Resetting of the Baroreflex Control of Sympathetic Vasomotor Activity
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Baroreflex Sensitivity Impairment During Hypoglycemia
Diabetes Volume 65, January 2016 209 Ajay D. Rao,1,2 Istvan Bonyhay,3 Joel Dankwa,1 Maria Baimas-George,1 Lindsay Kneen,1 Sarah Ballatori,3 Roy Freeman,3 and Gail K. Adler1 Baroreflex Sensitivity Impairment During Hypoglycemia: Implications for Cardiovascular Control Diabetes 2016;65:209–215 | DOI: 10.2337/db15-0871 Studies have shown associations between exposure to of cardiovascular benefit(4–7). These results raise the hypoglycemia and increased mortality, raising the pos- possibility that exposure to hypoglycemia has adverse sibility that hypoglycemia has adverse cardiovascular and unknown effects that persist after hypoglycemia effects. In this study, we determined the acute effects resolves and may oppose cardiovascular benefits of im- of hypoglycemia on cardiovascular autonomic control. proved glycemic control (8,9). Seventeen healthy volunteers were exposed to exper- Prior exposure to hypoglycemia impairs the hormonal imental hypoglycemia (2.8 mmol/L) for 120 min. Car- and muscle sympathetic nerve activity (MSNA) response fl COMPLICATIONS diac vagal barore ex function was assessed using the to subsequent hypoglycemia (10), the hormonal responses fi modi ed Oxford method before the initiation of the to subsequent exercise (11), and autonomic control of hypoglycemic-hyperinsulinemic clamp protocol and dur- cardiovascular function (12). After exposure to hypogly- ing the last 30 min of hypoglycemia. During hypoglycemia, cemia, induced by the hypoglycemic-hyperinsulinemic compared with baseline euglycemic conditions, 1)baro- clamp protocol, individuals exhibit decreased baroreflex reflex sensitivity decreases significantly (19.2 6 7.5 vs. 32.9 6 16.6 ms/mmHg, P < 0.005), 2) the systolic blood sensitivity (BRS), decreased MSNA response to transient pressure threshold for baroreflex activation increases hypotension, and decreased norepinephrine response to significantly (the baroreflex function shifts to the right; orthostatic stress compared with prior exposure to 120 6 14 vs. -
Baroreflex and Cerebral Autoregulation Are Inversely
2460 NASR N et al. Circulation Journal ORIGINAL ARTICLE Official Journal of the Japanese Circulation Society http://www.j-circ.or.jp Hypertension and Circulatory Control Baroreflex and Cerebral Autoregulation Are Inversely Correlated Nathalie Nasr, MD, PhD; Marek Czosnyka, PhD; Anne Pavy-Le Traon, MD, PhD; Marc-Antoine Custaud, MD, PhD; Xiuyun Liu, BSc; Georgios V. Varsos, BSc; Vincent Larrue, MD Background: The relative stability of cerebral blood flow is maintained by the baroreflex and cerebral autoregulation (CA). We assessed the relationship between baroreflex sensitivity (BRS) and CA in patients with atherosclerotic carotid stenosis or occlusion. Methods and Results: Patients referred for assessment of atherosclerotic unilateral >50% carotid stenosis or oc- clusion were included. Ten healthy volunteers served as a reference group. BRS was measured using the sequence method. CA was quantified by the correlation coefficient (Mx) between slow oscillations in mean arterial blood pres- sure and mean cerebral blood flow velocities from transcranial Doppler. Forty-five patients (M/F: 36/9), with a me- dian age of 68 years (IQR:17) were included. Thirty-four patients had carotid stenosis, and 11 patients had carotid occlusion (asymptomatic: 31 patients; symptomatic: 14 patients). The median degree of carotid steno-occlusive disease was 90% (IQR:18). Both CA (P=0.02) and BRS (P<0.001) were impaired in patients as compared with healthy volunteers. CA and BRS were inversely and strongly correlated with each other in patients (rho=0.58, P<0.001) and in healthy volunteers (rho=0.939; P<0.001). Increasing BRS remained strongly associated with im- paired CA on multivariate analysis (P=0.004). -
