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McGinty SJ, Matthews EL, Greaney JL, Shoemaker JK, Wenner MM. Sympathetic baroreflex sensitivity is enhanced in postmenopausal women. J Appl Physiol (1985) 2024; 137:374-381. [PMID: 38961825 DOI: 10.1152/japplphysiol.00833.2023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2023] [Revised: 07/02/2024] [Accepted: 07/02/2024] [Indexed: 07/05/2024] Open
Abstract
The sympathetic nervous system is critical for regulating blood pressure (BP) via the arterial baroreflex and sympathetic transduction in the peripheral vasculature. These mechanisms interact, and both may be altered with aging and impacted by menopause. Although age-related decreases in sympathetic transduction have been demonstrated in women, it remains unclear whether sympathetic baroreflex sensitivity (BRS) is impaired in postmenopausal women (POST). We tested the hypothesis that sympathetic BRS would be enhanced in POST compared with premenopausal women (PRE). We examined beat-by-beat BP and muscle sympathetic nerve activity (MSNA) in 19 PRE (22 ± 2 yr, 22 ± 3 kg/m2) and 12 POST (57 ± 5 yr, 24 ± 2 kg/m2) during 10 min of rest. Spontaneous sympathetic BRS was quantified as the slope of a linear regression between MSNA burst incidence and diastolic BP. Sympathetic transduction to mean arterial pressure (MAP) for the 10 cardiac cycles following spontaneous MSNA bursts was assessed via signal averaging method. Resting MAP was similar (PRE: 82 ± 8 vs. POST: 85 ± 8 mmHg, P = 0.43), whereas resting MSNA was elevated in POST (PRE: 10 ± 6 vs. POST: 45 ± 16 bursts/100 heart beats, P < 0.0001). Spontaneous sympathetic BRS was enhanced in POST (PRE: -2.0 ± 1.2 vs. POST: -5.2 ± 1.9 bursts/beat/mmHg, P < 0.0005). Sympathetic transduction to MAP was attenuated in POST (time: P < 0.001, group: P < 0.001, interaction: P < 0.01). These data suggest that sympathetic BRS may be enhanced in POST. Consistent with recent hypotheses, enhanced sensitivity of the arterial baroreflex's neural arc may signify a compensatory response to reduced efficiency of the peripheral arterial baroreflex arc (i.e., sympathetic transduction) to preserve BP buffering capacity.NEW & NOTEWORTHY Studies examining sympathetic baroreflex function with aging remain equivocal, with some studies showing an increase, decrease, or no change in sympathetic baroreflex sensitivity (BRS) in older adults compared with younger adults. With aging, women experience unique physiological changes due to menopause that influence autonomic function. For the first time, we show that postmenopausal women exhibit a greater sympathetic BRS compared with young premenopausal women.
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Affiliation(s)
- Shane J McGinty
- Department of Kinesiology and Applied Physiology, University of Delaware, Newark, Delaware, United States
| | - Evan L Matthews
- Department of Exercise Science and Physical Education, Montclair State University, Montclair, New Jersey, United States
| | - Jody L Greaney
- Department of Health Behaviour and Nutrition Sciences, University of Delaware, Newark, Delaware, United States
| | - J Kevin Shoemaker
- Neurovascular Research Laboratory, School of Kinesiology, Western University, London, Ontario, Canada
- Department of Physiology and Pharmacology, Western University, London, Ontario, Canada
| | - Megan M Wenner
- Department of Kinesiology and Applied Physiology, University of Delaware, Newark, Delaware, United States
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2
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Bagnall-Hare H, McLoone VI, Ringwood JV. On the accuracy of sequence methods for baroreflex sensitivity estimation. Phys Eng Sci Med 2024; 47:503-516. [PMID: 38564152 PMCID: PMC11166763 DOI: 10.1007/s13246-023-01380-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2023] [Accepted: 12/22/2023] [Indexed: 04/04/2024]
Abstract
In the absence of a true gold standard for non-invasive baroreflex sensitivity estimation, it is difficult to quantify the accuracy of the variety of techniques used. A popular family of methods, usually entitled 'sequence methods' involves the extraction of (apparently) correlated sequences from blood pressure and RR-interval data and the subsequent fitting of a regression line to the data. This paper discusses the accuracy of sequence methods from a system identification perspective, using both data generated from a known mathematical model and spontaneous baroreflex data. It is shown that sequence methods can introduce significant bias in the baroreflex sensitivity estimate, even when great care is taken in sequence selection.
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Affiliation(s)
- Hasana Bagnall-Hare
- Department of Electronic Engineering, Maynooth University, Maynooth, Co. Kildare, Ireland.
| | - Violeta I McLoone
- Department of Aero, Mechanical and Electronic Engineering, South East Technological University, Waterford, Co. Carlow, Ireland
| | - John V Ringwood
- Department of Electronic Engineering, Maynooth University, Maynooth, Co. Kildare, Ireland
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3
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Urbancsek R, Csanádi Z, Forgács IN, Papp TB, Boczán J, Barta J, Jenei C, Nagy L, Rudas L. The Feasibility of Baroreflex Sensitivity Measurements in Heart Failure Subjects: The Role of Slow-patterned Breathing. Clin Physiol Funct Imaging 2022; 42:260-268. [PMID: 35396907 DOI: 10.1111/cpf.12755] [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: 12/09/2021] [Revised: 03/14/2022] [Accepted: 03/28/2022] [Indexed: 11/27/2022]
Abstract
INTRODUCTION Increased muscle sympathetic nerve activity (MSNA) indicates an adverse outcome in heart failure. Decreased baroreflex modulation of MSNA is well known feature of the disease. The determinability of cardiovagal baroreflex sensitivity (BRS) in heart failure is low, however, the determinability of sympathetic BRS is not known. METHODS We have assessed the spontaneous, MSNA burst incidence-based baroreflex index (BRSsymp) in 33 stable heart failure patients and in 10 healthy controls using the traditional r≥0.5 cut-off for acceptable individual diastolic pressure-burst incidence slopes, and also a more stringent r≥0.7 cut-off. We have also assessed the influence of 6/min breathing. RESULTS The determinability of BRSsymp in heart failure patients was 64% during spontaneous breathing with r≥0.5 cut-off, and 39% using the r≥0.7 cut-off. The determinability of these indices further decreased during 6/min breathing, dropping to 29% with the r≥0.7 cut-off. In contrast, the determinability of the cardiovagal BRS indices increased significantly with 6/min breathing (from 24% to 66%; p<0.001). Patients who still had determinable BRSsymp at the r≥0.7 cut-off had a significantly lower baseline burst incidence than those with an undeterminable index (70±14 vs.89±10 burst/100 cycles; p<0.002). Neither the 6/min breathing, nor the r≥0.7 cut-off limit influenced the high availability of BRSsymp in healthy subjects. CONCLUSION The determinability of BRSsymp in heart failure patients is limited, especially with the 0.7 limit for correlation. Undeterminable BRSsymp in patients is associated with higher sympathetic activity. 6/min breathing improves the determinability of cardiovagal BRS indices, but not that of BRSsymp. This article is protected by copyright. All rights reserved.
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Affiliation(s)
- Réka Urbancsek
- Faculty of Medicine, Department of Cardiology, University of Debrecen, Debrecen, Hungary
| | - Zoltán Csanádi
- Faculty of Medicine, Department of Cardiology, University of Debrecen, Debrecen, Hungary
| | - Ildikó Noémi Forgács
- Faculty of Medicine, Department of Cardiology, University of Debrecen, Debrecen, Hungary
| | - Tímea Bianka Papp
- Faculty of Medicine, Department of Cardiology, University of Debrecen, Debrecen, Hungary
| | - Judit Boczán
- Faculty of Medicine, Department of Neurology, University of Debrecen, Debrecen, Hungary
| | - Judit Barta
- Faculty of Medicine, Department of Cardiology, University of Debrecen, Debrecen, Hungary
| | - Csaba Jenei
- Faculty of Medicine, Department of Cardiology, University of Debrecen, Debrecen, Hungary
| | - László Nagy
- Faculty of Medicine, Department of Cardiology, University of Debrecen, Debrecen, Hungary
| | - László Rudas
- Department of Anesthesiology and Intensive Care, University of Szeged, Szeged, Hungary
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Veiz E, Kieslich SK, Staab J, Czesnik D, Herrmann-Lingen C, Meyer T. Men Show Reduced Cardiac Baroreceptor Sensitivity during Modestly Painful Electrical Stimulation of the Forearm: Exploratory Results from a Sham-Controlled Crossover Vagus Nerve Stimulation Study. INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2021; 18:ijerph182111193. [PMID: 34769711 PMCID: PMC8582936 DOI: 10.3390/ijerph182111193] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/19/2021] [Revised: 10/06/2021] [Accepted: 10/16/2021] [Indexed: 11/30/2022]
Abstract
This paper presents data from a transcutaneous vagus nerve stimulation experiment that point towards a blunted cardiac baroreceptor sensitivity (cBRS) in young males compared to females during electrical stimulation of the forearm and a rhythmic breathing task. Continuous electrocardiography, impedance cardiography and continuous blood-pressure recordings were assessed in a sex-matched cohort of twenty young healthy subjects. Electrical stimulation of the median nerve was conducted by using a threshold-tracking method combined with two rhythmic breathing tasks (0.1 and 0.2 Hz) before, during and after active or sham transcutaneous vagus nerve stimulation. Autonomic and hemodynamic parameters were calculated, and differences were analyzed by using linear mixed models and post hoc F-tests. None of the autonomic and hemodynamic parameters differed between the sham and active conditions. However, compared to females, male participants had an overall lower total cBRS independent of stimulation condition during nerve stimulation (females: 14.96 ± 5.67 ms/mmHg, males: 11.89 ± 3.24 ms/mmHg, p = 0.031) and rhythmic breathing at 0.2 Hz (females: 21.49 ± 8.47 ms/mmHg, males: 15.12 ± 5.70 ms/mmHg, p = 0.004). Whereas vagus nerve stimulation at the left inner tragus did not affect the efferent vagal control of the heart, we found similar patterns of baroreceptor sensitivity activation over the stimulation period in both sexes, which, however, significantly differed in their magnitude, with females showing an overall higher cBRS.
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Affiliation(s)
- Elisabeth Veiz
- Department of Psychosomatic Medicine and Psychotherapy, University Medical Center, University of Göttingen, 37075 Göttingen, Germany; (S.-K.K.); (J.S.); (C.H.-L.)
- Department of Neurology, University Medical Center, University of Göttingen, 37075 Göttingen, Germany;
- Correspondence: (E.V.); (T.M.)
| | - Susann-Kristin Kieslich
- Department of Psychosomatic Medicine and Psychotherapy, University Medical Center, University of Göttingen, 37075 Göttingen, Germany; (S.-K.K.); (J.S.); (C.H.-L.)
| | - Julia Staab
- Department of Psychosomatic Medicine and Psychotherapy, University Medical Center, University of Göttingen, 37075 Göttingen, Germany; (S.-K.K.); (J.S.); (C.H.-L.)
- German Centre for Cardiovascular Research (DZHK), Partner Site Göttingen, 37075 Göttingen, Germany
| | - Dirk Czesnik
- Department of Neurology, University Medical Center, University of Göttingen, 37075 Göttingen, Germany;
| | - Christoph Herrmann-Lingen
- Department of Psychosomatic Medicine and Psychotherapy, University Medical Center, University of Göttingen, 37075 Göttingen, Germany; (S.-K.K.); (J.S.); (C.H.-L.)
- German Centre for Cardiovascular Research (DZHK), Partner Site Göttingen, 37075 Göttingen, Germany
| | - Thomas Meyer
- Department of Psychosomatic Medicine and Psychotherapy, University Medical Center, University of Göttingen, 37075 Göttingen, Germany; (S.-K.K.); (J.S.); (C.H.-L.)
- German Centre for Cardiovascular Research (DZHK), Partner Site Göttingen, 37075 Göttingen, Germany
- Correspondence: (E.V.); (T.M.)
