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O'Brien F, Staunton CA, Barrett-Jolley R. Systemic application of the transient receptor potential vanilloid-type 4 antagonist GSK2193874 induces tail vasodilation in a mouse model of thermoregulation. Biol Lett 2022; 18:20220129. [PMID: 35702981 PMCID: PMC9198786 DOI: 10.1098/rsbl.2022.0129] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
In humans, skin is a primary thermoregulatory organ, with vasodilation leading to rapid body cooling, whereas in Rodentia the tail performs an analogous function. Many thermodetection mechanisms are likely to be involved including transient receptor potential vanilloid-type 4 (TRPV4), an ion channel with thermosensitive properties. Previous studies have shown that TRPV4 is a vasodilator by local action in blood vessels, so here, we investigated whether constitutive TRPV4 activity affects Mus muscularis tail vascular tone and thermoregulation. We measured tail blood flow by pressure plethysmography in lightly sedated M. muscularis (CD1 strain) at a range of ambient temperatures, with and without intraperitoneal administration of the blood-brain barrier crossing TRPV4 antagonist GSK2193874. We also measured heart rate (HR) and blood pressure. As expected for a thermoregulatory organ, we found that tail blood flow increased with temperature. However, unexpectedly, we found that GSK2193874 increased tail blood flow at all temperatures, and we observed changes in HR variability. Since local TRPV4 activation causes vasodilation that would increase tail blood flow, these data suggest that increases in tail blood flow resulting from the TRPV4 antagonist may arise from a site other than the blood vessels themselves, perhaps in central cardiovascular control centres.
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Affiliation(s)
- Fiona O'Brien
- Department of Musculoskeletal Ageing, Faculty of Health and Life Sciences, University of Liverpool, Liverpool L7 8TX, UK
| | - Caroline A. Staunton
- Department of Musculoskeletal Ageing, Faculty of Health and Life Sciences, University of Liverpool, Liverpool L7 8TX, UK
| | - Richard Barrett-Jolley
- Department of Musculoskeletal Ageing, Faculty of Health and Life Sciences, University of Liverpool, Liverpool L7 8TX, UK
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2
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Mantovani G, Marozzi I, Rafanelli M, Rivasi G, Volpato S, Ungar A. Supine hypertension: A state of the art. Auton Neurosci 2022; 241:102988. [DOI: 10.1016/j.autneu.2022.102988] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2022] [Revised: 03/30/2022] [Accepted: 05/10/2022] [Indexed: 10/18/2022]
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3
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Yamasaki F, Sato T, Sato K, Diedrich A. Analytic and Integrative Framework for Understanding Human Sympathetic Arterial Baroreflex Function: Equilibrium Diagram of Arterial Pressure and Plasma Norepinephrine Level. Front Neurosci 2021; 15:707345. [PMID: 34335177 PMCID: PMC8322947 DOI: 10.3389/fnins.2021.707345] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2021] [Accepted: 06/24/2021] [Indexed: 11/15/2022] Open
Abstract
Background The sympathetic arterial baroreflex is a closed-loop feedback system for stabilizing arterial pressure (AP). Identification of unique functions of the closed system in humans is a challenge. Here we propose an analytic and integrative framework for identifying a static operating point and open-loop gain to characterize sympathetic arterial baroreflex in humans. Methods and Results An equilibrium diagram with two crossing functions of mechanoneural (MN) and neuromechanical (NM) arcs was analyzed during graded tilt maneuvers in seven healthy subjects. AP and plasma norepinephrine level (PNE), as a surrogate for sympathetic nerve activity, and were recorded after vagal modulation of heart function was blocked by atropine. The MN-arc curve was described as a locus of operating points during –7, 0, 15, and 60° head-up tilting (HUT) on a PNE-AP plane. The NM-arc curve was drawn as a line between operating points before and after ganglionic blockade (trimethaphan, 0.1 mg⋅ml–1⋅kg–1) during 0° or 15° HUT. Gain values were estimated from the slopes of these functional curves. Finally, an open-loop gain, which is a most important index for performance of arterial baroreflex, was given by a product of the gain values of MN (GMN) and NM arcs (GNM). Gain values of MN was 8.92 ± 3.07 pg⋅ml−1⋅mmHg−1; and GNM at 0° and 15° HUT were 0.61 ± 0.08 and 0.36 ± 0.05 mmHg⋅ml⋅pg–1, respectively. A postural change from supine to 15° HUT significantly reduced the open-loop gain from 5.62 ± 0.98 to 3.75 ± 0.62. The effects of HUT on the NM arc and open-loop gain seemed to be similar to those of blood loss observed in our previous animal studies. Conclusion An equilibrium-diagram analysis contributes to a quantitative and integrative understanding of function of human sympathetic arterial baroreflex.
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Affiliation(s)
- Fumiyasu Yamasaki
- Department of Clinical Laboratory, Kochi Medical School, Nankoku, Japan
| | - Takayuki Sato
- Department of Cardiovascular Control, Kochi Medical School, Nankoku, Japan
| | - Kyoko Sato
- Department of Clinical Laboratory, Kochi Medical School, Nankoku, Japan
| | - André Diedrich
- Department of Biomedical Engineering, Autonomic Dysfunction Center, Vanderbilt University Medical Center, Vanderbilt University, Nashville, TN, United States
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Ferreira-Junior NC, Crestani CC, Lagatta DC, Resstel LBM, Correa FMA, Alves FHF. Nitric oxide in the insular cortex modulates baroreflex responses in a cGMP-independent pathway. Brain Res 2020; 1747:147037. [PMID: 32738232 DOI: 10.1016/j.brainres.2020.147037] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2020] [Revised: 07/01/2020] [Accepted: 07/27/2020] [Indexed: 10/23/2022]
Abstract
Insular cortex is a brain structure involved in the modulation of autonomic activity and cardiovascular function. The nitric oxide/cyclic guanosine-3',5'-monophosphate pathway is a prominent signaling mechanism in the central nervous system, controlling behavioral and physiological responses. Nevertheless, despite evidence regarding the presence of nitric oxide-synthesizing neurons in the insular cortex, its role in the control of autonomic and cardiovascular function has never been reported. Thus, the present study aimed to investigate the involvement of nitric oxide/cyclic guanosine-3',5'-monophosphate pathway mediated by neuronal nitric oxide synthase (nNOS) activation within the insular cortex in the modulation of baroreflex responses in unanesthetized rats. For this, we evaluated the effect of bilateral microinjection of either the nitric oxide scavenger carboxy-PTIO, the selective neuronal nitric oxide synthase inhibitor Nω-Propyl-l-arginine or the soluble guanylate cyclase inhibitor ODQ into the insular cortex on the bradycardia evoked by blood pressure increases in response to intravenous infusion of phenylephrine, and the tachycardia caused by blood pressure decreases evoked by intravenous infusion of sodium nitroprusside. Bilateral microinjection of either NPLA or carboxy-PTIO into the insular cortex increased the reflex bradycardic response, whereas the reflex tachycardia was decreased by these treatments. Bilateral microinjection of the soluble guanylate cyclase inhibitor into the insular cortex did not affect any parameter of baroreflex function evaluated. Overall, our findings provide evidence that insular cortex nitrergic signaling, acting via neuronal nitric oxide synthase, plays a prominent role in control of baroreflex function. However, control of reflex responses seems to be independent of soluble guanylate cyclase activation.
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Affiliation(s)
- Nilson C Ferreira-Junior
- Department of Pharmacology, School of Medicine of Ribeirão Preto, University of São Paulo, Ribeirão Preto, SP, Brazil
| | - Carlos C Crestani
- Laboratory of Pharmacology, School of Pharmaceutical Sciences, São Paulo State University (UNESP), Araraquara, SP, Brazil
| | - Davi C Lagatta
- Department of Pharmacology, School of Medicine of Ribeirão Preto, University of São Paulo, Ribeirão Preto, SP, Brazil
| | - Leonardo B M Resstel
- Department of Pharmacology, School of Medicine of Ribeirão Preto, University of São Paulo, Ribeirão Preto, SP, Brazil
| | - Fernando M A Correa
- Department of Pharmacology, School of Medicine of Ribeirão Preto, University of São Paulo, Ribeirão Preto, SP, Brazil
| | - Fernando H F Alves
- Department of Health Sciences, Faculty of Medicine - Federal University of Lavras, Lavras, MG, Brazil.