Baroreceptor Activity and Sensitivity: Normal Values in Children and Young Adults Using the Head up Tilt Test
Baroreceptor activity and sensitivity: normal values in children and young adults using the head up tilt test Cite this article as: Mohammad S. Alnoor, Holly K. Varner, Ian J. Butler, Liang Zhu and Mohammed T. Numan, Baroreceptor activity and sensitivity: normal values in children and young adults using the head up tilt test, Pediatric Research doi:10.1038/s41390-019-0327-6 This Author Accepted Manuscript is a PDF file of an unedited peer-reviewed manuscript that has been accepted for publication but has not been copyedited or corrected. The official version of record that is published in the journal is kept up to date and so may therefore differ from this version. Terms of use and reuse: academic research for non-commercial purposes, see here for full terms. https://www.nature.com/authors/policies/license.html#AAMtermsV1 © 2019 Macmillan Publishers Limited, part of Springer Nature. Title: Baroreceptor activity and sensitivity: normal values in children and young adults using the head up tilt test. Authors: Mohammad S. Alnoor1, Holly K. Varner2, Ian J. Butler3, Liang Zhu4, Mohammed T. Numan5 Affiliations: 1. Department of Pediatrics, McGovern Medical School The University of Texas Health Science Center at Houston, Houston, Texas 2. Department of Neurology, McGovern Medical School The University of Texas Health Science Center at Houston, Houston, Texas 3. Department of Pediatrics, Division of Child and Adolescent Neurology, McGovern Medical School The University of Texas Health Science Center at Houston, Houston, Texas 4. Department of Internal Medicine, Division of Clinical and Translational Research, McGovern Medical School The University of Texas Health Science Center at Houston, Houston, Texas 5. -
Task Dependent Effects of Baroreceptor Unloading on Motor Cortical and Corticospinal Pathways
TASK DEPENDENT EFFECTS OF BARORECEPTOR UNLOADING ON MOTOR CORTICAL AND CORTICOSPINAL PATHWAYS A Thesis Presented to The Academic Faculty by Vasiliy E. Buharin In Partial Fulfillment of the Requirements for the Degree Doctor of Philosophy in the School of Applied Physiology Georgia Institute of Technology December 2013 Copyright c 2013 by Vasiliy E. Buharin TASK DEPENDENT EFFECTS OF BARORECEPTOR UNLOADING ON MOTOR CORTICAL AND CORTICOSPINAL PATHWAYS Approved by: Dr. T. Richard Nichols, Dr. Boris Prilutsky Committee Chair School of Applied Physiology School of Applied Physiology Georgia Institute of Technology Georgia Institute of Technology Dr. Minoru Shinohara, Advisor Dr. Lewis Wheaton School of Applied Physiology School of Applied Physiology Georgia Institute of Technology Georgia Institute of Technology Dr. Andrew J. Butler Date Approved: 21 August 2013 Department of Physical Therapy Georgia State University This thesis is for everyone. Read it. iii ACKNOWLEDGEMENTS I want to thank my wife for making me breakfast. iv TABLE OF CONTENTS DEDICATION .................................. iii ACKNOWLEDGEMENTS .......................... iv LIST OF TABLES ............................... ix LIST OF FIGURES .............................. x ABBREVIATIONS ............................... xi SUMMARY .................................... xiii I BACKGROUND .............................. 1 1.1 Introduction . 1 1.2 Baroreceptor unloading . 2 1.3 Methods for quantifying neuromuscular pathways of fine motor skill 4 1.3.1 Corticospinal Excitability . 5 1.3.2 Intracortical Excitability . 8 1.3.3 Spinal motor-neuron excitability . 13 1.3.4 Spinal interneuron excitability . 14 1.3.5 Muscle fiber excitability . 15 1.4 Joint-stabilizing co-contraction . 16 1.5 Potential for influence of baroreceptor unloading over motor pathways of fine motor skill . 19 1.6 Specific aims . 21 1.6.1 Specific Aim 1 . -
