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Tymko MM, Drapeau A, Vieira-Coelho MA, Labrecque L, Imhoff S, Coombs GB, Langevin S, Fortin M, Châteauvert N, Ainslie PN, Brassard P. Acute isometric and dynamic exercise do not alter cerebral sympathetic nerve activity in healthy humans. J Cereb Blood Flow Metab 2024:271678X241248228. [PMID: 38613232 DOI: 10.1177/0271678x241248228] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 04/14/2024]
Abstract
The impact of physiological stressors on cerebral sympathetic nervous activity (SNA) remains controversial. We hypothesized that cerebral noradrenaline (NA) spillover, an index of cerebral SNA, would not change during both submaximal isometric handgrip (HG) exercise followed by a post-exercise circulatory occlusion (PECO), and supine dynamic cycling exercise. Twelve healthy participants (5 females) underwent simultaneous blood sampling from the right radial artery and right internal jugular vein. Right internal jugular vein blood flow was measured using Duplex ultrasound, and tritiated NA was infused through the participants' right superficial forearm vein. Heart rate was recorded via electrocardiogram and blood pressure was monitored using the right radial artery. Total NA spillover increased during HG (P = 0.049), PECO (P = 0.006), and moderate cycling exercise (P = 0.03) compared to rest. Cerebral NA spillover remained unchanged during isometric HG exercise (P = 0.36), PECO after the isometric HG exercise (P = 0.45), and during moderate cycling exercise (P = 0.94) compared to rest. These results indicate that transient increases in blood pressure during acute exercise involving both small and large muscle mass do not engage cerebral SNA in healthy humans. Our findings suggest that cerebral SNA may be non-obligatory for exercise-related cerebrovascular adjustments.
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Affiliation(s)
- Michael M Tymko
- Integrative Cerebrovascular and Environmental Physiology SB Laboratory, Department of Human Health and Nutritional Sciences, College of Biological Science, University of Guelph, Guelph, Canada
- Department of Medicine, Faculty of Medicine, University of British Columbia, Vancouver, Canada
| | - Audrey Drapeau
- Department of Kinesiology, Faculty of Medicine, Université Laval, Québec, Canada
- Institut universitaire de cardiologie et de pneumologie de Québec-Université Laval, Québec, Canada
| | - Maria Augusta Vieira-Coelho
- Department of Biomedicine, Pharmacology and Therapeutics Unit, Faculty of Medicine, University of Porto, Portugal
- Department of Psychiatry and Mental Health, University Hospital Center of São João, Porto, Portugal
| | - Lawrence Labrecque
- Department of Kinesiology, Faculty of Medicine, Université Laval, Québec, Canada
- Institut universitaire de cardiologie et de pneumologie de Québec-Université Laval, Québec, Canada
| | - Sarah Imhoff
- Department of Kinesiology, Faculty of Medicine, Université Laval, Québec, Canada
- Institut universitaire de cardiologie et de pneumologie de Québec-Université Laval, Québec, Canada
| | - Geoff B Coombs
- Department of Kinesiology, Faculty of Science, McMaster University, Hamilton, Canada
| | - Stephan Langevin
- Institut universitaire de cardiologie et de pneumologie de Québec-Université Laval, Québec, Canada
| | - Marc Fortin
- Institut universitaire de cardiologie et de pneumologie de Québec-Université Laval, Québec, Canada
| | - Nathalie Châteauvert
- Institut universitaire de cardiologie et de pneumologie de Québec-Université Laval, Québec, Canada
| | - Philip N Ainslie
- Centre for Heart, Lung and Vascular Health, School of Health and Exercise Sciences, University of British Columbia - Okanagan, Kelowna, Canada
| | - Patrice Brassard
- Department of Kinesiology, Faculty of Medicine, Université Laval, Québec, Canada
- Institut universitaire de cardiologie et de pneumologie de Québec-Université Laval, Québec, Canada
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Geißler CF, Friehs MA, Frings C, Domes G. Time-dependent effects of acute stress on working memory performance: A systematic review and hypothesis. Psychoneuroendocrinology 2023; 148:105998. [PMID: 36493660 DOI: 10.1016/j.psyneuen.2022.105998] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/16/2022] [Revised: 12/01/2022] [Accepted: 12/01/2022] [Indexed: 12/12/2022]
Abstract
Laboratory procedures such as the Trier Social Stress Test or the (Socially Evaluated) Cold Pressor Test have been used to investigate working memory performance under stress. Researchers so far have reported a diverse spectrum of stress effects (including the lack thereof) on working memory tasks. We conducted a systematic review of the effect acute stress on working memory performance in standardized laboratory procedures. An overview of the existing literature suggests that acute stress affects working memory in a time-dependent manner, presumably due to the differing time scales of the main stress-reactive hormones involved. Based on the empirical evidence, we hypothesize that the immediate stress-induced release of noradrenaline decreases working memory performance within the first 10 min post stress. In addition, rapid cortisol effects impair working memory at a later time-interval beginning about 25 min post stress. We outline future research directions which could further explore the implications of our insights, as for example combined pharmacological and naturalistic stressor interventions.
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Affiliation(s)
| | - Maximilian A Friehs
- School of Psychology, University College Dublin, Ireland; Lise-Meitner Research Group Cognition and Plasticity, Max-Planck-Institute for Human and Cognitive Brain Science, Germany
| | - Christian Frings
- Department of Cognitive Psychology, University of Trier, Germany
| | - Gregor Domes
- Department of Biological and Clinical Psychology, University of Trier, Germany; Institute of Psychobiology, University of Trier, Germany.
