DOCSLIB.ORG

Activation of the Sinoaortic Baroreceptor Reflex Arc Induces Analgesia: Interactions Between Cardiovascular and Endogenous Pain Inhibition Systems

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Activation of the Sinoaortic Baroreceptor Reflex Arc Induces Analgesia: Interactions Between Cardiovascular and Endogenous Pain Inhibition Systems Physiological Psychology 1983, Vol. 11 (3),214-220 Activation of the sinoaortic baroreceptor reflex arc induces analgesia: Interactions between cardiovascular and endogenous pain inhibition systems ALAN RANDIeH and eERIe HARTUNIAN University ojIowa, Iowa City, Iowa Two experiments examined the view that activation of the sinoaortic baroreceptor reflex arc induces analgesia. Rats were instrumented with carotid artery and jugular vein cannulae for measurement of arterial blood pressure, central venous blood pressure, and heart rate during assays of pain sensitivity using tail-flick responses to radiant heat. In Experiment 1, increases in arterial blood pressure effected by infusion of phenylephrine resulted in profound analgesia that persisted for a 28-min observation period following termination of the infusion. During the phenylephrine infusion period, the degree of analgesia was significantly correlated to the degree of reflex bradycardia, but was not significantly correlated to changes in either arterial or venous blood pressure. In Experiment 2, increases in arterial blood pressure effected by in­ fusion of phenylephrine failed to induce analgesia in rats with bilateral sinoaortic deafferenta­ tions, indicating that activation of the sinoaortic baroreceptor reflex arc is required for this form of analgesia. As in Experiment 1, reflex bradycardia, rather than increases in arterial blood pressure, was correlated with analgesia. These outcomes are consistent with the view that sys­ tems involved in the regulation of blood pressure are physiologically linked to systems involved in the regulation of pain. The implications of these findings for the etiology of hypertension are discussed. Administration of sympathomimetic compounds Gebhart, & Long, 1982; Randich, 1982; Randich & induces a reduction in pain sensitivity, or analgesia, Maimer, 1981; Zarnir & Segal, 1979; Zarnir, Simantov, in a variety of species, including humans (Fellows & Segal, 1980). Specifically, it is possible that ac­ & Ullyot, 1951; Goetzl, Burrill, & Ivy, 1944; Randall tivation of the sinoaortic baroreceptor reflex arc re­ & Selitto, 1958; Witkin, Heubner, Galdi, O'Keefe, sulting from sympathomimetic-induced increases in Spitalletta, & Plummer, 1961). For instance, subcu­ arterial blood pressure is capable of engaging en­ taneous administration of norepinephrine, meth­ dogenous pain inhibition systems. This view is sup­ oxamine, methamphetamine, or 2-aminoindane in­ ported indirectly by a number of experimental find­ duces analgesia in rats and mice as assayed by the ings. First, peripheral administration of phenyle­ inflamed foot, writhing, or hot-plate tests of pain phrine in doses capable of increasing arterial blood sensitivity (Colville & Chaplin, 1964; Little & Rees, pressure attenuates wheel-turn escape/avoidance 1978). In general, these studies have favored the view responding produced by aversive trigeminal stimula­ that central, rather than peripheral, actions of sym­ tion in rats, but this attenuation effect does not occur pathomimetic compounds are responsible for the following bilateral sinoaortic deafferentation analgesia, an interpretation consistent with known (Dworkin, Filewich, Miller, Craigmyle, & Pickering, central adrenergic mechanisms of pain inhibition 1979). Second, bilateral sinoaortic deafferentation (see Harvey & Simansky, 1981). lowers the threshold for both flinch and jump re­ However, an alternative mechanism of action of sponses to an electric shock stimulus in spontane­ some sympathomimetic compounds is suggested by ously hypertensive rats (SHRs) and Wistar-Kyoto recent demonstrations that genetic, renal, and DOCA­ (WKYs) normotensive rats (Randich, 1982). Third, salt hypertensive rats manifest analgesia in some as­ treatments that lower arterial blood pressure in hy­ says of pain sensitivity (Maixner, Touw, Brody, pertensive rats, for example, administration of hex­ amethonium in SHRs (Maixner et aI., 1982) or re­ moval of the stenotic kidney in renal hypertensive This research was supported by an N_LH_ grant (NSI834l) to rats (Zamir & Segal, 1979), are associated with a loss A_ Randich. We gratefully acknowledge the technical and secre­ of analgesia. Finally, Maixner and Randich (Note 1) tarial help provided by P. Nichols and M. Bowersox, respectively. The authors' mailing address is: Department of Psychology, Uni­ demonstrated that elevations in central venous pres­ versity of Iowa, Iowa City, Iowa 52242. sure by a volume loading procedure induces a pro- 214 Copyright 1983 Psychonomic Society, Inc. BLOOD-PRESSURE-INDUCED ANALGESIA 215 found, long-lasting analgesia in rats. These