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5
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Biaggioni I, Shibao CA, Diedrich A, Muldowney JAS, Laffer CL, Jordan J. Blood Pressure Management in Afferent Baroreflex Failure: JACC Review Topic of the Week. J Am Coll Cardiol 2020; 74:2939-2947. [PMID: 31806138 DOI: 10.1016/j.jacc.2019.10.027] [Citation(s) in RCA: 30] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/16/2019] [Revised: 10/18/2019] [Accepted: 10/21/2019] [Indexed: 12/14/2022]
Abstract
Afferent baroreflex failure is most often due to damage of the carotid sinus nerve because of neck surgery or radiation. The clinical picture is characterized by extreme blood pressure lability with severe hypertensive crises, hypotensive episodes, and orthostatic hypotension, making it the most difficult form of hypertension to manage. There is little evidence-based data to guide treatment. Recommendations rely on understanding the underlying pathophysiology, relevant clinical pharmacology, and anecdotal experience. The goal of treatment should be improving quality of life rather than normalization of blood pressure, which is rarely achievable. Long-acting central sympatholytic drugs are the mainstay of treatment, used at the lowest doses that prevent the largest hypertensive surges. Short-acting clonidine should be avoided because of rebound hypertension, but can be added to control residual hypertensive episodes, often triggered by mental stress or exertion. Hypotensive episodes can be managed with countermeasures and short-acting pressor agents if necessary.
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Affiliation(s)
- Italo Biaggioni
- Division of Clinical Pharmacology, Vanderbilt University Medical Center, Nashville, Tennessee; Department of Medicine, Vanderbilt University Medical Center, Nashville, Tennessee; Department of Pharmacology, Vanderbilt University Medical Center, Nashville, Tennessee; Vanderbilt Autonomic Dysfunction Center, Nashville, Tennessee.
| | - Cyndya A Shibao
- Division of Clinical Pharmacology, Vanderbilt University Medical Center, Nashville, Tennessee; Department of Medicine, Vanderbilt University Medical Center, Nashville, Tennessee; Vanderbilt Autonomic Dysfunction Center, Nashville, Tennessee
| | - André Diedrich
- Division of Clinical Pharmacology, Vanderbilt University Medical Center, Nashville, Tennessee; Department of Medicine, Vanderbilt University Medical Center, Nashville, Tennessee; Vanderbilt Autonomic Dysfunction Center, Nashville, Tennessee
| | - James A S Muldowney
- Department of Medicine, Vanderbilt University Medical Center, Nashville, Tennessee; Vanderbilt Autonomic Dysfunction Center, Nashville, Tennessee; Division of Cardiovascular Medicine, Vanderbilt University Medical Center, Nashville, Tennessee
| | - Cheryl L Laffer
- Division of Clinical Pharmacology, Vanderbilt University Medical Center, Nashville, Tennessee; Department of Medicine, Vanderbilt University Medical Center, Nashville, Tennessee
| | - Jens Jordan
- Institute of Aerospace Medicine, German Aerospace Center, Cologne, Germany; Aerospace Medicine, University of Cologne, Cologne, Germany
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6
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Vallelonga F, Maule S. Diagnostic and therapeutical management of supine hypertension in autonomic failure. J Hypertens 2019; 37:1102-1111. [DOI: 10.1097/hjh.0000000000002008] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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7
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Sabharwal R, Mason BN, Kuburas A, Abboud FM, Russo AF, Chapleau MW. Increased receptor activity-modifying protein 1 in the nervous system is sufficient to protect against autonomic dysregulation and hypertension. J Cereb Blood Flow Metab 2019; 39:690-703. [PMID: 29297736 PMCID: PMC6446426 DOI: 10.1177/0271678x17751352] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Calcitonin gene-related peptide (CGRP) can cause migraines, yet it is also a potent vasodilator that protects against hypertension. Given the emerging role of CGRP-targeted antibodies for migraine prevention, an important question is whether the protective actions of CGRP are mediated by vascular or neural CGRP receptors. To address this, we have characterized the cardiovascular phenotype of transgenic nestin/hRAMP1 mice that have selective elevation of a CGRP receptor subunit in the nervous system, human receptor activity-modifying protein 1 (hRAMP1). Nestin/hRAMP1 mice had relatively little hRAMP1 RNA in blood vessels and intravenous injection of CGRP caused a similar blood pressure decrease in transgenic and control mice. At baseline, nestin/hRAMP1 mice exhibited similar mean arterial pressure, heart rate, baroreflex sensitivity, and sympathetic vasomotor tone as control mice. We previously reported that expression of hRAMP1 in all tissues favorably improved autonomic regulation and attenuated hypertension induced by angiotensin II (Ang II). Similarly, in nestin/hRAMP1 mice, hypertension caused by Ang II or phenylephrine was greatly attenuated, and associated autonomic dysregulation and increased sympathetic vasomotor tone were diminished or abolished. We conclude that increased expression of neuronal CGRP receptors is sufficient to induce a protective change in cardiovascular autonomic regulation with implications for migraine therapy.
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Affiliation(s)
- Rasna Sabharwal
- 1 Department of Internal Medicine, University of Iowa, Iowa City, IA, USA
| | - Bianca N Mason
- 2 Molecular and Cell Biology Program, University of Iowa, Iowa City, IA, USA
| | - Adisa Kuburas
- 3 Department of Molecular Physiology and Biophysics, University of Iowa, Iowa City, IA, USA
| | - Francois M Abboud
- 1 Department of Internal Medicine, University of Iowa, Iowa City, IA, USA.,3 Department of Molecular Physiology and Biophysics, University of Iowa, Iowa City, IA, USA
| | - Andrew F Russo
- 2 Molecular and Cell Biology Program, University of Iowa, Iowa City, IA, USA.,3 Department of Molecular Physiology and Biophysics, University of Iowa, Iowa City, IA, USA.,4 Department of Neurology, Carver College of Medicine, University of Iowa, Iowa City, IA, USA.,5 Veterans Affairs Medical Center, Iowa City, IA, USA
| | - Mark W Chapleau
- 1 Department of Internal Medicine, University of Iowa, Iowa City, IA, USA.,3 Department of Molecular Physiology and Biophysics, University of Iowa, Iowa City, IA, USA.,5 Veterans Affairs Medical Center, Iowa City, IA, USA
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8
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Abstract
Neurogenic orthostatic hypotension (NOH) can be present in a number of disorders, including synucleinopathies, autoimmune disorders, and various genetic disorders. All are characterized by defective norepinephrine release from sympathetic terminals upon standing, resulting in impaired vasoconstriction. NOH is defined as a drop in systolic blood pressure ≥20 mmHg or diastolic blood pressure ≥10 mmHg, or both, within 3 minutes of standing or head up-tilt at a minimum of 60°. However, approximately 50% of patients have associated supine hypertension, which greatly complicates treatment. Supine hypertension not only is a common side effect of many anti-hypotensive agents but is also present in untreated patients, suggesting it is, in part, innate to the pathophysiology of autonomic dysfunction. Pathological mechanisms differ depending on the underlying autonomic disorder. In central neurodegenerative disorders, residual post-ganglionic sympathetic activity is likely the primary mechanism, whereas plasma angiotensin, aldosterone, and inappropriate mineralocorticoid receptor activity may contribute in peripheral autonomic lesions. Baroreflex failure/loss of baroreflex buffering is common to both. More work is required. Clinically, there is much dispute regarding the treatment of supine hypertension when there is a risk of exacerbating orthostatic hypotension. However, given the similar levels of end-organ damage (i.e., heart attack and stroke) seen with transient hypertension, it seems clear that treatment is important. Current therapies for both NOH and supine hypertension include a combination of pharmacological and conservative measures. However, in addition to the current standard of care, protocols may consider 24-h blood pressure monitoring and potential future examination of the peripheral post-ganglionic sympathetic nerves in order to apply individualized adjunct therapies. Finally, no anti-hypertensive agents are currently approved for use in this patient population, and development of novel therapies should focus on short-acting agents, selective to the supine position, that act primarily at night when hypertension is most severe/prolonged.
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Affiliation(s)
- Jacquie Baker
- School of Kinesiology, Western University, London, ON, Canada.,Department of Clinical Neurological Sciences, Rm. C7-131, University Hospital, London Health Sciences Centre, 339 Windermere Road, London, ON, N6A 5A5, Canada
| | - Kurt Kimpinski
- School of Kinesiology, Western University, London, ON, Canada. .,Department of Clinical Neurological Sciences, Rm. C7-131, University Hospital, London Health Sciences Centre, 339 Windermere Road, London, ON, N6A 5A5, Canada. .,Schulich School of Medicine and Dentistry, Western University, London, ON, Canada.