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Sympathetic and baroreflex alterations in congestive heart failure with preserved, midrange and reduced ejection fraction. J Hypertens 2020; 37:443-448. [PMID: 30020242 DOI: 10.1097/hjh.0000000000001856] [Citation(s) in RCA: 41] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
AIM Although abnormalities in reflex sympathetic neural function represent a hallmark of heart failure, no information is available on the neuroadrenergic and baroreflex function in heart failure with preserved, midrange and reduced ejection fraction. The current study was designed to assess muscle sympathetic nerve traffic (MSNA) and baroreflex function in the clinical classes of heart failure defined by the new European Society of Cardiology/American College of Cardiology Foundation/American Heart Association guidelines. METHODS In 32 treated heart failure patients aged 69.3 ± 1.1 (mean ± SEM) classified according to new heart failure guidelines, we measured MSNA (microneurography), spontaneous baroreflex sensitivity and venous plasma norepinephrine (HPLC). Fourteen age-matched healthy individuals represented the control group. RESULTS MSNA was progressively and significantly increased from controls to heart failure conditions characterized by preserved, midrange and reduced ejection fraction (40.4 ± 2.5, 55.6 ± 2.1, 70.4 ± 3 and 78.6 ± 2.6 bursts/100 heart beats, P < 0.01). In contrast, plasma norepinephrine was significantly increased in heart failure with reduced ejection fraction only. Baroreflex sensitivity was significantly reduced in the latter two clinical conditions and almost unaltered in heart failure with preserved ejection fraction. There was an inverse relationship between different markers of adrenergic activity (MSNA, heart rate and plasma norepinephrine), left ventricular ejection fraction and baroreflex function. Brain natriuretic peptides were directly and significantly related to MSNA and plasma norepinephrine. CONCLUSION Thus clinical categories of heart failure patients defined by the new European Society of Cardiology/American College of Cardiology Foundation/American Heart Association classification share as a common pathophysiological link the marked overactivity of the sympathetic nervous system, whose magnitude is significantly and strongly related to the impairment of the left ventricular ejection fraction. A baroreflex dysfunction accompanies in the more severe heart failure state the neuroadrenergic activation.
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Lambert GW, Schlaich MP, Eikelis N, Lambert EA. Sympathetic activity in obesity: a brief review of methods and supportive data. Ann N Y Acad Sci 2019; 1454:56-67. [PMID: 31268175 DOI: 10.1111/nyas.14140] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2019] [Revised: 05/11/2019] [Accepted: 05/23/2019] [Indexed: 12/12/2022]
Abstract
The increase in the prevalence of obesity and the concomitant rise in obesity-related illness have led to substantial pressure on health care systems throughout the world. While the combination of reduced exercise, increased sedentary time, poor diet, and genetic predisposition is undoubtedly pivotal in generating obesity and increasing disease risk, a large body of work indicates that the sympathetic nervous system (SNS) contributes to obesity-related disease development and progression. In obesity, sympathetic nervous activity is regionalized, with activity in some outflows being particularly sensitive to the obese state, whereas other outflows, or responses to stimuli, may be blunted, thereby making the assessment of sympathetic nervous activation in the clinical setting difficult. Isotope dilution methods and direct nerve recording techniques have been developed and utilized in clinical research, demonstrating that in obesity there is preferential activation of the muscle vasoconstrictor and renal sympathetic outflows. With weight loss, sympathetic activity is reduced. Importantly, sympathetic nervous activity is associated with end-organ dysfunction and changes in sympathetic activation that accompany weight loss are often reflected in an improvement of end-organ function. Whether targeting the SNS directly improves obesity-related illness remains unknown, but merits further attention.
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Affiliation(s)
- Gavin W Lambert
- The Iverson Health Innovation Research Institute, Swinburne University of Technology, Hawthorn, Victoria, Australia.,The School of Health Sciences, Swinburne University of Technology, Hawthorn, Victoria, Australia
| | - Markus P Schlaich
- Dobney Hypertension Centre, School of Medicine, Royal Perth Hospital Unit, University of Western Australia, Perth, Western Australia, Australia
| | - Nina Eikelis
- The Iverson Health Innovation Research Institute, Swinburne University of Technology, Hawthorn, Victoria, Australia.,The School of Health Sciences, Swinburne University of Technology, Hawthorn, Victoria, Australia
| | - Elisabeth A Lambert
- The Iverson Health Innovation Research Institute, Swinburne University of Technology, Hawthorn, Victoria, Australia.,The School of Health Sciences, Swinburne University of Technology, Hawthorn, Victoria, Australia
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Chen DLT, Brown R, Liess C, Poljak A, Xu A, Zhang J, Trenell M, Jenkins A, Chisholm D, Samocha-Bonet D, Macefield VG, Greenfield JR. Muscle Sympathetic Nerve Activity Is Associated with Liver Insulin Sensitivity in Obese Non-Diabetic Men. Front Physiol 2017; 8:101. [PMID: 28293196 PMCID: PMC5328983 DOI: 10.3389/fphys.2017.00101] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2016] [Accepted: 02/07/2017] [Indexed: 12/14/2022] Open
Abstract
Introduction: Muscle sympathetic nerve activity (MSNA) may play a role in insulin resistance in obesity. However, the direction and nature of the relationship between MSNA and insulin resistance in obesity remain unclear. We hypothesized that resting MSNA would correlate inversely with both muscle and liver insulin sensitivity and that it would be higher in insulin-resistant vs. insulin-sensitive subjects. Materials and methods: Forty-five non-diabetic obese subjects were studied. As no significant relationships were found in women, the data presented in on 22 men aged 48 ± 12 years. Two-step (15 and 80 mU/m2/min) hyperinsulinaemic-euglycaemic clamps were performed using deuterated glucose to determine liver and muscle insulin sensitivity. Clinical and metabolic parameters were assessed. MSNA was measured via a microelectrode inserted percutaneously into the common peroneal nerve. Results: MSNA burst frequency correlated inversely with liver insulin sensitivity (r = −0.53, P = 0.02) and positively with the hepatokines C-reactive protein (CRP) and fibroblast growth factor (FGF)-19 (r = 0.57, P = 0.006, and r = −0.47, P = 0.03, respectively). MSNA burst frequency was lower in Liversen compared to Liverres (27 ± 5 vs. 38 ± 2 bursts per minute; P = 0.03). Muscle insulin sensitivity was unrelated to MSNA. Discussion: Sympathetic neural activation is related to liver insulin sensitivity and circulating hepatokines CRP and FGF-19 in non-diabetic obese men. These results suggest a potential hepato-endocrine-autonomic axis. Future studies are needed to clarify the influence of MSNA on liver insulin sensitivity in men.