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5
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O'Brien MW, Al-Hinnawi A, Johns JA, Kimmerly DS. Spontaneous cardiovagal baroreflex sensitivity is unaffected by an acute bout of prolonged sitting: no impact of sex, menstrual phase, or oral contraceptive pill phase. Clin Auton Res 2021; 31:783-786. [PMID: 34275025 DOI: 10.1007/s10286-021-00820-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2021] [Accepted: 07/09/2021] [Indexed: 10/20/2022]
Affiliation(s)
- Myles W O'Brien
- Autonomic Cardiovascular Control and Exercise Laboratory, Division of Kinesiology, Faculty of Health, School of Health and Human Performance, Dalhousie University, 6230 South Street, Halifax, NS, B3H 4R2, Canada
| | - Amera Al-Hinnawi
- Autonomic Cardiovascular Control and Exercise Laboratory, Division of Kinesiology, Faculty of Health, School of Health and Human Performance, Dalhousie University, 6230 South Street, Halifax, NS, B3H 4R2, Canada
| | - Jarrett A Johns
- Autonomic Cardiovascular Control and Exercise Laboratory, Division of Kinesiology, Faculty of Health, School of Health and Human Performance, Dalhousie University, 6230 South Street, Halifax, NS, B3H 4R2, Canada
| | - Derek S Kimmerly
- Autonomic Cardiovascular Control and Exercise Laboratory, Division of Kinesiology, Faculty of Health, School of Health and Human Performance, Dalhousie University, 6230 South Street, Halifax, NS, B3H 4R2, Canada.
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6
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Influence of Heart Rate Variability on Abstinence-Related Changes in Brain State in Everyday Drinkers. Brain Sci 2021; 11:brainsci11060817. [PMID: 34203005 PMCID: PMC8235786 DOI: 10.3390/brainsci11060817] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2021] [Revised: 06/14/2021] [Accepted: 06/16/2021] [Indexed: 11/16/2022] Open
Abstract
Alcohol consumption is now common practice worldwide, and functional brain networks are beginning to reveal the complex interactions observed with alcohol consumption and abstinence. The autonomic nervous system (ANS) has a well-documented relationship with alcohol use, and a growing body of research is finding links between the ANS and functional brain networks. This study recruited everyday drinkers in an effort to uncover the relationship between alcohol abstinence, ANS function, and whole brain functional brain networks. Participants (n = 29), 24-60 years-of-age, consumed moderate levels of alcohol regularly (males 2.4 (±0.26) drinks/day, females 2.3 (±0.96) drinks/day). ANS function, specifically cardiac vagal tone, was assessed using the Porges-Bohrer method for calculating respiratory sinus arrhythmia (PBRSA). Functional brain networks were generated from resting-state MRI scans obtained following 3-day periods of typical consumption and abstinence. A multi-task mixed-effects regression model determined the influences of HRV and drinking state on functional network connectivity. Results showed differences in the relationship between the strength of network connections and clustering coefficients across drinking states, moderated by PBRSA. Increases in connection strength between highly clustered nodes during abstinence as PBRSA increases demonstrates a greater possible range of topological configurations at high PBRSA values. This novel finding begins to shed light on the complex interactions between typical alcohol abstinence and physiological responses of the central and autonomic nervous system.
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7
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Sabino-Carvalho JL, Falquetto B, Takakura AC, Vianna LC. Baroreflex dysfunction in Parkinson's disease: integration of central and peripheral mechanisms. J Neurophysiol 2021; 125:1425-1439. [PMID: 33625931 DOI: 10.1152/jn.00548.2020] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
The incidence of Parkinson's disease (PD) is increasing worldwide. Although the PD hallmark is the motor impairments, nonmotor dysfunctions are now becoming more recognized. Recently, studies have suggested that baroreflex dysfunction is one of the underlying mechanisms of cardiovascular dysregulation observed in patients with PD. However, the large body of literature on baroreflex function in PD is unclear. The baroreflex system plays a major role in the autonomic, and ultimately blood pressure and heart rate, adjustments that accompany acute cardiovascular stressors on a daily basis. Therefore, impaired baroreflex function (i.e., decreased sensitivity or gain) can lead to altered neural cardiovascular responses. Since PD affects parasympathetic and sympathetic branches of the autonomic nervous system and both are orchestrated by the baroreflex system, understanding of this crucial mechanism in PD is necessary. In the present review, we summarize the potential altered central and peripheral mechanisms affecting the feedback-controlled loops that comprise the reflex arc in patients with PD. Major factors including arterial stiffness, reduced number of C1 and activation of non-C1 neurons, presence of central α-synuclein aggregation, cardiac sympathetic denervation, attenuated muscle sympathetic nerve activity, and lower norepinephrine release could compromise baroreflex function in PD. Results from patients with PD and from animal models of PD provide the reader with a clearer picture of baroreflex function in this clinical condition. By doing so, our intent is to stimulate future studies to evaluate several unanswered questions in this research area.
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Affiliation(s)
- Jeann L Sabino-Carvalho
- NeuroV̇ASQ̇-Integrative Physiology Laboratory, Faculty of Physical Education, University of Brasília, Brasília, DF, Brazil
| | - Barbara Falquetto
- Department of Pharmacology, Institute of Biomedical Sciences, University de Sao Paulo, Sao Paulo, Brazil
| | - Ana C Takakura
- Department of Pharmacology, Institute of Biomedical Sciences, University de Sao Paulo, Sao Paulo, Brazil
| | - Lauro C Vianna
- NeuroV̇ASQ̇-Integrative Physiology Laboratory, Faculty of Physical Education, University of Brasília, Brasília, DF, Brazil.,Graduate Program in Medical Sciences, Faculty of Medicine, University of Brasília, Brasília, DF, Brazil
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8
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Akerman AP, Meade RD, Notley SR, Rutherford MM, Kenny GP. Myths and methodologies: Reliability of non-invasive estimates of cardiac autonomic modulation during whole-body passive heating. Exp Physiol 2020; 106:593-614. [PMID: 33197089 DOI: 10.1113/ep089069] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2020] [Accepted: 11/10/2020] [Indexed: 12/16/2022]
Abstract
Observed individual variability in cardiac baroreflex sensitivity (cBRS) and heart rate variability (HRV) is extensive, especially during exposure to stressors such as heat. A large part of the observed variation may be related to the reliability (consistency) of the measurement. We therefore examined the test-retest reliability of cBRS and HRV measurements on three separate occasions in 14 young men (age: 24 (SD 5) years), at rest and during whole-body heating (water-perfused suit) to raise and clamp oesophageal temperature 0.6°C, 1.2°C and 1.8°C above baseline. Beat-to-beat measurements of RR interval and systolic blood pressure (BP) were obtained for deriving HRV (from RR), and cBRS calculated via (i) the spontaneous method, α coefficients and transfer function analysis at each level of heat strain, and (ii) during forced oscillations via squat-stand manoeuvres (0.1 Hz) before and after heating. Absolute values and changes in all cBRS estimates were variable but generally consistent with reductions in parasympathetic activity. cBRS estimates demonstrated poor absolute reliability (coefficient of variation ≥25%), but relative reliability (intraclass correlation coefficient; ICC) of some frequency estimates was acceptable (ICC ≥0.70) during low-heat strain (ICC: 0.56-0.74). After heating, forced oscillations in BP demonstrated more favourable responses than spontaneous oscillations (better reliability, lower minimum detectable change). Absolute reliability of HRV estimates were poor, but relative reliability estimates were often acceptable (≥0.70). Our findings illustrate how measurement consistency of cardiac autonomic modulation estimates are altered during heat stress, and we demonstrate the possible implications on research design and data interpretation.
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Affiliation(s)
- Ashley P Akerman
- Human and Environmental Physiology Research Unit, University of Ottawa, Ottawa, Ontario, Canada
| | - Robert D Meade
- Human and Environmental Physiology Research Unit, University of Ottawa, Ottawa, Ontario, Canada
| | - Sean R Notley
- Human and Environmental Physiology Research Unit, University of Ottawa, Ottawa, Ontario, Canada
| | - Maura M Rutherford
- Human and Environmental Physiology Research Unit, University of Ottawa, Ottawa, Ontario, Canada
| | - Glen P Kenny
- Human and Environmental Physiology Research Unit, University of Ottawa, Ottawa, Ontario, Canada
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9
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Nuckols VR, Holwerda SW, Luehrs RE, DuBose LE, Stroud AK, Brandt D, Betz AM, Fiedorowicz JG, Scroggins SM, Santillan DA, Grobe JL, Sigmund CD, Santillan MK, Pierce GL. Beat-to-Beat Blood Pressure Variability in the First Trimester Is Associated With the Development of Preeclampsia in a Prospective Cohort: Relation With Aortic Stiffness. Hypertension 2020; 76:1800-1807. [PMID: 32951467 DOI: 10.1161/hypertensionaha.120.15019] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Women with preeclampsia, a hypertensive disorder of pregnancy, exhibit greater beat-to-beat blood pressure variability (BPV) in the third trimester after clinical onset of the disorder. However, it remains unknown whether elevated BPV precedes the development of preeclampsia. A prospective study cohort of 139 women (age 30.2±4.0 years) were enrolled in early pregnancy (<14 weeks gestation). BPV was quantified by time domain analyses of 10-minute continuous beat-to-beat blood pressure recordings via finger photoplethysmography in the first, second, and third trimesters. Aortic stiffness (carotid-femoral pulse wave velocity) and spontaneous cardiovagal baroreflex sensitivity were also measured each trimester. Eighteen women (13%) developed preeclampsia. Systolic BPV was higher in all trimesters among women who developed versus did not develop preeclampsia (first: 4.8±1.3 versus 3.7±1.2, P=0.001; second: 5.1±1.8 versus 3.8±1.1, P=0.02; third: 5.2±0.8 versus 4.0±1.1 mm Hg, P=0.002). Elevated first trimester systolic BPV was associated with preeclampsia (odds ratio, 1.94 [95% CI, 1.27-2.99]), even after adjusting for risk factors (age, body mass index, systolic blood pressure, history of preeclampsia, and diabetes mellitus) and was a significant predictor of preeclampsia (area under the receiver operator characteristic curve=0.75±0.07; P=0.002). Carotid-femoral pulse wave velocity was elevated in the first trimester among women who developed preeclampsia (5.9±0.8 versus 5.2±0.8 m/s; P=0.002) and was associated with BPV after adjustment for mean blood pressure (r=0.26; P=0.005). First trimester baroreflex sensitivity did not differ between groups (P=0.23) and was not related to BPV (P=0.36). Elevated systolic BPV is independently associated with the development of preeclampsia as early as the first trimester, possibly mediated in part by higher aortic stiffness.