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9
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Hesse C, Schroeder DR, Nicholson WT, Hart EC, Curry TB, Penheiter AR, Turner ST, Joyner MJ, Eisenach JH. beta2-Adrenoceptor gene variation and systemic vasodilatation during ganglionic blockade. J Physiol 2010; 588:2669-78. [PMID: 20519311 DOI: 10.1113/jphysiol.2010.190058] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Regional infusions of beta(2)-adrenoceptor (ADRB2) agonist have generally shown that individuals homozygous for Gly16 produces greater vasodilatation than those homozygous for Arg16. Systemic infusions have shown an opposite effect on systemic vascular resistance (SVR), possibly confounded by baroreflexes or interactions between single nucleotide polymorphism (SNP) positions 16 and 27. We tested the hypothesis that ADRB2 gene variation would influence the SVR response to ADRB2 agonist terbutaline (Terb) during ganglionic blockade. Forty healthy young adults were recruited according to the double homozygous haplotypes: Arg16 + Gln27 (n = 13), the rare Gly16 + Gln27 (n = 6), and Gly16 + Glu27 (n = 21). Arterial pressure was measured by brachial arterial catheter, and cardiac output by acetylene breathing. Lymphocytes were sampled for ex vivo analysis of ADRB2 density and binding conformation. Following baroreflex ablation with trimethaphan (3-7 mg min(1)), continuous phenylephrine was titrated to restore blood pressure to baseline. Terb was infused i.v. at 33 and 67 ng kg(1) min(1) for 15 min/dose. There was partial evidence to suggest a main effect of haplotype on the change in SVR (P = 0.06). For SNP position 16, the highest dose of Terb produced lower SVR in Gly16 (mean +/- s.e.m.: 7.5 +/- 0.4) vs. Arg16 (8.9 +/- 0.7 units; P = 0.03). Lymphocyte ADRB2 binding conformation was similar but receptor density was greater in Gly16 vs. Arg16 (P = 0.05). We conclude that during ganglionic blockade, the SVR response to systemic ADRB2 agonist is suggestive of augmented ADRB2 function in Gly16 + Glu27 homozygotes, with greater influence from Gly16, providing further evidence that ADRB2 gene variation influences vasodilatation.
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Affiliation(s)
- Christiane Hesse
- Department of Anaesthesiology, Internal Medicine, Mayo Clinic, Rochester, MN 55905, USA
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10
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Hesse C, Eisenach JH. GENETIC VARIATION IN THE β(2)-ADRENERGIC RECEPTOR: IMPACT ON INTERMEDIATE CARDIOVASCULAR PHENOTYPES. ACTA ACUST UNITED AC 2008; 6:160-170. [PMID: 19727431 DOI: 10.2174/1875692110806030160] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Genetic variation in drug targets (e.g. receptors) can have pronounced effects on clinical responses to endogenous and exogenous agonists. Polymorphisms in the gene encoding the β(2)-adrenergic receptor (β(2)-AR) have been associated with altered expression, down-regulation, and altered cell signaling in vitro. Because β(2)-ARs play a crucial role in the regulation of the cardiovascular system, the functional importance of genetic variation in the β(2)-AR on cardiovascular responses to physiological or pharmacological stimuli has gained widespread attention. The objective of this review is to characterize these intermediate cardiovascular phenotypes and their influence on cardiovascular disease and adrenergic drug responses.Two common single nucleotide polymorphisms, encoded at codon 46 (Gly(16)Arg) and 79 (Gln(27)Glu) of the β(2)-AR gene, have been studied intensively. They have been shown to be associated with altered vasodilator responses to regional and systemic administration of β(2)-agonists, altered cardiovascular responses to sympathoexcitatory maneuvers, and altered myocardial function. Importantly, these intermediate physiological patterns may influence the development of and the outcomes associated with hypertension and other cardiovascular diseases. As recently reported, β(2)-AR gene variation can risk-stratify patients receiving β-blocker therapy and may predict β-blocker efficacy in patients post acute coronary syndrome or in patients with heart failure.Further studies will advance our understanding of the link between β(2)-AR genotypes, intermediate cardiovascular phenotypes, and clinical phenotypes. In the long term, reassessment of the benefits of β-blocker-therapy within genotype groups should be carried out with the ultimate goal to design the optimal therapeutic regimen for the individual patient.
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Affiliation(s)
- C Hesse
- Department of Anesthesiology, Mayo Clinic and Foundation, Rochester, MN, U.S.A
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11
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Wilkins BW, Hesse C, Charkoudian N, Nicholson WT, Sviggum HP, Moyer TP, Joyner MJ, Eisenach JH. Autonomic cardiovascular control during a novel pharmacologic alternative to ganglionic blockade. Clin Pharmacol Ther 2007; 83:692-701. [PMID: 17687267 DOI: 10.1038/sj.clpt.6100326] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The purpose of this study was to compare ganglionic blockade with trimethaphan (TMP) and an alternative drug strategy using combined muscarinic antagonist (glycopyrrolate, GLY) and alpha-2 agonist (dexmedetomidine, DEX). Protocol 1: incremental phenylephrine was administered during control and combined GLY-DEX, or control and TMP on two control combined GLY and DEX or TMP infusion on two randomized days. Protocol 2: muscle sympathetic nerve activity (MSNA) and the baroreflex MSNA relationship was determined before and after GLY-DEX. Blood pressure was higher with GLY-DEX (99+/-3 mm Hg) and lower with TMP (78+/-3 mm Hg) relative to control (GLY-DEX: 90+/-2 mm Hg; TMP: 91+/-2 mm Hg; P<0.05). Incremental phenylephrine increased pressure during GLY-DEX (P<0.01 vs control) and TMP (P<0.01 vs control) to a similar degree. Both GLY-DEX and TMP infusion inhibited norepinephrine release (P<0.01 vs control). GLY-DEX inhibited baseline MSNA (P<0.05) and baroreflex changes in MSNA (P<0.01). We conclude that the GLY-DEX alternative drug strategy can be used as a reasonable alternative to pharmacologic ganglionic blockade to examine autonomic cardiovascular control.
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Affiliation(s)
- B W Wilkins
- Department of Anesthesiology, Mayo Clinic College of Medicine, Rochester, Minnesota, USA
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12
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Gamboa A, Diedrich A, Biaggioni I. Pharmacological probes to measure the importance of the autonomic nervous system. Clin Auton Res 2007; 17:65-8. [PMID: 17401762 DOI: 10.1007/s10286-007-0406-3] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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13
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Wilkins BW, Hesse C, Sviggum HP, Nicholson WT, Moyer TP, Joyner MJ, Eisenach JH. Alternative to ganglionic blockade with anticholinergic and alpha-2 receptor agents. Clin Auton Res 2006; 17:77-84. [PMID: 17160588 DOI: 10.1007/s10286-006-0387-7] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2006] [Accepted: 11/14/2006] [Indexed: 10/23/2022]
Abstract
The ganglionic blocking agent trimethaphan (TMP) is no longer produced. Therefore, a need exists for alternative pharmacological approaches to investigate baroreflex control of the circulation. The aim of the present study was to examine baroreflex-mediated cardiovascular responses during the administration of a muscarinic receptor antagonist (glycopyrrolate; GLY: ) and a selective alpha-2 receptor agonist (dexmedetomidine; DEX: ) and to compare responses to ganglionic blockade with TMP. We hypothesized that combined GLY-: DEX: would inhibit the baroreflex similar to TMP. Ten volunteers participated in two study days and were instrumented with pulse oximeter, nasal cannula, ECG, continuous blood pressure monitoring (Finapres), and I.V. catheter for drug infusions. Each study day consisted of a control condition followed by either combined GLY: -DEX: or TMP on alternating days. A Valsalva maneuver was performed under each condition with every subject and six subjects received bolus phenylephrine (25 mug) during GLY: -DEX: and TMP. Combined GLY: -DEX: increased (P < 0.05) blood pressure (99 +/- 4 mmHg) and heart rate (99 +/- 3 bpm) relative to control condition (BP: 90 +/- 2 mmHg; HR: 64 +/- 3 bpm) and TMP infusion decreased (P < 0.05) blood pressure (79 +/- 3 mmHg) while increasing heart rate (88 +/- 3 bpm). Valsalva maneuver elicited a persistent drop in arterial pressure (no phase IIb recovery) with the absence of a phase IV overshoot during both GLY: -DEX: and TMP conditions. Phenylephrine increased systolic pressure 34 +/- 4 mmHg under GLY: -DEX: and 23 +/- 3 mmHg with TMP (P < 0.05). Heart rate only decreased 1 +/- 2 bpm during GLY: -DEX: and 1 +/- 1 bpm with TMP. Taken together, our results suggest that GLY: -DEX: is a reasonable alternative to TMP for baroreflex inhibition.