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Affiliation(s)
- Daniel L T Chen
- Diabetes and Metabolism Division, Garvan Institute of Medical Research Sydney, NSW, Australia
| | - Rachael Brown
- School of Medicine, University of Western SydneySydney, NSW, Australia; Neuroscience Research AustraliaSydney, NSW, Australia
| | - Carsten Liess
- Philips Healthcare Luebeckertordamm, Hamburg, Germany
| | - Anne Poljak
- Bioanalytical Mass Spectrometry Facility, UNSW SydneySydney, NSW, Australia; School of Medical Sciences, UNSW SydneySydney, NSW, Australia
| | - Aimin Xu
- State Key Laboratory of Pharmaceutical Biotechnology, University of Hong Kong Hong Kong, Hong Kong
| | - Jialiang Zhang
- State Key Laboratory of Pharmaceutical Biotechnology, University of Hong Kong Hong Kong, Hong Kong
| | | | - Arthur Jenkins
- Diabetes and Metabolism Division, Garvan Institute of Medical ResearchSydney, NSW, Australia; School of Health Science, University of WollongongWollongong, NSW, Australia
| | - Donald Chisholm
- Diabetes and Metabolism Division, Garvan Institute of Medical Research Sydney, NSW, Australia
| | - Dorit Samocha-Bonet
- Diabetes and Metabolism Division, Garvan Institute of Medical ResearchSydney, NSW, Australia; School of Medical Sciences, UNSW SydneySydney, NSW, Australia
| | - Vaughan G Macefield
- School of Medicine, University of Western SydneySydney, NSW, Australia; Neuroscience Research AustraliaSydney, NSW, Australia
| | - Jerry R Greenfield
- Diabetes and Metabolism Division, Garvan Institute of Medical ResearchSydney, NSW, Australia; Department of Endocrinology and Diabetes Center, St. Vincent's HospitalSydney, NSW, Australia
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Grassi G, Seravalle G, Brambilla G, Trabattoni D, Cuspidi C, Corso R, Pieruzzi F, Genovesi S, Stella A, Facchetti R, Spaziani D, Bartorelli A, Mancia G. Blood Pressure Responses to Renal Denervation Precede and Are Independent of the Sympathetic and Baroreflex Effects. Hypertension 2015; 65:1209-16. [DOI: 10.1161/hypertensionaha.114.04823] [Citation(s) in RCA: 57] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2014] [Accepted: 03/05/2015] [Indexed: 01/05/2023]
Affiliation(s)
- Guido Grassi
- From the Clinica Medica, Dipartimento di Scienze Della Salute, Universita` Milano-Bicocca (G.G., G.B., C.C., R.F., G.M.); IRCCS Multimedica, Sesto San Giovanni, Milano, Italy (G.G.); Istituto Auxologico Italiano, Milano, Italy (G.S., C.C., G.M.); Centro Cardiologico Monzino, Milano, Italy (D.T., A.B.); Clinica Nefrologica, Ospedale San Gerardo, Monza, Italy (R.C., F.P., S.G., A.S.); and Unità Operativa di Cardiologia, Ospedale Magenta, Milano, Italy (D.S.)
| | - Gino Seravalle
- From the Clinica Medica, Dipartimento di Scienze Della Salute, Universita` Milano-Bicocca (G.G., G.B., C.C., R.F., G.M.); IRCCS Multimedica, Sesto San Giovanni, Milano, Italy (G.G.); Istituto Auxologico Italiano, Milano, Italy (G.S., C.C., G.M.); Centro Cardiologico Monzino, Milano, Italy (D.T., A.B.); Clinica Nefrologica, Ospedale San Gerardo, Monza, Italy (R.C., F.P., S.G., A.S.); and Unità Operativa di Cardiologia, Ospedale Magenta, Milano, Italy (D.S.)
| | - Gianmaria Brambilla
- From the Clinica Medica, Dipartimento di Scienze Della Salute, Universita` Milano-Bicocca (G.G., G.B., C.C., R.F., G.M.); IRCCS Multimedica, Sesto San Giovanni, Milano, Italy (G.G.); Istituto Auxologico Italiano, Milano, Italy (G.S., C.C., G.M.); Centro Cardiologico Monzino, Milano, Italy (D.T., A.B.); Clinica Nefrologica, Ospedale San Gerardo, Monza, Italy (R.C., F.P., S.G., A.S.); and Unità Operativa di Cardiologia, Ospedale Magenta, Milano, Italy (D.S.)
| | - Daniela Trabattoni
- From the Clinica Medica, Dipartimento di Scienze Della Salute, Universita` Milano-Bicocca (G.G., G.B., C.C., R.F., G.M.); IRCCS Multimedica, Sesto San Giovanni, Milano, Italy (G.G.); Istituto Auxologico Italiano, Milano, Italy (G.S., C.C., G.M.); Centro Cardiologico Monzino, Milano, Italy (D.T., A.B.); Clinica Nefrologica, Ospedale San Gerardo, Monza, Italy (R.C., F.P., S.G., A.S.); and Unità Operativa di Cardiologia, Ospedale Magenta, Milano, Italy (D.S.)
| | - Cesare Cuspidi
- From the Clinica Medica, Dipartimento di Scienze Della Salute, Universita` Milano-Bicocca (G.G., G.B., C.C., R.F., G.M.); IRCCS Multimedica, Sesto San Giovanni, Milano, Italy (G.G.); Istituto Auxologico Italiano, Milano, Italy (G.S., C.C., G.M.); Centro Cardiologico Monzino, Milano, Italy (D.T., A.B.); Clinica Nefrologica, Ospedale San Gerardo, Monza, Italy (R.C., F.P., S.G., A.S.); and Unità Operativa di Cardiologia, Ospedale Magenta, Milano, Italy (D.S.)
| | - Rocco Corso
- From the Clinica Medica, Dipartimento di Scienze Della Salute, Universita` Milano-Bicocca (G.G., G.B., C.C., R.F., G.M.); IRCCS Multimedica, Sesto San Giovanni, Milano, Italy (G.G.); Istituto Auxologico Italiano, Milano, Italy (G.S., C.C., G.M.); Centro Cardiologico Monzino, Milano, Italy (D.T., A.B.); Clinica Nefrologica, Ospedale San Gerardo, Monza, Italy (R.C., F.P., S.G., A.S.); and Unità Operativa di Cardiologia, Ospedale Magenta, Milano, Italy (D.S.)
| | - Federico Pieruzzi
- From the Clinica Medica, Dipartimento di Scienze Della Salute, Universita` Milano-Bicocca (G.G., G.B., C.C., R.F., G.M.); IRCCS Multimedica, Sesto San Giovanni, Milano, Italy (G.G.); Istituto Auxologico Italiano, Milano, Italy (G.S., C.C., G.M.); Centro Cardiologico Monzino, Milano, Italy (D.T., A.B.); Clinica Nefrologica, Ospedale San Gerardo, Monza, Italy (R.C., F.P., S.G., A.S.); and Unità Operativa di Cardiologia, Ospedale Magenta, Milano, Italy (D.S.)
| | - Simonetta Genovesi
- From the Clinica Medica, Dipartimento di Scienze Della Salute, Universita` Milano-Bicocca (G.G., G.B., C.C., R.F., G.M.); IRCCS Multimedica, Sesto San Giovanni, Milano, Italy (G.G.); Istituto Auxologico Italiano, Milano, Italy (G.S., C.C., G.M.); Centro Cardiologico Monzino, Milano, Italy (D.T., A.B.); Clinica Nefrologica, Ospedale San Gerardo, Monza, Italy (R.C., F.P., S.G., A.S.); and Unità Operativa di Cardiologia, Ospedale Magenta, Milano, Italy (D.S.)
