51
|
Carter JR. Microneurography and sympathetic nerve activity: a decade-by-decade journey across 50 years. J Neurophysiol 2019; 121:1183-1194. [PMID: 30673363 DOI: 10.1152/jn.00570.2018] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
The technique of microneurography has advanced the field of neuroscience for the past 50 years. While there have been a number of reviews on microneurography, this paper takes an objective approach to exploring the impact of microneurography studies. Briefly, Web of Science (Thomson Reuters) was used to identify the highest citation articles over the past 50 years, and key findings are presented in a decade-by-decade highlight. This includes the establishment of microneurography in the 1960s, the acceleration of the technique by Gunnar Wallin in the 1970s, the international collaborations of the 1980s and 1990s, and finally the highest impact studies from 2000 to present. This journey through 50 years of microneurographic research related to peripheral sympathetic nerve activity includes a historical context for several of the laboratory interventions commonly used today (e.g., cold pressor test, mental stress, lower body negative pressure, isometric handgrip, etc.) and how these interventions and experimental approaches have advanced our knowledge of cardiovascular, cardiometabolic, and other human diseases and conditions.
Collapse
Affiliation(s)
- Jason R Carter
- Department of Kinesiology and Integrative Physiology, Michigan Technological University , Houghton, Michigan
| |
Collapse
|
52
|
Matthews EL, Sebzda KN, Wenner MM. Altered baroreflex sensitivity in young women with a family history of hypertension. J Neurophysiol 2019; 121:1011-1017. [PMID: 30673356 DOI: 10.1152/jn.00471.2018] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
A positive family history of hypertension (+FH) is a risk factor for the future development of hypertension. Hypertension is associated with reductions in baroreflex sensitivity (BRS). Therefore, we hypothesized that young women with a +FH [ n = 12, 22 ± 1 yr, body mass index (BMI) 21 ± 1 kg/m2, mean arterial pressure (MAP) 79 ± 1 mmHg] would have lower BRS compared with young women without a family history of hypertension (-FH) ( n = 13, 22 ± 1 yr, BMI 21 ± 1 kg/m2, MAP 77 ± 2 mmHg, all P > 0.05 between groups). Continuous measurements of muscle sympathetic nerve activity, blood pressure, and electrocardiogram derived R-R interval were recorded at rest and during a Valsalva maneuver. Both cardiovagal BRS and vascular sympathetic BRS were assessed. Resting cardiovagal BRS was reduced in the +FH women (all sequences: -FH 32.3 ± 3.7 vs. +FH 20.2 ± 2.9 ms/mmHg, P = 0.02). Cardiovagal BRS during phase IV (-FH 16.5 ± 2.7 vs. +FH 7.6 ± 1.3 ms/mmHg, P < 0.01) but not phase II (-FH 5.5 ± 0.9 vs. +FH 5.0 ± 0.8 ms/mmHg, P = 0.67) of the Valsalva maneuver was also lower in the +FH women. Vascular sympathetic BRS at rest (-FH -2.38 ± 0.7 vs. +FH -2.33 ± 0.3 bursts· min-1·mmHg-1, P = 0.58) and during the Valsalva (-FH -0.74 ± 0.23 vs. +FH -0.66 ± 0.18 bursts·15 s-1·mmHg-1, P = 0.79) were not different between groups. These data suggest that healthy young women with a positive family history of hypertension have reduced cardiovagal BRS. This may be one mechanism contributing to the increased incidence of hypertension in this population later in life. NEW & NOTEWORTHY Having a family history of hypertension increases the risk of developing future hypertension. Reductions in baroreflex function have been demonstrated in hypertension and are an important marker for future cardiovascular disease. We show that young women with a family history of hypertension have lower cardiovagal baroreflex sensitivity. This alteration in autonomic function may be one mechanism contributing to the future incidence of hypertension in this patient population.
Collapse
Affiliation(s)
- Evan L Matthews
- Department of Kinesiology and Applied Physiology, University of Delaware , Newark, Delaware.,Exercise Science and Physical Education Department, Montclair State University , Montclair, New Jersey
| | - Kelly N Sebzda
- Department of Kinesiology and Applied Physiology, University of Delaware , Newark, Delaware
| | - Megan M Wenner
- Department of Kinesiology and Applied Physiology, University of Delaware , Newark, Delaware
| |
Collapse
|
53
|
Huggins J, Rakobowchuk M. Utility of lacrimal caruncle infrared thermography when monitoring alterations in autonomic activity in healthy humans. Eur J Appl Physiol 2018; 119:531-538. [PMID: 30515591 DOI: 10.1007/s00421-018-4041-6] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2018] [Accepted: 11/24/2018] [Indexed: 10/27/2022]
Abstract
PURPOSE Physiological markers that estimate sympathetic activation may be used to infer pain and stress in humans. To date, effective reproducible methods are invasive and pose an undesired risk to participants. Previous work in animal models has used infrared thermography to measure the temperature of the lacrimal caruncle region and may be a promising method for measuring stress and pain non-invasively. The current study aimed to determine whether this method is useful in humans. METHODS Sixteen young healthy participants (age: 18-35) were recruited and underwent sympathetic activation using a cold pressor test (CPT) and a muscle chemoreflex (MCR), and completed a control trial. Throughout all trials, infrared thermographic imaging of the lacrimal caruncle, heart rate, heart rate variability, mean arterial blood pressure and pulse transit time were measured. RESULTS Heart rate (MCR: 4 ± 3 bpm, CPT: 17 ± 4 bpm p < 0.01) and mean arterial pressure increased (MCR: 6 ± 2, CPT: 5 ± 2 mmHg, p < 0.01) and pulse transit time decreased (p = 0.03) with both sympathetic activation interventions. However, lacrimal caruncle temperature did not vary under any condition remaining at 35.2 ± 0.2 °C which was similar to baseline. CONCLUSIONS Our findings suggest infrared thermographic monitoring of eye temperature in humans does not reliably relate to sympathetic activation. This could be due to hemodynamic responses at the lacrimal caruncle that may be more complex than previously proposed with sympathetic activation. Alternatively, pulse transit time seems like a promising non-invasive measure of changes in sympathetic activation in humans.
Collapse
Affiliation(s)
- J Huggins
- Extracellular Vesicles and the Endothelial Dynamics Laboratory, Department of Biological Sciences, Thompson Rivers University, Kamloops, BC, V2C 0C8, Canada
| | - Mark Rakobowchuk
- Extracellular Vesicles and the Endothelial Dynamics Laboratory, Department of Biological Sciences, Thompson Rivers University, Kamloops, BC, V2C 0C8, Canada.
| |
Collapse
|
54
|
Socha MJ, Segal SS. Microvascular mechanisms limiting skeletal muscle blood flow with advancing age. J Appl Physiol (1985) 2018; 125:1851-1859. [PMID: 30412030 PMCID: PMC6737458 DOI: 10.1152/japplphysiol.00113.2018] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2018] [Revised: 10/22/2018] [Accepted: 11/06/2018] [Indexed: 02/08/2023] Open
Abstract
Effective oxygen delivery to active muscle fibers requires that vasodilation initiated in distal arterioles, which control flow distribution and capillary perfusion, ascends the resistance network into proximal arterioles and feed arteries, which govern total blood flow into the muscle. With exercise onset, ascending vasodilation reflects initiation and conduction of hyperpolarization along endothelium from arterioles into feed arteries. Electrical coupling of endothelial cells to smooth muscle cells evokes the rapid component of ascending vasodilation, which is sustained by ensuing release of nitric oxide during elevated luminal shear stress. Concomitant sympathetic neural activation inhibits ascending vasodilation by stimulating α-adrenoreceptors on smooth muscle cells to constrict the resistance vasculature. We hypothesized that compromised muscle blood flow in advanced age reflects impaired ascending vasodilation through actions on both cell layers of the resistance network. In the gluteus maximus muscle of old (24 mo) vs. young (4 mo) male mice (corresponding to mid-60s vs. early 20s in humans) inhibition of α-adrenoreceptors in old mice restored ascending vasodilation, whereas even minimal activation of α-adrenoreceptors in young mice attenuated ascending vasodilation in the manner seen with aging. Conduction of hyperpolarization along the endothelium is impaired in old vs. young mice because of "leaky" membranes resulting from the activation of potassium channels by hydrogen peroxide released from endothelial cells. Exposing the endothelium of young mice to hydrogen peroxide recapitulates this effect of aging. Thus enhanced α-adrenoreceptor activation of smooth muscle in concert with electrically leaky endothelium restricts muscle blood flow by impairing ascending vasodilation in advanced age.
Collapse
Affiliation(s)
- Matthew J Socha
- Biology Department, University of Scranton , Scranton, Pennsylvania
| | - Steven S Segal
- Department of Medical Pharmacology and Physiology, University of Missouri , Columbia, Missouri
- Dalton Cardiovascular Research Center , Columbia, Missouri
| |
Collapse
|
55
|
Shorakae S, Lambert EA, Jona E, Ika Sari C, de Courten B, Dixon JB, Lambert GW, Teede HJ. Effect of Central Sympathoinhibition With Moxonidine on Sympathetic Nervous Activity in Polycystic Ovary Syndrome-A Randomized Controlled Trial. Front Physiol 2018; 9:1486. [PMID: 30410448 PMCID: PMC6210452 DOI: 10.3389/fphys.2018.01486] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2018] [Accepted: 10/01/2018] [Indexed: 12/19/2022] Open
Abstract
Sympathetic nervous system (SNS) activity is increased in polycystic ovary syndrome (PCOS). Moxonidine is a centrally acting sympatholytic drug with known beneficial effects on hypertension, insulin sensitivity, dyslipidemia and inflammation. In this double-blind placebo controlled randomized clinical trial we examined the effect of moxonidine on modulating sympathetic activity and downstream metabolic abnormalities in 48 pre-menopausal women with PCOS (Rotterdam diagnostic criteria), recruited from the community (January 2013-August 2015). Participants received moxonidine (0.2 mg daily initially, up titrated to 0.4 mg daily in 2 weeks) (n = 23) or placebo (n = 25) for 12 weeks. Multiunit muscle sympathetic activity (by microneurography) and plasma noradrenaline levels were measured (primary outcomes). Fasting lipids, insulin resistance, serum androgens, and inflammatory markers were measured as secondary outcomes. Forty three women completed the trial (19 moxonidine, 24 placebo). Mean change in burst frequency (-3 ± 7 vs. -3 ± 8 per minute) and burst incidence (-3 ± 10 vs. -4 ± 12 per 100 heartbeat) did not differ significantly between moxonidine and placebo groups. Women on moxonidine had a significant reduction in hs-CRP compared to placebo group (-0.92 ± 2.3 vs. -0.04 ± 1.5) which did not persist post Bonferroni correction. There was a significant association between markers of insulin resistance at baseline and reduction in sympathetic activity with moxonidine. Moxonidine was not effective in modulating sympathetic activity in PCOS. Anti-inflammatory effects of moxonidine and a relationship between insulin resistance and sympathetic response to moxonidine are suggested which need to be further explored. Clinical Trial Registration Number: (NCT01504321).