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Affiliation(s)
- Brad W Wilkins
- Dept of Anesthesiology, Mayo Clinic, Rochester, MN 55905, USA
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14
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Eisenach JH, Schroeder DR, Pike TL, Johnson CP, Schrage WG, Snyder EM, Johnson BD, Garovic VD, Turner ST, Joyner MJ. Dietary sodium restriction and beta2-adrenergic receptor polymorphism modulate cardiovascular function in humans. J Physiol 2006; 574:955-65. [PMID: 16740612 PMCID: PMC1817745 DOI: 10.1113/jphysiol.2006.112102] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Dietary Na+ intake influences beta2-adrenergic receptor (beta2AR) responsiveness. While receiving a normal Na+ diet (150 mmol day(-1)), subjects homozygous for glycine at amino acid 16 (Gly16) have greater forearm beta2AR-mediated vasodilatation than subjects homozygous for arginine (Arg16), an effect that is mediated by endothelial NO. We tested the hypothesis that dietary Na+ restriction eliminates genotype differences in forearm and systemic beta2AR-mediated dilatation in these groups. We measured heart rate, mean arterial pressure and cardiac output (CO, acetylene breathing) responses to administration of intravenous terbutaline (TRB) before and after 5 days of low dietary Na+ intake (10 mmol day(-1)) in healthy Gly16 (n = 17; age, 31 +/- 7 year) and Arg16 homozygotes (n = 15; age, 29 +/- 8 year). After the low-Na+ diet, a catheter was placed in the brachial artery to measure forearm blood flow (FBF, plethysmography) responses to administration of isoprenaline (isoproterenol) before and after NO inhibition with NG-mono-methyl-L-arginine (L-NMMA). In the Gly16 group, the low-Na+ diet decreased baseline CO from 6.4 +/- 1.4 to 5.5 +/- 1.2 l min(-1) (P = 0.003, paired t test), tended to decrease stroke volume from 97.0 +/- 20.6 to 86.9 +/- 21.7 ml (P = 0.06) and increased peripheral resistance from 1106 +/- 246 to 1246 +/- 222 dynes s cm(-5) (P = 0.02); significant effects of the low-Na+ diet were not observed in Arg16 subjects. In a repeated measures ANOVA, the responses of all cardiovascular measures to systemic administration of TRB were not influenced by genotype or diet. Additionally, the FBF response to incremental doses of isoprenaline did not differ between genotype groups before or after administration of L-NMMA. We conclude that dietary Na+ restriction blunted the increased forearm NO-mediated beta2AR responsiveness in Gly16 homozygotes observed in a previous study after normal dietary Na+ intake, while baseline CO decreased and peripheral resistance increased in this group. This study provides evidence that dietary Na+ modulates effects of the Arg16Gly polymorphism on cardiovascular function.
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Affiliation(s)
- John H Eisenach
- Department of Anaesthesiology, Mayo Clinic College of Medicine, Rochester, MN 55905, USA.
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15
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Freeman R. Assessment of cardiovascular autonomic function. Clin Neurophysiol 2006; 117:716-30. [PMID: 16464634 DOI: 10.1016/j.clinph.2005.09.027] [Citation(s) in RCA: 161] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2004] [Revised: 09/15/2005] [Accepted: 09/23/2005] [Indexed: 12/20/2022]
Abstract
Autonomic assessment has played an important role in elucidating the role of the autonomic nervous system in diverse clinical and research settings. The techniques most widely used in the clinical setting entail the measurement of an end-organ response to a physiological provocation. The non-invasive measures of cardiovascular parasympathetic function involve the analysis of heart rate variability while the measures of cardiovascular sympathetic function assess the blood pressure response to physiological stimuli. Prolonged tilt-table testing, with or without pharmacological provocation, has become an important tool in the investigation of a predisposition to neurally mediated (vasovagal) syncope. Frequency domain analyses of heart rate and blood pressure variability, microneurography, occlusion plethysmography, laser Doppler imaging and flowmetry, and cardiac sympathetic imaging are currently research tools but may find a place in the clinical assessment of autonomic function in the future.
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Affiliation(s)
- Roy Freeman
- Anatomic and Peripheral Neerve Laboratory, Department of Neurology, Beth Israel Deaconess Medical Center, Boston, MA 02215, USA.
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Schroeder C, Vernino S, Birkenfeld AL, Tank J, Heusser K, Lipp A, Benter T, Lindschau C, Kettritz R, Luft FC, Jordan J. Plasma exchange for primary autoimmune autonomic failure. N Engl J Med 2005; 353:1585-90. [PMID: 16221781 DOI: 10.1056/nejmoa051719] [Citation(s) in RCA: 74] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
We report on a patient with long-standing severe autonomic failure that affected his sympathetic and parasympathetic nervous systems. Antibodies against the ganglionic acetylcholine receptors were detected in the serum. Removal of the antibodies by means of plasma exchange resulted in a dramatic clinical improvement.
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Affiliation(s)
- Christoph Schroeder
- Franz Volhard Clinical Research Center and the Max Delbrück Center for Molecular Medicine, Berlin
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17
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Christou DD, Jones PP, Pimentel AE, Seals DR. Increased abdominal-to-peripheral fat distribution contributes to altered autonomic-circulatory control with human aging. Am J Physiol Heart Circ Physiol 2004; 287:H1530-7. [PMID: 15178547 DOI: 10.1152/ajpheart.00322.2004] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Autonomic nervous system (ANS) control of the circulation is altered with aging in adult humans. Similar changes are observed in obesity, particularly abdominal obesity. To determine whether age-associated differences in ANS-circulatory function can be partially explained by increased body fatness, we examined ANS function and three expressions of adiposity (total body fat, abdominal body fat, and abdominal-to-peripheral body fat distribution; dual-energy X-ray absorptiometry) in 43 healthy men: 27 young (25 ± 1 yr) and 16 older (65 ± 1). ANS functions assessed included 1) autonomic support of arterial blood pressure (BP; radial artery catheter), i.e., the reduction in BP during versus before acute ganglionic blockade (GB; intravenous trimethaphan); 2) baroreflex buffering, i.e., the increase in systolic BP with continuous incremental and bolus infusions of phenylephrine during versus before GB; 3) cardiovagal baroreflex sensitivity (Oxford technique); and 4) heart rate variability (time- and frequency-domain analyses). Covarying for abdominal-to-peripheral fat distribution reduced or abolished age-related differences in ANS support of BP, cardiovagal baroreflex sensitivity, and heart rate variability but did not affect age-related differences in baroreflex buffering. Covarying for abdominal and total fat had small selective or no effects on age-associated differences in autonomic-circulatory control. Abdominal-to-peripheral fat distribution explains a significant portion of the variance in a number of autonomic-circulatory functions attributable to aging. Therefore, the development of this fat pattern may contribute to several changes in ANS-cardiovascular function observed with aging. These results may help explain how changes in body fat distribution with advancing age are linked to impairments in circulatory control.
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Affiliation(s)
- Demetra D Christou
- Dept. of Integrative Physiology, University of Colorado at Boulder, UCB 354, Boulder, CO 80309, USA.
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18
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Waring WS, Chui M, Japp A, Nicol EF, Ford MJ. Autonomic cardiovascular responses are impaired in women with irritable bowel syndrome. J Clin Gastroenterol 2004; 38:658-63. [PMID: 15319647 DOI: 10.1097/01.mcg.0000135362.35665.49] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
GOALS This study characterizes cardiovascular autonomic function in women with irritable bowel syndrome (IBS), using standardized techniques. BACKGROUND Autonomic dysfunction is believed to contribute to abnormal gastrointestinal motility and visceral hypersensitivity in IBS. There is mounting evidence of generalized impairment of autonomic activity in patients with IBS. STUDY Thirty women aged 39 years (95% C.I. 25-53 years) diagnosed with IBS, and 30 age-matched healthy women were studied. The ratio of low frequency to high frequency heart rate variability domains (LF:HF ratio) was used to represent cardiac sympathovagal activity, and orthostatic testing and sustained isometric handgrip exercise were used as sympathetic stimuli. Parasympathetic activity was represented by the expiratory to inspiratory R-R interval (E:I) ratio during deep breathing at 6 minutes. RESULTS LF:HF responses to handgrip exercise (316%, C.I. 134% to 498% vs. 107%, C.I. 15% to 153%; P < 0.05) and orthostatic testing (648%, C.I. 520% to 904% vs. 330%, C.I. 140% to 520%; P < 0.05) were higher in IBS patients than controls, and the E:I ratio was significantly lower (1.47, C.I. 1.33-1.61 vs. 1.20, C.I. 1.14-1.26; P < 0.01). CONCLUSIONS Autonomic cardiovascular function is impaired in IBS, manifest as attenuated cardio-vagal tone, and relative sympathetic excess during stimulated conditions.
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Affiliation(s)
- W Stephen Waring
- Clinical Pharmacology Unit and Research Centre, University of Edinburgh.