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Affiliation(s)
- Virginia R Nuckols
- From the Departments of Health and Human Physiology (V.R.N., S.W.H., R.E.L., L.E.D., A.K.S., G.L.P.), University of Iowa, Iowa City, IA
| | - Seth W Holwerda
- From the Departments of Health and Human Physiology (V.R.N., S.W.H., R.E.L., L.E.D., A.K.S., G.L.P.), University of Iowa, Iowa City, IA.,the Abboud Cardiovascular Research Center (S.W.H., M.K.S., G.L.P.), University of Iowa, Iowa City, IA
| | - Rachel E Luehrs
- From the Departments of Health and Human Physiology (V.R.N., S.W.H., R.E.L., L.E.D., A.K.S., G.L.P.), University of Iowa, Iowa City, IA
| | - Lyndsey E DuBose
- From the Departments of Health and Human Physiology (V.R.N., S.W.H., R.E.L., L.E.D., A.K.S., G.L.P.), University of Iowa, Iowa City, IA
| | - Amy K Stroud
- From the Departments of Health and Human Physiology (V.R.N., S.W.H., R.E.L., L.E.D., A.K.S., G.L.P.), University of Iowa, Iowa City, IA
| | - Debra Brandt
- Obstetrics and Gynecology (D.B., A.M.B., S.M.S., D.A.S., M.K.S.), University of Iowa, Iowa City, IA
| | - Alexandria M Betz
- Obstetrics and Gynecology (D.B., A.M.B., S.M.S., D.A.S., M.K.S.), University of Iowa, Iowa City, IA
| | - Jess G Fiedorowicz
- Psychiatry (J.G.F.), University of Iowa, Iowa City, IA.,Epidemiology (J.G.F.), University of Iowa, Iowa City, IA.,Internal Medicine (J.G.F.), University of Iowa, Iowa City, IA
| | - Sabrina M Scroggins
- Obstetrics and Gynecology (D.B., A.M.B., S.M.S., D.A.S., M.K.S.), University of Iowa, Iowa City, IA
| | - Donna A Santillan
- Obstetrics and Gynecology (D.B., A.M.B., S.M.S., D.A.S., M.K.S.), University of Iowa, Iowa City, IA
| | - Justin L Grobe
- Departments of Physiology (J.L.G., C.D.S.), Medical College of Wisconsin, Milwaukee, WI.,Biomedical Engineering (J.L.G.), Medical College of Wisconsin, Milwaukee, WI.,Cardiovascular Research Center (J.L.G., C.D.S.), Medical College of Wisconsin, Milwaukee, WI
| | - Curt D Sigmund
- Departments of Physiology (J.L.G., C.D.S.), Medical College of Wisconsin, Milwaukee, WI.,Cardiovascular Research Center (J.L.G., C.D.S.), Medical College of Wisconsin, Milwaukee, WI
| | - Mark K Santillan
- Obstetrics and Gynecology (D.B., A.M.B., S.M.S., D.A.S., M.K.S.), University of Iowa, Iowa City, IA.,the Abboud Cardiovascular Research Center (S.W.H., M.K.S., G.L.P.), University of Iowa, Iowa City, IA
| | - Gary L Pierce
- From the Departments of Health and Human Physiology (V.R.N., S.W.H., R.E.L., L.E.D., A.K.S., G.L.P.), University of Iowa, Iowa City, IA.,the Abboud Cardiovascular Research Center (S.W.H., M.K.S., G.L.P.), University of Iowa, Iowa City, IA.,Fraternal Order of Eagles Diabetes Research Center (G.L.P.), University of Iowa, Iowa City, IA
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10
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Hissen SL, Taylor CE. Sex differences in vascular transduction of sympathetic nerve activity. Clin Auton Res 2020; 30:381-392. [PMID: 32865664 DOI: 10.1007/s10286-020-00722-0] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2020] [Accepted: 08/18/2020] [Indexed: 12/21/2022]
Abstract
PURPOSE Sympathetic vasoconstriction plays a major role in the beat-to-beat control of blood pressure. To be effective and thus avoid dangerously high or low blood pressures, this mechanism relies upon transduction of sympathetic nerve activity at the level of the vasculature. However, recent evidence suggests that considerable variability exists in beat-to-beat vascular transduction, particularly between the sexes. METHODS We reviewed the methods available for quantifying beat-to-beat transduction of muscle sympathetic nerve activity (MSNA) and explored the recent evidence for sex differences in vascular transduction. We paid specific attention to relationships between vascular transduction and factors such as resting levels of sympathetic nerve activity and baroreflex sensitivity. RESULTS There are two dominant methods now available for the quantification of beat-to-beat transduction of muscle sympathetic nerve activity at rest. Whilst there is some evidence to suggest that young females exhibit lower levels of vascular transduction, results vary depending on the method used and the direction of change in MSNA. Evidence suggests that compensatory relationships may exist between key components of neurovascular control, such as vascular transduction and resting levels of MSNA. Also consistent is the presence of such relationships in young males but not young females. CONCLUSION The lack of significant relationships in young females may reflect the influence of vasodilator mechanisms that counteract sympathetic vasoconstriction. The assessment of vascular transduction following MSNA bursts and non-bursts in males and females, both young and older, may help to gain a mechanistic understanding of the prevalence of hypotensive and hypertensive disorders across the lifespan.
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Affiliation(s)
- Sarah L Hissen
- Institute for Exercise and Environmental Medicine at Texas Health Presbyterian Hospital Dallas, Dallas, TX, USA
- The University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Chloe E Taylor
- School of Health Sciences, Western Sydney University, Campbelltown Campus, Locked Bag 1797, Penrith, Sydney, NSW, 2751, Australia.
- School of Medicine, Western Sydney University, Sydney, Australia.
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11
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Simpson LL, Meah VL, Steele AR, Gasho C, Howe CA, Dawkins TG, Busch SA, Oliver SJ, Moralez G, Lawley JS, Tymko MM, Vizcardo-Galindo GA, Figueroa-Mujíca RJ, Villafuerte FC, Ainslie PN, Stembridge M, Steinback CD, Moore JP. Global REACH 2018: Andean highlanders, chronic mountain sickness and the integrative regulation of resting blood pressure. Exp Physiol 2020; 106:104-116. [PMID: 32271969 DOI: 10.1113/ep088473] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2020] [Accepted: 04/06/2020] [Indexed: 12/17/2022]
Abstract
NEW FINDINGS What is the central question of this study? Does chronic mountain sickness (CMS) alter sympathetic neural control and arterial baroreflex regulation of blood pressure in Andean (Quechua) highlanders? What is the main finding and its importance? Compared to healthy Andean highlanders, basal sympathetic vasomotor outflow is lower, baroreflex control of muscle sympathetic nerve activity is similar, supine heart rate is lower and cardiovagal baroreflex gain is greater in mild CMS. Taken together, these findings reflect flexibility in integrative regulation of blood pressure that may be important when blood viscosity and blood volume are elevated in CMS. ABSTRACT The high-altitude maladaptation syndrome chronic mountain sickness (CMS) is characterized by excessive erythrocytosis and frequently accompanied by accentuated arterial hypoxaemia. Whether altered autonomic cardiovascular regulation is apparent in CMS is unclear. Therefore, during the 2018 Global REACH expedition to Cerro de Pasco, Peru (4383 m), we assessed integrative control of blood pressure (BP) and determined basal sympathetic vasomotor outflow and arterial baroreflex function in eight Andean natives with CMS ([Hb] 22.6 ± 0.9 g·dL-1 ) and seven healthy highlanders ([Hb] 19.3 ± 0.8 g·dL-1 ). R-R interval (RRI, electrocardiogram), beat-by-beat BP (photoplethysmography) and muscle sympathetic nerve activity (MSNA; microneurography) were recorded at rest and during pharmacologically induced changes in BP (modified Oxford test). Although [Hb] and blood viscosity (7.8 ± 0.7 vs. 6.6 ± 0.7 cP; d = 1.7, P = 0.01) were elevated in CMS compared to healthy highlanders, cardiac output, total peripheral resistance and mean BP were similar between groups. The vascular sympathetic baroreflex MSNA set-point (i.e. MSNA burst incidence) and reflex gain (i.e. responsiveness) were also similar between groups (MSNA set-point, d = 0.75, P = 0.16; gain, d = 0.2, P = 0.69). In contrast, in CMS the cardiovagal baroreflex operated around a longer RRI (960 ± 159 vs. 817 ± 50 ms; d = 1.4, P = 0.04) with a greater reflex gain (17.2 ± 6.8 vs. 8.8 ± 2.6 ms·mmHg-1 ; d = 1.8, P = 0.01) versus healthy highlanders. Basal sympathetic vasomotor activity was also lower compared to healthy highlanders (33 ± 11 vs. 45 ± 13 bursts·min-1 ; d = 1.0, P = 0.08). In conclusion, our findings indicate adaptive differences in basal sympathetic vasomotor activity and heart rate compensate for the haemodynamic consequences of excessive erythrocyte volume and contribute to integrative blood pressure regulation in Andean highlanders with mild CMS.
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Affiliation(s)
- Lydia L Simpson
- Extremes Research Group, School of Sport, Health and Exercise Sciences, Bangor University, Bangor, UK
| | - Victoria L Meah
- Neurovascular Health Laboratory, Faculty of Kinesiology, Sport, and Recreation, University of Alberta, Edmonton, Canada
| | - Andrew R Steele
- Neurovascular Health Laboratory, Faculty of Kinesiology, Sport, and Recreation, University of Alberta, Edmonton, Canada
| | - Christopher Gasho
- Division of Pulmonary and Critical Care, School of Medicine, Loma Linda University, Loma Linda, CA, USA
| | - Connor A Howe
- Centre for Heart, Lung, and Vascular Health, University of British Columbia Okanagan, Kelowna, Canada
| | - Tony G Dawkins
- Cardiff School of Sport and Health Sciences, Cardiff Metropolitan University, Cardiff, UK
| | - Stephen A Busch
- Neurovascular Health Laboratory, Faculty of Kinesiology, Sport, and Recreation, University of Alberta, Edmonton, Canada
| | - Samuel J Oliver
- Extremes Research Group, School of Sport, Health and Exercise Sciences, Bangor University, Bangor, UK
| | - Gilberto Moralez
- Department of Applied Clinical Research, University of Texas Southwestern Medical Centre, Dallas, TX, USA
| | - Justin S Lawley
- Department of Sport Science, Division of Physiology, University of Innsbruck, Innsbruck, Austria
| | - Michael M Tymko
- Neurovascular Health Laboratory, Faculty of Kinesiology, Sport, and Recreation, University of Alberta, Edmonton, Canada
| | | | - Rómulo J Figueroa-Mujíca
- Department of Biological and Physiological Sciences, Universidad Peruana Cayetano Heredia, Lima, Peru
| | - Francisco C Villafuerte
- Department of Biological and Physiological Sciences, Universidad Peruana Cayetano Heredia, Lima, Peru
| | - Phillip N Ainslie
- Centre for Heart, Lung, and Vascular Health, University of British Columbia Okanagan, Kelowna, Canada
| | - Mike Stembridge
- Cardiff School of Sport and Health Sciences, Cardiff Metropolitan University, Cardiff, UK
| | - Craig D Steinback
- Neurovascular Health Laboratory, Faculty of Kinesiology, Sport, and Recreation, University of Alberta, Edmonton, Canada
| | - Jonathan P Moore
- Extremes Research Group, School of Sport, Health and Exercise Sciences, Bangor University, Bangor, UK
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12
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Krohova J, Faes L, Czippelova B, Pernice R, Turianikova Z, Wiszt R, Mazgutova N, Busacca A, Javorka M. Vascular resistance arm of the baroreflex: methodology and comparison with the cardiac chronotropic arm. J Appl Physiol (1985) 2020; 128:1310-1320. [PMID: 32213110 DOI: 10.1152/japplphysiol.00512.2019] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Baroreflex response consists of cardiac chronotropic (effect on heart rate), cardiac inotropic (on contractility), venous (on venous return) and vascular (on vascular resistance) arms. Because of the simplicity of its measurement, the cardiac chronotropic arm is most often analyzed. The aim was to introduce a method to assess the vascular baroreflex arm and to characterize its changes during stress. We evaluated the effect of orthostasis and mental arithmetics (MA) in 39 (22 women, 17 men; median age: 18.7 yr) and 36 (21 women, 15 men; 19.2 yr) healthy volunteers, respectively. We recorded systolic (SBP) and mean (MBP) blood pressure by volume-clamp method and R-R interval (RR) by ECG. Cardiac output (CO) was recorded by impedance cardiography. From MBP and CO, peripheral vascular resistance (PVR) was calculated. The directional spectral coupling and gain of cardiac chronotropic (SBP to RR) and vascular (SBP to PVR) arms were quantified. The strength of the causal coupling from SBP to PVR was significantly higher than that of SBP to RR coupling over the whole protocol (P < 0.001). Along both arms, the coupling was higher during orthostasis compared with the supine position (P < 0.001 and P = 0.006); no MA effect was observed. No significant changes in the spectral gain (ratio of RR or PVR change to a unit SBP change) across all phases were found (0.111 ≤ P ≤ 0.907). We conclude that changes in PVR are tightly coupled with SBP oscillations via the baroreflex, providing an approach for baroreflex vascular arm analysis with the potential to reveal new aspects of blood pressure dysregulation.NEW & NOTEWORTHY Baroreflex response consists of several arms, but the cardiac chronotropic arm (blood pressure changes evoking heart rate response) is usually analyzed. This study introduces a method to assess the vascular baroreflex arm with the continuous noninvasive measurement of peripheral vascular resistance as an output considering causality in the interaction between oscillations and slower dynamics of vascular tone changes. We conclude that although vascular baroreflex arm involvement becomes dominant during orthostasis, gain of this interaction is relatively stable.