Collapse
Affiliation(s)
- Soulmaz Shorakae
- Monash Centre for Health Research and Implementation, School of Public Health and Preventive Medicine, Monash University, Melbourne, VIC, Australia.,Diabetes and Vascular Medicine Unit, Monash Health, Melbourne, VIC, Australia
| | - Elisabeth A Lambert
- Faculty of Health, Arts and Design, Iverson Health Innovation Research Institute, Swinburne University of Technology, Melbourne, VIC, Australia
| | - Eveline Jona
- Monash Centre for Health Research and Implementation, School of Public Health and Preventive Medicine, Monash University, Melbourne, VIC, Australia
| | - Carolina Ika Sari
- Human Neurotransmitters Laboratory, Baker IDI Heart & Diabetes Institute, Melbourne, VIC, Australia
| | - Barbora de Courten
- Monash Centre for Health Research and Implementation, School of Public Health and Preventive Medicine, Monash University, Melbourne, VIC, Australia.,Diabetes and Vascular Medicine Unit, Monash Health, Melbourne, VIC, Australia
| | - John B Dixon
- Human Neurotransmitters Laboratory, Baker IDI Heart & Diabetes Institute, Melbourne, VIC, Australia.,Clinical Obesity Research Laboratories, Baker Heart & Diabetes Institute, Melbourne, VIC, Australia
| | - Gavin W Lambert
- Faculty of Health, Arts and Design, Iverson Health Innovation Research Institute, Swinburne University of Technology, Melbourne, VIC, Australia.,Human Neurotransmitters Laboratory, Baker IDI Heart & Diabetes Institute, Melbourne, VIC, Australia
| | - Helena J Teede
- Monash Centre for Health Research and Implementation, School of Public Health and Preventive Medicine, Monash University, Melbourne, VIC, Australia.,Diabetes and Vascular Medicine Unit, Monash Health, Melbourne, VIC, Australia
| |
Collapse
|
56
|
Bronzwaer ASGT, Verbree J, Stok WJ, Daemen MJAP, van Buchem MA, van Osch MJP, van Lieshout JJ. Aging modifies the effect of cardiac output on middle cerebral artery blood flow velocity. Physiol Rep 2018; 5:5/17/e13361. [PMID: 28912128 PMCID: PMC5599856 DOI: 10.14814/phy2.13361] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2017] [Revised: 06/17/2017] [Accepted: 06/20/2017] [Indexed: 11/24/2022] Open
Abstract
An association between cerebral blood flow (CBF) and cardiac output (CO) has been established in young healthy subjects. As of yet it is unclear how this association evolves over the life span. To that purpose, we continuously recorded mean arterial pressure (MAP; finger plethysmography), CO (pulse contour; CO‐trek), mean blood flow velocity in the middle cerebral artery (MCAV; transcranial Doppler ultrasonography), and end‐tidal CO2 partial pressure (PetCO2) in healthy young (19–27 years), middle‐aged (51–61 years), and elderly subjects (70–79 years). Decreases and increases in CO were accomplished using lower body negative pressure and dynamic handgrip exercise, respectively. Aging in itself did not alter dynamic cerebral autoregulation or cerebrovascular CO2 reactivity. A linear relation between changes in CO and MCAVmean was observed in middle‐aged (P < 0.01) and elderly (P = 0.04) subjects but not in young (P = 0.45) subjects, taking concurrent changes in MAP and PetCO2 into account. These data imply that with aging, brain perfusion becomes increasingly dependent on CO.
Collapse
Affiliation(s)
- Anne-Sophie G T Bronzwaer
- Department of Internal Medicine, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands.,Laboratory for Clinical Cardiovascular Physiology, Center for Heart Failure Research, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands
| | - Jasper Verbree
- Department of Radiology, Leiden University Medical Center, Leiden, The Netherlands
| | - Wim J Stok
- Laboratory for Clinical Cardiovascular Physiology, Center for Heart Failure Research, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands.,Department of Medical Biology, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands
| | - Mat J A P Daemen
- Department of Pathology, Academic Medical Center, University of Amsterdam, Amsterdam, the Netherlands
| | - Mark A van Buchem
- Department of Radiology, Leiden University Medical Center, Leiden, The Netherlands
| | | | - Johannes J van Lieshout
- Department of Internal Medicine, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands .,Laboratory for Clinical Cardiovascular Physiology, Center for Heart Failure Research, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands.,Department of Medical Biology, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands.,MRC/Arthritis Research UK Centre for Musculoskeletal Ageing Research, School of Life Sciences, University of Nottingham Medical School Queen's Medical Centre, Nottingham, UK
| |
Collapse
|
57
|
Bunsawat K, Ratchford SM, Clifton HL, Theisen JK, Barrett‐O'Keefe Z, Broxterman RM, Gifford JR, Hydren J, Rossman MJ, Ives SJ, Trinity JD, Witman MA, Garten RS, Morgan DE, Nelson AD, Richardson RS, Wray DW. Sex Differences in the Sympathetic Restraint of Skeletal Muscle Blood Flow in the Human Leg Vasculature. FASEB J 2018. [DOI: 10.1096/fasebj.2018.32.1_supplement.594.4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Kanokwan Bunsawat
- Geriatric Research, Educationand Clinical CenterVAMCSalt Lake CityUT
- Department of Internal MedicineDivision of GeriatricsUniversity of UtahSalt Lake CityUT
| | - Stephen M. Ratchford
- Geriatric Research, Educationand Clinical CenterVAMCSalt Lake CityUT
- Department of Internal MedicineDivision of GeriatricsUniversity of UtahSalt Lake CityUT
| | - Heather L. Clifton
- Geriatric Research, Educationand Clinical CenterVAMCSalt Lake CityUT
- Department of Internal MedicineDivision of GeriatricsUniversity of UtahSalt Lake CityUT
| | - Jeremy K. Theisen
- Department of Nutrition and Integrative PhysiologyUniversity of UtahSalt Lake CityUT
| | | | - Ryan M. Broxterman
- Geriatric Research, Educationand Clinical CenterVAMCSalt Lake CityUT
- Department of Internal MedicineDivision of GeriatricsUniversity of UtahSalt Lake CityUT
| | - Jayson R. Gifford
- Department of Internal MedicineDivision of GeriatricsUniversity of UtahSalt Lake CityUT
- Department of Exercise SciencesBrigham Young UniversityProvoUT
| | - Jay Hydren
- Department of Nutrition and Integrative PhysiologyUniversity of UtahSalt Lake CityUT
| | - Matthew J. Rossman
- Department of Nutrition and Integrative PhysiologyUniversity of UtahSalt Lake CityUT
| | - Stephen J. Ives
- Department of Internal MedicineDivision of GeriatricsUniversity of UtahSalt Lake CityUT
| | - Joel D. Trinity
- Geriatric Research, Educationand Clinical CenterVAMCSalt Lake CityUT
- Department of Internal MedicineDivision of GeriatricsUniversity of UtahSalt Lake CityUT
- Department of Nutrition and Integrative PhysiologyUniversity of UtahSalt Lake CityUT
- University of Utah Center on AgingSalt Lake CityUT
| | - Melissa A.H. Witman
- Department of Internal MedicineDivision of GeriatricsUniversity of UtahSalt Lake CityUT
- Department of Kinesiology and Applied PhysiologyUniversity of DelawareNewarkDE
| | - Ryan S. Garten
- Department of Nutrition and Integrative PhysiologyUniversity of UtahSalt Lake CityUT
| | - David E. Morgan
- Department of AnesthesiologyUniversity of UtahSalt Lake CityUT
| | - Ashley D. Nelson
- Geriatric Research, Educationand Clinical CenterVAMCSalt Lake CityUT
| | - Russell S. Richardson
- Geriatric Research, Educationand Clinical CenterVAMCSalt Lake CityUT
- Department of Internal MedicineDivision of GeriatricsUniversity of UtahSalt Lake CityUT
- Department of Nutrition and Integrative PhysiologyUniversity of UtahSalt Lake CityUT
- University of Utah Center on AgingSalt Lake CityUT
| | - D. Walter Wray
- Geriatric Research, Educationand Clinical CenterVAMCSalt Lake CityUT
- Department of Internal MedicineDivision of GeriatricsUniversity of UtahSalt Lake CityUT
- Department of Nutrition and Integrative PhysiologyUniversity of UtahSalt Lake CityUT
- University of Utah Center on AgingSalt Lake CityUT
| |
Collapse
|
58
|
Deuchars SA, Lall VK, Clancy J, Mahadi M, Murray A, Peers L, Deuchars J. Mechanisms underpinning sympathetic nervous activity and its modulation using transcutaneous vagus nerve stimulation. Exp Physiol 2018; 103:326-331. [PMID: 29205954 PMCID: PMC5887928 DOI: 10.1113/ep086433] [Citation(s) in RCA: 56] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2017] [Accepted: 11/10/2017] [Indexed: 12/20/2022]
Abstract
NEW FINDINGS What is the topic of this review? This review briefly considers what modulates sympathetic nerve activity and how it may change as we age or in pathological conditions. It then focuses on transcutaneous vagus nerve stimulation, a method of neuromodulation in autonomic cardiovascular control. What advances does it highlight? The review considers the pathways involved in eliciting the changes in autonomic balance seen with transcutaneous vagus nerve stimulation in relationship to other neuromodulatory techniques. The autonomic nervous system, consisting of the sympathetic and parasympathetic branches, is a major contributor to the maintenance of cardiovascular variables within homeostatic limits. As we age or in certain pathological conditions, the balance between the two branches changes such that sympathetic activity is more dominant, and this change in dominance is negatively correlated with prognosis in conditions such as heart failure. We have shown that non-invasive stimulation of the tragus of the ear increases parasympathetic activity and reduces sympathetic activity and that the extent of this effect is correlated with the baseline cardiovascular parameters of different subjects. The effects could be attributable to activation of the afferent branch of the vagus and, potentially, other sensory nerves in that region. This indicates that tragus stimulation may be a viable treatment in disorders where autonomic activity to the heart is compromised.
Collapse
Affiliation(s)
- Susan A. Deuchars
- School of Biomedical Science, Faculty of Biological ScienceUniversity of LeedsLeedsUK
| | - Varinder K. Lall
- School of Biomedical Science, Faculty of Biological ScienceUniversity of LeedsLeedsUK
| | - Jennifer Clancy
- School of Biomedical Science, Faculty of Biological ScienceUniversity of LeedsLeedsUK
| | - Mohd Mahadi
- School of Biomedical Science, Faculty of Biological ScienceUniversity of LeedsLeedsUK
- Faculty of PharmacyUniversiti Kebangsaan MalaysiaKuala LumpurMalaysia
| | - Aaron Murray
- School of Biomedical Science, Faculty of Biological ScienceUniversity of LeedsLeedsUK
| | - Lucy Peers
- School of Biomedical Science, Faculty of Biological ScienceUniversity of LeedsLeedsUK
| | - Jim Deuchars
- School of Biomedical Science, Faculty of Biological ScienceUniversity of LeedsLeedsUK
| |
Collapse
|
59
|
Milan-Mattos JC, Porta A, Perseguini NM, Minatel V, Rehder-Santos P, Takahashi ACM, Mattiello SM, Catai AM. Influence of age and gender on the phase and strength of the relation between heart period and systolic blood pressure spontaneous fluctuations. J Appl Physiol (1985) 2017; 124:791-804. [PMID: 29212671 DOI: 10.1152/japplphysiol.00903.2017] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Aging affects baroreflex regulation. The effect of senescence on baroreflex control was assessed from spontaneous fluctuations of heart period (HP) and systolic arterial pressure (SAP) through the HP-SAP gain, while the HP-SAP phase and strength are usually disregarded. This study checks whether the HP-SAP phase and strength, as estimated, respectively, via the phase of the HP-SAP cross spectrum (PhHP-SAP) and squared coherence function (K2HP-SAP), vary with age in healthy individuals and trends are gender-dependent. We evaluated 110 healthy volunteers (55 males) divided into five age subgroups (21-30, 31-40, 41-50, 51-60, and 61-70 yr). Each subgroup was formed by 22 subjects (11 males). HP series was extracted from electrocardiogram and SAP from finger arterial pressure at supine resting (REST) and during active standing (STAND). PhHP-SAP and K2HP-SAP functions were sampled in low-frequency (LF, from 0.04 to 0.15 Hz) and in high-frequency (HF, above 0.15 Hz) bands. Both at REST and during STAND PhHP-SAP(LF) showed a negative correlation with age regardless of gender even though values were more negative in women. This trend was shown to be compatible with a progressive increase of the baroreflex latency with age. At REST K2HP-SAP(LF) decreased with age regardless of gender, but during STAND the high values of K2HP-SAP(LF) were more preserved in men than women. At REST and during STAND the association of PhHP-SAP(HF) and K2HP-SAP(HF) with age was absent. The findings points to a greater instability of baroreflex control with age that seems to affect to a greater extent women than men. NEW & NOTEWORTHY Aging increases cardiac baroreflex latency and decreases the degree of cardiac baroreflex involvement in regulating cardiovascular variables. These trends are gender independent but lead to longer delays and asmaller degree of cardiac baroreflex involvement in women than in men, especially during active standing, with important implications on the tolerance to an orthostatic stressor.