authors constant for all subjects, was adjusted to produce a tail-flick re­ argued that activation of low-pressure cardiopul­ sponse of approximately 3-4 sec in a normal rat. Arterial blood pressure, heart rate, and central venous blood monary baroreceptors is a sufficient condition for pressure were recorded on a Beckman RIIA rectilinear dynagraph. the production of analgesia. Although this experi­ The arterial blood pressure signal was transduced by a Century ment does not bear directly upon the role of arterial pressure transducer, and the venous blood pressure signal was blood pressure in modulating pain sensitivity, it is transduced by a Statham pressure transducer. consistent with the more general proposal that sys­ Suqical teebalques. Each rat was anesthetized with Equithesin (3 rat/kg). An incision was made in the pectoral region 1 cm to tems involved in cardiovascular regulation are physio­ the right of the midventralline and extending 2 cm craniad from logically linked to systems modulating pain percep­ the pectoralis. The external jugular vein was exposed at its junc­ tion. tion with the right subclavian vein, and the connective tissue sur­ The purpose of the present experiments was to as­ rounding the area was cleared. A cannula (Silastic) was inserted caudad through the brachiocephalic vein approximately 4 cm. sess directly the view that increases in arterial blood The cannula was anchored to adjacent tissue. pressure and concomitant activation of the sinoaortic A 3-cm midventral incision was then made in the cervical re­ baroreceptor reflex arc are capable of activating en­ gion. Dissection continued until the underlying sternocleido­ dogenous pain inhibition systems. In these experi­ mastoid group was exposed. The left sternomastoid was displayed ments, increases in arterial blood pressure were pro­ laterally, and the deeper omohyoid was cut at right angles to its fiber direction. The left common carotid artery was then separated duced by infusions of phenylephrine and pain sensi­ from the surrounding tissues and nerves. A cannula was advanced tivity was assayed by tail-flick responses to radiant caudad 3-4 cm and anchored to adjacent muscles (Micro-line). heat. Arterial blood pressure, central venous blood The arterial and venous cannulae were then drawn subcutane­ pressure, and heart rate were recorded during all ously around the neck and exited through a dorsal incision. The phases of the experiment. Experiment 1 examined cannulas were anchored to the neck and flushed with a saline­ heparin solution. whether increases in arterial blood pressure induced Testing. All rats were allowed a minimum of 1 day of recovery analgesia in normal rats. Experiment 2 examined prior to testing. Each rat was then placed in a Plexiglas restrain­ whether phenylephrine-induced analgesia was a con­ ing tube, and the cannulas were connected to the pressure trans­ sequence of arterial pressure activation of the sino­ ducers and an infusion pump (Harvard Apparatus 941). Saline was then infused through the venous cannula, and initial base­ aortic baroreceptor reflex arc by assessing pain sen­ line tail-flick latencies were obtained every 2 min. sitivity in rats with either sham operations or bilateral Following stabilization of the tail-flick response, phenylephrine sinoaortic deafferentations. (1 mg/ml) was infused through the venous cannula at rates rang­ ing from 24 to 192 ",g/min. Tail-flick trials were presented every EXPERIMENT 1 2 min, and the infusion procedure continued until the rat exhibited a tail-flick latency of no more than 10 sec. When a 100sec latency was obtained, the infusion procedure was stopped and tail-flick In Experiment I, rats were implanted with a right trials were administered across a 28-min observation period. Trials jugular vein cannula, for administration of phenyle­ were administered every I min during the first 10 min of the ob­ phrine and recording of central venous pressure, and servation period and every 3 min during the remaining 18 min of the observation period. Arterial blood pressure, central venous a left carotid cannula, for recording of arterial blood blood pressure, and heart rate were recorded simultaneously dur­ pressure and heart rate. Phenylephrine was infused ing all tail-flick trials. at various rates to produce graded increases in ar­ Data aaalysls. Linear regression was used to analyze the data. terial blood pressure as a means of determining Alpha was set at 0.05 in all analyses. whether the degree of analgesia reflected the magni­ tude of the pressure increment. Measurements of Results pain sensitivity (tail-flick) to a radiant heat stimulus Arterial blood pressure, heart rate, and venous were obtained every 2 min. If increases in arterial blood pressure were recorded during the infusions of blood pressure and concomitant activation of the phenylephrine and tail-flick trials. The changes in sinoaortic
Load more

Recommended publications
  • 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.