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Affiliation(s)
- J Krohova
- Department of Physiology and Biomedical Centre Martin (BioMed Martin), Jessenius Faculty of Medicine, Comenius University, Martin, Slovakia
| | - L Faes
- Department of Engineering, University of Palermo, Palermo, Italy
| | - B Czippelova
- Department of Physiology and Biomedical Centre Martin (BioMed Martin), Jessenius Faculty of Medicine, Comenius University, Martin, Slovakia
| | - R Pernice
- Department of Engineering, University of Palermo, Palermo, Italy
| | - Z Turianikova
- Department of Physiology and Biomedical Centre Martin (BioMed Martin), Jessenius Faculty of Medicine, Comenius University, Martin, Slovakia
| | - R Wiszt
- Department of Physiology and Biomedical Centre Martin (BioMed Martin), Jessenius Faculty of Medicine, Comenius University, Martin, Slovakia
| | - N Mazgutova
- Department of Physiology and Biomedical Centre Martin (BioMed Martin), Jessenius Faculty of Medicine, Comenius University, Martin, Slovakia
| | - A Busacca
- Department of Engineering, University of Palermo, Palermo, Italy
| | - M Javorka
- Department of Physiology and Biomedical Centre Martin (BioMed Martin), Jessenius Faculty of Medicine, Comenius University, Martin, Slovakia
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13
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Usselman CW, Adler TE, Coovadia Y, Leone C, Paidas MJ, Stachenfeld NS. A recent history of preeclampsia is associated with elevated central pulse wave velocity and muscle sympathetic outflow. Am J Physiol Heart Circ Physiol 2020; 318:H581-H589. [DOI: 10.1152/ajpheart.00578.2019] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
We demonstrate that resting muscle sympathetic nerve activity is elevated in women with a recent history of preeclampsia relative to women who have recently had uncomplicated pregnancies and without a history of preeclampsia. Structural changes in the central arteries are associated with arterial stiffness following preeclampsia, independent of changes in the sympathetic nervous system. The structural changes are observed in these relatively young previously preeclamptic women, indicating elevated cardiovascular risk. Our data suggest that with aging (and the gradual loss of vascular protection for women, as established by others), this risk will become exaggerated compared with women who have had normal pregnancies.
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Affiliation(s)
- Charlotte W. Usselman
- Cardiovascular Health and Autonomic Regulation Laboratory, Department of Kinesiology and Physical Education, McGill University, Montreal, Quebec, Canada
- McGill Research Centre for Physical Activity and Health, McGill University, Montreal, Quebec, Canada
- The John B. Pierce Laboratory, Yale School of Medicine, New Haven, Connecticut
- Department of Obstetrics, Gynecology, and Reproductive Sciences, Yale School of Medicine, New Haven, Connecticut
| | - Tessa E. Adler
- Cardiovascular Health and Autonomic Regulation Laboratory, Department of Kinesiology and Physical Education, McGill University, Montreal, Quebec, Canada
- The John B. Pierce Laboratory, Yale School of Medicine, New Haven, Connecticut
| | - Yasmine Coovadia
- Cardiovascular Health and Autonomic Regulation Laboratory, Department of Kinesiology and Physical Education, McGill University, Montreal, Quebec, Canada
| | - Cheryl Leone
- The John B. Pierce Laboratory, Yale School of Medicine, New Haven, Connecticut
| | - Michael J. Paidas
- Department of Obstetrics, Gynecology, and Reproductive Sciences, Yale School of Medicine, New Haven, Connecticut
- Department of Obstetrics, Gynecology, and Reproductive Sciences, University of Miami Miller School of Medicine, Miami, Florida
| | - Nina S. Stachenfeld
- The John B. Pierce Laboratory, Yale School of Medicine, New Haven, Connecticut
- Department of Obstetrics, Gynecology, and Reproductive Sciences, Yale School of Medicine, New Haven, Connecticut
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14
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Porta A, Elstad M. Editorial: Probing the Cardiac Arm of the Baroreflex and Complementary Branches. Front Neurosci 2020; 13:1422. [PMID: 31998069 PMCID: PMC6967736 DOI: 10.3389/fnins.2019.01422] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2019] [Accepted: 12/16/2019] [Indexed: 11/19/2022] Open
Affiliation(s)
- Alberto Porta
- Department of Biomedical Sciences for Health, University of Milan, Milan, Italy.,Department of Cardiothoracic, Vascular Anesthesia and Intensive Care, IRCCS Policlinico San Donato, Milan, Italy
| | - Maja Elstad
- Division of Physiology, Institute of Basic Medical Sciences, University of Oslo, Oslo, Norway
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15
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Wang HH, Chen PM, Lin CL, Jau RC, Hsiao SM, Ko JL. Joint effects of risk factors on adverse events associated with adult blood donations. Medicine (Baltimore) 2019; 98:e17758. [PMID: 31689834 PMCID: PMC6946510 DOI: 10.1097/md.0000000000017758] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
Abstract
The process for blood donation is considered safe, but some adverse events have been reported. Risk factors for adverse events were assessed in this study.A retrospective case-control study was conducted to investigate the risk factors for adverse events after blood donation between 2010 and 2013. Variables such as gender, age, body mass index (BMI), donation status, donation volume, donation site, pre-donation systolic blood pressure (SBP), and pre-donation diastolic blood pressure were compared between donors with and without adverse events. Multiple logistic regression analysis was performed to assess the joint effects of age, gender, and donation status on adverse events.The incidence of adverse events among adult blood donations was 1287/1,253,678 (0.1%). On multivariate logistic regression analysis, blood donors aged <35 years (odds ratio [OR], 2.99, 95% confidence interval [CI], 2.57-3.48), of female gender (OR, 3.30, 95% CI, 2.62-4.15), and with first-time donor status (OR, 6.40, 95% CI, 5.17-7.93), donation of 500 mL (OR, 2.22, 95% CI, 1.83-2.69), predonation SBP <124 mm Hg (OR, 1.25, 95% CI,1.05-1.48) and BMI <24 kg/m (OR, 1.67, 95% CI, 1.42-1.96) were associated with increased likelihood of adverse event. Further analysis with joint effects method revealed that first-time female donors aged <35 years are associated with the highest odds of adverse events when compared with repeat male donors aged ≧35 years (OR, 100.57, 95% CI, 48.45-208.75).The findings of our study should prove useful in identifying donors at risk and planning appropriate strategies for the prevention of adverse effects.
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Affiliation(s)
- Hsuan-Hui Wang
- Institute of Medicine, Chung Shan Medical University, Taichung
- Taichung Blood Center, Taiwan Blood Services Foundation
| | - Po-Ming Chen
- Institute of Medicine, Chung Shan Medical University, Taichung
| | - Chi-Ling Lin
- Taichung Blood Center, Taiwan Blood Services Foundation
| | | | - Sheng-Mou Hsiao
- Department of Obstetrics and Gynecology, Far Eastern Memorial Hospital, New Taipei
- Department of Obstetrics and Gynecology, National Taiwan University College of Medicine and National Taiwan University Hospital, Taipei
- Graduate School of Biotechnology and Bioengineering, Yuan Ze University, Taoyuan
| | - Jiunn-Liang Ko
- Institute of Medicine, Chung Shan Medical University, Taichung
- Department of Medical Oncology and Chest Medicine, Chung Shan Medical University Hospital, Taichung, Taiwan
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16
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Cardiovascular responses to a glucose drink in young male individuals with overweight/obesity and mild alterations in glucose metabolism, but without impaired glucose tolerance. Eur J Nutr 2019; 59:2747-2757. [PMID: 31637465 DOI: 10.1007/s00394-019-02120-3] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2019] [Accepted: 10/11/2019] [Indexed: 10/25/2022]
Abstract
PURPOSE Little is known about whether mild aberrations in glucose metabolism, which are seen in overweight/obese subjects (OW/OB) without impaired glucose tolerance, affect regulator control elements for blood pressure homeostasis. METHODS Hence, we measured in age-matched male subjects with normal weight (n = 16; BMI = 22.4 kg m-2) and OW/OB (n = 11; BMI = 28.6 kg m-2) continuous beat-to-beat blood pressure, heart rate, stroke volume, myocardial contractility and baroreflex sensitivity during a 30 min baseline and for 120 min after the ingestion of 75 g glucose dissolved in 300 mL tap water (OGTT). Blood samples for the assessment of plasma glucose and insulin were collected at baseline and every 30 min after the drink and homeostatic model assessment of insulin resistance (HOMA-IR) was calculated. RESULTS At baseline, glucose (5.3 ± 0.4 SD vs 5.0 ± 0.4 mmol L-1; p = 0.01), insulin (7.4 ± 0.4 vs 3.7 ± 2.7 mU L-1; p = 0.02) and HOMA-IR (1.8 ± 1.3 vs 0.8 ± 0.6; p = 0.01) were significantly higher in subjects with OW/OB, but none classified as having impaired glucose tolerance (plasma glucose levels < 7.8 mmol L-1 at 120 min post-OGTT) or hypertension (all < 130/80 mmHg at baseline). In response to the glucose drink, and in comparison to subjects with normal weight, we observed in subjects with OW/OB a trend towards increased plasma insulin levels (+7445 ± 4858 vs. +4968 ± 1924 mU h L-1; p = 0.08), which was not seen for blood glucose (p = 0.59). Moreover, subjects with OW/OB showed impaired peripheral vasodilation, diminished heart rate and myocardial contractility responses but increased peripheral pulse pressure (all p < 0.05). CONCLUSIONS Young male subjects with OW/OB, but without glucose intolerance or hypertension, showed attenuated peripheral vasodilation and diminished cardiac responses to a glucose drink.
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17
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Barbic F, Heusser K, Minonzio M, Shiffer D, Cairo B, Tank J, Jordan J, Diedrich A, Gauger P, Zamuner RA, Porta A, Furlan R. Effects of Prolonged Head-Down Bed Rest on Cardiac and Vascular Baroreceptor Modulation and Orthostatic Tolerance in Healthy Individuals. Front Physiol 2019; 10:1061. [PMID: 31507438 PMCID: PMC6716544 DOI: 10.3389/fphys.2019.01061] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2019] [Accepted: 08/02/2019] [Indexed: 11/13/2022] Open
Abstract
Orthostatic intolerance commonly occurs after prolonged bed rest, thus increasing the risk of syncope and falls. Baroreflex-mediated adjustments of heart rate and sympathetic vasomotor activity (muscle sympathetic nerve activity – MSNA) are crucial for orthostatic tolerance. We hypothesized that prolonged bed rest deconditioning alters overall baroreceptor functioning, thereby reducing orthostatic tolerance in healthy volunteers. As part of the European Space Agency Medium-term Bed Rest protocol, 10 volunteers were studied before and after 21 days of −6° head down bed rest (HDBR). In both conditions, subjects underwent ECG, beat-by-beat blood pressure, respiratory activity, and MSNA recordings while supine (REST) and during a 15-min 80° head-up tilt (TILT) followed by a 3-min −10 mmHg stepwise increase of lower body negative pressure to pre-syncope. Cardiac baroreflex sensitivity (cBRS) was obtained in the time (sequence method) and frequency domain (spectrum and cross-spectrum analyses of RR interval and systolic arterial pressure – SAP, variability). Baroreceptor modulation of sympathetic discharge activity to the vessels (sBRS) was estimated by the slope of the regression line between the percentage of MSNA burst occurrence and diastolic arterial pressure. Orthostatic tolerance significantly decreased after HDBR (12 ± 0.6 min) compared to before (21 ± 0.6 min). While supine, heart rate, SAP, and cBRS were unchanged before and after HDBR, sBRS gain was slightly depressed after than before HDBR (sBRS: −6.0 ± 1.1 versus −2.9 ± 1.5 burst% × mmHg−1, respectively). During TILT, HR was higher after than before HDBR (116 ± 4 b/min versus 100 ± 4 b/min, respectively), SAP was unmodified in both conditions, and cBRS indexes were lower after HDBR (α index: 3.4 ± 0.7 ms/mmHg; BRSSEQ 4.0 ± 1.0) than before (α index: 6.4 ± 1.0 ms/mmHg; BRSSEQ 6.8 ± 1.2). sBRS gain was significantly more depressed after HDBR than before (sBRS: −2.3 ± 0.7 versus −4.4 ± 0.4 burst% × mmHg−1, respectively). Our findings suggest that baroreflex-mediated adjustments in heart rate and MSNA are impaired after prolonged bed rest. The mechanism likely contributes to the decrease in orthostatic tolerance.