| | - Andrea Stella
- From the Clinica Medica, Dipartimento di Scienze Della Salute, Universita` Milano-Bicocca (G.G., G.B., C.C., R.F., G.M.); IRCCS Multimedica, Sesto San Giovanni, Milano, Italy (G.G.); Istituto Auxologico Italiano, Milano, Italy (G.S., C.C., G.M.); Centro Cardiologico Monzino, Milano, Italy (D.T., A.B.); Clinica Nefrologica, Ospedale San Gerardo, Monza, Italy (R.C., F.P., S.G., A.S.); and Unità Operativa di Cardiologia, Ospedale Magenta, Milano, Italy (D.S.)
| | - Rita Facchetti
- From the Clinica Medica, Dipartimento di Scienze Della Salute, Universita` Milano-Bicocca (G.G., G.B., C.C., R.F., G.M.); IRCCS Multimedica, Sesto San Giovanni, Milano, Italy (G.G.); Istituto Auxologico Italiano, Milano, Italy (G.S., C.C., G.M.); Centro Cardiologico Monzino, Milano, Italy (D.T., A.B.); Clinica Nefrologica, Ospedale San Gerardo, Monza, Italy (R.C., F.P., S.G., A.S.); and Unità Operativa di Cardiologia, Ospedale Magenta, Milano, Italy (D.S.)
| | - Domenico Spaziani
- From the Clinica Medica, Dipartimento di Scienze Della Salute, Universita` Milano-Bicocca (G.G., G.B., C.C., R.F., G.M.); IRCCS Multimedica, Sesto San Giovanni, Milano, Italy (G.G.); Istituto Auxologico Italiano, Milano, Italy (G.S., C.C., G.M.); Centro Cardiologico Monzino, Milano, Italy (D.T., A.B.); Clinica Nefrologica, Ospedale San Gerardo, Monza, Italy (R.C., F.P., S.G., A.S.); and Unità Operativa di Cardiologia, Ospedale Magenta, Milano, Italy (D.S.)
| | - Antonio Bartorelli
- From the Clinica Medica, Dipartimento di Scienze Della Salute, Universita` Milano-Bicocca (G.G., G.B., C.C., R.F., G.M.); IRCCS Multimedica, Sesto San Giovanni, Milano, Italy (G.G.); Istituto Auxologico Italiano, Milano, Italy (G.S., C.C., G.M.); Centro Cardiologico Monzino, Milano, Italy (D.T., A.B.); Clinica Nefrologica, Ospedale San Gerardo, Monza, Italy (R.C., F.P., S.G., A.S.); and Unità Operativa di Cardiologia, Ospedale Magenta, Milano, Italy (D.S.)
| | - Giuseppe Mancia
- From the Clinica Medica, Dipartimento di Scienze Della Salute, Universita` Milano-Bicocca (G.G., G.B., C.C., R.F., G.M.); IRCCS Multimedica, Sesto San Giovanni, Milano, Italy (G.G.); Istituto Auxologico Italiano, Milano, Italy (G.S., C.C., G.M.); Centro Cardiologico Monzino, Milano, Italy (D.T., A.B.); Clinica Nefrologica, Ospedale San Gerardo, Monza, Italy (R.C., F.P., S.G., A.S.); and Unità Operativa di Cardiologia, Ospedale Magenta, Milano, Italy (D.S.)
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Simonds SE, Cowley MA. Hypertension in obesity: is leptin the culprit? Trends Neurosci 2013; 36:121-32. [PMID: 23333346 DOI: 10.1016/j.tins.2013.01.004] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2012] [Accepted: 01/07/2013] [Indexed: 01/15/2023]
Abstract
The number of obese or overweight humans continues to increase worldwide. Hypertension is a serious disease that often develops in obesity, but it is not clear how obesity increases the risk of hypertension. However, both obesity and hypertension increase the risk of cardiovascular diseases (CVD). In this review, we examine how obesity may increase the risk of developing hypertension. Specifically, we discuss how the adipose-derived hormone leptin influences the sympathetic nervous system (SNS), through actions in the brain to elevate energy expenditure (EE) while also contributing to hypertension in obesity.
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Affiliation(s)
- Stephanie E Simonds
- Monash Obesity & Diabetes Institute, Department of Physiology, Monash University, Clayton, VIC, Australia
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Kalk NJ, Nutt DJ, Lingford-Hughes AR. The role of central noradrenergic dysregulation in anxiety disorders: evidence from clinical studies. J Psychopharmacol 2011; 25:3-16. [PMID: 20530586 DOI: 10.1177/0269881110367448] [Citation(s) in RCA: 60] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
The nature of the noradrenergic dysregulation in clinical anxiety disorders remains unclear. In panic disorder, the predominant view has been that central noradrenergic neuronal networks and/or the sympathetic nervous system was normal in patients at rest, but hyper-reactive to specific stimuli, for example carbon dioxide. These ideas have been extended to other anxiety disorders, which share with panic disorder characteristic subjective anxiety and physiological symptoms of excess sympathetic activity. For example, Generalized Anxiety Disorder is characterized by chronic free-floating anxiety, muscle tension, palpitation and insomnia. It has been proposed that there is chronic central hypersecretion of noradrenaline in Generalized Anxiety Disorder, with consequent hyporesponsiveness of central post-synaptic receptors. With regards to other disorders, it has been suggested that there is noradrenergic involvement or derangement, but a more specific hypothesis has not been enunciated. This paper reviews the evidence for noradrenergic dysfunction in anxiety disorders, derived from indirect measures of noradrenergic function in clinical populations.
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Affiliation(s)
- N J Kalk
- Department of Psychopharmacology, University of Bristol, Bristol, UK.