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19
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Diedrich A, Jordan J, Tank J, Shannon JR, Robertson R, Luft FC, Robertson D, Biaggioni I. The sympathetic nervous system in hypertension: assessment by blood pressure variability and ganglionic blockade. J Hypertens 2003; 21:1677-86. [PMID: 12923400 DOI: 10.1097/00004872-200309000-00017] [Citation(s) in RCA: 74] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
OBJECTIVE To determine if the contribution of the sympathetic nervous system to blood pressure could be evidenced by low-frequency oscillations of systolic blood pressure (LF(SBP)), reflecting vascular sympathetic modulation, or by the decrease in blood pressure after autonomic blockade. DESIGN We studied multiple system atrophy (MSA) patients, in whom supine hypertension is maintained by residual sympathetic tone ('positive controls'); pure autonomic failure (PAF) patients, in whom supine hypertension is largely independent of sympathetic tone ('negative controls'); essential hypertensive patients (HTN) and normotensive subjects (NTN). RESULTS Supine systolic blood pressure (SBP) was 204 +/- 8, 185 +/- 6, 177 +/- 9 and 130 +/- 4 mmHg in MSA, PAF, HTN and NTN, respectively. LF(SBP) was higher in MSA and HTN (5.7 +/- 1.5 and 5.8 +/- 1.4 mmHg(2) compared to NTN and PAF (3.3 +/- 0.5 and 1.1 +/- 0.5 mmHg(2). Trimethaphan 2-4 mg/min induced complete autonomic blockade and lowered SBP below 125 mmHg in all NTN and all but one MSA (to 111 +/- 3 and 97 +/- 9 mmHg). SBP remained elevated in PAF (164 +/- 7 mmHg). Responses in HTN were variable; SBP decreased below 125 mmHg in three and remained elevated in four patients. The decrease in LF(SBP) correlated with the reduction in SBP, with a steeper slope in MSA and HTN compared to NTN (29.0 +/- 5.5, 8.4 +/- 1.6 and 3.6 +/- 1.2 mmHg/mmH (2), respectively). CONCLUSION Ganglionic blockade, alone or coupled to LF(SBP), discriminated between human models of sympathetic-dependent (MSA) and independent (PAF) hypertension. This approach may aid in assessing the contribution of the sympathetic nervous system in essential hypertension, in which sympathetic dependence is variably expressed.
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Affiliation(s)
- André Diedrich
- Autonomic Dysfunction Center, Vanderbilt University, Nashville, TN 37232-2195, USA
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20
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Carson RP, Diedrich A, Robertson D. Autonomic control after blockade of the norepinephrine transporter: a model of orthostatic intolerance. J Appl Physiol (1985) 2002; 93:2192-8. [PMID: 12391111 DOI: 10.1152/japplphysiol.00033.2002] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Orthostatic intolerance is a debilitating syndrome characterized by tachycardia on assumption of upright posture. The norepinephrine (NE) transporter (NET) has been implicated in a genetic form of the disorder. We assessed the combined central and peripheral effects of pharmacological NET blockade on cardiovascular regulation and baroreflex sensitivity in rats. NE reuptake was blocked chronically in female Sprague-Dawley rats by the NET antagonist desipramine (DMI). Treated animals demonstrated an elevated supine heart rate, reduced tyramine responsiveness, and a reduced plasma ratio of the intraneuronal NE metabolite dihydroxyphenylglycol relative to NE, all of which are consistent with observations in human NET deficiency. Spectral analysis revealed a dramatic decrease in low-frequency spectral power after DMI that was consistent with decreased sympathetic outflow. Stimulation of the baroreflex with the vasodilator nitroprusside revealed an attenuated tachycardia in DMI-treated animals. This indicated that the DMI-induced sympathoinhibitory effects of increased NE in the brain stem predominates over the functional elevation of NE stimulation of peripheral targets. Thus attenuated baroreflex function and reduced sympathetic outflow may contribute to the orthostatic intolerance of severe NET deficiency.
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Affiliation(s)
- Robert P Carson
- Autonomic Dysfunction Center, Vanderbilt University, Nashville, Tennessee 37232-2195, USA
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21
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Garland EM, Hahn MK, Ketch TP, Keller NR, Kim CH, Kim KS, Biaggioni I, Shannon JR, Blakely RD, Robertson D. Genetic basis of clinical catecholamine disorders. Ann N Y Acad Sci 2002; 971:506-14. [PMID: 12438171 DOI: 10.1111/j.1749-6632.2002.tb04515.x] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Norepinephrine and epinephrine are critical determinants of minute-to-minute regulation of blood pressure. Here we review the characterization of two syndromes associated with a genetic abnormality in the noradrenergic pathway. In 1986, we reported a congenital syndrome of undetectable tissue and circulating levels of norepinephrine and epinephrine, elevated levels of dopamine, and absence of dopamine-beta-hydroxylase (DBH). These patients appeared with ptosis and severe orthostatic hypotension and lacked sympathetic noradrenergic function. In two persons with DBH deficiency, we identified seven novel polymorphisms. Both patients are compound heterozygotes for a variant that affects expression of DBH protein via impairment of splicing. Patient 1 also has a missense mutation in DBH exon 2, and patient 2 carries missense mutations in exons 1 and 6. Orthostatic intolerance is a common syndrome affecting young women, presenting with orthostatic tachycardia and symptoms of cerebral hypoperfusion on standing. We tested the hypothesis that abnormal norepinephrine transporter (NET) function might contribute to its etiology. In our proband, we found an elevated plasma norepinephrine with standing that was disproportionate to the increase in levels of dihydroxphenylglycol, as well as impaired norepinephrine clearance and tyramine resistance. Studies of NET gene structure revealed a coding mutation converting a conserved alanine residue in transmembrane domain 9 to proline. Analysis of the protein produced by the mutant cDNA demonstrated greater than 98% reduction in activity relative to normal. The finding of genetic mutations responsible for DBH deficiency and orthostatic intolerance leads us to believe that genetic causes of other autonomic disorders will be found, enabling us to design more effective therapeutic interventions.
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Affiliation(s)
- Emily M Garland
- Department of Pharmacology, Autonomic Dysfunction Center, Department of Medicine, Department of Neurology, Vanderbilt University, Nashville, Tennessee 37232, USA
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22
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Parikh SM, Diedrich A, Biaggioni I, Robertson D. The nature of the autonomic dysfunction in multiple system atrophy. J Neurol Sci 2002; 200:1-10. [PMID: 12127669 DOI: 10.1016/s0022-510x(02)00126-0] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The concept that multiple system atrophy (MSA, Shy-Drager syndrome) is a disorder of the autonomic nervous system is several decades old. While there has been renewed interest in the movement disorder associated with MSA, two recent consensus statements confirm the centrality of the autonomic disorder to the diagnosis. Here, we reexamine the autonomic pathophysiology in MSA. Whereas MSA is often thought of as "autonomic failure", new evidence indicates substantial persistence of functioning sympathetic and parasympathetic nerves even in clinically advanced disease. These findings help explain some of the previously poorly understood features of MSA. Recognition that MSA entails persistent, constitutive autonomic tone requires a significant revision of our concepts of its diagnosis and therapy. We will review recent evidence bearing on autonomic tone in MSA and discuss their therapeutic implications, particularly in terms of the possible development of a bionic baroreflex for better control of blood pressure.
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Affiliation(s)
- Samir M Parikh
- Autonomic Dysfunction Center, Department of Medicine, Vanderbilt University, AA 3228 MCN, Nashville, TN 37232-2195, USA
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Zhang R, Iwasaki K, Zuckerman JH, Behbehani K, Crandall CG, Levine BD. Mechanism of blood pressure and R-R variability: insights from ganglion blockade in humans. J Physiol 2002; 543:337-48. [PMID: 12181304 PMCID: PMC2290470 DOI: 10.1113/jphysiol.2001.013398] [Citation(s) in RCA: 80] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
Spontaneous blood pressure (BP) and R-R variability are used frequently as 'windows' into cardiovascular control mechanisms. However, the origin of these rhythmic fluctuations is not completely understood. In this study, with ganglion blockade, we evaluated the role of autonomic neural activity versus other 'non-neural' factors in the origin of BP and R-R variability in humans. Beat-to-beat BP, R-R interval and respiratory excursions were recorded in ten healthy subjects (aged 30 +/- 6 years) before and after ganglion blockade with trimethaphan. The spectral power of these variables was calculated in the very low (0.0078-0.05 Hz), low (0.05-0.15 Hz) and high (0.15-0.35 Hz) frequency ranges. The relationship between systolic BP and R-R variability was examined by cross-spectral analysis. After blockade, R-R variability was virtually abolished at all frequencies; however, respiration and high frequency BP variability remained unchanged. Very low and low frequency BP variability was reduced substantially by 84 and 69 %, respectively, but still persisted. Transfer function gain between systolic BP and R-R interval variability decreased by 92 and 88 % at low and high frequencies, respectively, while the phase changed from negative to positive values at the high frequencies. These data suggest that under supine resting conditions with spontaneous breathing: (1) R-R variability at all measured frequencies is predominantly controlled by autonomic neural activity; (2) BP variability at high frequencies (> 0.15 Hz) is mediated largely, if not exclusively, by mechanical effects of respiration on intrathoracic pressure and/or cardiac filling; (3) BP variability at very low and low frequencies (< 0.15 Hz) is probably mediated by both sympathetic nerve activity and intrinsic vasomotor rhythmicity; and (4) the dynamic relationship between BP and R-R variability as quantified by transfer function analysis is determined predominantly by autonomic neural activity rather than other, non-neural factors.