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Affiliation(s)
- Franca Barbic
- Humanitas Clinical and Research Center, Department of Internal Medicine, Istituto di Ricovero e Cura a Carattere Scientifico (IRCCS), Humanitas University, Rozzano, Italy
| | - Karsten Heusser
- German Aerospace Center (DLR), Institute of Aerospace Medicine, Cologne, Germany
| | - Maura Minonzio
- Humanitas Clinical and Research Center, Department of Internal Medicine, Istituto di Ricovero e Cura a Carattere Scientifico (IRCCS), Humanitas University, Rozzano, Italy
| | - Dana Shiffer
- Humanitas Clinical and Research Center, Department of Internal Medicine, Istituto di Ricovero e Cura a Carattere Scientifico (IRCCS), Humanitas University, Rozzano, Italy
| | - Beatrice Cairo
- Department of Biomedical Sciences for Health, University of Milan, Milan, Italy
| | - Jens Tank
- German Aerospace Center (DLR), Institute of Aerospace Medicine, Cologne, Germany
| | - Jens Jordan
- German Aerospace Center (DLR), Institute of Aerospace Medicine, Cologne, Germany
| | - André Diedrich
- Autonomic Dysfunction Center, Clinical Research Center (CRC), Department of Medicine, Vanderbilt University, Nashville, TN, United States
| | - Peter Gauger
- German Aerospace Center (DLR), Institute of Aerospace Medicine, Cologne, Germany
| | | | - Alberto Porta
- Department of Biomedical Sciences for Health, University of Milan, Milan, Italy.,Department of Cardiothoracic, Vascular Anesthesia and Intensive Care, Istituto di Ricovero e Cura a Carattere Scientifico (IRCCS) Policlinico di San Donato, San Donato Milanese, Italy
| | - Raffaello Furlan
- Humanitas Clinical and Research Center, Department of Internal Medicine, Istituto di Ricovero e Cura a Carattere Scientifico (IRCCS), Humanitas University, Rozzano, Italy
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18
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Simpson LL, Busch SA, Oliver SJ, Ainslie PN, Stembridge M, Steinback CD, Moore JP. Baroreflex control of sympathetic vasomotor activity and resting arterial pressure at high altitude: insight from Lowlanders and Sherpa. J Physiol 2019; 597:2379-2390. [PMID: 30893472 DOI: 10.1113/jp277663] [Citation(s) in RCA: 34] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2019] [Accepted: 03/18/2019] [Indexed: 01/23/2023] Open
Abstract
KEY POINTS Hypoxia, a potent activator of the sympathetic nervous system, is known to increase muscle sympathetic nerve activity (MSNA) to the peripheral vasculature of native Lowlanders during sustained high altitude (HA) exposure. We show that the arterial baroreflex control of MSNA functions normally in healthy Lowlanders at HA, and that upward baroreflex resetting permits chronic activation of basal sympathetic vasomotor activity under this condition. The baroreflex MSNA operating point and resting sympathetic vasomotor outflow both are lower for highland Sherpa compared to acclimatizing Lowlanders; these lower levels may represent beneficial hypoxic adaptation in Sherpa. Acute hyperoxia at HA had minimal effect on baroreflex control of MSNA in Lowlanders and Sherpa, raising the possibility that mechanisms other than peripheral chemoreflex activation contribute to vascular sympathetic baroreflex resetting and sympathoexcitation. These findings provide a better understanding of sympathetic nervous system activation and the control of blood pressure during the physiological stress of sustained HA hypoxia. ABSTRACT Exposure to high altitude (HA) is characterized by heightened muscle sympathetic neural activity (MSNA); however, the effect on arterial baroreflex control of MSNA is unknown. Furthermore, arterial baroreflex control at HA may be influenced by genotypic and phenotypic differences between lowland and highland natives. Fourteen Lowlanders (12 male) and nine male Sherpa underwent haemodynamic and sympathetic neural assessment at low altitude (Lowlanders, low altitude; 344 m, Sherpa, Kathmandu; 1400 m) and following gradual ascent to 5050 m. Beat-by-beat haemodynamics (photoplethysmography) and MSNA (microneurography) were recorded lying supine. Indices of vascular sympathetic baroreflex function were determined from the relationship of diastolic blood pressure (DBP) and corresponding MSNA at rest (i.e. DBP 'operating pressure' and MSNA 'operating point'), as well as during a modified Oxford baroreflex test (i.e. 'gain'). Operating pressure and gain were unchanged for Lowlanders during HA exposure; however, the operating point was reset upwards (48 ± 16 vs. 22 ± 12 bursts 100 HB-1 , P = 0.001). Compared to Lowlanders at 5050 m, Sherpa had similar gain and operating pressure, although the operating point was lower (30 ± 13 bursts 100 HB-1 , P = 0.02); MSNA burst frequency was lower for Sherpa (22 ± 11 vs. 30 ± 9 bursts min-1 P = 0.03). Breathing 100% oxygen did not alter vascular sympathetic baroreflex function for either group at HA. For Lowlanders, upward baroreflex resetting promotes heightened sympathetic vasoconstrictor activity and maintains blood pressure stability, at least during early HA exposure; mechanisms other than peripheral chemoreflex activation could be involved. Sherpa adaptation appears to favour a lower sympathetic vasoconstrictor activity compared to Lowlanders for blood pressure homeostasis.
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Affiliation(s)
- Lydia L Simpson
- Extremes Research Group, School of Sport, Health and Exercise Sciences, Bangor University, Bangor, Wales, UK
| | - Stephen A Busch
- Neurovascular Health Laboratory, Faculty of Kinesiology, Sport and Recreation, University of Alberta, Edmonton, Alberta, Canada
| | - Samuel J Oliver
- Extremes Research Group, School of Sport, Health and Exercise Sciences, Bangor University, Bangor, Wales, UK
| | - Philip N Ainslie
- Centre for Heart, Lung, and Vascular Health, University of British Columbia Okanagan, BC, Kelowna, Canada
| | - Mike Stembridge
- Cardiff School of Sport and Health Sciences, Cardiff Metropolitan University, Cardiff, Wales, UK
| | - Craig D Steinback
- Neurovascular Health Laboratory, Faculty of Kinesiology, Sport and Recreation, University of Alberta, Edmonton, Alberta, Canada
| | - Jonathan P Moore
- Extremes Research Group, School of Sport, Health and Exercise Sciences, Bangor University, Bangor, Wales, UK
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19
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De Maria B, Bari V, Cairo B, Vaini E, Esler M, Lambert E, Baumert M, Cerutti S, Dalla Vecchia L, Porta A. Characterization of the Asymmetry of the Cardiac and Sympathetic Arms of the Baroreflex From Spontaneous Variability During Incremental Head-Up Tilt. Front Physiol 2019; 10:342. [PMID: 31001137 PMCID: PMC6454064 DOI: 10.3389/fphys.2019.00342] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2018] [Accepted: 03/13/2019] [Indexed: 11/13/2022] Open
Abstract
Hysteresis of the baroreflex (BR) is the result of the different BR sensitivity (BRS) when arterial pressure (AP) rises or falls. This phenomenon has been poorly studied and almost exclusively examined by applying pharmacological challenges and static approaches disregarding causal relations. This study inspects the asymmetry of the cardiac BR (cBR) and vascular sympathetic BR (sBR) in physiological closed loop conditions from spontaneous fluctuations of physiological variables, namely heart period (HP) and systolic AP (SAP) leading to the estimation of cardiac BRS (cBRS) and muscle sympathetic nerve activity (MSNA) and diastolic AP (DAP) leading to the estimation of vascular sympathetic BRS (sBRS). The assessment was carried out in 12 young healthy subjects undergoing incremental head-up tilt with table inclination gradually increased from 0 to 60°. Two analytical methods were exploited and compared, namely the sequence (SEQ) and phase-rectified signal averaging (PRSA) methods. SEQ analysis is based on the detection of joint causal schemes representing the HP and MSNA burst rate delayed responses to spontaneous SAP and DAP modifications, respectively. PRSA analysis averages HP and MSNA burst rate patterns after aligning them according to the direction of SAP and DAP changes, respectively. Since cBRSs were similar when SAP went up or down, hysteresis of cBR was not detected. Conversely, hysteresis of sBR was evident with sBRS more negative when DAP was falling than rising. sBR hysteresis was no longer visible during sympathetic activation induced by the orthostatic challenge. These results were obtained via the SEQ method, while the PRSA technique appeared to be less powerful in describing the BR asymmetry due to the strong association between BRS estimates computed over positive and negative AP variations. This study suggests that cBR and sBR provide different information about the BR control, sBR exhibits more relevant non-linear features that are evident even during physiological changes of AP, and the SEQ method can be fruitfully exploited to characterize the BR hysteresis with promising applications to BR branches different from cBR and sBR.
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Affiliation(s)
| | - Vlasta Bari
- Department of Cardiothoracic, Vascular Anesthesia and Intensive Care, IRCCS Policlinico San Donato, Milan, Italy
| | - Beatrice Cairo
- Department of Biomedical Sciences for Health, University of Milan, Milan, Italy
| | - Emanuele Vaini
- Department of Cardiothoracic, Vascular Anesthesia and Intensive Care, IRCCS Policlinico San Donato, Milan, Italy
| | - Murray Esler
- Human Neurotransmitters Laboratory, Baker IDI Heart and Diabetes Institute, Melbourne, VIC, Australia
| | - Elisabeth Lambert
- Human Neurotransmitters Laboratory, Baker IDI Heart and Diabetes Institute, Melbourne, VIC, Australia.,Faculty of Health, Arts and Design, Iverson Health Innovation Research Institute, Swinburne University of Technology, Hawthorn, VIC, Australia
| | - Mathias Baumert
- School of Electrical and Electronic Engineering, The University of Adelaide, Adelaide, SA, Australia
| | - Sergio Cerutti
- Department of Electronics Information and Bioengineering, Politecnico di Milano, Milan, Italy
| | | | - Alberto Porta
- Department of Cardiothoracic, Vascular Anesthesia and Intensive Care, IRCCS Policlinico San Donato, Milan, Italy.,Department of Biomedical Sciences for Health, University of Milan, Milan, Italy
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20
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Fonkoue IT, Le N, Kankam ML, DaCosta D, Jones TN, Marvar PJ, Park J. Sympathoexcitation and impaired arterial baroreflex sensitivity are linked to vascular inflammation in individuals with elevated resting blood pressure. Physiol Rep 2019; 7:e14057. [PMID: 30968587 PMCID: PMC6456445 DOI: 10.14814/phy2.14057] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2019] [Revised: 03/15/2019] [Accepted: 03/21/2019] [Indexed: 12/31/2022] Open
Abstract
Elevated Resting Blood Pressure (ERBP) in the prehypertensive range is associated with increased risk of hypertension and cardiovascular disease, the mechanisms of which remain unclear. Prior studies have suggested that ERBP may be associated with overactivation and dysregulation of the sympathetic nervous system (SNS). We hypothesized that compared to normotensives (≤120/80 mmHg), ERBP (120/80-139/89 mmHg) has higher SNS activity, impaired arterial baroreflex sensitivity (BRS), and increased vascular inflammation. Twenty-nine participants were studied: 16 otherwise healthy individuals with ERBP (blood pressure (BP) 130 ± 2/85 ± 2 mmHg) and 13 matched normotensive controls (mean BP 114 ± 2/73 ± 2 mmHg). We measured muscle sympathetic nerve activity (MSNA), beat-to-beat BP, and continuous electrocardiogram at rest and during arterial BRS testing via the modified Oxford technique. Blood was analyzed for the following biomarkers of vascular inflammation: lipoprotein-associated phospholipase A2 (Lp-PLA2), E-selectin, and intercellular adhesion molecule 1 (ICAM-1). Resting MSNA burst frequency (22 ± 2 vs. 16 ± 2 bursts/min, P = 0.036) and burst incidence (36 ± 3 vs. 25 ± 3 bursts/100 heart beats, P = 0.025) were higher in ERBP compared to controls. Cardiovagal BRS was blunted in ERBP compared to controls (13 ± 2 vs. 20 ± 3 msec/mmHg, P = 0.032), while there was no difference in sympathetic BRS between groups. Lp-PLA2 (169 ± 8 vs. 142 ± 9 nmol/min/mL, P = 0.020) and E-selectin (6.89 ± 0.6 vs. 4.45 ± 0.51 ng/mL, P = 0.004) were higher in ERBP versus controls. E-selectin (r = 0.501, P = 0.011) and ICAM-1 (r = 0.481, P = 0.015) were positively correlated with MSNA, while E-selectin was negatively correlated with cardiovagal BRS (r = -0.427, P = 0.030). These findings demonstrate that individuals with ERBP have SNS overactivity and impaired arterial BRS that are linked to biomarkers of vascular inflammation.