Collapse
Affiliation(s)
- Juliana C Milan-Mattos
- Cardiovascular Physical Therapy Laboratory, Department of Physical Therapy, Federal University of São Carlos , São Paulo , Brazil
| | - 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
| | - Natália M Perseguini
- Cardiovascular Physical Therapy Laboratory, Department of Physical Therapy, Federal University of São Carlos , São Paulo , Brazil
| | - Vinicius Minatel
- Cardiovascular Physical Therapy Laboratory, Department of Physical Therapy, Federal University of São Carlos , São Paulo , Brazil
| | - Patricia Rehder-Santos
- Cardiovascular Physical Therapy Laboratory, Department of Physical Therapy, Federal University of São Carlos , São Paulo , Brazil
| | - Anielle C M Takahashi
- Cardiovascular Physical Therapy Laboratory, Department of Physical Therapy, Federal University of São Carlos , São Paulo , Brazil
| | - Stela M Mattiello
- Articular Function Laboratory, Department of Physical Therapy, Federal University of São Carlos , São Paulo , Brazil
| | - Aparecida M Catai
- Cardiovascular Physical Therapy Laboratory, Department of Physical Therapy, Federal University of São Carlos , São Paulo , Brazil
| |
Collapse
|
60
|
Liu H, Zheng X, Zhang L, Yang X, Shao Y, Zhang S. Bilateral superior cervical ganglionectomy attenuates the progression of β-aminopropionitrile-induced aortic dissection in rats. Life Sci 2017; 193:200-206. [PMID: 29104105 DOI: 10.1016/j.lfs.2017.10.043] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2017] [Revised: 10/20/2017] [Accepted: 10/31/2017] [Indexed: 12/15/2022]
Abstract
AIMS Aortic dissection (AD) represents one of the most common aortic emergencies with high incidence of morbidity and mortality. Clinical studies have shown that the increased excitability of the sympathetic nerve may be associated with the formation of AD. In this study, we examined the effects of bilateral superior cervical sympathectomy (SCGx) on the progression of β-aminopropionitrile (BAPN)-induced AD in rats. MAIN METHODS Sprague-Dawley rats were randomly divided into three groups, including BAPN, BAPN+SCGx and control groups. For terminal measurements, the mean arterial pressure (MAP) and heart rate (HR) were monitored and the basal sympathetic nerve activity (SNA) was assessed through recording the variation in arterial pressure in response to hexamethonium application. Pathological changes in the aortic wall were observed by histological staining. Matrix metalloproteinase-2 (MMP-2) and MMP-9 concentrations within the aortic wall were analyzed by western blot. KEY FINDINGS The results show that BAPN administration could elevate SNA and cause the formation of AD in rats with a high incidence (67.7%), while SCGx treatment inhibited the elevation of SNA and significantly reduced the incidence (20%). SCGx may suppress the formation of BAPN-induced AD via restraining the rise of HR and reducing the MMP-9 concentration in aortic wall. SIGNIFICANCE These results indicate that surgical techniques such as sympathetic nerve block may be a potentially useful therapy for the prevention of AD.
Collapse
Affiliation(s)
- Huan Liu
- Department of Cardiovascular Surgery, The First Affiliated Hospital, Nanjing Medical University, Nanjing, Jiangsu, China
| | - Xiangxiang Zheng
- Department of Cardiovascular Surgery, The First Affiliated Hospital, Nanjing Medical University, Nanjing, Jiangsu, China
| | - Linfei Zhang
- Department of Cardiovascular Surgery, The First Affiliated Hospital, Nanjing Medical University, Nanjing, Jiangsu, China
| | - Xuechao Yang
- Department of Cardiovascular Surgery, The First Affiliated Hospital, Nanjing Medical University, Nanjing, Jiangsu, China
| | - Yongfeng Shao
- Department of Cardiovascular Surgery, The First Affiliated Hospital, Nanjing Medical University, Nanjing, Jiangsu, China
| | - Shijiang Zhang
- Department of Cardiovascular Surgery, The First Affiliated Hospital, Nanjing Medical University, Nanjing, Jiangsu, China.
| |
Collapse
|
61
|
Schrover IM, Dorresteijn JAN, Smits JE, Danser AHJ, Visseren FLJ, Spiering W. Identifying treatment response to antihypertensives in patients with obesity-related hypertension. Clin Hypertens 2017; 23:20. [PMID: 29085669 PMCID: PMC5654008 DOI: 10.1186/s40885-017-0077-x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2017] [Accepted: 09/18/2017] [Indexed: 12/29/2022] Open
Abstract
BACKGROUND In patients with obesity-related hypertension (ORH), reaction to antihypertensive medication is likely influenced by patientcharacteristics. METHODS Effects of aliskiren, moxonidine and hydrochlorothiazide on 24-h blood pressure (BP) were compared to placebo. Linear mixed effect models were used to analyze the effect of patient characteristics on BP levels and treatment response. RESULTS Systolic BP response to aliskiren was higher in patients with a BMI > 30.7 kg/m2 compared to patients with a BMI ≤ 30.7 kg/m2 (-21 mmHg versus -4 mmHg). In patients with a hsCRP > 1.8 mg/L the systolic BP response to aliskiren was higher than in patients with a low hsCRP (-15 mmHg versus -7 mmHg). Hydrochlorothiazide (HCTZ) treatment effect on systolic BP was -13 mmHg when heart rate > 71 beats/min compared to -3 mmHg when heart rate was ≤ 71 beats/min. CONCLUSION In patients with ORH, BP response to aliskiren is positively related to BMI and hsCRP. Systolic BP response to HCTZ is positively related to heart rate and negatively to renin levels. TRIAL REGISTRATION NCT01138423. Registered June 4th, 2010.
Collapse
Affiliation(s)
- Ilse M Schrover
- Department of Vascular Medicine, University Medical Center Utrecht, P.O. Box 85500, 3584 GA Utrecht, The Netherlands
| | - Jannick A N Dorresteijn
- Department of Vascular Medicine, University Medical Center Utrecht, P.O. Box 85500, 3584 GA Utrecht, The Netherlands
| | - Jodine E Smits
- Department of Vascular Medicine, University Medical Center Utrecht, P.O. Box 85500, 3584 GA Utrecht, The Netherlands
| | - A H Jan Danser
- Division of Pharmacology and Vascular Medicine, Department of Internal Medicine, Erasmus Medical Center, Rotterdam, The Netherlands
| | - Frank L J Visseren
- Department of Vascular Medicine, University Medical Center Utrecht, P.O. Box 85500, 3584 GA Utrecht, The Netherlands
| | - Wilko Spiering
- Department of Vascular Medicine, University Medical Center Utrecht, P.O. Box 85500, 3584 GA Utrecht, The Netherlands
| |
Collapse
|
62
|
Lang JA, Smaller KA. Orall-tyrosine supplementation augments the vasoconstriction response to whole-body cooling in older adults. Exp Physiol 2017; 102:835-844. [DOI: 10.1113/ep086329] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2017] [Accepted: 05/03/2017] [Indexed: 11/08/2022]
Affiliation(s)
- James A. Lang
- Department of Physical Therapy; Des Moines University; Des Moines IA 50312 USA
| | - Kevin A. Smaller
- Department of Neuroscience; Drake University; Des Moines IA 50311 USA
| |
Collapse
|
63
|
Joshi A, Kiran R, Singla HK, Sah AN. Stress management through regulation of blood pressure among college students. Work 2017; 54:745-52. [PMID: 27286072 DOI: 10.3233/wor-162308] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
BACKGROUND This paper introduces the concept of Deep Breathing and its applications as one of the means towards stress management through regulation of blood pressure among Indian College Engineering students. The underlying concept of deep breathing is that the relation between emotions and breathing is two way, i.e. not only do emotions affect the breathing, but controlled deep breathing also has an effect on emotions. OBJECTIVE The objective of the paper is to find out whether deep breathing technique is able to control blood pressure, and in turn, the level of stress. METHODS Sample students had a selection through initial screening and the students who reported high mental stress during interview were selected for the main drills. All the readings are taken using a sphygmomanometer (digital blood pressure meter). Students' t test are used for the purpose of hypothesis testing. RESULTS The results indicated that the deep breathing technique provided significant results. CONCLUSION It is recommended that this amazingly simple and yet highly effective ancient technique of deep breathing become part of students' routine curriculum. The paper aims at spreading the awareness of this yogic technique as one of the modes of Stress Management amongst Indian college students.
Collapse
Affiliation(s)
- Anurag Joshi
- School of Humanities and Social Sciences, Thapar University, Patiala, Punjab, India.,Electrical Engineering, Thapar Polytechnic College, Patiala, Punjab, India
| | - Ravi Kiran
- School of Humanities and Social Sciences, Thapar University, Patiala, Punjab, India
| | | | - Ash Narayan Sah
- School of Humanities and Social Sciences, Thapar University, Patiala, Punjab, India
| |
Collapse
|
64
|
Just TP, DeLorey DS. Sex differences in sympathetic vasoconstrictor responsiveness and sympatholysis. J Appl Physiol (1985) 2017; 123:128-135. [PMID: 28473610 DOI: 10.1152/japplphysiol.00139.2017] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2017] [Revised: 04/10/2017] [Accepted: 04/29/2017] [Indexed: 11/22/2022] Open
Abstract
Sex differences in the neurovascular control of blood pressure and vascular resistance have been reported. However, the mechanisms underlying the modulatory influence of sex have not been fully elucidated. Nitric oxide (NO) has been shown to inhibit sympathetic vasoconstriction in resting and contracting skeletal muscle, and estrogen modulates NO synthase (NOS) expression and NO bioavailability. Therefore NO-mediated inhibition of sympathetic vasoconstriction may be enhanced in females. Thus the purpose of the present study was to investigate the hypothesis that sympathetic vasoconstrictor responsiveness would be blunted and NO-mediated inhibition of sympathetic vasoconstriction would be enhanced in females compared with males. Male (M; n = 8) and female (F; n = 10) Sprague-Dawley rats were anesthetized and surgically instrumented for measurement of arterial blood pressure and femoral artery blood flow and stimulation of the lumbar sympathetic chain. The percentage change of femoral vascular conductance in response to sympathetic chain stimulation delivered at 2 and 5 Hz was determined at rest and during triceps surae muscle contraction before (control) and after NOS blockade [Nω-nitro-l-arginine methyl ester (l-NAME), 10 mg/kg iv]. At rest, sympathetic vasoconstrictor responsiveness was augmented (P < 0.05) in female compared with male rats at 2 Hz [F: -33 ± 8% (SD); M: -26 ± 6%] but was not different at 5 Hz (F: -55 ± 7%; M: -47 ± 7%). During muscle contraction, evoked vasoconstriction was similar (P > 0.05) in females and males at 2 Hz (F: -12 ± 5%; M: -13 ± 5%) but was blunted (P < 0.05) in females compared with males at 5 Hz (F: -24 ± 5%; M: -34 ± 8%). l-NAME increased (P < 0.05) sympathetic vasoconstrictor responsiveness in both groups at rest and during contraction. Contraction-mediated inhibition of vasoconstriction (sympatholysis) was enhanced (P < 0.05) in females compared with males; however, sympatholysis was not different (P > 0.05) between males and females in the presence of NOS blockade, indicating that NO-mediated sympatholysis was augmented in female rats. These data suggest that sex modulates sympathetic vascular control in resting and contracting skeletal muscle and that a portion of the enhanced sympatholysis in female rats was NO dependent.NEW & NOTEWORTHY Sex differences in the neurovascular regulation of blood pressure and vascular resistance have been documented. However, our understanding of the underlying mechanisms that mediate these differences is incomplete. The present study demonstrates that female rats have an enhanced capacity to inhibit sympathetic vasoconstriction during exercise (sympatholysis) and that NO mediates a portion of the enhanced sympatholysis.