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Affiliation(s)
- Rong Zhang
- Institute for Exercise and Environmental Medicine, Presbyterian Hospital of Dallas, TX 75231, USA
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24
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Hirshoren N, Tzoran I, Makrienko I, Edoute Y, Plawner MM, Itskovitz-Eldor J, Jacob G. Menstrual cycle effects on the neurohumoral and autonomic nervous systems regulating the cardiovascular system. J Clin Endocrinol Metab 2002; 87:1569-75. [PMID: 11932284 DOI: 10.1210/jcem.87.4.8406] [Citation(s) in RCA: 90] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Gonadal hormones may affect homeostatic mechanisms regulating the cardiovascular system. We investigated this relationship at five different crucial hormonal time points along the menstrual cycle. Eight eumenorrheic healthy subjects underwent a battery of autonomic tests, hemodynamics, and volume-regulatory hormone measurements. Fluid-regulatory hormones, plasma renin activity, and aldosterone increased along the luteal phase (P = 0.003 and 0.02, respectively), whereas rest supine-corrected hematocrit declined in the course of the menstrual cycle (P = 0.001). Plasma norepinephrine decreased from 1.4 +/- 0.2 to 0.95 +/- 0.1 nmol/liter (P < 0.02) [early follicular (EF) to late follicular]. Thereafter, concentrations gradually returned to EF levels. Lf to Hf domain ratio (spectral analysis of electrocardiogram) showed a difference from that of norepinephrine. The cardiovagal baroreflex sensitivity increased significantly along the luteal phase (P = 0.04). The dose of isoproterenol required to increase heart rate (HR) 15 beats per minute was 0.19 +/- 0.04 microg during the EF time point, and it increased to 0.39 +/- 0.06 microg during the late luteal time point (P = 0.05). However, blood pressure, HR, and their responses to orthostatic stress remained unchanged. Fluctuations in the ovarian hormones along the menstrual cycle are associated with unchanged blood pressure and HR, despite the significant variations in the different homeostatic mechanisms regulating the cardiovascular system.
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Affiliation(s)
- Nir Hirshoren
- Jacob Recanati Autonomic Dysfunction Center, Department of Medicine "C", Rambam Medical Center, Technion-Israel Institute of Technology, Haifa, Israel
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Jordan J, Tank J, Hohenbleicher H, Toka H, Schröder C, Sharma AM, Luft FC. Heterogeneity of autonomic regulation in hypertension and neurovascular contact. J Hypertens 2002; 20:701-6. [PMID: 11910306 DOI: 10.1097/00004872-200204000-00028] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
OBJECTIVE Brainstem neurovascular contact (NVC) may interfere with central autonomic regulation and contribute to essential hypertension. We have previously shown that patients with autosomal-dominant hypertension, brachydactyly, and NVC feature extreme phenylephrine hypersensitivity due to impaired baroreflex buffering. We tested the hypothesis that similar abnormalities are present in patients with essential hypertension who have NVC. METHODS Six patients with NVC and essential hypertension and five patients with NVC and monogenic hypertension and brachydactyly were studied. Responses to incremental phenylephrine doses were assessed before and during ganglionic blockade with trimethaphan. RESULTS Supine blood pressure was 172 +/- 8.8/89 +/- 6.1 mmHg before ganglionic blockade. Blood pressure decreased 47 +/- 5/18 +/- 3 mmHg with trimethaphan (16 +/- 4.4/4 +/- 4.0 mmHg in autosomal-dominant hypertension, P < 0.05). Before ganglionic blockade, 25 microg phenylephrine increased systolic blood pressure 17 +/- 4 mmHg in patients with essential hypertension and 30 +/- 3 mmHg in patients with autosomal-dominant hypertension (P < 0.05). During ganglionic blockade, the same dose increased systolic blood pressure 32 +/- 1 and 33 +/- 4 mmHg in patients with essential and with autosomal-dominant hypertension, respectively (NS). CONCLUSIONS Phenylephrine hypersensitivity due to baroreflex dysfunction is uncommon in patients with essential hypertension and NVC. This finding may suggest that the effect of NVC on autonomic regulation is heterogeneous. An alternative explanation is that radiological NVC is not necessarily functionally relevant.
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Affiliation(s)
- Jens Jordan
- Helios Klinikum-Berlin, Franz-Volhard Clinic and Clinical Research Center, Medical Faculty of the Charité, Humboldt-University, Berlin, Germany.
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Deschamps A, Backman SB, Novak V, Plourde G, Fiset P, Chartrand D. Effects of the anticholinesterase edrophonium on spectral analysis of heart rate and blood pressure variability in humans. J Pharmacol Exp Ther 2002; 300:112-7. [PMID: 11752105 DOI: 10.1124/jpet.300.1.112] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Edrophonium, an anticholinesterase, exerts a biphasic effect on cardiovascular autonomic drive in humans (lower doses enhance; higher doses reduce). Twenty-five anesthetized, mechanically respired (10 breaths. min(-1), constant tidal volume) patients were given either saline (n = 10) or edrophonium (0.01-1.0 mg. kg(-1), n = 15) following surgery. ECG, radial arterial pressure, and respiratory rate were sampled at 250 Hz to obtain time series for consecutive R-R intervals (RRIs), and systolic (SBP) and diastolic blood pressure (DBP). A Wigner distribution was used for time frequency mapping of spectral powers at high (HFP, 0.15-0.5 Hz) and low (LFP, 0.0-0.05 Hz) frequency. Edrophonium produced a dose-dependent decrease in heart rate [baseline 66.8 +/- 1.9 (S.E.M.) beats per minute; maximum decrease to 55.8 +/- 1.4 beats per minute with 1.0 mg. kg(-1), P < 0.01]. HFP of the RRI increased at low doses (0.2-0.4 mg. kg(-1); maximum increase to 111.0 +/- 58.2% baseline; P < 0.01) but decreased (-49.5 +/- 35.5% baseline; P < 0.01) at higher (1.0 mg. kg(-1)) doses. Edrophonium had no effect on SBP and DBP. HFP of SBP decreased with increasing doses (maximal decrease to -26.2 +/- 7.5% baseline, P < 0.01, 1.0 mg. kg(-1)). LFP of SBP was also decreased (-46.3 +/- 10.9% baseline, P < 0.01, 1.0 mg. kg(-1)). Edrophonium may enhance (lower dose) or reduce (higher dose) cardiovascular autonomic drive in humans, as evidenced by the significant changes it evokes in HFP of the RRI (parasympathetic drive), and in the HFP and LFP of SBP (sympathetic drive). These observations may account for the modest autonomic side effects of edrophonium when this drug is used clinically.
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Affiliation(s)
- Alain Deschamps
- Department of Anesthesia, Royal Victoria Hospital, McGill University, Montreal, Quebec, Canada
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27
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Tank J, Toka O, Toka HR, Jordan J, Diedrich A, Busjahn A, Luft FC. Autonomic nervous system function in patients with monogenic hypertension and brachydactyly: a field study in north-eastern Turkey. J Hum Hypertens 2001; 15:787-92. [PMID: 11687923 DOI: 10.1038/sj.jhh.1001271] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2000] [Revised: 06/05/2001] [Accepted: 06/13/2001] [Indexed: 11/09/2022]
Abstract
Laboratory studies in patients with autosomal-dominant hypertension and brachydactyly showed increased sensitivity to sympathetic stimuli and severe abnormalities in baroreflex buffering. To further elucidate the mechanisms by which impaired baroreflex sensitivity could influence blood pressure (BP), we conducted autonomic testing under field conditions. We studied 17 hypertensive affected (13 to 48 years, BMI 22.7 +/- 6.5 kg/m(2), 160 +/- 23/98 +/- 15 mm Hg) and 12 normotensive non-affected (9 to 60 years, BMI 24.0 +/- 4.7 kg/m(2), 120 +/- 16/70 +/- 10 mm Hg) family members. Pulse intervals and finger BP were measured using the Portapres device. Valsalva ratio, the blood pressure overshoot during phase IV of the Valsalva manoeuver, the Ewing coefficient (RR30/15 ratio), and heart rate and BP variability were similar in affected and non-affected family members. Overall, baroreflex sensitivity calculated using the cross-spectral (BRSLF, BRSHF) and sequence techniques (BRS+, BRS-) was not different between the groups. However, in younger family members, BRS+ was 12 +/- 3.7 and 22 +/- 13 msec/mm Hg in affected and in non-affected family members, respectively. The decline in BRS with age and with increasing blood pressure was absent in affected family members. We conclude that autonomic reflex testing conducted under field conditions is not impaired in patients with monogenic hypertension and brachydactyly. However, noninvasive testing showed impaired baroreflex control of heart rate at a young age. The reduced BRS in young family members with moderate arterial hypertension may suggest that the impaired baroreflex function is not secondary to the hypertension but rather a primary abnormality, which aggravates the progression of hypertension.