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Stener-Victorin E, Jedel E, Janson PO, Sverrisdottir YB. Low-frequency electroacupuncture and physical exercise decrease high muscle sympathetic nerve activity in polycystic ovary syndrome. Am J Physiol Regul Integr Comp Physiol 2009; 297:R387-95. [PMID: 19494176 DOI: 10.1152/ajpregu.00197.2009] [Citation(s) in RCA: 112] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
We have recently shown that polycystic ovary syndrome (PCOS) is associated with high muscle sympathetic nerve activity (MSNA). Animal studies support the concept that low-frequency electroacupuncture (EA) and physical exercise, via stimulation of ergoreceptors and somatic afferents in the muscles, may modulate the activity of the sympathetic nervous system. The aim of the present study was to investigate the effect of these interventions on sympathetic nerve activity in women with PCOS. In a randomized controlled trial, 20 women with PCOS were randomly allocated to one of three groups: low-frequency EA (n = 9), physical exercise (n = 5), or untreated control (n = 6) during 16 wk. Direct recordings of multiunit efferent postganglionic MSNA in a muscle fascicle of the peroneal nerve before and following 16 wk of treatment. Biometric, hemodynamic, endocrine, and metabolic parameters were measured. Low-frequency EA (P = 0.036) and physical exercise (P = 0.030) decreased MSNA burst frequency compared with the untreated control group. The low-frequency EA group reduced sagittal diameter (P = 0.001), while the physical exercise group reduced body weight (P = 0.004) and body mass index (P = 0.004) compared with the untreated control group. Sagittal diameter was related to MSNA burst frequency (Rs = 0.58, P < 0.005) in the EA group. No correlation was found for body mass index and MSNA in the exercise group. There were no differences between the groups in hemodynamic, endocrine, and metabolic variables. For the first time we demonstrate that low-frequency EA and physical exercise lowers high sympathetic nerve activity in women with PCOS. Thus, treatment with low-frequency EA or physical exercise with the aim to reduce MSNA may be of importance for women with PCOS.
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Affiliation(s)
- Elisabet Stener-Victorin
- Institute of Neuroscience and Physiology, Dept. of Physiology, Sahlgrenska Academy, Univ. of Gothenburg, Box 434, SE-405 30 Göteborg, Sweden.
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Kasparov S, Teschemacher AG. Altered central catecholaminergic transmission and cardiovascular disease. Exp Physiol 2008; 93:725-40. [PMID: 18326552 DOI: 10.1113/expphysiol.2007.041814] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Numerous studies, some of which date back more than three decades, have established a link between disorders of the cardiovascular system and the catecholaminergic system of the brain. Central noradrenergic (and putative adrenergic) neurones are involved in numerous brain functions, and there appears to be more than one mechanism via which a dysfunction of central nor/adrenergic signalling may be detrimental to the cardiovascular system. Moreover, in some cases, such as essential hypertension, altered noradrenergic transmission could play a causative role. Numerous controversies are evident throughout the literature, which are very difficult to explain without much better understanding of the basic physiology of central noradrenergic transmission. Recently, using a combination of novel molecular, electrochemical and imaging techniques, we have started to unravel how noradrenergic neurones in the brain store and release their transmitter. Targeted long-term modulation of specific noradrenergic cell groups in defined brain areas using viral gene transfer is helping to clarify the links between central catecholamines and cardiovascular control in health and disease. These studies may reveal new therapeutic strategies for various cardiovascular diseases which are accompanied by heightened sympathetic nerve activity.
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Affiliation(s)
- S Kasparov
- Department of Physiology and Pharmacology, University of Bristol, Bristol BS8 1TD, UK
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11
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Lambert G, Elam M, Friberg P, Lundborg C, Gao S, Bergquist J, Nitescu P. Acute response to intracisternal bupivacaine in patients with refractory pain of the head and neck. J Physiol 2006; 570:421-8. [PMID: 16254013 PMCID: PMC1464318 DOI: 10.1113/jphysiol.2005.095562] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
Continuous intracisternal infusion of bupivacaine for the management of intractable pain of the head and neck is effective in controlling pain in this patient group. With the catheter tip being located at the height of the C1 vertebral body, autonomic regulatory information may also be influenced by the infusion of bupivacaine. By combining direct sampling of cerebrospinal fluid (CSF), via a percutaneously placed catheter in the cisterna magna, with a noradrenaline and adrenaline isotope dilution method for examining sympathetic and adrenal medullary activity, we were able to quantify the release of brain neurotransmitters and examine efferent sympathetic nervous outflow in patients following intracisternal administration of bupivacaine. Despite severe pain, sympathetic and adrenal medullary activities were well within normal range (4.2 +/- 0.6 and 0.7 +/- 0.2 nmol min(-1), respectively, mean +/-S.E.M.). Intracisternal bupivacaine administration caused an almost instantaneous elevation in mean arterial blood pressure, increasing by 17 +/- 7 mmHg after 10 min (P < 0.01). Heart rate increased in parallel (17 +/- 5 beats min(-1)), and these changes coincided with an increase in sympathetic nervous activity, peaking with an approximately 50% increase over resting level 10 min after injection (P < 0.01). CSF levels of GABA were reduced following bupivacaine (P < 0.05). CSF catecholamines and serotonin, and EEG, remained unaffected. These results show that acutely administered bupivacaine in the cisterna magna of chronic pain sufferers leads to an activation of the sympathetic nervous system. The results suggest that the haemodynamic consequences occur as a result of interference with the neuronal circuitry in the brainstem. Although these effects are transient, they warrant caution at the induction of intracisternal local anaesthesia.
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Affiliation(s)
- Gavin Lambert
- Department of Clinical Physiology, Sahlgrenska Hospital, Göteborg, Sweden.
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Boguszewski MCS, Johannsson G, Fortes LC, Sverrisdóttir YB. Low birth size and final height predict high sympathetic nerve activity in adulthood. J Hypertens 2004; 22:1157-63. [PMID: 15167451 DOI: 10.1097/00004872-200406000-00017] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
OBJECTIVE Being born small for gestational age (SGA) is associated with insulin resistance, hypertension and increased cardiovascular morbidity/mortality in adulthood. Sympathetic nerve hyperactivity is a well-known risk factor for cardiovascular disease mortality and is proposed to link insulin resistance with hypertension. The objective of this study was to test the hypothesis that sympathetic nerve activity is altered in individuals born SGA. DESIGN A cross-sectional, comparative study of 20 healthy adults (21-25 years old) born SGA (birth weight < -2SD score for healthy newborns) with normal and short stature, and 12 age, gender and body mass index matched individuals, born appropriate for gestational age (AGA) with normal stature. METHODS Direct recordings of resting sympathetic nerve activity to the muscle vascular bed (MSA) were obtained from the peroneal nerve posterior to the fibular head. Heart rate, respiration and blood pressure were recorded during the microneurographic session. RESULTS MSA was increased in both groups of young adults born SGA as compared to those born AGA (P < 0.05 and P < 0.005, respectively). In the combined study group MSA was inversely correlated to birth weight, length (r = -0.59, P < 0.001 and r = -0.69, P < 0.0005, respectively) and final adult height (r = -0.58; P < 0.001). CONCLUSIONS Being born SGA and achieving a short final height is associated with increased sympathetic nerve traffic. We suggest that the increase in sympathetic nerve traffic in young adults born SGA with normal and short stature may be the link between low birth size, hypertension and cardiovascular morbidity later in life.