Collapse
Affiliation(s)
- Timothy P Just
- Faculty of Physical Education and Recreation, University of Alberta, Edmonton, Alberta, Canada
| | - Darren S DeLorey
- Faculty of Physical Education and Recreation, University of Alberta, Edmonton, Alberta, Canada
| |
Collapse
|
65
|
Macey PM, Rieken NS, Ogren JA, Macey KE, Kumar R, Harper RM. Sex differences in insular cortex gyri responses to a brief static handgrip challenge. Biol Sex Differ 2017; 8:13. [PMID: 28435658 PMCID: PMC5397762 DOI: 10.1186/s13293-017-0135-9] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/17/2017] [Accepted: 04/11/2017] [Indexed: 01/02/2023] Open
Abstract
Background Cardiovascular disease varies between sexes, suggesting male-female autonomic control differences. Insular gyri help coordinate autonomic regulation and show a sex-dependent response to a sympathetic challenge. Methods We examined sex-related insular gyral responses to a short static handgrip exercise challenge eliciting parasympathetic withdrawal with functional magnetic resonance imaging (fMRI) during four 16-s challenges (80% maximum strength) in 23 healthy females (age; mean ± std 50 ± 8 years) and 40 males (46 ± 9 years). Heart rate (HR) and fMRI signals were compared with repeated measures ANOVA (P < 0.05). Additional analyses were performed with age and age interactions, as well as right-handed only subjects. Results Females showed higher resting HR than males, but smaller percent HR change increases to the challenges. All gyri showed fMRI patterns concurrent with an HR peak and decline to baseline. fMRI signals followed an anterior-posterior organization in both sexes, but lateralization varied by gyri and sex. All subjects showed greater signals in the anterior vs. posterior gyri (females 0.3%, males 0.15%). The middle gyri showed no lateralization in females but left-sided dominance in males (0.1%). The posterior gyri showed greater left than right activation in both sexes. The anterior-most gyri exhibited a prominent sex difference, with females showing a greater right-sided activation (0.2%) vs. males displaying a greater left-sided activation (0.15%). Age and handedness affected a minority of findings but did not alter the overall pattern of results. Conclusions The anterior insula plays a greater role in cardiovascular regulation than posterior areas during a predominantly parasympathetic withdrawal challenge, with opposite lateralization between sexes. In females, the left anterior-most gyrus responded distinctly from other regions than males. Those sex-specific structural and functional brain patterns may contribute over time to variations in cardiovascular disease between the sexes. Electronic supplementary material The online version of this article (doi:10.1186/s13293-017-0135-9) contains supplementary material, which is available to authorized users.
Collapse
Affiliation(s)
- Paul M Macey
- UCLA School of Nursing, University of California at Los Angeles, 700 Tiverton Avenue, Los Angeles, CA 90095-1702 USA.,Brain Research Institute, David Geffen School of Medicine at UCLA, University of California at Los Angeles, Los Angeles, CA 90095 USA
| | - Nicholas S Rieken
- UCLA School of Nursing, University of California at Los Angeles, 700 Tiverton Avenue, Los Angeles, CA 90095-1702 USA
| | - Jennifer A Ogren
- Department of Neurobiology, David Geffen School of Medicine at UCLA, University of California at Los Angeles, Los Angeles, CA 90095 USA
| | - Katherine E Macey
- UCLA School of Nursing, University of California at Los Angeles, 700 Tiverton Avenue, Los Angeles, CA 90095-1702 USA
| | - Rajesh Kumar
- Brain Research Institute, David Geffen School of Medicine at UCLA, University of California at Los Angeles, Los Angeles, CA 90095 USA.,Department of Anesthesiology, David Geffen School of Medicine at UCLA, University of California at Los Angeles, Los Angeles, CA 90095 USA.,Department of Radiological Sciences, David Geffen School of Medicine at UCLA, University of California at Los Angeles, Los Angeles, CA 90095 USA
| | - Ronald M Harper
- Brain Research Institute, David Geffen School of Medicine at UCLA, University of California at Los Angeles, Los Angeles, CA 90095 USA.,Department of Neurobiology, David Geffen School of Medicine at UCLA, University of California at Los Angeles, Los Angeles, CA 90095 USA
| |
Collapse
|
66
|
Richards JC, Crecelius AR, Larson DG, Luckasen GJ, Dinenno FA. Impaired peripheral vasodilation during graded systemic hypoxia in healthy older adults: role of the sympathoadrenal system. Am J Physiol Heart Circ Physiol 2017; 312:H832-H841. [PMID: 28159810 DOI: 10.1152/ajpheart.00794.2016] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/05/2016] [Revised: 01/26/2017] [Accepted: 01/27/2017] [Indexed: 02/01/2023]
Abstract
Systemic hypoxia is a physiological and pathophysiological stress that activates the sympathoadrenal system and, in young adults, leads to peripheral vasodilation. We tested the hypothesis that peripheral vasodilation to graded systemic hypoxia is impaired in older healthy adults and that this age-associated impairment is due to attenuated β-adrenergic mediated vasodilation and elevated α-adrenergic vasoconstriction. Forearm blood flow was measured (Doppler ultrasound), and vascular conductance (FVC) was calculated in 12 young (24 ± 1 yr) and 10 older (63 ± 2 yr) adults to determine the local dilatory responses to graded hypoxia (90, 85, and 80% O2 saturations) in control conditions, following local intra-arterial blockade of β-receptors (propranolol), and combined blockade of α- and β-receptors (phentolamine + propranolol). Under control conditions, older adults exhibited impaired vasodilation to hypoxia compared with young participants at all levels of hypoxia (peak ΔFVC at 80% [Formula: see text] = 4 ± 6 vs. 35 ± 8%; P < 0.01). During β-blockade, older adults actively constricted at 85 and 80% [Formula: see text] (peak ΔFVC at 80% [Formula: see text] = -13 ± 6%; P < 0.05 vs. control), whereas the response in the young was not significantly impacted (peak ΔFVC = 28 ± 8%). Combined α- and β-blockade increased the dilatory response to hypoxia in young adults; however, older adults failed to significantly vasodilate (peak ΔFVC at 80% [Formula: see text]= 12 ± 11% vs. 58 ± 11%; P < 0.05). Our findings indicate that peripheral vasodilation to graded systemic hypoxia is significantly impaired in older adults, which cannot be fully explained by altered sympathoadrenal control of vascular tone. Thus, the impairment in hypoxic vasodilation is likely due to attenuated local vasodilatory and/or augmented vasoconstrictor signaling with age.NEW & NOTEWORTHY We found that the lack of peripheral vasodilation during graded systemic hypoxia with aging is not mediated by the sympathoadrenal system, strongly implicating local vascular control mechanisms in this impairment. Understanding these mechanisms may lead to therapeutic advances for improving tissue blood flow and oxygen delivery in aging and disease.
Collapse
Affiliation(s)
- Jennifer C Richards
- Human Cardiovascular Physiology Laboratory, Department of Health and Exercise Science, Center for Cardiovascular Research, Colorado State University, Fort Collins, Colorado; and
| | - Anne R Crecelius
- Human Cardiovascular Physiology Laboratory, Department of Health and Exercise Science, Center for Cardiovascular Research, Colorado State University, Fort Collins, Colorado; and
| | - Dennis G Larson
- Medical Center of the Rockies Foundation, University of Colorado Health System, Loveland, Colorado
| | - Gary J Luckasen
- Medical Center of the Rockies Foundation, University of Colorado Health System, Loveland, Colorado
| | - Frank A Dinenno
- Human Cardiovascular Physiology Laboratory, Department of Health and Exercise Science, Center for Cardiovascular Research, Colorado State University, Fort Collins, Colorado; and
| |
Collapse
|
67
|
Zempo H, Isobe M, Naito H. Link between blood flow and muscle protein metabolism in elderly adults. ACTA ACUST UNITED AC 2017. [DOI: 10.7600/jpfsm.6.25] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Affiliation(s)
- Hirofumi Zempo
- Japan Society for the Promotion of Science
- Graduate School of Health and Sports Science, Juntendo University
| | - Mitsuaki Isobe
- Department of Cardiovascular Medicine, Tokyo Medical and Dental University
| | - Hisashi Naito
- Graduate School of Health and Sports Science, Juntendo University
| |
Collapse
|
68
|
Tremblay JC, Boulet LM, Tymko MM, Foster GE. Intermittent hypoxia and arterial blood pressure control in humans: role of the peripheral vasculature and carotid baroreflex. Am J Physiol Heart Circ Physiol 2016; 311:H699-706. [PMID: 27402667 DOI: 10.1152/ajpheart.00388.2016] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/27/2016] [Accepted: 07/06/2016] [Indexed: 11/22/2022]
Abstract
Intermittent hypoxia (IH) occurs in association with obstructive sleep apnea and likely contributes to the pathogenesis of hypertension. The purpose of this study was to examine the putative early adaptations at the level of the peripheral vasculature and carotid baroreflex (CBR) that may promote the development of hypertension. Ten healthy male participants (26 ± 1 yr, BMI = 24 ± 1 kg/m(2)) were exposed to 6 h of IH (1-min cycles of normoxia and hypoxia) and SHAM in a single-blinded, counterbalanced crossover study design. Ambulatory blood pressure was measured during each condition and the following night. Vascular strain of the carotid and femoral artery, a measure of localized arterial stiffness, and hemodynamic shear patterns in the brachial and femoral arteries were measured during each condition. Brachial artery reactive hyperemia flow-mediated vasodilation was assessed before and after each condition as a measure of endothelial function. CBR function and its control over leg vascular conductance (LVC) were measured after each condition with a variable-pressure neck chamber. Intermittent hypoxia 1) increased nighttime pulse pressure by 3.2 ± 1.3 mmHg, 2) altered femoral but not brachial artery hemodynamics, 3) did not affect brachial artery endothelial function, 4) reduced vascular strain in the carotid and possibly femoral artery, and 5) shifted CBR mean arterial pressure (MAP) to higher MAP while blunting LVC responses to CBR loading. These results suggest limb-specific vascular impairments, reduced vascular strain, and CBR resetting combined with blunted LVC responses are factors in the early pathogenesis of IH-induced development of hypertension.