Increased Baroreflex Sensitivity and Reduced Cardiovascular Reactivity
1873 Hypertens Res Vol.31 (2008) No.10 p.1873-1878 Original Article Increased Baroreflex Sensitivity and Reduced Cardiovascular Reactivity in Individuals with Chronic Low Blood Pressure Stefan DUSCHEK1), Anja DIETEL1), Rainer SCHANDRY1), and Gustavo A. REYES DEL PASO2) This study investigated aberrations in baroreflex function and cardiovascular reactivity related to the con- dition of chronic low blood pressure. In 40 hypotensive and 40 normotensive control subjects, blood pres- sures were continuously recorded at rest and during mental stress. Baroreflex sensitivity was determined in the time domain using sequence analysis. Beat-to-beat hemodynamic indices were estimated from the blood pressure waveforms by means of Modelflow analysis. In the hypotensive sample, a higher baroreflex sensitivity was observed under both conditions. Furthermore, this group experienced a less pronounced increase of blood pressure and stroke volume under stress. The findings underline the involvement of the baroreflex in the long-term setting of tonic blood pressure and suggest its relevance in the etiology of chronic hypotension. In addition, this study documents reduced cardiovascular reactivity and thus deficient hemodynamic adjustment to situational requirements in chronic low blood pressure. (Hypertens Res 2008; 31: 1873–1878) Key Words: hypotension, blood pressure, baroreflex, cardiac output, mental stress tory problems when assuming an upright position (5). Introduction The cardiac baroreflex has been considered to be involved in the etiology of chronic hypotension (1, 6). This regulatory Chronic low blood pressure is relatively widespread; it affects system consists of a negative feedback loop in which changes approximately 3% of the general population (1). It is typically in the firing rate of the arterial baroreceptors lead to compen- accompanied by symptoms such as fatigue, reduced drive, satory alterations of heart rate, cardiac contractility, and vaso- faintness, dizziness, headaches, cold limbs, and reduced cog- motor activity (7, 8). -
Evaluation and Management of Bradydysrhythmias
VISIT US AT BOOTH # 116 AT THE ACEP SCIENTIFIC ASSEMBLY IN SEATTLE, OCTOBER 14-16, 2013 September 2013 Evaluation And Management Volume 15, Number 9 Of Bradydysrhythmias In The Author Nathan Deal, MD Assistant Professor, Section of Emergency Medicine, Baylor Emergency Department College of Medicine, Houston, TX Peer Reviewers Abstract Joshua M. Kosowsky, MD Vice Chair for Clinical Affairs, Department of Emergency Medicine, Brigham and Women’s Hospital; Assistant Professor, Bradydysrhythmias represent a collection of cardiac conduction Harvard Medical School, Boston, MA abnormalities that span the spectrum of emergency presentations, Charles V. Pollack, Jr., MA, MD, FACEP Professor and Chair, Department of Emergency Medicine, from relatively benign conditions to conditions that represent Pennsylvania Hospital, Perelman School of Medicine, University serious, life-threatening emergencies. This review presents the of Pennsylvania, Philadelphia, PA electrocardiographic findings seen in common bradydysrhythmias CME Objectives and emphasizes prompt recognition of these patterns. Underlying Upon completion of this article, you should be able to: etiologies that may accompany these conduction abnormalities are 1. Recognize the electrocardiographic features of common discussed, including bradydysrhythmias that are reflex mediated bradydysrhythmias. (including trauma induced) and those with metabolic, environ- 2. Consider a variety of pathologies that give rise to mental, infectious, and toxicologic causes. Evidence regarding the bradydysrhythmias. 3. Identify the emergent therapies for the unstable patient management of bradydysrhythmias in the emergency department with bradycardia. is limited; however, there are data to guide the approach to the un- 4. Be familiar with common antidotes for acute toxicities that stable bradycardic patient. When decreased end-organ perfusion is result in bradydysrhythmias. -