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Abstract
Primary aging in adult humans is associated with a progressive, tonic activation of the peripheral sympathetic nervous system (SNS). The purpose of this SNS activation and its physiological impact are, however, unknown. We hypothesize that the chronic stimulation of the SNS with aging is driven in part by a progressive accumulation of body fat. This "error" is sensed by the central nervous system via increases in adiposity-sensitive humoral signals (e.g., leptin, insulin) that cross the blood-brain barrier, activate subcortical areas involved in the regulation of energy balance (e.g., ventromedial hypothalamus), and stimulate SNS outflow to peripheral tissues. The SNS activation is intended to increase beta-adrenergic thermogenesis in order to expend excess energy as heat rather than by storage of fat. Recent evidence, however, indicates that these adjustments are not effective in augmenting energy expenditure with aging. Indeed, older sedentary adults demonstrate reduced, not increased, beta-adrenergic stimulation of metabolic rate because of reduced tissue responsiveness, presumably mediated by SNS-induced impairment of beta-adrenergic signaling. As a result, age-associated SNS activation, initiated as a consequence of accumulating adiposity with the intent of preventing further fat storage, ironically, may in time evolve into a potential mechanism contributing to the development of obesity with aging.
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Affiliation(s)
- Douglas R Seals
- Department of Integrative Physiology, University of Colorado, Boulder, Colorado, USA.
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14
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The effect of growth hormone (GH) replacement therapy on sympathetic nerve hyperactivity in hypopituitary adults. J Hypertens 2003. [DOI: 10.1097/00004872-200310000-00018] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Affiliation(s)
- Christopher J Mathias
- Neurovascular Medicine Unit, Imperial College London at St Mary's Hospital, London, UK.
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Lambert GW. Paring down on Descartes: a review of brain noradrenaline and sympathetic nervous function. Clin Exp Pharmacol Physiol 2001; 28:979-82. [PMID: 11903297 DOI: 10.1046/j.1440-1681.2001.03578.x] [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: 11/20/2022]
Abstract
1. The conceptual framework of mind-body interaction can be traced back to the seminal observations of the French philosopher and mathematician René Descartes (1596-1650). Descartes succeeded in eliminating the soul's apparent physiological role and established the brain as the body's control centre. 2. While the pivotal role played by the central nervous system (CNS) in the maintenance of physiological and psychological health has long been recognized, the development of methods designed for the direct examination of human CNS processes has only recently come to fruition. 3. There exists a substantial body of evidence derived from clinical and experimental studies indicating that CNS monoaminergic cell groups, in particular those using noradrenaline as their neurotransmitter, participate in the excitatory regulation of the sympathetic nervous system and the development and maintenance of the hypertensive state. 4. In essential hypertension, particularly in younger patients, there occurs an activation of sympathetic nervous outflows to the kidneys, heart and skeletal muscle. The existence of a correlation between subcortical brain noradrenaline turnover and total body noradrenaline spillover to plasma, resting blood pressure and heart rate provides further support for the observation that elevated subcortical noradrenergic activity subserves a sympathoexcitatory role in the regulation of sympathetic preganglionic neurons of the thorocolumbar cord.
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Affiliation(s)
- G W Lambert
- Human Neurotransmitter Laboratory, Baker Medical Research Institute, Melbourne, Victoria, Australia.
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Sverrisdóttir YB, Johannsson G, Jungersten L, Wallin BG, Elam M. Is the somatotropic axis related to sympathetic nerve activity in healthy ageing men? J Hypertens 2001; 19:2019-24. [PMID: 11677367 DOI: 10.1097/00004872-200111000-00012] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
OBJECTIVE The mechanisms underlying the age-related increase in blood pressure and sympathetic nerve activity remain largely unknown. The decline in growth hormone (GH) secretion and insulin-like growth factor-I (IGF-I) with age has been related to several cardiovascular risk factors. Low serum IGF-I levels in severe adult GH deficiency is associated with markedly increased sympathetic nerve activity. This study evaluates whether a relationship between serum IGF-I and sympathetic nerve traffic exists in healthy aging men. DESIGN AND METHODS Sympathetic nerve activity to the muscle vascular bed (MSA) was recorded in 56 healthy normotensive males, and related to age (range 21-71 years), body mass index (BMI, range 18.4-32.2), serum IGF-I and plasma nitrate levels. Blood pressure, BMI and MSA increased with age, whereas IGF-I and plasma nitrate decreased. In a forward stepwise multiple regression analysis, age explained 40% of the variability in MSA and excluded other variables. Omitting age, IGF-I became the strongest independent predictor, explaining 23% of the variability in MSA. MSA was an independent predictor of diastolic blood pressure, but its influence (10%) was less than that of BMI (28%). BMI was not related to MSA or IGF-I. CONCLUSIONS Decreased serum IGF-I levels are coupled to increased MSA during ageing, an effect independent from the impact of increased body weight. Although MSA is a weak predictor of rising blood pressure with age, it constitutes one possible pathway for the somatotropic axis to affect cardiovascular function in ageing.
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Affiliation(s)
- Y B Sverrisdóttir
- Department of Clinical Neurophysiology, Sahlgren University Hospital, Göteborg, Sweden.