Collapse
Affiliation(s)
- Joshua C Tremblay
- Centre for Heart, Lung, and Vascular Health, School of Health and Exercise Science, University of British Columbia, Kelowna, Canada
| | - Lindsey M Boulet
- Centre for Heart, Lung, and Vascular Health, School of Health and Exercise Science, University of British Columbia, Kelowna, Canada
| | - Michael M Tymko
- Centre for Heart, Lung, and Vascular Health, School of Health and Exercise Science, University of British Columbia, Kelowna, Canada
| | - Glen E Foster
- Centre for Heart, Lung, and Vascular Health, School of Health and Exercise Science, University of British Columbia, Kelowna, Canada
| |
Collapse
|
69
|
Macey PM, Rieken NS, Kumar R, Ogren JA, Middlekauff HR, Wu P, Woo MA, Harper RM. Sex Differences in Insular Cortex Gyri Responses to the Valsalva Maneuver. Front Neurol 2016; 7:87. [PMID: 27375549 PMCID: PMC4899449 DOI: 10.3389/fneur.2016.00087] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2016] [Accepted: 05/27/2016] [Indexed: 12/26/2022] Open
Abstract
Sex differences in autonomic regulation may underlie cardiovascular disease variations between females and males. One key autonomic brain region is the insular cortex, which typically consists of five main gyri in each hemisphere, and shows a topographical organization of autonomic function across those gyri. The present study aims to identify possible sex differences in organization of autonomic function in the insula. We studied brain functional magnetic resonance imaging (fMRI) responses to a series of four 18-s Valsalva maneuvers in 22 healthy females (age ± SD: 50.0 ± 7.9 years) and 36 healthy males (45.3 ± 9.2 years). Comparisons of heart rate (HR) and fMRI signals were performed with repeated measures ANOVA (threshold P < 0.05 for all findings). All subjects achieved the target 30 mmHg expiratory pressure for all challenges. Typical HR responses were elicited by the maneuver, including HR increases from ~4 s into the strain period (Phase II) and rapid declines to below baseline 5–10 s, following strain release (Phase IV). Small, but significant, sex differences in HR percent change occurred during the sympathetic-dominant Phase II (female < male) and parasympathetic-dominant Phase IV (female > male, i.e., greater undershoot in males). The insular cortices showed similar patterns in all gyri, with greater signal decreases in males than females. Both sexes exhibited an anterior–posterior topographical organization of insular responses during Phase II, with anterior gyri showing higher responses than more posterior gyri. The exception was the right anterior-most gyrus in females, which had lower responses than the four other right gyri. Responses were lateralized, with right-sided dominance during Phase II in both sexes, except the right anterior-most gyrus in females, which showed lower responses than the left. The findings confirm the anterior and right-sided sympathetic dominance of the insula. Although sex differences were prominent in response magnitude, organization differences between males and females were limited to the right anterior-most gyrus, which showed a lower fMRI response in females vs. males (and vs. other gyri in females). The sex differences suggest a possible differing baseline state of brain physiology or tonic functional activity between females and males, especially in the right anterior-most gyrus.
Collapse
Affiliation(s)
- Paul M Macey
- UCLA School of Nursing, University of California at Los Angeles, Los Angeles, CA, USA; Brain Research Institute, University of California at Los Angeles, Los Angeles, CA, USA
| | - Nicholas S Rieken
- UCLA School of Nursing, University of California at Los Angeles , Los Angeles, CA , USA
| | - Rajesh Kumar
- Brain Research Institute, University of California at Los Angeles, Los Angeles, CA, USA; Department of Anesthesiology, University of California at Los Angeles, Los Angeles, CA, USA; Department of Radiological Sciences, University of California at Los Angeles, Los Angeles, CA, USA
| | - Jennifer A Ogren
- Department of Neurobiology, University of California at Los Angeles , Los Angeles, CA , USA
| | - Holly R Middlekauff
- Department of Medicine, Division of Cardiology, David Geffen School of Medicine, University of California at Los Angeles , Los Angeles, CA , USA
| | - Paula Wu
- Department of Neurobiology, University of California at Los Angeles, Los Angeles, CA, USA; Yale School of Medicine, Yale University, New Haven, CT, USA
| | - Mary A Woo
- UCLA School of Nursing, University of California at Los Angeles , Los Angeles, CA , USA
| | - Ronald M Harper
- Brain Research Institute, University of California at Los Angeles, Los Angeles, CA, USA; Department of Neurobiology, University of California at Los Angeles, Los Angeles, CA, USA
| |
Collapse
|
70
|
Vranish JR, Bailey EF. Inspiratory Muscle Training Improves Sleep and Mitigates Cardiovascular Dysfunction in Obstructive Sleep Apnea. Sleep 2016; 39:1179-85. [PMID: 27091540 DOI: 10.5665/sleep.5826] [Citation(s) in RCA: 43] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2016] [Accepted: 03/09/2016] [Indexed: 01/26/2023] Open
Abstract
STUDY OBJECTIVES New and effective strategies are needed to manage the autonomic and cardiovascular sequelae of obstructive sleep apnea (OSA). We assessed the effect of daily inspiratory muscle strength training (IMT) on sleep and cardiovascular function in adults unable to use continuous positive airway pressure (CPAP) therapy. METHODS This is a placebo-controlled, single-blind study conducted in twenty four adults with mild, moderate, and severe OSA. Subjects were randomly assigned to placebo or inspiratory muscle strength training. Subjects in each group performed 5 min of training each day for 6 w. All subjects underwent overnight polysomnography at intake and again at study close. RESULTS We evaluated the effects of placebo training or IMT on sleep, blood pressure, and plasma catecholamines. Relative to placebo-trained subjects with OSA, subjects with OSA who performed IMT manifested reductions in systolic and diastolic blood pressures (-12.3 ± 1.6 SBP and -5.0 ± 1.3 DBP mmHg; P < 0.01); plasma norepinephrine levels (536.3 ± 56.6 versus 380.6 ± 41.2 pg/mL; P = 0.01); and registered fewer nighttime arousals and reported improved sleep (Pittsburgh Sleep Quality Index scores: 9.1 ± 0.9 versus 5.1 ± 0.7; P = 0.001). These favorable outcomes were achieved without affecting apneahypopnea index. CONCLUSIONS The results are consistent with our previously published findings in normotensive adults but further indicate that IMT can modulate blood pressure and plasma catecholamines in subjects with ongoing nighttime apnea and hypoxemia. Accordingly, we suggest IMT offers a low cost, nonpharmacologic means of improving sleep and blood pressure in patients who are intolerant of CPAP.
Collapse
Affiliation(s)
| | - E Fiona Bailey
- The University of Arizona College of Medicine, Tucson, AZ
| |
Collapse
|
71
|
Berg T. α2-Adrenoreceptor Constraint of Catecholamine Release and Blood Pressure Is Enhanced in Female Spontaneously Hypertensive Rats. Front Neurosci 2016; 10:130. [PMID: 27065790 PMCID: PMC4812064 DOI: 10.3389/fnins.2016.00130] [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: 02/07/2016] [Accepted: 03/15/2016] [Indexed: 12/30/2022] Open
Abstract
UNLABELLED α2-adrenoceptors (α2AR) lower central sympathetic output and peripheral catecholamine release, and may therefore prevent sympathetic hyperactivity and hypertension. The α2AR are dysfunctional in male spontaneously hypertensive rats (SHR). Premenopausal females are less hypertensive than males. The purpose of this study was to test if this difference could be explained by functional α2AR in the female SHR. A 15-min tyramine-infusion was used to stimulate norepinephrine release through the re-uptake transporter, consequently preventing re-uptake. Presynaptic control of vesicular release will therefore be reflected as differences in overflow to plasma. The surgical trauma activates secretion of epinephrine, also subjected to α2AR auto-inhibition. Blood pressure was monitored through a femoral artery catheter and cardiac output by ascending aorta flow in 12-14 weeks-old (early hypertension) SHR and normotensive rats (WKY). Total peripheral vascular resistance (TPR) was calculated. Female SHR, unlike male, were close to normotensive. Pre-treatment with none-selective (clonidine) or non-A-selective (ST-91) α2AR agonist reduced, and none-selective α2AR antagonist (L-659,066) increased tyramine-induced norepinephrine overflow in female WKY and SHR. L-659,066 also increased secretion of epinephrine. The L-659,066-induced increase in catecholamine release was further enhanced by additional pre-treatment with ST-91 or angiotensin AT1 receptor antagonist (losartan) in SHR only. L-659,066 eliminated the tyramine-induced rise in TPR in both strains in female rats. CONCLUSION α2AR-mediated control of catecholamine release and vascular tension was therefore functional in female SHR, unlike that previously observed in male SHR. Functional α2AR is likely to have a protective function and may explain the lack of hypertension in the young female SHR.
Collapse
Affiliation(s)
- Torill Berg
- Division of Physiology, Department of Molecular Medicine, Institute of Basic Medical Sciences, University of Oslo Oslo, Norway
| |
Collapse
|
72
|
Lee JF, Barrett-O'Keefe Z, Nelson AD, Garten RS, Ryan JJ, Nativi-Nicolau JN, Richardson RS, Wray DW. Impaired skeletal muscle vasodilation during exercise in heart failure with preserved ejection fraction. Int J Cardiol 2016; 211:14-21. [PMID: 26970959 DOI: 10.1016/j.ijcard.2016.02.139] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/22/2016] [Accepted: 02/28/2016] [Indexed: 01/25/2023]
Abstract
BACKGROUND Exercise intolerance is a hallmark symptom of heart failure patients with preserved ejection fraction (HFpEF), which may be related to an impaired ability to appropriately increase blood flow to the exercising muscle. METHODS We evaluated leg blood flow (LBF, ultrasound Doppler), heart rate (HR), stroke volume (SV), cardiac output (CO), and mean arterial blood pressure (MAP, photoplethysmography) during dynamic, single leg knee-extensor (KE) exercise in HFpEF patients (n=21; 68 ± 2 yrs) and healthy controls (n=20; 71 ± 2 yrs). RESULTS HFpEF patients exhibited a marked attrition during KE exercise, with only 60% able to complete the exercise protocol. In participants who completed all exercise intensities (0-5-10-15 W; HFpEF, n=13; Controls, n=16), LBF was not different at 0 W and 5 W, but was 15-25% lower in HFpEF compared to controls at 10 W and 15 W (P<0.001). Likewise, leg vascular conductance (LVC), an index of vasodilation, was not different at 0 W and 5 W, but was 15-20% lower in HFpEF compared to controls at 10 W and 15 W (P<0.05). In contrast to these peripheral deficits, exercise-induced changes in central variables (HR, SV, CO), as well as MAP, were similar between groups. CONCLUSIONS These data reveal a marked reduction in LBF and LVC in HFpEF patients during exercise that cannot be attributed to a disease-related alteration in central hemodynamics, suggesting that impaired vasodilation in the exercising skeletal muscle vasculature may play a key role in the exercise intolerance associated with this patient population.