    [Show full text]
  • 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 .
    [Show full text]
  • 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.
    [Show full text]
  • 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.
    [Show full text]
  • 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.
    [Show full text]
  • 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
    [Show full text]
  • 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).
    [Show full text]
  • Investigation of the Cardiovascular Action of Sympathetic Amines Using Two Kinds of Strain Gauge Instrument
    Nagoya ]. med. Sci. 29: 155-165, 1966. INVESTIGATION OF THE CARDIOVASCULAR ACTION OF SYMPATHETIC AMINES USING TWO KINDS OF STRAIN GAUGE INSTRUMENT ATSUSHI SEKIYA, MITSUYOSHI NAKASHIMA, AND ZENGO KANDA Department of Pharmcology, Nagoya University School of Medicine (Director: Prof. Zen go Kanda) SUMMARY Ventricular responses of a few catecholamines in rabbits were studied with the use of various parameters: blood pressure, systemic output or stroke volume, heart rate, ventricular contractile force and change of segment length of ventricular muscle. In recording ventricular contraction, two kinds of apparatus, strain gauge compass and arch, which we devised, were used. Simultaneous recordings of these various factors permit characterization and direct comparison of the nature and sequence of left ventricular responses by infusion of catecholamines. Epinephrine or norepinephrine, in smaller dose produced almost the same changes in ventricular contractile force and segment length of ventricular muscle. However, in the course of a short time after the administration of the large dose of these drugs, the change of coutractile force by means of strain gauge arch was significant, but the change of muscle segment length measused by means of strain gauge compass was more complicated and gave us much information of cardiac function. Namely, there were a decrease of stroke deflection with a decrease of stroke volume and a downward displacement of systolic and diastolic excursion curve which meant heart dilatation. By the administration of methoxamine, the changes of muscle segment length were more marked than the changes of contractile force. By the administration of isoproterenol, the changes of contractile force were more marked than the changes of muscle segment length changes.
    [Show full text]
  • Sympathetic and Baroreceptor Reflex Function in Neurally Mediated Syncope Evoked by Tilt
    Sympathetic and baroreceptor reflex function in neurally mediated syncope evoked by tilt. R Mosqueda-Garcia, … , R M Robertson, D Robertson J Clin Invest. 1997;99(11):2736-2744. https://doi.org/10.1172/JCI119463. Research Article The pathophysiology of neurally mediated syncope is poorly understood. It has been widely assumed that excessive sympathetic activation in a setting of left ventricular hypovolemia stimulates ventricular afferents that trigger hypotension and bradycardia. We tested this hypothesis by determining if excessive sympathetic activation precedes development of neurally mediated syncope, and if this correlates with alterations in baroreflex function. We studied the changes in intraarterial blood pressure (BP), heart rate (HR), central venous pressure (CVP), muscle sympathetic nerve activity (MSNA), and plasma catecholamines evoked by upright tilt in recurrent neurally mediated syncope patients (SYN, 5+/-1 episodes/mo, n = 14), age- and sex-matched controls (CON, n = 23), and in healthy subjects who consistently experienced syncope during tilt (FS+, n = 20). Baroreflex responses were evaluated from changes in HR, BP, and MSNA that were obtained after infusions of phenylephrine and sodium nitroprusside. Compared to CON, patients with SYN had blunted increases in MSNA at low tilt levels, followed by a progressive decrease and ultimately complete disappearance of MSNA with syncope. SYN patients also had attenuation of norepinephrine increases and lower baroreflex slope sensitivity, both during tilt and after pharmacologic
    [Show full text]
  • Heartbeats Entrain Breathing Via Baroreceptor-Mediated Modulation 2 of Expiratory Activity 3 4 William H
    bioRxiv preprint doi: https://doi.org/10.1101/2020.12.09.416776; this version posted December 11, 2020. The copyright holder for this preprint (which was not certified by peer review) is the author/funder. All rights reserved. No reuse allowed without permission. 1 Heartbeats entrain breathing via baroreceptor-mediated modulation 2 of expiratory activity 3 4 William H. Barnett1, David M. Baekey2, Julian F. R. Paton3, Thomas E. Dick4&5,#, Erica A. 5 Wehrwein6,#, Yaroslav I. Molkov1&7,# 6 7 1 Department of Mathematics and Statistics, Georgia State University, Atlanta, GA 8 2 Department of Pharmacology and Therapeutics, University of Florida, Gainesville, FL 9 3 Manaaki Mānawa – The Centre for Heart Research, Department of Physiology, Faculty of 10 Medical and Health Sciences, University of Auckland, Auckland, New Zealand 11 4 Division of Pulmonary, Critical Care and Sleep Medicine, Department of Medicine, Case 12 Western Reserve University, Cleveland, OH 13 5 Department of Neurosciences, Case Western Reserve University, Cleveland, OH 14 6 Department of Physiology, Michigan State University, East Lansing, MI 15 7 Neuroscience Institute, Georgia State University, Atlanta, GA 16 17 #shared senior authorship 18 19 20 Running Head: Cardio-Ventilatory Coupling 21 22 Corresponding Authors 23 Yaroslav I. Molkov, PhD Erica A. Wehrwein, Ph.D. Department of Mathematics and Statistics Department of Physiology Georgia State University Michigan State University 25 Park Place, Rm 1415 567 Wilson Rd, Rm 2201J Atlanta, GA 30303 East Lansing, MI 48824 Email: [email protected] Email: [email protected] Phone: (404) 413-6422 Phone: (517) 884-5043 24 1 bioRxiv preprint doi: https://doi.org/10.1101/2020.12.09.416776; this version posted December 11, 2020.