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Montpetit CJ, McKendry J, Perry SF. The effects of C-type natriuretic peptide on catecholamine release in the pacific spiny dogfish (Squalus acanthias). Gen Comp Endocrinol 2001; 123:210-21. [PMID: 11482942 DOI: 10.1006/gcen.2001.7666] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The interaction between homologous C-type natriuretic peptide (dfCNP) and catecholamine release in cardiovascular control was assessed in the marine dogfish (Squalus acanthias). This was accomplished by evaluation of the dynamics of the dfCNP-elicited secretion of catecholamines in situ and in vivo. With an in situ saline-perfused postcardinal sinus preparation, it was demonstrated that perfusion with saline containing dfCNP (10(-9) mol x L(-1)) did not affect the secretion of either noradrenaline or adrenaline. However, the presence of dfCNP in the perfusate significantly enhanced carbachol-evoked secretion of noradrenaline. In vivo, intravascular injection of dfCNP (10(-9) mol x kg(-1)) caused a biphasic pressor-depressor response consisting of a brief increase in caudal artery blood pressure (P(CA)) followed by a prolonged reduction in P(CA). Furthermore, although systemic resistance initially increased, it was subsequently maintained at baseline values in the face of persistent decreases in both P(CA) and cardiac output. Bolus injection of dfCNP elicited significant increases in plasma noradrenaline levels that peaked within 10 min; plasma adrenaline levels were unaffected. The release of noradrenaline elicited by dfCNP was unaffected by prior blockade of the renin-angiotensin system (RAS) (with the angiotensin converting enzyme inhibitor lisinopril) or by pretreatment with the nicotinic receptor blocker hexamethonium. The delayed decrease in P(CA) was not observed in the hexamethonium-treated fish. Prior blockade of beta-adrenoreceptors (with sotalol) or alpha-adrenoreceptors (with prazosin) either significantly reduced (sotalol) or abolished (prazosin) the increase in plasma noradrenaline levels after dfCNP injection. The results of this investigation demonstrate that the elevation of plasma noradrenaline levels observed in vivo following dfCNP injection is not caused by a direct effect of dfCNP on catecholamine secretion from axillary body chromaffin cells. Furthermore, the dfCNP-mediated increase of plasma noradrenaline appears to be unrelated to changes in P(CA) and is insensitive to blockade of the RAS or nicotinic receptors. However, stimulation of adrenergic receptors, in particular the alpha-adrenoreceptors, appears to be a key mechanism underlying the dfCNP-elicited secretion of noradrenaline.
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Affiliation(s)
- C J Montpetit
- Department of Biology, University of Ottawa, Ottawa, Ontario, K1N 6N5, Canada
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Armario P, Hernández del Rey R, Almendros Ribas M. Papel del sistema nervioso simpático en la etiopatogenia de la hipertensión arterial. HIPERTENSION Y RIESGO VASCULAR 2001. [DOI: 10.1016/s1889-1837(01)71175-0] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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Serrador JM, Picot PA, Rutt BK, Shoemaker JK, Bondar RL. MRI measures of middle cerebral artery diameter in conscious humans during simulated orthostasis. Stroke 2000; 31:1672-8. [PMID: 10884472 DOI: 10.1161/01.str.31.7.1672] [Citation(s) in RCA: 551] [Impact Index Per Article: 23.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
BACKGROUND AND PURPOSE The relationship between middle cerebral artery (MCA) flow velocity (CFV) and cerebral blood flow (CBF) is uncertain because of unknown vessel diameter response to physiological stimuli. The purpose of this study was to directly examine the effect of a simulated orthostatic stress (lower body negative pressure [LBNP]) as well as increased or decreased end-tidal carbon dioxide partial pressure (P(ET)CO(2)) on MCA diameter and CFV. METHODS Twelve subjects participated in a CO(2) manipulation protocol and/or an LBNP protocol. In the CO(2) manipulation protocol, subjects breathed room air (normocapnia) or 6% inspired CO(2) (hypercapnia), or they hyperventilated to approximately 25 mm Hg P(ET)CO(2) (hypocapnia). In the LBNP protocol, subjects experienced 10 minutes each of -20 and -40 mm Hg lower body suction. CFV and diameter of the MCA were measured by transcranial Doppler and MRI, respectively, during the experimental protocols. RESULTS Compared with normocapnia, hypercapnia produced increases in both P(ET)CO(2) (from 36+/-3 to 40+/-4 mm Hg, P<0.05) and CFV (from 63+/-4 to 80+/-6 cm/s, P<0.001) but did not change MCA diameters (from 2.9+/-0.3 to 2.8+/-0.3 mm). Hypocapnia produced decreases in both P(ET)CO(2) (24+/-2 mm Hg, P<0.005) and CFV (43+/-7 cm/s, P<0.001) compared with normocapnia, with no change in MCA diameters (from 2.9+/-0.3 to 2.9+/-0.4 mm). During -40 mm Hg LBNP, P(ET)CO(2) was not changed, but CFV (55+/-4 cm/s) was reduced from baseline (58+/-4 cm/s, P<0.05), with no change in MCA diameter. CONCLUSIONS Under the conditions of this study, changes in MCA diameter were not detected. Therefore, we conclude that relative changes in CFV were representative of changes in CBF during the physiological stimuli of moderate LBNP or changes in P(ET)CO(2).
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Affiliation(s)
- J M Serrador
- Neurovascular Research Laboratory, School of Kinesiology, and the Robarts Research Institute, The University of Western Ontario, London, Ontario, Canada
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Abstract
Although the pivotal role played by the brain in the maintenance of optimal physiologic and psychologic health has long been recognized, methods for the direct examination of human central nervous system processes have only recently been developed. A growing body of evidence indicates that central nervous systemmonoaminergic cell groups, in particular those utilizing norepinephrine as their neurotransmitter, participate in the excitatory regulation of the sympathetic nervous system and the development of the hypertensive state.
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Affiliation(s)
- G W Lambert
- Human Neurotransmitters Laboratory, Baker Medical Research Institute, PO Box 6492, St. Kilda Road Central, Melbourne, Victoria 8008, Australia.
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Abstract
Near-infrared (IR) light easily penetrates biological tissue, and the information offered by in vivo spectroscopy of cerebral oxygenation is detailed and comes with a high temporal resolution. Near-IR light spectroscopy (NIRS) reflects cerebral oxygenation during arterial hypotension, hypoxic hypoxaemia and hypo- and hypercapnia. As determined by dual-wavelength NIRS, the cerebral O2 saturation integrates the arterial O2 content and the cerebral perfusion, and as established for skeletal muscle, NIRS obtains information on tissue oxygenation and metabolism beyond that obtained by venous blood sampling. Caveats of cerebral NIRS include insufficient light shielding, optode displacement and a sample volume including muscle or the frontal sinus mucous membrane. The relative influence from the extracranial tissue is minimized by optode separation and correction for an extracranial sample volume, or both. The natural pigment melatonin and also water are of little influence to spectroscopic analysis of cerebral oxygenation, whereas bilirubin systematically lowers ScO2 and attenuates the detection of changes in cerebral oxygenation. By NIRS, reduction of cytochrome oxidase is demonstrated during hypoxic hypoxaemia and head-up tilt-induced arterial hypotension, but the changes are small. In the clinical setting, NIRS offers useful information in patients with both systemic and local cerebral circulatory impairment, for example, during cranial trauma, surgery on the cerebral arteries, orthostasis and acute heart failure. Whereas mapping of the brain circulation is needed for jugular venous sampling to reflect either global or local oxygenation, the determination of cerebral oxygenation by NIRS has the advantage of localized monitoring of the cerebral cortex.