Collapse
Affiliation(s)
- Joshua F Lee
- Division of Geriatrics, Department of Internal Medicine, University of Utah, Salt Lake City, UT, United States; Geriatric Research, Education, and Clinical Center, VA Medical Center, Salt Lake City, UT, United States
| | - Zachary Barrett-O'Keefe
- Geriatric Research, Education, and Clinical Center, VA Medical Center, Salt Lake City, UT, United States; Department of Exercise & Sport Science, University of Utah, Salt Lake City, UT, United States
| | - Ashley D Nelson
- Division of Geriatrics, Department of Internal Medicine, University of Utah, Salt Lake City, UT, United States
| | - Ryan S Garten
- Division of Geriatrics, Department of Internal Medicine, University of Utah, Salt Lake City, UT, United States; Geriatric Research, Education, and Clinical Center, VA Medical Center, Salt Lake City, UT, United States
| | - John J Ryan
- Division of Cardiovascular Medicine, Department of Internal Medicine, University of Utah, Salt Lake City, UT, United States
| | - Jose N Nativi-Nicolau
- Division of Cardiovascular Medicine, Department of Internal Medicine, University of Utah, Salt Lake City, UT, United States
| | - Russell S Richardson
- Division of Geriatrics, Department of Internal Medicine, University of Utah, Salt Lake City, UT, United States; Geriatric Research, Education, and Clinical Center, VA Medical Center, Salt Lake City, UT, United States; Department of Exercise & Sport Science, University of Utah, Salt Lake City, UT, United States
| | - D Walter Wray
- Division of Geriatrics, Department of Internal Medicine, University of Utah, Salt Lake City, UT, United States; Geriatric Research, Education, and Clinical Center, VA Medical Center, Salt Lake City, UT, United States; Department of Exercise & Sport Science, University of Utah, Salt Lake City, UT, United States.
| |
Collapse
|
73
|
Lindenfeld J, Cleveland JC, Kao DP, White M, Wichman S, Bristow JC, Peterson V, Rodegheri-Brito J, Korst A, Blain-Nelson P, Sederberg J, Hunt SA, Gilbert EM, Ambardekar AV, Minobe W, Port JD, Bristow MR. Sex-related differences in age-associated downregulation of human ventricular myocardial β1-adrenergic receptors. J Heart Lung Transplant 2016; 35:352-361. [PMID: 26970472 DOI: 10.1016/j.healun.2015.10.021] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2015] [Revised: 09/24/2015] [Accepted: 10/14/2015] [Indexed: 12/12/2022] Open
Affiliation(s)
| | | | - David P Kao
- University of Colorado Anschutz Medical Campus, Aurora, Colorado
| | - Michel White
- The Montreal Heart Institute, Montreal, Quebec, Canada
| | - Scott Wichman
- University of Colorado Anschutz Medical Campus, Aurora, Colorado
| | | | | | | | - Armin Korst
- University of Colorado Anschutz Medical Campus, Aurora, Colorado
| | | | - James Sederberg
- University of Colorado Anschutz Medical Campus, Aurora, Colorado
| | | | | | | | - Wayne Minobe
- University of Colorado Anschutz Medical Campus, Aurora, Colorado
| | - Jonathan D Port
- University of Colorado Anschutz Medical Campus, Aurora, Colorado
| | | |
Collapse
|
74
|
Heusser K, Tank J, Brinkmann J, Menne J, Kaufeld J, Linnenweber-Held S, Beige J, Wilhelmi M, Diedrich A, Haller H, Jordan J. Acute Response to Unilateral Unipolar Electrical Carotid Sinus Stimulation in Patients With Resistant Arterial Hypertension. Hypertension 2016; 67:585-91. [PMID: 26831195 DOI: 10.1161/hypertensionaha.115.06486] [Citation(s) in RCA: 52] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2015] [Accepted: 01/06/2016] [Indexed: 01/14/2023]
Abstract
Bilateral bipolar electric carotid sinus stimulation acutely reduced muscle sympathetic nerve activity (MSNA) and blood pressure (BP) in patients with resistant arterial hypertension but is no longer available. The second-generation device uses a smaller unilateral unipolar disk electrode to reduce invasiveness while saving battery life. We hypothesized that the second-generation device acutely lowers BP and MSNA in treatment-resistant hypertensive patients. Eighteen treatment-resistant hypertensive patients (9 women/9 men; 53±11 years; 33±5 kg/m(2)) on stable medications have been included in the study. We monitored finger and brachial BP, heart rate, and MSNA. Without stimulation, BP was 165±31/91±18 mm Hg, heart rate was 75±17 bpm, and MSNA was 48±14 bursts per minute. Acute stimulation with intensities producing side effects that were tolerable in the short term elicited interindividually variable changes in systolic BP (-16.9±15.0 mm Hg; range, 0.0 to -40.8 mm Hg; P=0.002), heart rate (-3.6±3.6 bpm; P=0.004), and MSNA (-2.0±5.8 bursts per minute; P=0.375). Stimulation intensities had to be lowered in 12 patients to avoid side effects at the expense of efficacy (systolic BP, -6.3±7.0 mm Hg; range, 2.8 to -14.5 mm Hg; P=0.028 and heart rate, -1.5±2.3 bpm; P=0.078; comparison against responses with side effects). Reductions in diastolic BP and MSNA (total activity) were correlated (r(2)=0.329; P=0.025). In our patient cohort, unilateral unipolar electric baroreflex stimulation acutely lowered BP. However, side effects may limit efficacy. The approach should be tested in a controlled comparative study.
Collapse
Affiliation(s)
- Karsten Heusser
- From the Institute of Clinical Pharmacology (K.H., J.T., J.B., J.J.), Clinic for Nephrology (J.M., J.K., S.L.-H., H.H.), Division for Cardiothoracic, Transplantation- and Vascular Surgery (M.W.), Hannover Medical School, Hannover, Germany; Department of Nephrology and KfH Renal Unit, Hospital St. Georg, Leipzig, Germany (J.B.); and Division of Clinical Pharmacology, Department of Medicine, Autonomic Dysfunction Service, Vanderbilt University, Nashville, TN (A.D.)
| | - Jens Tank
- From the Institute of Clinical Pharmacology (K.H., J.T., J.B., J.J.), Clinic for Nephrology (J.M., J.K., S.L.-H., H.H.), Division for Cardiothoracic, Transplantation- and Vascular Surgery (M.W.), Hannover Medical School, Hannover, Germany; Department of Nephrology and KfH Renal Unit, Hospital St. Georg, Leipzig, Germany (J.B.); and Division of Clinical Pharmacology, Department of Medicine, Autonomic Dysfunction Service, Vanderbilt University, Nashville, TN (A.D.)
| | - Julia Brinkmann
- From the Institute of Clinical Pharmacology (K.H., J.T., J.B., J.J.), Clinic for Nephrology (J.M., J.K., S.L.-H., H.H.), Division for Cardiothoracic, Transplantation- and Vascular Surgery (M.W.), Hannover Medical School, Hannover, Germany; Department of Nephrology and KfH Renal Unit, Hospital St. Georg, Leipzig, Germany (J.B.); and Division of Clinical Pharmacology, Department of Medicine, Autonomic Dysfunction Service, Vanderbilt University, Nashville, TN (A.D.)
| | - Jan Menne
- From the Institute of Clinical Pharmacology (K.H., J.T., J.B., J.J.), Clinic for Nephrology (J.M., J.K., S.L.-H., H.H.), Division for Cardiothoracic, Transplantation- and Vascular Surgery (M.W.), Hannover Medical School, Hannover, Germany; Department of Nephrology and KfH Renal Unit, Hospital St. Georg, Leipzig, Germany (J.B.); and Division of Clinical Pharmacology, Department of Medicine, Autonomic Dysfunction Service, Vanderbilt University, Nashville, TN (A.D.)
| | - Jessica Kaufeld
- From the Institute of Clinical Pharmacology (K.H., J.T., J.B., J.J.), Clinic for Nephrology (J.M., J.K., S.L.-H., H.H.), Division for Cardiothoracic, Transplantation- and Vascular Surgery (M.W.), Hannover Medical School, Hannover, Germany; Department of Nephrology and KfH Renal Unit, Hospital St. Georg, Leipzig, Germany (J.B.); and Division of Clinical Pharmacology, Department of Medicine, Autonomic Dysfunction Service, Vanderbilt University, Nashville, TN (A.D.)
| | - Silvia Linnenweber-Held
- From the Institute of Clinical Pharmacology (K.H., J.T., J.B., J.J.), Clinic for Nephrology (J.M., J.K., S.L.-H., H.H.), Division for Cardiothoracic, Transplantation- and Vascular Surgery (M.W.), Hannover Medical School, Hannover, Germany; Department of Nephrology and KfH Renal Unit, Hospital St. Georg, Leipzig, Germany (J.B.); and Division of Clinical Pharmacology, Department of Medicine, Autonomic Dysfunction Service, Vanderbilt University, Nashville, TN (A.D.)
| | - Joachim Beige
- From the Institute of Clinical Pharmacology (K.H., J.T., J.B., J.J.), Clinic for Nephrology (J.M., J.K., S.L.-H., H.H.), Division for Cardiothoracic, Transplantation- and Vascular Surgery (M.W.), Hannover Medical School, Hannover, Germany; Department of Nephrology and KfH Renal Unit, Hospital St. Georg, Leipzig, Germany (J.B.); and Division of Clinical Pharmacology, Department of Medicine, Autonomic Dysfunction Service, Vanderbilt University, Nashville, TN (A.D.)
| | - Mathias Wilhelmi
- From the Institute of Clinical Pharmacology (K.H., J.T., J.B., J.J.), Clinic for Nephrology (J.M., J.K., S.L.-H., H.H.), Division for Cardiothoracic, Transplantation- and Vascular Surgery (M.W.), Hannover Medical School, Hannover, Germany; Department of Nephrology and KfH Renal Unit, Hospital St. Georg, Leipzig, Germany (J.B.); and Division of Clinical Pharmacology, Department of Medicine, Autonomic Dysfunction Service, Vanderbilt University, Nashville, TN (A.D.)
| | - André Diedrich
- From the Institute of Clinical Pharmacology (K.H., J.T., J.B., J.J.), Clinic for Nephrology (J.M., J.K., S.L.-H., H.H.), Division for Cardiothoracic, Transplantation- and Vascular Surgery (M.W.), Hannover Medical School, Hannover, Germany; Department of Nephrology and KfH Renal Unit, Hospital St. Georg, Leipzig, Germany (J.B.); and Division of Clinical Pharmacology, Department of Medicine, Autonomic Dysfunction Service, Vanderbilt University, Nashville, TN (A.D.)
| | - Hermann Haller
- From the Institute of Clinical Pharmacology (K.H., J.T., J.B., J.J.), Clinic for Nephrology (J.M., J.K., S.L.-H., H.H.), Division for Cardiothoracic, Transplantation- and Vascular Surgery (M.W.), Hannover Medical School, Hannover, Germany; Department of Nephrology and KfH Renal Unit, Hospital St. Georg, Leipzig, Germany (J.B.); and Division of Clinical Pharmacology, Department of Medicine, Autonomic Dysfunction Service, Vanderbilt University, Nashville, TN (A.D.)
| | - Jens Jordan
- From the Institute of Clinical Pharmacology (K.H., J.T., J.B., J.J.), Clinic for Nephrology (J.M., J.K., S.L.-H., H.H.), Division for Cardiothoracic, Transplantation- and Vascular Surgery (M.W.), Hannover Medical School, Hannover, Germany; Department of Nephrology and KfH Renal Unit, Hospital St. Georg, Leipzig, Germany (J.B.); and Division of Clinical Pharmacology, Department of Medicine, Autonomic Dysfunction Service, Vanderbilt University, Nashville, TN (A.D.).
| |
Collapse
|
75
|
Hearon CM, Dinenno FA. Regulation of skeletal muscle blood flow during exercise in ageing humans. J Physiol 2015; 594:2261-73. [PMID: 26332887 DOI: 10.1113/jp270593] [Citation(s) in RCA: 74] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2015] [Accepted: 08/13/2015] [Indexed: 12/12/2022] Open
Abstract
The regulation of skeletal muscle blood flow and oxygen delivery to contracting skeletal muscle is complex and involves the mechanical effects of muscle contraction; local metabolic, red blood cell and endothelium-derived substances; and the sympathetic nervous system (SNS). With advancing age in humans, skeletal muscle blood flow is typically reduced during dynamic exercise and this is due to a lower vascular conductance, which could ultimately contribute to age-associated reductions in aerobic exercise capacity, a primary predictor of mortality in both healthy and diseased ageing populations. Recent findings have highlighted the contribution of endothelium-derived substances to blood flow control in contracting muscle of older adults. With advancing age, impaired nitric oxide availability due to scavenging by reactive oxygen species, in conjunction with elevated vasoconstrictor signalling via endothelin-1, reduces the local vasodilatory response to muscle contraction. Additionally, ageing impairs the ability of contracting skeletal muscle to blunt sympathetic vasoconstriction (i.e. 'functional sympatholysis'), which is critical for the proper regulation of tissue blood flow distribution and oxygen delivery, and could further reduce skeletal muscle perfusion during high intensity and/or large muscle mass exercise in older adults. We propose that initiation of endothelium-dependent hyperpolarization is the underlying signalling event necessary to properly modulate sympathetic vasoconstriction in contracting muscle, and that age-associated impairments in red blood cell adenosine triphosphate release and stimulation of endothelium-dependent vasodilatation may explain impairments in both local vasodilatation and functional sympatholysis with advancing age in humans.