    [Show full text]
  • Fetal Heart Rate Tracing Study
    FHR Monitoring: Maternal Fetal Physiology M. Sean Esplin, MD and Alexandra Eller, MD Maternal Fetal Medicine Intermountain Healthcare University of Utah Health Sciences Center Disclosures • I have no financial relationships to disclose • I want to acknowledge ACOG District II for open sharing of their teaching modules http://www.acog.org/About-ACOG/ACOG-Districts/District- II/Quick-Guide-and-Teaching-Modules Goals • Review the basic physiology and adaptive responses that regulate the FHR • Review oxygen delivery to the fetus, potential disruptions, and route to injury • Correlate physiologic fetal adaptations to stress with FHR deceleration patterns Goal of Intrapartum Monitoring Assess the adequacy of intrapartum fetal oxygenation • Reduce perinatal morbidity and mortality • Perinatal death • Intrapartum and neonatal • Birth asphyxia • Long-term neurological impairment The Basic Assumption Fetal adaptive responses to progressive hypoxemia and acidosis are detectable FHR monitoring = fetal brain oxygenation monitoring Basic Heart Rate Physiology • Cardiorespiratory Center (medulla oblongata) • Determines FHR baseline, variability, pattern • Coordinates input from intrinsic influences • Parasympathetic nervous system • Sympathetic nervous system • Baroreceptors (aortic arch, carotid) • Chemoreceptors (central and peripheral) • Endocrine system (hormones) • Sleep-wake cycle • Breathing/Pain/Sound/Temperature http://images.slideplayer.com/25/7741495/slides/slide_24.jpg Parasympathetic Influence • Vagus (CN X) nerve originates in CRC • Innervates
    [Show full text]
  • Resetting of the Baroreflex Control of Sympathetic Vasomotor Activity
    REVIEW published: 15 August 2017 doi: 10.3389/fnins.2017.00461 Resetting of the Baroreflex Control of Sympathetic Vasomotor Activity during Natural Behaviors: Description and Conceptual Model of Central Mechanisms Roger A. L. Dampney* Physiology, School of Medical Sciences, The University of Sydney, Sydney, NSW, Australia The baroreceptor reflex controls arterial pressure primarily via reflex changes in vascular resistance, rather than cardiac output. The vascular resistance in turn is dependent upon the activity of sympathetic vasomotor nerves innervating arterioles in different vascular beds. In this review, the major theme is that the baroreflex control of sympathetic vasomotor activity is not constant, but varies according to the behavioral state of the animal. In contrast to the view that was generally accepted up until the 1980s, I argue that the baroreflex control of sympathetic vasomotor activity is not inhibited or overridden during behaviors such as mental stress or exercise, but instead is reset under those Edited by: Chloe E. Taylor, conditions so that it continues to be highly effective in regulating sympathetic activity and Western Sydney University, Australia arterial blood pressure at levels that are appropriate for the particular ongoing behavior. A Reviewed by: major challenge is to identify the central mechanisms and neural pathways that subserve Satoshi Iwase, Aichi Medical University, Japan such resetting in different states. A model is proposed that is capable of simulating the Craig D. Steinback, different ways in which baroreflex resetting is occurred. Future studies are required to University of Alberta, Canada determine whether this proposed model is an accurate representation of the central *Correspondence: mechanisms responsible for baroreflex resetting.
    [Show full text]