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Affiliation(s)
- Ida T. Fonkoue
- Renal DivisionDepartment of MedicineEmory University School of MedicineAtlantaGeorgia
- Research Service LineAtlanta VA Healthcare SystemDecaturGeorgia
| | - Ngoc‐Anh Le
- Biomarker Core LaboratoryAtlanta VA Healthcare SystemDecaturGeorgia
| | - Melanie L. Kankam
- Renal DivisionDepartment of MedicineEmory University School of MedicineAtlantaGeorgia
- Research Service LineAtlanta VA Healthcare SystemDecaturGeorgia
| | - Dana DaCosta
- Renal DivisionDepartment of MedicineEmory University School of MedicineAtlantaGeorgia
- Research Service LineAtlanta VA Healthcare SystemDecaturGeorgia
| | - Toure N. Jones
- Renal DivisionDepartment of MedicineEmory University School of MedicineAtlantaGeorgia
- Research Service LineAtlanta VA Healthcare SystemDecaturGeorgia
| | - Paul J. Marvar
- Department of Pharmacology and PhysiologyInstitute for NeuroscienceGeorge Washington UniversityWashingtonDistrict of Columbia
| | - Jeanie Park
- Renal DivisionDepartment of MedicineEmory University School of MedicineAtlantaGeorgia
- Research Service LineAtlanta VA Healthcare SystemDecaturGeorgia
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21
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El Sayed K, Macefield VG, Hissen SL, Joyner MJ, Taylor CE. Blood pressure reactivity at onset of mental stress determines sympathetic vascular response in young adults. Physiol Rep 2018; 6:e13944. [PMID: 30552755 PMCID: PMC6294720 DOI: 10.14814/phy2.13944] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2018] [Accepted: 11/22/2018] [Indexed: 11/24/2022] Open
Abstract
We have previously shown in young males that the rate of rise in blood pressure (BP) at the onset of mental stress determines whether or not muscle sympathetic nerve activity (MSNA) has a role in driving the pressor response. The aim of this study was to investigate these interactions in young females. BP and MSNA were recorded continuously in 19 females and 21 males during 2-min mental stressors (mental arithmetic and Stroop test). Physical stressor tasks (cold pressor, handgrip exercise, postexercise ischemia) were also performed. During the first minute of mental arithmetic, the rate of rise in mean arterial pressure (MAP) was significantly greater in negative responders (mean decrease in MSNA) compared with positive responders (mean increase in MSNA) in both males (1.9 ± 0.7 vs. 0.7 ± 0.3 mmHg/sec) and females (1.0 ± 0.3 vs. 0.5 ± 0.2 mmHg/sec). For the Stroop test, there was no significant difference in the rate of the rise in BP between positive and negative responders (P > 0.05). However, peak changes in MAP were significantly greater in negative responders compared with positive responders in both males (22 ± 6 vs. 13 ± 3 mmHg) and females (12 ± 2 vs. 6 ± 1 mmHg). Sympathetic baroreflex sensitivity was greater in negative responders and may contribute to the fall in MSNA experienced by these individuals during mental stress. During physical stressors there were consistent increases in BP and MSNA in males and females. The findings suggest that, in both males and females, BP reactivity at the onset of mental stress dictates whether or not there is an increase or decrease in MSNA.
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Affiliation(s)
- Khadigeh El Sayed
- School of MedicineWestern Sydney UniversitySydneyNew South WalesAustralia
| | - Vaughan G. Macefield
- School of MedicineWestern Sydney UniversitySydneyNew South WalesAustralia
- Neuroscience Research AustraliaSydneyNew South WalesAustralia
- Baker Heart and Diabetes InstituteMelbourneVictoriaAustralia
| | - Sarah L Hissen
- School of Science and HealthWestern Sydney UniversitySydneyNew South WalesAustralia
| | | | - Chloe E. Taylor
- School of MedicineWestern Sydney UniversitySydneyNew South WalesAustralia
- School of Science and HealthWestern Sydney UniversitySydneyNew South WalesAustralia
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22
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Vianna LC, Fernandes IA, Martinez DG, Teixeira AL, Silva BM, Fadel PJ, Nóbrega ACL. Water drinking enhances the gain of arterial baroreflex control of muscle sympathetic nerve activity in healthy young humans. Exp Physiol 2018; 103:1318-1325. [DOI: 10.1113/ep087095] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2018] [Accepted: 07/26/2018] [Indexed: 01/29/2023]
Affiliation(s)
- Lauro C. Vianna
- NeuroVASQ - Integrative Physiology Laboratory; Faculty of Physical Education; University of Brasília; Brasília DF Brazil
| | - Igor A. Fernandes
- NeuroVASQ - Integrative Physiology Laboratory; Faculty of Physical Education; University of Brasília; Brasília DF Brazil
- Department of Physiology and Pharmacology; Fluminense Federal University; Niterói RJ Brazil
| | - Daniel G. Martinez
- Research Unit for Cardiovascular and Exercise Physiology; Faculty of Physical Education and Sports; Federal University of Juiz de Fora; Juiz de Fora MG Brazil
| | - André L. Teixeira
- NeuroVASQ - Integrative Physiology Laboratory; Faculty of Physical Education; University of Brasília; Brasília DF Brazil
| | - Bruno M. Silva
- Department of Physiology; Federal University of Sao Paulo (UNIFESP); Sao Paulo SP Brazil
| | - Paul J. Fadel
- Department of Kinesiology; University of Texas at Arlington; Arlington TX USA
| | - Antonio C. L. Nóbrega
- Department of Physiology and Pharmacology; Fluminense Federal University; Niterói RJ Brazil
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23
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Porta A, Bari V, Ranuzzi G, De Maria B, Malacarne M, Pagani M, Lucini D. Evaluating the association between cardiac and peripheral resistance arms of the baroreflex. ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. ANNUAL INTERNATIONAL CONFERENCE 2018; 2017:3114-3117. [PMID: 29060557 DOI: 10.1109/embc.2017.8037516] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The study proposes an extension of cardiac baroreflex (cBR) sequence analysis, traditionally performed over spontaneous fluctuations of heart period and systolic arterial pressure, to typify peripheral resistance baroreflex (prBR) from spontaneous variations of peripheral resistances and diastolic arterial pressure. The prBR baroreflex sensitivity (BRSprBR) and percentage of prBR sequences (SEQ%prBR) were computed along with analogous quantities assessed over cBR (i.e. BRScBR and SEQ%cBR). The cBR and prBR were typified in healthy subjects at rest (REST) and during light bicycle ergometer exercise at 10 percent of the maximal effort (EXE). Both cBR and prBR were affected by EXE: indeed, BRScBR and SEQ%prBR were significantly reduced. Moreover, while BRScBR and BRSprBR were not significantly associated, SEQ%cBR and SEQ%prBR were, and the correlation coefficient was positive. This study suggests that prBR can be typified from spontaneous variabilities along with the more traditional cBR, thus enlarging the possibility of monitoring human cardiovascular control mechanisms.
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24
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de Zambotti M, Trinder J, Silvani A, Colrain IM, Baker FC. Dynamic coupling between the central and autonomic nervous systems during sleep: A review. Neurosci Biobehav Rev 2018; 90:84-103. [PMID: 29608990 PMCID: PMC5993613 DOI: 10.1016/j.neubiorev.2018.03.027] [Citation(s) in RCA: 99] [Impact Index Per Article: 16.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2017] [Revised: 02/16/2018] [Accepted: 03/24/2018] [Indexed: 12/19/2022]
Abstract
Sleep is characterized by coordinated cortical and cardiac oscillations reflecting communication between the central (CNS) and autonomic (ANS) nervous systems. Here, we review fluctuations in ANS activity in association with CNS-defined sleep stages and cycles, and with phasic cortical events during sleep (e.g., arousals, K-complexes). Recent novel analytic methods reveal a dynamic organization of integrated physiological networks during sleep and indicate how multiple factors (e.g., sleep structure, age, sleep disorders) affect "CNS-ANS coupling". However, these data are mostly correlational and there is a lack of clarity of the underlying physiology, making it challenging to interpret causality and direction of coupling. Experimental manipulations (e.g., evoking K-complexes or arousals) provide information on the precise temporal sequence of cortical-cardiac activity, and are useful for investigating physiological pathways underlying CNS-ANS coupling. With the emergence of new analytical approaches and a renewed interest in ANS and CNS communication during sleep, future work may reveal novel insights into sleep and cardiovascular interactions during health and disease, in which coupling could be adversely impacted.
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Affiliation(s)
| | - John Trinder
- Melbourne School of Psychological Sciences, University of Melbourne, Parkville, Victoria, Australia.
| | - Alessandro Silvani
- Department of Biomedical and Neuromotor Sciences, University of Bologna, Italy.
| | - Ian M Colrain
- Center for Health Sciences, SRI International, Menlo Park, CA, USA; Melbourne School of Psychological Sciences, University of Melbourne, Parkville, Victoria, Australia.
| | - Fiona C Baker
- Center for Health Sciences, SRI International, Menlo Park, CA, USA; Brain Function Research Group, School of Physiology, University of the Witwatersrand, Johannesburg, South Africa.
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25
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Hissen SL, Sayed KE, Macefield VG, Brown R, Taylor CE. The Stability and Repeatability of Spontaneous Sympathetic Baroreflex Sensitivity in Healthy Young Individuals. Front Neurosci 2018; 12:403. [PMID: 29962929 PMCID: PMC6010576 DOI: 10.3389/fnins.2018.00403] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2018] [Accepted: 05/25/2018] [Indexed: 01/18/2023] Open
Abstract
Spontaneous sympathetic baroreflex sensitivity (BRS) is a valuable tool for assessing how well the baroreflex buffers beat-to-beat changes in blood pressure. However, there has yet to be a study involving appropriate statistical tests to examine the stability of sympathetic BRS within an experimental session and the repeatability between separate sessions. The aim of this study was to use intra-class correlations, ordinary least products regression, and Bland–Altman analyses to examine the stability and repeatability of spontaneous sympathetic BRS assessment. In addition, the influence of recording duration on values of BRS was assessed. In eighty-four healthy young individuals (49 males, 35 females), continuous measurements of blood pressure, heart rate and muscle sympathetic nerve activity (MSNA) were recorded for 10 min. In a subgroup of 13 participants (11 male, 2 female) the measurements were repeated on a separate day. Sympathetic BRS was quantified using MSNA burst incidence (BRSinc) and total MSNA (BRStotal) for the first 5-min period, the second 5-min period, and a 2-min segment taken from the second 5-min period. Intra-class correlation coefficients indicated moderate stability in sympathetic BRSinc and BRStotal between the first and second 5-min periods in males (BRSincr = 0.63, BRStotalr = 0.78) and females (BRSincr = 0.61, BRStotalr = 0.47) with no proportional bias, but with fixed bias for BRSinc in females. When comparing the first 5-min with the 2-min period (n = 76), the intra-class correlation coefficient indicated poor to moderate repeatability in sympathetic BRSinc and BRStotal for males (BRSincr = -0.01, BRStotalr = 0.70) and females (BRSincr = 0.46, BRStotalr = 0.39). However, Bland–Altman analysis revealed a fixed bias for BRStotal in males and proportional bias for BRStotal in females, with lower BRS values for 5-min recordings. In the subgroup, intra-class correlations indicated moderate repeatability for measures of BRSinc (9 male, 2 female, r = 0.63) and BRStotal (6 male, 2 female, r = 0.68) assessed using 5-min periods recorded on separate days. However, Bland–Altman analysis indicated proportional bias for BRSinc and fixed bias for BRStotal. In conclusion, measures of spontaneous sympathetic BRS are moderately stable and repeatable within and between testing sessions in healthy young adults, provided that the same length of recording is used when making comparisons.