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Affiliation(s)
- P L Madsen
- Department of Anaesthesia, the Copenhagen Muscle Research Centre, Rigshospitalet 2041, Denmark
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23
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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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Tanaka H, Davy KP, Seals DR. Cardiopulmonary baroreflex inhibition of sympathetic nerve activity is preserved with age in healthy humans. J Physiol 1999; 515 ( Pt 1):249-54. [PMID: 9925894 PMCID: PMC2269118 DOI: 10.1111/j.1469-7793.1999.249ad.x] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
1. We tested the hypothesis that the ability of the cardiopulmonary baroreflex to produce sympathoinhibition is reduced with age in humans. Eleven young (23 +/- 1 years, mean +/- s.e.m.) and ten older (64 +/- 1) healthy adult males were studied under supine conditions (control) and in response to cardiopulmonary baroreflex stimulation evoked by acute central circulatory hypervolaemia (10 deg head-down tilt). The two groups were normotensive and free of overt cardiovascular disease. 2. Supine baseline (control) levels of efferent muscle sympathetic nerve activity (MSNA) burst frequency were twice as high in the older men (41 +/- 2 vs. 21 +/- 2 bursts min-1, P < 0.05). In both groups in response to head-down tilt arterial blood pressure and heart rate were unchanged, peripheral venous pressure (PVP) increased (P < 0.05), MSNA total activity decreased (P < 0.05), antecubital venous plasma noradrenaline concentrations did not change significantly, and forearm blood flow and vascular conductance increased (vascular resistance decreased) (all P < 0.05). The mean absolute DeltaMSNA/DeltaPVP was similar in the young and older men, although the higher control levels of MSNA in the older men resulted in a smaller percentage DeltaMSNA/DeltaPVP (P < 0.05). Per DeltaPVP, the reduction in forearm vascular resistance was smaller in the older men, but there were no age group differences when expressed as increases in forearm vascular conductance. 3. These results indicate that the ability of the cardiopulmonary baroreflex to inhibit MSNA is well preserved with age in healthy adult humans. As such, these findings are not consistent with the concept that this mechanism plays a role in the age-associated elevation in basal MSNA.
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Affiliation(s)
- H Tanaka
- Human Cardiovascular Research Laboratory, Center for Physical Activity, Disease Prevention, and Aging, Department of Kinesiology and Applied Physiology, University of Colorado at Boulder, Boulder, CO 80309,
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Davy KP, Tanaka H, Andros EA, Gerber JG, Seals DR. Influence of age on arterial baroreflex inhibition of sympathetic nerve activity in healthy adult humans. THE AMERICAN JOURNAL OF PHYSIOLOGY 1998; 275:H1768-72. [PMID: 9815084 DOI: 10.1152/ajpheart.1998.275.5.h1768] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Resting levels of muscle sympathetic nerve activity (MSNA) increase markedly with age in healthy adult humans. An age-related reduction in arterial baroreflex inhibition of MSNA could contribute to these elevations. To test this hypothesis, we measured MSNA using peroneal microneurography in young (age, 25 +/- 1 yr; n = 8) and older (69 +/- 1 yr; n = 7) healthy normotensive men before (baseline control) and during graded constant infusion of phenylephrine hydrochloride (0.5-2.0 microgram . kg-1. min-1) that produced a sustained approximately 10-mmHg increase in arterial blood pressure. Central venous pressure was controlled at baseline levels (+/-1 mmHg) using lower body negative pressure. Resting MSNA was approximately 95% higher in the older compared with the young subjects (43 +/- 5 vs. 22 +/- 3 bursts/min; P < 0.05). However, arterial baroreflex MSNA inhibitory responsiveness was similar in the older compared with the young subjects (254 +/- 112 vs. 259 +/- 40 arbitrary integration units/mmHg, respectively), although the percent reduction in MSNA was smaller in the older men (8.9 +/- 0.7 vs. 5.2 +/- 1.1%/mmHg), due to their elevated baseline levels. The reflex increase in the R-R interval was not different in the two groups (13 +/- 10 vs. 16 +/- 7 ms/mmHg). In summary, our findings suggest that arterial baroreflex inhibition of MSNA is preserved with age in healthy normotensive adult humans. As such, this mechanism does not appear to contribute to the age-related rise in tonic MSNA.
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Affiliation(s)
- K P Davy
- Human Cardiovascular Research Laboratory, Center for Physical Activity, Disease Prevention, and Aging, Department of Kinesiology and Applied Physiology, University of Colorado at Boulder, Boulder, Colorado 80309, USA
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Sverrisdóttir YB, Elam M, Herlitz H, Bengtsson BA, Johannsson G. Intense sympathetic nerve activity in adults with hypopituitarism and untreated growth hormone deficiency. J Clin Endocrinol Metab 1998; 83:1881-5. [PMID: 9626113 DOI: 10.1210/jcem.83.6.4895] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Perturbations in the sympathetic nervous system may be anticipated in adults with hypopituitarism and untreated GH deficiency, because the syndrome is associated with both peripheral and central factors known to modulate sympathetic traffic. The higher prevalence of hypertension and increased cardiovascular morbidity/mortality reported in GH-deficient patients may suggest increased activity of the sympathetic nervous system. We recorded muscle sympathetic nerve activity (MSNA) in 10 hypopituitary adults with adequate hormonal replacement therapy except GH and in 10 healthy controls matched for age, gender, and body mass index to test whether hormonal aberrations in hypopituitarism and untreated GH deficiency are associated with an increase in sympathetic nerve traffic. Blood samples for insulin-like growth factor I, free T4, and TSH were taken after an overnight fast, followed by an oral glucose tolerance test. Direct intraneural recordings of MSNA were performed with a tungsten microelectrode from the peroneal nerve. The hypopituitary subjects had markedly increased MSNA (54 +/- 4 bursts/min vs. 34 +/- 4 in controls; P < 0.002), which was not related to abdominal obesity or altered glucose metabolism. When assessed for the whole study group, MSNA was inversely correlated to serum insulin-like growth factor I (r = -0.59; P < 0.006) and TSH (r = -0.46; P < 0.04). MSNA was positively correlated to diastolic blood pressure (r = 0.80; P < 0.0005) in patients, but not in controls. The intense sympathetic discharge is suggested to be of central origin and may be an important underlying mechanism for the secondary hypertension and increased cardiovascular morbidity/mortality in this patient group.
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Affiliation(s)
- Y B Sverrisdóttir
- Department of Clinical Neurophysiology, Sahlgren University Hospital, Goteborg, Sweden.
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