Peripheral Nervous System (PNS) Composed of the Cranial and Spinal
“My green thumb came only as a result of the mistakes I made while learning to see things from the plant’s point of view.” -H. Fred Ale Nervous System 1 Classroom Rules You'll get one warning, then you'll have to leave the room! Punctuality- Everybody's time is precious: •! You get here by the start of class, I'll have you out of here on time. •! Getting back from breaks counts as being late to class. Participation- No distractions: •! No side talking. •! No laying down. •! No inappropriate clothing. •! No food or drink except water. •! No phones in classrooms, clinic or bathrooms. Lesson Plan: 42a Nervous System 1 •! 5 minutes: Breath of Arrival and Attendance •! 50 minutes: Nervous System 1 Introduction Introduction The body uses two systems to monitor and stimulate changes needed to maintain homeostasis: endocrine and nervous. Endocrine System Nervous System Introduction The endocrine system responds more slowly and uses hormones as chemical messengers to cause physiologic changes. Endocrine System Nervous System 1.! Slow response 2.! Hormones Introduction The nervous system responds to changes more rapidly and uses nerve impulses to cause physiologic changes. Endocrine System Nervous System 1.! Slow response 1.! Rapid response 2.! Hormones 2.! Nerve impulses (and neurotransmitters too) Introduction It is the nervous system that is the body's master control and communications system. It also monitors and regulates many aspects of the endocrine system. Endocrine System Nervous System 1.! Slow response 1.! Rapid response 2.! Hormones 2.! Nerve impulses (and neurotransmitters too) 3.! Body control 4.! Body communications 5.! Monitors and regulates the endocrine system Introduction Every thought, action, and sensation reflects nerve activity. -
Cardiac Rhythms Gate Central Initiation of Sympathetic Reflexes
The Journal of Neuroscience, February 11, 2009 • 29(6):1817–1825 • 1817 Behavioral/Systems/Cognitive Following One’s Heart: Cardiac Rhythms Gate Central Initiation of Sympathetic Reflexes Marcus A. Gray,1,2 Karin Rylander,4 Neil A. Harrison,3 B. Gunnar Wallin,4 and Hugo D. Critchley1 1Clinical Imaging Sciences Centre, Brighton and Sussex Medical School, University of Sussex, Brighton, East Sussex BN1 9RR, United Kingdom, 2Wellcome Trust Centre for Neuroimaging, University College London, London WC1N 3BG, United Kingdom, 3Institute of Cognitive Neuroscience, University College London, London WC1N 3AR, United Kingdom, and 4Institute of Neuroscience and Physiology, Department of Clinical Neurophysiology, Sahlgren University Hospital, SE-413 45 Gothenburg, Sweden Central nervous processing of environmental stimuli requires integration of sensory information with ongoing autonomic control of cardiovascular function. Rhythmic feedback of cardiac and baroreceptor activity contributes dynamically to homeostatic autonomic control. We examined how the processing of brief somatosensory stimuli is altered across the cardiac cycle to evoke differential changes in bodily state. Using functional magnetic resonance imaging of brain and noninvasive beat-to-beat cardiovascular monitoring, we show that stimuli presented before and during early cardiac systole elicited differential changes in neural activity within amygdala, anterior insula and pons, and engendered different effects on blood pressure. Stimulation delivered during early systole inhibited blood pressure increases. Individual differences in heart rate variability predicted magnitude of differential cardiac timing responses within periaque- ductal gray, amygdala and insula. Our findings highlight integration of somatosensory and phasic baroreceptor information at cortical, limbic and brainstem levels, with relevance to mechanisms underlying pain control, hypertension and anxiety. -