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Affiliation(s)
- Sarah L Hissen
- School of Science and Health, Western Sydney University, Sydney, NSW, Australia
| | - Khadigeh El Sayed
- School of Medicine, Western Sydney University, Sydney, NSW, Australia
| | - Vaughan G Macefield
- School of Medicine, Western Sydney University, Sydney, NSW, Australia.,Baker Heart and Diabetes Institute, Melbourne, VIC, Australia.,Neuroscience Research Australia, Sydney, NSW, Australia
| | - Rachael Brown
- School of Medicine, Western Sydney University, Sydney, NSW, Australia
| | - Chloe E Taylor
- School of Science and Health, Western Sydney University, Sydney, NSW, Australia.,School of Medicine, Western Sydney University, Sydney, NSW, Australia
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26
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Porta A, Bari V, Maria BD, Cairo B, Vaini E, Malacarne M, Pagani M, Lucini D. Peripheral Resistance Baroreflex During Incremental Bicycle Ergometer Exercise: Characterization and Correlation With Cardiac Baroreflex. Front Physiol 2018; 9:688. [PMID: 29922179 PMCID: PMC5996055 DOI: 10.3389/fphys.2018.00688] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2018] [Accepted: 05/17/2018] [Indexed: 11/13/2022] Open
Abstract
The arm of the baroreflex (BR) controlling peripheral resistances (PR), labeled as BR of PR (prBR), was characterized through an extension of the cardiac BR (cBR) sequence analysis. The method exploits recordings of skin blood flow (SBF) from the palm of the non-dominant hand via a laser Doppler flowmeter and of arterial pressure (AP) from the middle finger of the same hand via a plethysmographic device. PR was estimated beat-by-beat as the ratio of mean AP to mean SBF computed over the same heart period (HP). Peripheral resistances-diastolic arterial pressure (PR-DAP) sequences featuring simultaneous increases of PR and decreases of diastolic AP (DAP) or vice versa were identified and the slope of the regression line in the (DAP, PR) plane was taken as an estimate of prBR sensitivity (BRSprBR). The percentage of prBR sequences (SEQ%prBR) was taken as a measure of prBR involvement and the prBR effectiveness index (EIprBR) was computed as the fraction of DAP sequences capable to drive antiparallel PR variations. Analogous markers were computed over cBR from HP and systolic AP (SAP) variability [i.e., cBR sensitivity (BRScBR), percentage of cBR sequences (SEQ%cBR), and effectiveness index of the cBR (EIcBR)]. prBR and cBR were typified during incremental light-to-moderate bicycle ergometer exercise at 10, 20, and 30% of the maximum effort in 16 healthy subjects (aged from 22 to 58 years, six males). We found that: (i) BRScBR decreased gradually with the challenge, while BRSprBR declined only at the heaviest workload; (ii) SEQ%cBR decreased solely at the lightest workload, while the decline of SEQ%prBR was significant regardless of the intensity of the challenge; (iii) EIprBR and EIcBR were not affected by exercise; (iv) after pooling together all the data regardless of the experimental conditions, BRSprBR and BRScBR were uncorrelated, while SEQ%cBR and SEQ%prBR as well as EIcBR and EIprBR, were significantly and positively correlated; (v) when the correlation between SEQ%cBR and SEQ%prBR and between EIcBR and EIprBR was assessed separately in each experimental condition, it was not systematically detected. This study suggests that prBR characterization provides information complementary to cBR that might be fruitfully exploited to improve patients' risk stratification.
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Affiliation(s)
- Alberto Porta
- Department of Biomedical Sciences for Health, University of Milan, Milan, Italy.,Department of Cardiothoracic, Vascular Anesthesia and Intensive Care, IRCCS Policlinico San Donato, Milan, Italy
| | - Vlasta Bari
- Department of Cardiothoracic, Vascular Anesthesia and Intensive Care, IRCCS Policlinico San Donato, Milan, Italy
| | | | - Beatrice Cairo
- Department of Biomedical Sciences for Health, University of Milan, Milan, Italy
| | - Emanuele Vaini
- Department of Cardiothoracic, Vascular Anesthesia and Intensive Care, IRCCS Policlinico San Donato, Milan, Italy
| | - Mara Malacarne
- Dipartimento di Biotecnologie Mediche e Medicina Traslazionale, University of Milan, Milan, Italy.,Exercise Medicine Unit, Humanitas Clinical and Research Center, Milan, Italy
| | - Massimo Pagani
- Dipartimento di Biotecnologie Mediche e Medicina Traslazionale, University of Milan, Milan, Italy
| | - Daniela Lucini
- Dipartimento di Biotecnologie Mediche e Medicina Traslazionale, University of Milan, Milan, Italy.,Exercise Medicine Unit, Humanitas Clinical and Research Center, Milan, Italy
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27
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Coates AM, INCOGNITO ANTHONYV, SEED JEREMYD, DOHERTY CONNORJ, MILLAR PHILIPJ, BURR JAMIEF. Three Weeks of Overload Training Increases Resting Muscle Sympathetic Activity. Med Sci Sports Exerc 2018; 50:928-937. [DOI: 10.1249/mss.0000000000001514] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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28
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Witter T, Tzeng YC, O'Donnell T, Kusel J, Walker B, Berry M, Taylor CE. Inter-individual Relationships between Sympathetic Arterial Baroreflex Function and Cerebral Perfusion Control in Healthy Males. Front Neurosci 2017; 11:457. [PMID: 28860964 PMCID: PMC5559461 DOI: 10.3389/fnins.2017.00457] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2017] [Accepted: 07/28/2017] [Indexed: 12/29/2022] Open
Abstract
Maintenance of adequate cerebral perfusion during normal physiological challenges requires integration between cerebral blood flow (CBF) and systemic blood pressure control mechanisms. Previous studies have shown that cardiac baroreflex sensitivity (BRS) is inversely related to some measures of cerebral autoregulation. However, interactions between the sympathetic arterial baroreflex and cerebral perfusion control mechanisms have not been explored. To determine the nature and magnitude of these interactions we measured R–R interval, blood pressure, CBF velocity, and muscle sympathetic nerve activity (MSNA) in 11 healthy young males. Sympathetic BRS was estimated using modified Oxford method as the relationship between beat-to-beat diastolic blood pressure (DBP) and MSNA. Integrated control of CBF was quantified using transfer function analysis (TFA) metrics derived during rest and Tieck's autoregulatory index following bilateral thigh cuff deflation. Sympathetic BRS during modified Oxford trials was significantly related to autoregulatory index (r = 0.64, p = 0.03). Sympathetic BRS during spontaneous baseline was significantly related to transfer function gain (r = −0.74, p = 0.01). A more negative value for sympathetic BRS indicates more effective arterial baroreflex regulation, and a lower transfer function gain reflects greater cerebral autoregulation. Therefore, these findings indicate that males with attenuated CBF regulation have greater sympathetic BRS (and vice versa), consistent with compensatory interactions between blood pressure and cerebral perfusion control mechanisms.
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Affiliation(s)
- Trevor Witter
- Wellington Medical Technology Group, Centre for Translational Physiology, University of OtagoWellington, New Zealand
| | - Yu-Chieh Tzeng
- Wellington Medical Technology Group, Centre for Translational Physiology, University of OtagoWellington, New Zealand
| | - Terry O'Donnell
- Wellington Medical Technology Group, Centre for Translational Physiology, University of OtagoWellington, New Zealand
| | - Jessica Kusel
- Wellington Medical Technology Group, Centre for Translational Physiology, University of OtagoWellington, New Zealand
| | - Bridget Walker
- Wellington Medical Technology Group, Centre for Translational Physiology, University of OtagoWellington, New Zealand
| | - Mary Berry
- Wellington Medical Technology Group, Centre for Translational Physiology, University of OtagoWellington, New Zealand
| | - Chloe E Taylor
- School of Science and Health, Western Sydney UniversitySydney, NSW, Australia.,School of Medicine, Western Sydney UniversitySydney, NSW, Australia
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29
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Hissen SL, El Sayed K, Macefield VG, Brown R, Taylor CE. Muscle sympathetic nerve activity peaks in the first trimester in healthy pregnancy: a longitudinal case study. Clin Auton Res 2017; 27:401-406. [DOI: 10.1007/s10286-017-0439-1] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2017] [Accepted: 06/16/2017] [Indexed: 11/29/2022]
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30
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El Sayed K, Macefield VG, Hissen SL, Joyner MJ, Taylor CE. Rate of rise in diastolic blood pressure influences vascular sympathetic response to mental stress. J Physiol 2016; 594:7465-7482. [PMID: 27690366 DOI: 10.1113/jp272963] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2016] [Accepted: 09/26/2016] [Indexed: 11/08/2022] Open
Abstract
KEY POINTS Research indicates that individuals may experience a rise (positive responders) or fall (negative responders) in muscle sympathetic nerve activity (MSNA) during mental stress. In this study, we examined the early blood pressure responses (including the peak, time of peak and rate of rise in blood pressure) to mental stress in positive and negative responders. Negative MSNA responders to mental stress exhibit a more rapid rise in diastolic pressure at the onset of the stressor, suggesting a baroreflex-mediated suppression of MSNA. In positive responders there is a more sluggish rise in blood pressure during mental stress, which appears to be MSNA-driven. This study suggests that whether MSNA has a role in the pressor response is dependent upon the reactivity of blood pressure early in the task. ABSTRACT Research indicates that individuals may experience a rise (positive responders) or fall (negative responders) in muscle sympathetic nerve activity (MSNA) during mental stress. The aim was to examine the early blood pressure response to stress in positive and negative responders and thus its influence on the direction of change in MSNA. Blood pressure and MSNA were recorded continuously in 21 healthy young males during 2 min mental stressors (mental arithmetic, Stroop test) and physical stressors (cold pressor, handgrip exercise, post-exercise ischaemia). Participants were classified as negative or positive responders according to the direction of the mean change in MSNA during the stressor tasks. The peak changes, time of peak and rate of changes in blood pressure were compared between groups. During mental arithmetic negative responders experienced a significantly greater rate of rise in diastolic blood pressure in the first minute of the task (1.3 ± 0.5 mmHg s-1 ) compared with positive responders (0.4 ± 0.1 mmHg s-1 ; P = 0.03). Similar results were found for the Stroop test. Physical tasks elicited robust parallel increases in blood pressure and MSNA across participants. It is concluded that negative MSNA responders to mental stress exhibit a more rapid rise in diastolic pressure at the onset of the stressor, suggesting a baroreflex-mediated suppression of MSNA. In positive responders there is a more sluggish rise in blood pressure during mental stress, which appears to be MSNA-driven. This study suggests that whether MSNA has a role in the pressor response is dependent upon the reactivity of blood pressure early in the task.