Collapse
Affiliation(s)
- Christopher M Hearon
- Human Cardiovascular Physiology Laboratory, Department of Health and Exercise Science, Colorado State University, Fort Collins, CO, 80523, USA
| | - Frank A Dinenno
- Human Cardiovascular Physiology Laboratory, Department of Health and Exercise Science, Colorado State University, Fort Collins, CO, 80523, USA.,Center for Cardiovascular Research, Colorado State University, Fort Collins, CO, 80523, USA
| |
Collapse
|
76
|
Notarius CF, Millar PJ, Floras JS. Muscle sympathetic activity in resting and exercising humans with and without heart failure. Appl Physiol Nutr Metab 2015; 40:1107-15. [PMID: 26481289 DOI: 10.1139/apnm-2015-0289] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The sympathetic nervous system is critical for coordinating the cardiovascular response to various types of physical exercise. In a number of disease states, including human heart failure with reduced ejection fraction (HFrEF), this regulation can be disturbed and adversely affect outcome. The purpose of this review is to describe sympathetic activity at rest and during exercise in both healthy humans and those with HFrEF and outline factors, which influence these responses. We focus predominately on studies that report direct measurements of efferent sympathetic nerve traffic to skeletal muscle (muscle sympathetic nerve activity; MSNA) using intraneural microneurographic recordings. Differences in MSNA discharge between subjects with and without HFrEF both at rest and during exercise and the influence of exercise training on the sympathetic response to exercise will be discussed. In contrast to healthy controls, MSNA increases during mild to moderate dynamic exercise in the presence of HFrEF. This increase may contribute to the exercise intolerance characteristic of HFrEF by limiting muscle blood flow and may be attenuated by exercise training. Future investigations are needed to clarify the neural afferent mechanisms that contribute to efferent sympathetic activation at rest and during exercise in HFrEF.
Collapse
Affiliation(s)
- Catherine F Notarius
- a University Health Network and Mount Sinai Hospital Division of Cardiology, University of Toronto, Toronto, ON M5G 2C4, Canada
| | - Philip J Millar
- b Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, ON N1G 2W1, Canada
| | - John S Floras
- a University Health Network and Mount Sinai Hospital Division of Cardiology, University of Toronto, Toronto, ON M5G 2C4, Canada
| |
Collapse
|
77
|
Cui J, Muller MD, Blaha C, Kunselman AR, Sinoway LI. Seasonal variation in muscle sympathetic nerve activity. Physiol Rep 2015; 3:3/8/e12492. [PMID: 26265752 PMCID: PMC4562578 DOI: 10.14814/phy2.12492] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Epidemiologic data suggest there are seasonal variations in the incidence of severe cardiac events with peak levels being evident in the winter. Whether autonomic indices including muscle sympathetic nerve activity (MSNA) vary with season remains unclear. In this report, we tested the hypothesis that resting MSNA varies with the seasons of the year with peak levels evident in the winter. We analyzed the supine resting MSNA in 60 healthy subjects. Each subject was studied during two, three, or four seasons (total 237 visits). MSNA burst rate in the winter (21.0 ± 6.8 burst/min, mean ± SD) was significantly greater than in the summer (13.5 ± 5.8 burst/min, P < 0.001), the spring (17.1 ± 9.0 burst/min, P = 0.03), and the fall (17.9 ± 7.7 burst/min, P = 0.002). There was no significant difference in MSNA for other seasonal comparisons. The results suggest that resting sympathetic nerve activity varies along the seasons, with peak levels evident in the winter. We speculate that the seasonal changes in sympathetic activity may be a contribution to the previously observed seasonal variations in cardiovascular morbidity and mortality.
Collapse
Affiliation(s)
- Jian Cui
- Penn State Hershey Heart and Vascular Institute, Pennsylvania State University College of Medicine Milton S. Hershey Medical Center, Hershey, Pennsylvania
| | - Matthew D Muller
- Penn State Hershey Heart and Vascular Institute, Pennsylvania State University College of Medicine Milton S. Hershey Medical Center, Hershey, Pennsylvania
| | - Cheryl Blaha
- Penn State Hershey Heart and Vascular Institute, Pennsylvania State University College of Medicine Milton S. Hershey Medical Center, Hershey, Pennsylvania
| | - Allen R Kunselman
- Division of Biostatistics and Bioinformatics, Department of Public Health Sciences, Pennsylvania State University College of Medicine Milton S. Hershey Medical Center, Hershey, Pennsylvania
| | - Lawrence I Sinoway
- Penn State Hershey Heart and Vascular Institute, Pennsylvania State University College of Medicine Milton S. Hershey Medical Center, Hershey, Pennsylvania
| |
Collapse
|
78
|
Sladek CD, Michelini LC, Stachenfeld NS, Stern JE, Urban JH. Endocrine‐Autonomic Linkages. Compr Physiol 2015; 5:1281-323. [DOI: 10.1002/cphy.c140028] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
|
79
|
Effects of the Fourth Ventricle Compression in the Regulation of the Autonomic Nervous System: A Randomized Control Trial. EVIDENCE-BASED COMPLEMENTARY AND ALTERNATIVE MEDICINE 2015. [PMID: 26199632 PMCID: PMC4496659 DOI: 10.1155/2015/148285] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Introduction. Dysfunction of the autonomic nervous system is an important factor in the development of chronic pain. Fourth ventricle compression (CV-4) has been shown to influence autonomic activity. Nevertheless, the physiological mechanisms behind these effects remain unclear. Objectives. This study is aimed at evaluating the effects of fourth ventricle compression on the autonomic nervous system. Methods. Forty healthy adults were randomly assigned to an intervention group, on whom CV-4 was performed, or to a control group, who received a placebo intervention (nontherapeutic touch on the occipital bone). In both groups, plasmatic catecholamine levels, blood pressure, and heart rate were measured before and immediately after the intervention. Results. No effects related to the intervention were found. Although a reduction of norepinephrine, systolic blood pressure, and heart rate was found after the intervention, it was not exclusive to the intervention group. In fact, only the control group showed an increment of dopamine levels after intervention. Conclusion. Fourth ventricle compression seems not to have any effect in plasmatic catecholamine levels, blood pressure, or heart rate. Further studies are needed to clarify the CV-4 physiologic mechanisms and clinical efficacy in autonomic regulation and pain treatment.
Collapse
|
80
|
Wray DW, Richardson RS. 'Fine-tuning' blood flow to the exercising muscle with advancing age: an update. Exp Physiol 2015; 100:589-602. [PMID: 25858164 DOI: 10.1113/ep085076] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2014] [Accepted: 04/08/2015] [Indexed: 11/08/2022]
Abstract
NEW FINDINGS What is the topic of this review? This review focuses on age-related changes in the regulatory pathways that exist at the unique interface between the vascular smooth muscle and the endothelium of the skeletal muscle vasculature, and how these changes contribute to impairments in exercising skeletal muscle blood flow in the elderly. What advances does it highlight? Several recent in vivo human studies from our group and others are highlighted that have examined age-related changes in nitric oxide, endothelin-1, alpha adrenergic, and renin-angiotensin-aldosterone (RAAS) signaling. During dynamic exercise, oxygen demand from the exercising muscle is dramatically elevated, requiring a marked increase in skeletal muscle blood flow that is accomplished through a combination of systemic sympathoexcitation and local metabolic vasodilatation. With advancing age, the balance between these factors appears to be disrupted in favour of vasoconstriction, leading to an impairment in exercising skeletal muscle blood flow in the elderly. This 'hot topic' review aims to provide an update to our current knowledge of age-related changes in the neural and local mechanisms that contribute to this 'fine-tuning' of blood flow during exercise. The focus is on results from recent human studies that have adopted a reductionist approach to explore how age-related changes in both vasodilators (nitric oxide) and vasoconstrictors (endothelin-1, α-adrenergic agonists and angiotensin II) interact and how these changes impact blood flow to the exercising skeletal muscle with advancing age.
Collapse
Affiliation(s)
- D Walter Wray
- Department of Exercise and Sport Science, University of Utah, Salt Lake City, UT, USA.,Geriatric Research, Education, and Clinical Center, Veterans Affairs Medical Center, Salt Lake City, UT, USA.,Department of Internal Medicine, University of Utah, Salt Lake City, UT, USA.,University of Utah Center on Aging, Salt Lake City, UT, USA
| | - Russell S Richardson
- Department of Exercise and Sport Science, University of Utah, Salt Lake City, UT, USA.,Geriatric Research, Education, and Clinical Center, Veterans Affairs Medical Center, Salt Lake City, UT, USA.,Department of Internal Medicine, University of Utah, Salt Lake City, UT, USA.,University of Utah Center on Aging, Salt Lake City, UT, USA
| |
Collapse
|
81
|
O’Donnell E, Goodman JM, Mak S, Murai H, Morris BL, Floras JS, Harvey PJ. Discordant Orthostatic Reflex Renin–Angiotensin and Sympathoneural Responses in Premenopausal Exercising-Hypoestrogenic Women. Hypertension 2015; 65:1089-95. [DOI: 10.1161/hypertensionaha.114.04976] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2014] [Accepted: 02/19/2015] [Indexed: 12/20/2022]
Affiliation(s)
- Emma O’Donnell
- From the Cardiovascular Research Laboratory, Department of Exercise Sciences, University of Toronto, Toronto, Ontario, Canada (E.O’D., J.M.G.); and Department of Medicine, Division of Cardiology, University Health Network at Mount Sinai Hospital (J.M.G., S.M., H.M., B.L.M, J.S.F.), and Department of Medicine, Division of Cardiology at the Women’s College Hospital (P.J.H.), University of Toronto, Ontario, Canada
| | - Jack M. Goodman
- From the Cardiovascular Research Laboratory, Department of Exercise Sciences, University of Toronto, Toronto, Ontario, Canada (E.O’D., J.M.G.); and Department of Medicine, Division of Cardiology, University Health Network at Mount Sinai Hospital (J.M.G., S.M., H.M., B.L.M, J.S.F.), and Department of Medicine, Division of Cardiology at the Women’s College Hospital (P.J.H.), University of Toronto, Ontario, Canada
| | - Susanna Mak
- From the Cardiovascular Research Laboratory, Department of Exercise Sciences, University of Toronto, Toronto, Ontario, Canada (E.O’D., J.M.G.); and Department of Medicine, Division of Cardiology, University Health Network at Mount Sinai Hospital (J.M.G., S.M., H.M., B.L.M, J.S.F.), and Department of Medicine, Division of Cardiology at the Women’s College Hospital (P.J.H.), University of Toronto, Ontario, Canada
| | - Hisayoshi Murai
- From the Cardiovascular Research Laboratory, Department of Exercise Sciences, University of Toronto, Toronto, Ontario, Canada (E.O’D., J.M.G.); and Department of Medicine, Division of Cardiology, University Health Network at Mount Sinai Hospital (J.M.G., S.M., H.M., B.L.M, J.S.F.), and Department of Medicine, Division of Cardiology at the Women’s College Hospital (P.J.H.), University of Toronto, Ontario, Canada
| | - Beverley L. Morris
- From the Cardiovascular Research Laboratory, Department of Exercise Sciences, University of Toronto, Toronto, Ontario, Canada (E.O’D., J.M.G.); and Department of Medicine, Division of Cardiology, University Health Network at Mount Sinai Hospital (J.M.G., S.M., H.M., B.L.M, J.S.F.), and Department of Medicine, Division of Cardiology at the Women’s College Hospital (P.J.H.), University of Toronto, Ontario, Canada
| | - John S. Floras