Baroreceptor Dysfunction Induced by Nitric Oxide Synthase Inhibition in Humans Lukas E
View metadata, citation and similar papers at core.ac.uk brought to you by CORE provided by Elsevier - Publisher Connector Journal of the American College of Cardiology Vol. 36, No. 1, 2000 © 2000 by the American College of Cardiology ISSN 0735-1097/00/$20.00 Published by Elsevier Science Inc. PII S0735-1097(00)00674-4 Cardiac Physiology Baroreceptor Dysfunction Induced by Nitric Oxide Synthase Inhibition in Humans Lukas E. Spieker, MD, Roberto Corti, MD, Christian Binggeli, MD, Thomas F. Lu¨scher, MD, FACC, FRCP, FESC, Georg Noll, MD, FESC Zurich, Switzerland OBJECTIVES We sought to investigate baroreceptor regulation of sympathetic nerve activity and hemody- namics after inhibition of nitric oxide (NO) synthesis. BACKGROUND Both the sympathetic nervous system and endothelium-derived substances play essential roles in cardiovascular homeostasis and diseases. Little is known about their interactions. METHODS In healthy volunteers, we recorded muscle sympathetic nerve activity (MSA) with microneu- rography and central hemodynamics measured at different levels of central venous pressure induced by lower body negative pressure. G RESULTS After administration of the NO synthase inhibitor N -monomethyl-L-arginine (L-NMMA, 1 mg/kg/min), systolic blood pressure increased by 24 mm Hg (p ϭ 0.01) and diastolic blood pressure by 12 mm Hg (p ϭ 0.009), while stroke volume index (measured by thermodilution) fell from 53 to 38 mL/min/m2 (p Ͻ 0.002). Administration of L-NMMA prevented the compensatory increase of heart rate, but not MSA, to orthostatic stress. The altered response of heart rate was not due to higher blood pressure, because heart rate responses were not altered during infusion of the alpha-1-adrenoceptor agonist phenylephrine (titrated to an equal increase of systolic blood pressure). -
Arterial Baroreflex Buffering of Sympathetic Activation During Exercise-Induced Elevations in Arterial Pressure
Arterial baroreflex buffering of sympathetic activation during exercise-induced elevations in arterial pressure. U Scherrer, … , L A Bertocci, R G Victor J Clin Invest. 1990;86(6):1855-1861. https://doi.org/10.1172/JCI114916. Research Article Static muscle contraction activates metabolically sensitive muscle afferents that reflexively increase sympathetic nerve activity and arterial pressure. To determine if this contraction-induced reflex is modulated by the sinoaortic baroreflex, we performed microelectrode recordings of sympathetic nerve activity to resting leg muscle during static handgrip in humans while attempting to clamp the level of baroreflex stimulation by controlling the exercise-induced rise in blood pressure with pharmacologic agents. The principal new finding is that partial pharmacologic suppression of the rise in blood pressure during static handgrip (nitroprusside infusion) augmented the exercise-induced increases in heart rate and sympathetic activity by greater than 300%. Pharmacologic accentuation of the exercise-induced rise in blood pressure (phenylephrine infusion) attenuated these reflex increases by greater than 50%. In contrast, these pharmacologic manipulations in arterial pressure had little or no effect on: (a) forearm muscle cell pH, an index of the metabolic stimulus to skeletal muscle afferents; or (b) central venous pressure, an index of the mechanical stimulus to cardiopulmonary afferents. We conclude that in humans the sinoaortic baroreflex is much more effective than previously thought in buffering the reflex sympathetic activation caused by static muscle contraction. Find the latest version: https://jci.me/114916/pdf Arterial Baroreflex Buffering of Sympathetic Activation during Exercise-induced Elevations in Arterial Pressure Urs Scherrer,* Susan L. Pryor,* Loren A. Bertocci,t and Ronald G. -
