Therapy
https://www.readbyqxmd.com/read/28724309/effects-of-long-term-device-guided-slow-breathing-on-sympathetic-nervous-activity-in-hypertensive-patients-a-randomized-open-label-clinical-trial
#16
Silvana de Barros, Giovanio Vieira da Silva, Josiane Lima de Gusmão, Tatiana Goveia de Araújo, Dinoélia Rosa de Souza, Crivaldo Gomes Cardoso, Bruna Oneda, Décio Mion
PURPOSE: Device-guided slow breathing (DGB) is indicated as nonpharmacological treatment for hypertension. The sympathetic nerve activity (SNA) reduction may be one of the mechanisms involved in blood pressure (BP) decrease. The aim of this study is to evaluate the long-term use of DGB in BP and SNA. SUBJECTS AND METHODS: Hypertensive patients were randomized to listen music (Control Group-CG) or DGB (aim to reduce respiratory rate to less than 10 breaths/minute during 15 minutes/day for 8 weeks)...
July 20, 2017: Blood Pressure
https://www.readbyqxmd.com/read/28720715/ischemic-preconditioning-does-not-alter-muscle-sympathetic-responses-to-static-handgrip-and-metaboreflex-activation-in-young-healthy-men
#17
Anthony V Incognito, Connor J Doherty, Jordan B Lee, Matthew J Burns, Philip J Millar
Ischemic preconditioning (IPC) has been hypothesized to elicit ergogenic effects by reducing feedback from metabolically sensitive group III/IV muscle afferents during exercise. If so, reflex efferent neural outflow should be attenuated. We investigated the effects of IPC on muscle sympathetic nerve activity (MSNA) during static handgrip (SHG) and used post-exercise circulatory occlusion (PECO) to isolate for the muscle metaboreflex. Thirty-seven healthy men (age: 24 ± 5 years [mean ± SD]) were randomized to receive sham (n = 16) or IPC (n = 21) interventions...
July 2017: Physiological Reports
https://www.readbyqxmd.com/read/28701539/measuring-and-quantifying-skin-sympathetic-nervous-system-activity-in-humans
#18
REVIEW
Jody L Greaney, W Larry Kenney
Development of the technique of microneurography has substantially increased our understanding of the function of the sympathetic nervous system (SNS) in health and in disease. The ability to directly record signals from peripheral autonomic nerves in conscious humans allows for qualitative and quantitative characterization of SNS responses to specific stimuli and over time. Furthermore, distinct neural outflow to muscle (MSNA) and skin (SSNA) can be delineated. However, there are limitations and caveats to the use of microneurography, measurement criteria, and signal analysis and interpretation...
October 1, 2017: Journal of Neurophysiology
https://www.readbyqxmd.com/read/28679842/the-firing-characteristics-of-foot-sole-cutaneous-mechanoreceptor-afferents-in-response-to-vibration-stimuli
#19
Nicholas D J Strzalkowski, R Ayesha Ali, Leah R Bent
Single unit microneurography was used to record the firing characteristics of the four classes of foot sole cutaneous afferents [fast and slowly adapting type I and II (FAI, FAII, SAI, and SAII)] in response to sinusoidal vibratory stimuli. Frequency (3-250 Hz) and amplitude (0.001-2 mm) combinations were applied to afferent receptive fields through a 6-mm diameter probe. The impulses per cycle, defined as the number of action potentials evoked per vibration sine wave, were measured over 1 s of vibration at each frequency-amplitude combination tested...
October 1, 2017: Journal of Neurophysiology
https://www.readbyqxmd.com/read/28663324/new-indices-from-microneurography-to-investigate-the-arterial-baroreflex
#20
Alexandre Laurin, Matthew G Lloyd, Tesshin Hachiya, Mitsuru Saito, Victoria E Claydon, Andrew Blaber
Baroreflex-mediated changes in heart rate and vascular resistance in response to variations in blood pressure are critical to maintain homeostasis. We aimed to develop time domain analysis methods to complement existing cross-spectral techniques in the investigation of the vascular resistance baroreflex response to orthostatic stress. A secondary goal was to apply these methods to distinguish between levels of orthostatic tolerance using baseline data. Eleven healthy, normotensive males participated in a graded lower body negative pressure protocol...
June 2017: Physiological Reports
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