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Affiliation(s)
| | - Vaughan G Macefield
- School of Medicine, Western Sydney University, Sydney, Australia.,Neuroscience Research Australia, Sydney, Australia
| | - Sarah L Hissen
- School of Science and Health, Western Sydney University, Sydney, Australia
| | | | - Chloe E Taylor
- School of Science and Health, Western Sydney University, Sydney, Australia
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31
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Marchi A, Bari V, De Maria B, Esler M, Lambert E, Baumert M, Porta A. Simultaneous Characterization of Sympathetic and Cardiac Arms of the Baroreflex through Sequence Techniques during Incremental Head-Up Tilt. Front Physiol 2016; 7:438. [PMID: 27746741 PMCID: PMC5041323 DOI: 10.3389/fphys.2016.00438] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2016] [Accepted: 09/14/2016] [Indexed: 11/17/2022] Open
Abstract
We propose a sympathetic baroreflex (sBR) sequence method for characterizing sBR from spontaneous beat-to-beat fluctuations of muscle sympathetic nerve activity (MSNA) and diastolic arterial pressure (DAP). The method exploits a previously defined MSNA variability quantifying the fluctuations of MSNA burst rate. The method is based on the detection of MSNA and DAP sequences characterized by the contemporaneous DAP increase and MSNA decrease or vice versa. The percentage of sBR sequences (SEQ%sBR) was taken as an indication of the degree of sBR solicitation and the average slope of the regression lines in the (DAP, MSNA) plane was taken as sBR sensitivity (sBRSSEQ) and expressed in bursts.s−1.mmHg−1. sBRSSEQ was compared to a more traditional estimate based on the baroreflex threshold analysis (sBRSBTA). An incremental head-up tilt protocol, carried out in 12 young healthy subjects (age: 20–36 yr, median = 22.5 yr, 9 females) sequentially tilted at 0, 20, 30, 40, 60° table inclinations, was utilized to set the sBR sequence method parameters. Traditional sequence analysis was exploited to estimate cardiac baroreflex (cBR) sensitivity (cBRSSEQ) and percentage of cBR sequences (SEQ%cBR). The head-up tilt induced the progressive increase of SEQ%sBR and SEQ%cBR and gradual decrease of both sBRSSEQ and cBRSSEQ, thus suggesting the gradual rise of the sBR and cBR solicitations and the progressive reduction of their effectiveness with the stimulus. sBRSSEQ was significantly associated with sBRSBTA. sBRSSEQ and cBRSSEQ were significantly correlated as well as SEQ%sBR and SEQ%cBR, even though the correlation was not strong, thus suggesting a certain degree of independence between the baroreflex arms. The proposed sBR sequence approach provides a dynamical characterization of the sBR alternative to more traditional static pharmacological and nonpharmacological methods and fully homogenous with the cBR sequence technique.
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Affiliation(s)
- Andrea Marchi
- Department of Electronics Information and Bioengineering, Politecnico di MilanoMilan, Italy; Department of Emergency and Intensive Care, San Gerardo HospitalMonza, Italy
| | - Vlasta Bari
- Department of Biomedical Sciences for Health, University of Milan Milan, Italy
| | - Beatrice De Maria
- Department of Electronics Information and Bioengineering, Politecnico di MilanoMilan, Italy; IRCCS Fondazione Salvatore MaugeriMilan, Italy
| | - Murray Esler
- Human Neurotransmitter Laboratory, Baker IDI Heart and Diabetes Institute Melbourne, VIC, Australia
| | - Elisabeth Lambert
- Human Neurotransmitter Laboratory, Baker IDI Heart and Diabetes Institute Melbourne, VIC, Australia
| | - Mathias Baumert
- School of Electrical and Electronic Engineering, University of Adelaide Adelaide, SA, Australia
| | - Alberto Porta
- Department of Biomedical Sciences for Health, University of MilanMilan, Italy; Department of Cardiothoracic, Vascular Anesthesia and Intensive Care, IRCCS Policlinico San DonatoMilan, Italy
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Johnson AW, Hissen SL, Macefield VG, Brown R, Taylor CE. Magnitude of Morning Surge in Blood Pressure Is Associated with Sympathetic but Not Cardiac Baroreflex Sensitivity. Front Neurosci 2016; 10:412. [PMID: 27660603 PMCID: PMC5014858 DOI: 10.3389/fnins.2016.00412] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2016] [Accepted: 08/25/2016] [Indexed: 11/13/2022] Open
Abstract
The ability of the arterial baroreflex to regulate blood pressure may influence the magnitude of the morning surge in blood pressure (MSBP). The aim was to investigate the relationships between sympathetic and cardiac baroreflex sensitivity (BRS) and the morning surge. Twenty-four hour ambulatory blood pressure was recorded in 14 young individuals. The morning surge was defined via the pre-awakening method, which is calculated as the difference between mean blood pressure values 2 h before and 2 h after rising from sleep. The mean systolic morning surge, diastolic morning surge, and morning surge in mean arterial pressures were 15 ± 2, 13 ± 1, and 11 ± 1 mmHg, respectively. During the laboratory protocol, continuous measurements of blood pressure, heart rate, and muscle sympathetic nerve activity (MSNA) were made over a 10-min period of rest. Sympathetic BRS was quantified by plotting MSNA burst incidence against diastolic pressure (sympathetic BRSinc), and by plotting total MSNA against diastolic pressure (sympathetic BRStotal). Cardiac BRS was quantified using the sequence method. The mean values for sympathetic BRSinc, sympathetic BRStotal and cardiac BRS were −1.26 ± 0.26 bursts/100 hb/mmHg, −1.60 ± 0.37 AU/beat/mmHg, and 13.1 ± 1.5 ms/mmHg respectively. Significant relationships were identified between sympathetic BRSinc and the diastolic morning surge (r = 0.62, p = 0.02) and the morning surge in mean arterial pressure (r = 0.57, p = 0.03). Low sympathetic BRS was associated with a larger morning surge in mean arterial and diastolic blood pressure. Trends for relationships were identified between sympathetic BRStotal and the diastolic morning surge (r = 0.52, p = 0.066) and the morning surge in mean arterial pressure (r = 0.48, p = 0.095) but these did not reach significance. There were no significant relationships between cardiac BRS and the morning surge. These findings indicate that the ability of the baroreflex to buffer increases in blood pressure via reflexive changes in MSNA may play a role in determining the magnitude of the MSBP.
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Affiliation(s)
- Aaron W Johnson
- School of Medicine, Western Sydney University Sydney, NSW, Australia
| | - Sarah L Hissen
- School of Science and Health, Western Sydney University Sydney, NSW, Australia
| | - Vaughan G Macefield
- School of Medicine, Western Sydney UniversitySydney, NSW, Australia; Neuroscience Research AustraliaSydney, NSW, Australia
| | - Rachael Brown
- School of Medicine, Western Sydney University Sydney, NSW, Australia
| | - Chloe E Taylor
- School of Science and Health, Western Sydney University Sydney, NSW, Australia
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Skoog J, Zachrisson H, Länne T, Lindenberger M. Slower Lower Limb Blood Pooling Increases Orthostatic Tolerance in Women with Vasovagal Syncope. Front Physiol 2016; 7:232. [PMID: 27378941 PMCID: PMC4906053 DOI: 10.3389/fphys.2016.00232] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2016] [Accepted: 05/30/2016] [Indexed: 11/28/2022] Open
Abstract
Background and Aim: Slower lower limb blood pooling and associated blunted sympathetic activation has been detected in healthy women prone to orthostatic syncope. Whether these findings are true also for patients with vasovagal syncope (VVS) is unknown. The aim was to investigate initial blood pooling time (poolingtime, time to 50% of total blood pooling) together with hemodynamic responses and orthostatic tolerance during lower body negative pressure (LBNP) in VVS and healthy controls. Methods and Results: Fourteen VVS women (25.7 ± 1.3 years) and 15 healthy women (22.8 ± 0.8 years) were subjected to single-step and graded LBNP to pre-syncope. Lower limb blood pooling (ml · 100 ml−1), poolingtime (s), hemodynamic responses and LBNP-tolerance were evaluated. LBNP induced comparable lower limb blood pooling in both groups (controls, 3.1 ± 0.3; VVS, 2.9 ± 0.3 ml · 100 ml−1, P = 0.70). In controls, shorter poolingtime correlated to higher LBNP-tolerance (r = –0.550, P < 0.05) as well as better maintained stroke volume (r = –0.698, P < 0.01) and cardiac output (r = –0.563, P < 0.05). In contrast, shorter poolingtime correlated to lower LBNP-tolerance in VVS (r = 0.821, P < 0.001) and larger decline in stroke volume (r = 0.611, P < 0.05). Furthermore, in controls, shorter poolingtime correlated to baroreflex-mediated hemodynamic changes during LBNP, e.g., increased vasoconstriction (P < 0.001). In VVS, poolingtime was not correlated with LBNP-induced baroreceptor unloading, but rather highly correlated to resting calf blood flow (P < 0.001). Conclusions: Shorter poolingtime seems to elicit greater sympathetic activation with a concomitant higher orthostatic tolerance in healthy women. The contrasting findings in VVS indicate a deteriorated vascular sympathetic control suggesting well-defined differences already in the initial responses during orthostatic stress.
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Affiliation(s)
- Johan Skoog
- Department of Medical and Health Sciences, Linköping UniversityLinköping, Sweden
- *Correspondence: Johan Skoog
| | - Helene Zachrisson
- Department of Clinical Physiology and Department of Medical and Health Sciences, Linköping UniversityLinköping, Sweden
| | - Toste Länne
- Department of Medical and Health Sciences, Linköping UniversityLinköping, Sweden
| | - Marcus Lindenberger
- Department of Cardiology and Department of Medical and Health Sciences, Linköping UniversityLinköping, Sweden
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Sivakumar SS, Namath AG, Tuxhorn IE, Lewis SJ, Galán RF. Decreased heart rate and enhanced sinus arrhythmia during interictal sleep demonstrate autonomic imbalance in generalized epilepsy. J Neurophysiol 2016; 115:1988-99. [PMID: 26888110 DOI: 10.1152/jn.01120.2015] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2015] [Accepted: 02/15/2016] [Indexed: 02/07/2023] Open
Abstract
We hypothesized that epilepsy affects the activity of the autonomic nervous system even in the absence of seizures, which should manifest as differences in heart rate variability (HRV) and cardiac cycle. To test this hypothesis, we investigated ECG traces of 91 children and adolescents with generalized epilepsy and 25 neurologically normal controls during 30 min of stage 2 sleep with interictal or normal EEG. Mean heart rate (HR) and high-frequency HRV corresponding to respiratory sinus arrhythmia (RSA) were quantified and compared. Blood pressure (BP) measurements from physical exams of all subjects were also collected and analyzed. RSA was on average significantly stronger in patients with epilepsy, whereas their mean HR was significantly lower after adjusting for age, body mass index, and sex, consistent with increased parasympathetic tone in these patients. In contrast, diastolic (and systolic) BP at rest was not significantly different, indicating that the sympathetic tone is similar. Remarkably, five additional subjects, initially diagnosed as neurologically normal but with enhanced RSA and lower HR, eventually developed epilepsy, suggesting that increased parasympathetic tone precedes the onset of epilepsy in children. ECG waveforms in epilepsy also displayed significantly longer TP intervals (ventricular diastole) relative to the RR interval. The relative TP interval correlated positively with RSA and negatively with HR, suggesting that these parameters are linked through a common mechanism, which we discuss. Altogether, our results provide evidence for imbalanced autonomic function in generalized epilepsy, which may be a key contributing factor to sudden unexpected death in epilepsy.
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Affiliation(s)
- Siddharth S Sivakumar
- Department of Neurosciences, School of Medicine, Case Western Reserve University, Cleveland, Ohio
| | - Amalia G Namath
- Department of Neurosciences, School of Medicine, Case Western Reserve University, Cleveland, Ohio
| | - Ingrid E Tuxhorn
- Division of Pediatric Epilepsy, Department of Pediatrics, School of Medicine, Case Western Reserve University, Cleveland, Ohio
| | - Stephen J Lewis
- Division of Pulmonology, Allergy and Immunology, Department of Pediatrics, School of Medicine, Case Western Reserve University, Cleveland, Ohio; and
| | - Roberto F Galán
- Department of Electrical Engineering and Computer Science, School of Engineering, Case Western Reserve University, Cleveland, Ohio
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