Fernando De Castro and the Discovery of the Arterial Chemoreceptors
REVIEW ARTICLE published: 12 May 2014 doi: 10.3389/fnana.2014.00025 Fernando de Castro and the discovery of the arterial chemoreceptors Constancio Gonzalez 1,2 *, Silvia V. Conde 1,2 ,Teresa Gallego-Martín 1,2 , Elena Olea 1,2 , Elvira Gonzalez-Obeso 1,2 , Maria Ramirez 1,2 , SaraYubero 1,2 , MariaT.Agapito 1,2 , Angela Gomez-Niño 1,2 , Ana Obeso 1,2 , Ricardo Rigual 1,2 and Asunción Rocher 1,2 1 Departamento de Bioquímica y Biología Molecular y Fisiología, Instituto de Biología y Genética Molecular, Consejo Superior de Investigaciones Científicas, Universidad de Valladolid, Valladolid, España 2 CIBER de Enfermedades Respiratorias, Instituto de Salud Carlos III, Facultad de Medicina, Universidad de Valladolid, Valladolid, España Edited by: When de Castro entered the carotid body (CB) field, the organ was considered to be a Fernando de Castro, Hospital Nacional small autonomic ganglion, a gland, a glomus or glomerulus, or a paraganglion. In his 1928 de Parapléjicos – Servicio de Salud de Castilla-La Mancha, Spain paper, de Castro concluded: “In sum, the Glomus caroticum is innervated by centripetal fibers, whose trophic centers are located in the sensory ganglia of the glossopharyngeal, Reviewed by: José A. Armengol, University Pablo de and not by centrifugal [efferent] or secretomotor fibers as is the case for glands; these are Olavide, Spain precisely the facts which lead to suppose that the Glomus caroticum is a sensory organ.” Ping Liu, University of Connecticut A few pages down, de Castro wrote: “The Glomus represents an organ with multiple -
Cardiovascular Responses to Hypoxemia in Sinoaortic-Denervated Fetal Sheep
003 1-399819 1 /3004-038 1$03.0010 PEDIATRIC RESEARCH Vol. 30. No. 4, I991 Copyright ID1991 International Pediatric Research Foundation. Inc. I1riiirc~c/it1 U.S. ,.I Cardiovascular Responses to Hypoxemia in Sinoaortic-Denervated Fetal Sheep JOSEPH ITSKOVITZ (ELDOR), EDMOND F. LAGAMMA. JAMES BRISTOW, AND ABRAHAM M. RUDOLPH Ccirdiovascz~karResearch Instillrle. Unlver:c.i/yqf Califi~rniu,Sari Francisco. Sun Francisco. Cu11fi)rilia94/43 ABSTRACT. Fetal cardiovascular response to acute hy- hypoxemia in postnatal life (1 3). The vascular effects of periph- poxemia is characterized by bradycardia, hypertension, and eral chemoreceptor stimulation, with ventilation held constant, redistribution of cardiac output. The role of aortic and include coronary vasodilation and vasoconstriction in the carotid chemoreceptors in mediating these responses was splanchnic organs and the skeletal muscles. Stimulation of the examined in eight sinoaortic-denervated and nine sham- carotid body chemoreceptors results in reflex bradycardia and operated fetal lambs. Blood gases, pH, heart rate, arterial negative inotropic responses. The bradycardia and peripheral pressure, and blood flow distribution were determined be- vasoconstriction during carotid chemoreceptor stimulation can fore and during hypoxemia. In intact fetuses, heart rate be reversed by effects arising from concurrent hypernea (13). fell from 184 -+ 12 to 165 + 23 beatslmin (p< 0.01) but The arterial chemoreceptors (aortic and carotid bodies) are increased from 184 + 22 to 200 + 16 beatslmin (p< 0.05) active in the fetal lamb and are responsive to hypoxemia (14- in the sinoaortic-denervated fetuses. Intact fetuses showed 21). Stimulation of the fetal arterial chemoreceptors result in an early hypertensive response to hypoxemia, whereas the bradycardia, which is abolished by SAD (19, 20, 22).