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Affiliation(s)
- J Tank
- Clinical Research Center, Franz Volhard Clinic, Helios Kliniken-Berlin Medical Faculty of the Charité Humboldt-University, Berlin, Germany
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28
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Robertson D, Flattem N, Tellioglu T, Carson R, Garland E, Shannon JR, Jordan J, Jacob G, Blakely RD, Biaggioni I. Familial orthostatic tachycardia due to norepinephrine transporter deficiency. Ann N Y Acad Sci 2001; 940:527-43. [PMID: 11458707 DOI: 10.1111/j.1749-6632.2001.tb03703.x] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
UNLABELLED Orthostatic intolerance (OI) or postural tachycardia syndrome (POTS) is a syndrome primarily affecting young females, and is characterized by lightheadedness, palpitations, fatigue, altered mentation, and syncope primarily occurring with upright posture and being relieved by lying down. There is typically tachycardia and raised plasma norepinephrine levels on upright posture, but little or no orthostatic hypotension. The pathophysiology of OI is believed to be very heterogeneous. Most studies of the syndrome have focused on abnormalities in norepinephrine release. Here the hypothesis that abnormal norepinephrine transporter (NET) function might contribute to the pathophysiology in some patients with OI was tested. In a proband with significant orthostatic symptoms and tachycardia, disproportionately elevated plasma norepinephrine with standing, impaired systemic, and local clearance of infused tritiated norepinephrine, impaired tyramine responsiveness, and a dissociation between stimulated plasma norepinephrine and DHPG elevation were found. Studies of NET gene structure in the proband revealed a coding mutation that converts a highly conserved transmembrane domain Ala residue to Pro. Analysis of the protein produced by the mutant cDNA in transfected cells demonstrated greater than 98% reduction in activity relative to normal. NE, DHPG/NE, and heart rate correlated with the mutant allele in this family. CONCLUSION These results represent the first identification of a specific genetic defect in OI and the first disease linked to a coding alteration in a Na+/Cl(-)-dependent neurotransmitter transporter. Identification of this mechanism may facilitate our understanding of genetic causes of OI and lead to the development of more effective therapeutic modalities.
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Affiliation(s)
- D Robertson
- Autonomic Dysfunction Center, AA3228 MCN, Vanderbilt University, Nashville, TN 37232-2195, USA.
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Abstract
Nonpharmacologic and pharmacologic treatment can significantly attenuate the symptoms of orthostatic hypotension. Some of the interventions that are used to treat orthostatic hypotension have been known for decades. However, several new treatment strategies have been developed in recent years. New knowledge about the pathophysiology of orthostatic syndromes has been gathered that will strongly influence the way treatments are tailored to individual patients. For example, patients with and without residual autonomic function exhibit differential responses to certain treatments. A large subgroup of patients with severe autonomic failure show a profound pressor response to water drinking. This simple effect can be exploited to treat orthostatic and postprandial hypotension in some patients. New bioengineering technologies that attempt to replicate normal baroreflex mechanisms may become available for selected patients with central autonomic dysfunction.
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Affiliation(s)
- J Jordan
- Franz-Volhard-Clinic, Haus 129, Humboldt University, Wiltbergstr. 50, 13125 Berlin, Germany.
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30
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Shannon JR, Flattem NL, Jordan J, Jacob G, Black BK, Biaggioni I, Blakely RD, Robertson D. Orthostatic intolerance and tachycardia associated with norepinephrine-transporter deficiency. N Engl J Med 2000; 342:541-9. [PMID: 10684912 DOI: 10.1056/nejm200002243420803] [Citation(s) in RCA: 447] [Impact Index Per Article: 18.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
BACKGROUND Orthostatic intolerance is a syndrome characterized by lightheadedness, fatigue, altered mentation, and syncope and associated with postural tachycardia and plasma norepinephrine concentrations that are disproportionately high in relation to sympathetic outflow. We tested the hypothesis that impaired functioning of the norepinephrine transporter contributes to the pathophysiologic mechanism of orthostatic intolerance. METHODS In a patient with orthostatic intolerance and her relatives, we measured postural blood pressure, heart rate, plasma catecholamines, and systemic norepinephrine spillover and clearance, and we sequenced the norepinephrine-transporter gene and evaluated its function. RESULTS The patient had a high mean plasma norepinephrine concentration while standing, as compared with the mean (+/-SD) concentration in normal subjects (923 vs. 439+/-129 pg per milliliter [5.46 vs. 2.59+/-0.76 nmol per liter]), reduced systemic norepinephrine clearance (1.56 vs. 2.42+/-0.71 liters per minute), impairment in the increase in the plasma norepinephrine concentration after the administration of tyramine (12 vs. 56+/-63 pg per milliliter [0.07 vs. 0.33+/-0.37 pmol per liter]), and a disproportionate increase in the concentration of plasma norepinephrine relative to that of dihydroxyphenylglycol. Analysis of the norepinephrine-transporter gene revealed that the proband was heterozygous for a mutation in exon 9 (encoding a change from guanine to cytosine at position 237) that resulted in more than a 98 percent loss of function as compared with that of the wild-type gene. Impairment of synaptic norepinephrine clearance may result in a syndrome characterized by excessive sympathetic activation in response to physiologic stimuli. The mutant allele in the proband's family segregated with the postural heart rate and abnormal plasma catecholamine homeostasis. CONCLUSIONS Genetic or acquired deficits in norepinephrine inactivation may underlie hyperadrenergic states that lead to orthostatic intolerance.
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Affiliation(s)
- J R Shannon
- Autonomic Dysfunction Center, Department of Medicine, Vanderbilt University, Nashville 37232-2195, USA
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Jordan J, Shannon JR, Black BK, Ali Y, Farley M, Costa F, Diedrich A, Robertson RM, Biaggioni I, Robertson D. The pressor response to water drinking in humans : a sympathetic reflex? Circulation 2000; 101:504-9. [PMID: 10662747 DOI: 10.1161/01.cir.101.5.504] [Citation(s) in RCA: 240] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
BACKGROUND Water drinking increases blood pressure profoundly in patients with autonomic failure and substantially in older control subjects. The mechanism that mediates this response is not known. METHODS AND RESULTS We studied the effect of drinking tap water on seated blood pressure in 47 patients with severe autonomic failure (28 multiple system atrophy [MSA], 19 pure autonomic failure patients [PAF]). Eleven older controls and 8 young controls served as control group. We also studied the mechanisms that could increase blood pressure with water drinking. Systolic blood pressure increased profoundly with water drinking, reaching a maximum of 33+/-5 mm Hg in MSA and 37+/-7 in PAF mm Hg after 30 to 35 minutes. The pressor response was greater in patients with more retained sympathetic function and was almost completely abolished by trimethaphan infusion. Systolic blood pressure increased by 11+/-2.4 mm Hg in elderly but not in young controls. Plasma norepinephrine increased in both groups. Plasma renin activity, vasopressin, and blood volume did not change in any group. CONCLUSIONS Water drinking significantly and rapidly raises sympathetic activity. Indeed, it raises plasma norepinephrine as much as such classic sympathetic stimuli as caffeine and nicotine. This effect profoundly increases blood pressure in autonomic failure patients, and this effect can be exploited to improve symptoms due to orthostatic hypotension. Water drinking also acutely raises blood pressure in older normal subjects. The pressor effect of oral water is an important yet unrecognized confounding factor in clinical studies of pressor agents and antihypertensive medications.
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Affiliation(s)
- J Jordan
- Clinical Research Center, Franz Volhard Clinic, Berlin, Germany
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Jordan J, Shannon JR, Jacob G, Pohar B, Robertson D. Interaction of genetic predisposition and environmental factors in the pathogenesis of idiopathic orthostatic intolerance. Am J Med Sci 1999; 318:298-303. [PMID: 10555091 DOI: 10.1097/00000441-199911000-00003] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
BACKGROUND The hemodynamic and autonomic abnormalities in idiopathic orthostatic intolerance (IOI) have been studied extensively. However, the mechanisms underlying these abnormalities are not understood. If genetic predisposition were important in the pathogenesis of IOI, monozygotic twins of patients with IOI should have similar hemodynamic and autonomic abnormalities. METHODS We studied two patients with IOI and their identical twins. Both siblings in the first twin pair had orthostatic symptoms, significant orthostatic tachycardia, increased plasma norepinephrine levels with standing, and a greater than normal decrease in systolic blood pressure with trimethaphan infusion. RESULTS Both siblings had a normal response of plasma renin activity to upright posture. In the second twin pair, only one sibling had symptoms of orthostatic intolerance, an orthostatic tachycardia, and raised plasma catecholamines with standing. The affected sibling had inappropriately low plasma renin activity with standing and was 8-fold more sensitive to the pressor effect of phenylephrine than the unaffected sibling. CONCLUSIONS We conclude that in some patients, IOI seems to be strongly influenced by genetic factors. In others, however, IOI may be mainly caused by nongenetic factors. These findings suggest that IOI is heterogenous, and that both genetic and environmental factors contribute individually or collectively to create the IOI phenotype.
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Affiliation(s)
- J Jordan
- Clinical Research Center, Franz Volhard Clinic at the Max Delbrueck Centrum, Berlin, Germany
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Jordan J, Shannon JR, Jacob G, Pohar B, Robertson D. Interaction of Genetic Predisposition and Environmental Factors in the Pathogenesis of Idiopathic Orthostatic Intolerance. Am J Med Sci 1999. [DOI: 10.1016/s0002-9629(15)40642-1] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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Abstract
Sympathetic factors play a central role not only in cardiovascular homeostatic control but also in the pathogenesis and/or in the progression of several cardiovascular diseases, such as essential hypertension, myocardial infarction, cardiac arrhythmias and congestive heart failure. This explains why assessment of adrenergic neural function in humans has been, and certainly still remains, one of the major fields in cardiovascular research. The present paper will review in detail the haemodynamic, pharmacological, biochemical, neurophysiological, neurochemical and neural imaging techniques by which sympathetic activity is assessed in humans, highlighting the main advantages and limitations of each of them. Although plasma noradrenaline measurement represents a useful guide to assess sympathetic neural function, direct recording of sympathetic nerve traffic via microneurography and noradrenaline radiotracer methods have in recent years largely supplanted the plasma noradrenaline approach. This is because they allow (1) discrimination between the central or peripheral nature of increased plasma noradrenaline levels, and (2) precise estimation of the behaviour of regional sympathetic neural function both under physiological and pathological conditions. In contrast, the approach based on spectral analysis of heart rate and blood pressure signals has been shown to have important limitations which prevent the method from faithfully reflecting sympathetic cardiovascular drive. Neural imaging techniques, which require expensive technical support, allow direct visualization of sympathetic enervation of human organs, thus providing information on the 'in vivo' metabolism of noradrenaline in different cardiovascular districts. Although technical improvements have allowed a more precise assessment of human adrenergic function, no technique so far available can be viewed as a 'gold standard' with which the others might be compared. Limitations and disadvantages of the various techniques may be reduced if these methods are seen as being complementary and employed in combination, allowing more reliable information to be achieved on the sympathetic abnormalities characterizing cardiovascular diseases, and thus hopefully providing a stronger rationale for newer therapeutic approaches involving pharmacological modification of the sympathetic nervous system and adrenoreceptors.
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Affiliation(s)
- G Grassi
- Università di Milano, Centro de Fisiologia Clinica e Ipertensione IRCCS, Ospedale Maggiore, Milano, Italy
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Sato T, Kawada T, Inagaki M, Shishido T, Takaki H, Sugimachi M, Sunagawa K. New analytic framework for understanding sympathetic baroreflex control of arterial pressure. THE AMERICAN JOURNAL OF PHYSIOLOGY 1999; 276:H2251-61. [PMID: 10362709 DOI: 10.1152/ajpheart.1999.276.6.h2251] [Citation(s) in RCA: 58] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The sympathetic baroreflex is an important feedback system in stabilization of arterial pressure. This system can be decomposed into the controlling element (mechanoneural arc) and the controlled element (neuromechanical arc). We hypothesized that the intersection of the two operational curves representing their respective functions on an equilibrium diagram should define the operating point of the arterial baroreflex. Both carotid sinuses were isolated in 16 halothane-anesthetized rats. The vagi and aortic depressor nerves were cut bilaterally. Carotid sinus pressure (CSP) was sequentially altered in 10-mmHg increments from 80 to 160 mmHg while sympathetic efferent nerve activity (SNA) and systemic arterial pressure (SAP) were recorded simultaneously under various hemorrhagic conditions. The mechanoneural arc was characterized by the response of SNA to CSP and the neuromechanical arc by the response of SAP to SNA. We parametrically analyzed the relationship between input and output for each arc using a four-parameter logistic equation model. In baseline states, the two arcs intersected each other at the point at which the instantaneous gain of each arc attained its maximum. Severe hemorrhage lowered the gain and offset of the neuromechanical arc and moved the operating point, whereas the mechanoneural arc remained unchanged. The operating points measured under the closed-loop conditions were indistinguishable from those estimated from the intersections of the two arc curves on the equilibrium diagram. The average root mean square errors of estimate for arterial pressure and SNA were 2 and 3%, respectively. Such an analytic approach could explain a mechanism for the determination of the operating point of the sympathetic baroreflex system and thus helps us integratively understand its function.
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Affiliation(s)
- T Sato
- Department of Cardiovascular Dynamics, National Cardiovascular Center Research Institute, Suita, Osaka 565-8565, Japan
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Jordan J, Shannon JR, Pohar B, Paranjape SY, Robertson D, Robertson RM, Biaggioni I. Contrasting effects of vasodilators on blood pressure and sodium balance in the hypertension of autonomic failure. J Am Soc Nephrol 1999; 10:35-42. [PMID: 9890307 DOI: 10.1681/asn.v10135] [Citation(s) in RCA: 81] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022] Open
Abstract
Supine hypertension, which is very common in patients with autonomic failure, limits the use of pressor agents and induces nighttime natriuresis. In 13 patients with severe orthostatic hypotension due to autonomic failure (7 women, 6 men, 72 +/- 3 yr) and supine hypertension, the effect of 30 mg nifedipine (n = 10) and 0.025 to 0.2 mg/h nitroglycerin patch (n = 11) on supine BP, renal sodium handling, and orthostatic tolerance was determined. Medications were given at 8 p.m.; patients stood up at 8 a.m. Nitroglycerin was removed at 6 a.m. Compared with placebo, nifedipine and nitroglycerin decreased systolic BP during the night by a maximum of 37 +/- 9 and 36 +/- 10 mmHg, respectively (P < 0.01). At 8 a.m., supine systolic BP was 23 +/- 7 mmHg lower with nifedipine than with placebo (P < 0.05), but was similar with nitroglycerin and placebo. Sodium excretion during the night was not reduced with nitroglycerin (0.13 +/- 0.02 mmol/mg creatinine [Cr] versus 0.15 +/- 0.03 mmol/mg Cr with placebo), but it was increased with nifedipine (0.35 +/- 0.06 mmol/mg Cr versus 0.13 +/- 0.02 mmol/mg Cr with placebo, P < 0.05). Nifedipine but not nitroglycerin worsened orthostatic hypotension in the morning. It is concluded that nifedipine and transdermal nitroglycerin are effective in controlling supine hypertension in patients with autonomic failure. However, nifedipine has a prolonged depressor effect and worsens orthostatic hypotension in the morning. The decrease in pressure natriuresis that would be expected with the substantial decrease in BP obtained with nitroglycerin and nifedipine may be offset by a direct effect of both drugs on renal sodium handling.
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Affiliation(s)
- J Jordan
- Clinical Research Center, Franz Volhard Clinic, Berlin, Germany
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Jordan J, Shannon JR, Biaggioni I, Norman R, Black BK, Robertson D. Contrasting actions of pressor agents in severe autonomic failure. Am J Med 1998; 105:116-24. [PMID: 9727818 DOI: 10.1016/s0002-9343(98)00193-4] [Citation(s) in RCA: 108] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
BACKGROUND Orthostatic hypotension is the most disabling symptom of autonomic failure. The choice of a pressor agent is largely empiric, and it would be of great value to define predictors of a response. PATIENTS AND METHODS In 35 patients with severe orthostatic hypotension due to multiple system atrophy or pure autonomic failure, we determined the effect on seated systolic blood pressure (SBP) of placebo, phenylpropanolamine (12.5 mg and 25 mg), yohimbine (5.4 mg), indomethacin (50 mg), ibuprofen (600 mg), caffeine (250 mg), and methylphenidate (5 mg). In a subgroup of patients, we compared the pressor effect of midodrine (5 mg) with the effect of phenylpropanolamine (12.5 mg). RESULTS There were no significant differences in the pressor responses between patients with multiple system atrophy or pure autonomic failure. When compared with placebo, the pressor response was significant for phenylpropanolamine, yohimbine, and indomethacin. In a subgroup of patients, we confirmed that this pressor effect of phenylpropanolamine, yohimbine, and indomethacin corresponded to a significant increase in standing SBP. The pressor responses to ibuprofen, caffeine, and methylphenidate were not significantly different from placebo. Phenylpropanolamine and midodrine elicited similar pressor responses. There were no significant associations between drug response and autonomic function testing, postprandial hypotension, or plasma catecholamine levels. CONCLUSIONS We conclude that significant increases in systolic blood pressure can be obtained in patients with orthostatic hypotension due to primary autonomic failure with phenylpropanolamine in low doses or yohimbine or indomethacin in moderate doses. The response to a pressor agent cannot be predicted by autonomic function testing or plasma catecholamines. Therefore, empiric testing with a sequence of medications, based on the risk of side effects in the individual patient and the probability of a response, is a useful approach.
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Affiliation(s)
- J Jordan
- Clinical Research Center, Franz Volhard Clinic, Berlin, Germany
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