- From the Cardiovascular Research Laboratory, Department of Exercise Sciences, University of Toronto, Toronto, Ontario, Canada (E.O’D., J.M.G.); and Department of Medicine, Division of Cardiology, University Health Network at Mount Sinai Hospital (J.M.G., S.M., H.M., B.L.M, J.S.F.), and Department of Medicine, Division of Cardiology at the Women’s College Hospital (P.J.H.), University of Toronto, Ontario, Canada
| | - Paula J. Harvey
- From the Cardiovascular Research Laboratory, Department of Exercise Sciences, University of Toronto, Toronto, Ontario, Canada (E.O’D., J.M.G.); and Department of Medicine, Division of Cardiology, University Health Network at Mount Sinai Hospital (J.M.G., S.M., H.M., B.L.M, J.S.F.), and Department of Medicine, Division of Cardiology at the Women’s College Hospital (P.J.H.), University of Toronto, Ontario, Canada
| |
Collapse
|
82
|
Gagnon D, Schlader ZJ, Crandall CG. Sympathetic activity during passive heat stress in healthy aged humans. J Physiol 2015; 593:2225-35. [PMID: 25752842 DOI: 10.1113/jp270162] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2015] [Accepted: 02/20/2015] [Indexed: 12/31/2022] Open
Abstract
KEY POINTS Cardiovascular adjustments to heat stress are attenuated in healthy aged individuals, which could contribute to their greater prevalence of heat-related illnesses and deaths during heat waves. The attenuated cardiovascular adjustments in the aged could be due to lower increases in sympathetic nerve activity during heat stress. We examined muscle sympathetic nerve activity (MSNA) and plasma catecholamine concentrations in healthy young and aged individuals during whole-body passive heat stress. The main finding of this study is that increases in MSNA and plasma catecholamine concentrations did not differ between young and aged healthy individuals during passive heating. Furthermore, the increase in these variables did not differ when a cold pressor test and lower body negative pressure were superimposed upon heating. These findings suggest that attenuated cardiovascular adjustments to heat stress in healthy aged individuals are unlikely to be related to attenuated increases in sympathetic activity. ABSTRACT Cardiovascular adjustments during heat stress are generally attenuated in healthy aged humans, which could be due to lower increases in sympathetic activity compared to the young. We compared muscle sympathetic nerve activity (MSNA) between 11 young (Y: 28 ± 4 years) and 10 aged (A: 70 ± 5 years) subjects prior to and during passive heating. Furthermore, MSNA responses were compared when a cold pressor test (CPT) and lower body negative pressure (LBNP) were superimposed upon heating. Baseline MSNA burst frequency (Y: 15 ± 4 vs. A: 31 ± 3 bursts min(-1) , P ≤ 0.01) and burst incidence (Y: 26 ± 8 vs. A: 50 ± 7 bursts (100 cardiac cycles (CC))(-1) , P ≤ 0.01) were greater in the aged. Heat stress increased core temperature to a similar extent in both groups (Y: +1.2 ± 0.1 vs. A: +1.2 ± 0.0°C, P = 0.99). Absolute levels of MSNA remained greater in the aged during heat stress (burst frequency: Y: 47 ± 6 vs. A: 63 ± 11 bursts min(-1) , P ≤ 0.01; burst incidence: Y: 48 ± 8 vs. A: 67 ± 9 bursts (100 CC)(-1) , P ≤ 0.01); however, the increase in both variables was similar between groups (both P ≥ 0.1). The CPT and LBNP further increased MSNA burst frequency and burst incidence, although the magnitude of increase was similar between groups (both P ≥ 0.07). These results suggest that increases in sympathetic activity during heat stress are not attenuated in healthy aged humans.
Collapse
Affiliation(s)
- Daniel Gagnon
- Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital Dallas and University of Texas Southwestern Medical Centre, Dallas, TX, USA
| | | | | |
Collapse
|
83
|
Upadhya B, Taffet GE, Cheng CP, Kitzman DW. Heart failure with preserved ejection fraction in the elderly: scope of the problem. J Mol Cell Cardiol 2015; 83:73-87. [PMID: 25754674 DOI: 10.1016/j.yjmcc.2015.02.025] [Citation(s) in RCA: 99] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/03/2014] [Revised: 02/25/2015] [Accepted: 02/26/2015] [Indexed: 12/13/2022]
Abstract
Heart failure with preserved ejection fraction (HFpEF) is the most common form of heart failure (HF) in older adults, particularly women, and is increasing in prevalence as the population ages. With morbidity and mortality on par with HF with reduced ejection fraction, it remains a most challenging clinical syndrome for the practicing clinician and basic research scientist. Originally considered to be predominantly caused by diastolic dysfunction, more recent insights indicate that HFpEF in older persons is typified by a broad range of cardiac and non-cardiac abnormalities and reduced reserve capacity in multiple organ systems. The globally reduced reserve capacity is driven by: 1) inherent age-related changes; 2) multiple, concomitant co-morbidities; 3) HFpEF itself, which is likely a systemic disorder. These insights help explain why: 1) co-morbidities are among the strongest predictors of outcomes; 2) approximately 50% of clinical events in HFpEF patients are non-cardiovascular; 3) clinical drug trials in HFpEF have been negative on their primary outcomes. Embracing HFpEF as a true geriatric syndrome, with complex, multi-factorial pathophysiology and clinical heterogeneity could provide new mechanistic insights and opportunities for progress in management. This article is part of a Special Issue entitled CV Aging.
Collapse
Affiliation(s)
- Bharathi Upadhya
- Cardiology Section, Department of Internal Medicine, Wake Forest School of Medicine, Winston-Salem, NC, USA
| | - George E Taffet
- Geriatrics and Cardiovascular Sciences, Baylor College of Medicine, Houston Methodist Hospital, Houston, TX, USA
| | - Che Ping Cheng
- Cardiology Section, Department of Internal Medicine, Wake Forest School of Medicine, Winston-Salem, NC, USA
| | - Dalane W Kitzman
- Cardiology Section, Department of Internal Medicine, Wake Forest School of Medicine, Winston-Salem, NC, USA.
| |
Collapse
|
84
|
Moore DJ, Barlow MA, Gonzales JU, McGowan CL, Pawelczyk JA, Proctor DN. Evidence for the emergence of leg sympathetic vasoconstrictor tone with age in healthy women. Physiol Rep 2015; 3:3/1/e12275. [PMID: 25626874 PMCID: PMC4387747 DOI: 10.14814/phy2.12275] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
While muscle sympathetic nerve activity (MSNA) is elevated with advancing age, correlational evidence suggests that, in contrast to men, basal MSNA is not related to resting lower limb hemodynamics in women. However, limited data exists in women that have attempted to directly assess the degree of limb sympathetic vasoconstrictor tone, and whether it is altered with age. To address this issue, we measured changes in femoral artery vascular conductance (FVC) during an acute sympatho‐inhibitory stimulus (−60 mm Hg neck suction, NS) in groups of healthy younger (n = 8, 23 ± 1 years) and older (n = 7, 66 ± 1 years) women. The percent change in FVC in response to NS was significantly augmented in the older (P = 0.006 vs. young) women. Although NS caused no significant change (3 ± 3%, P = 0.33) in FVC in the young women, there was a robust increase in FVC (21 ± 5%, P = 0.003) in the old women. Collectively, these findings provide evidence that in women, leg sympathetic vasoconstrictor tone emerges with age. In the present study, we sought to compare the amount of sympathetic vasoconstriction in the resting lower limbs (i.e., legs) of younger and older women. Leg (femoral artery) vascular conductance increased in older but not younger women during an acute sympatho‐inhibitory stimulus. These findings suggest that in women there is an emergence of lower limb sympathetic vasoconstrictor tone with advanced age.
Collapse
Affiliation(s)
- David J Moore
- Noll Laboratory, Department of Kinesiology, The Pennsylvania State University, University Park, Pennsylvania Intercollege Graduate Degree Program in Physiology, The Pennsylvania State University, University Park, Pennsylvania
| | - Matthew A Barlow
- Noll Laboratory, Department of Kinesiology, The Pennsylvania State University, University Park, Pennsylvania Department of Biology, Eastern New Mexico University, Portales, New Mexico
| | - Joaquin U Gonzales
- Noll Laboratory, Department of Kinesiology, The Pennsylvania State University, University Park, Pennsylvania Department of Health, Exercise & Sport Sciences, Texas Tech University, Lubbock, Texas
| | - Cheri L McGowan
- Department of Kinesiology, University of Windsor, Windsor, Ontario, Canada
| | - James A Pawelczyk
- Noll Laboratory, Department of Kinesiology, The Pennsylvania State University, University Park, Pennsylvania Intercollege Graduate Degree Program in Physiology, The Pennsylvania State University, University Park, Pennsylvania
| | - David N Proctor
- Noll Laboratory, Department of Kinesiology, The Pennsylvania State University, University Park, Pennsylvania Intercollege Graduate Degree Program in Physiology, The Pennsylvania State University, University Park, Pennsylvania
| |
Collapse
|
85
|
Joyner MJ, Barnes JN, Hart EC, Wallin BG, Charkoudian N. Neural control of the circulation: how sex and age differences interact in humans. Compr Physiol 2015; 5:193-215. [PMID: 25589269 PMCID: PMC4459710 DOI: 10.1002/cphy.c140005] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
The autonomic nervous system is a key regulator of the cardiovascular system. In this review, we focus on how sex and aging influence autonomic regulation of blood pressure in humans in an effort to understand general issues related to the cardiovascular system as a whole. Younger women generally have lower blood pressure and sympathetic activity than younger men. However, both sexes show marked interindividual variability across age groups with significant overlap seen. Additionally, while men across the lifespan show a clear relationship between markers of whole body sympathetic activity and vascular resistance, such a relationship is not seen in young women. In this context, the ability of the sympathetic nerves to evoke vasoconstriction is lower in young women likely as a result of concurrent β2-mediated vasodilation that offsets α-adrenergic vasoconstriction. These differences reflect both central sympatho-inhibitory effects of estrogen and also its influence on peripheral vasodilation at the level of the vascular smooth muscle and endothelium. By contrast postmenopausal women show a clear relationship between markers of whole body sympathetic traffic and vascular resistance, and sympathetic activity rises progressively in both sexes with aging. These major findings in humans are discussed in the context of differences in population-based trends in blood pressure and orthostatic intolerance. The many areas where there is little sex-specific data on how the autonomic nervous system participates in the regulation of the human cardiovascular system are highlighted.
Collapse
Affiliation(s)
| | - Jill N. Barnes
- Department of Anesthesiology, Mayo Clinic, Rochester, MN
| | - Emma C. Hart
- School of Physiology and Pharmacology, University of Bristol, Bristol UK
| | - B. Gunnar Wallin
- Institute of Neuroscience and Physiology, The Sahlgren Academy at Gothenburg University, Goteborg, Sweden
| | - Nisha Charkoudian
- Thermal and Mountain Medicine Division, U.S. Army Research Institute of Environmental Medicine, Natick, MA
| |
Collapse
|
86
|
Usselman CW, Gimon TI, Nielson CA, Luchyshyn TA, Coverdale NS, Van Uum SHM, Shoemaker JK. Menstrual cycle and sex effects on sympathetic responses to acute chemoreflex stress. Am J Physiol Heart Circ Physiol 2014; 308:H664-71. [PMID: 25527774 DOI: 10.1152/ajpheart.00345.2014] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
This study aimed to examine the effects of sex (males vs. females) and sex hormones (menstrual cycle phases in women) on sympathetic responsiveness to severe chemoreflex activation in young, healthy individuals. Muscle sympathetic nerve activity (MSNA) was measured at baseline and during rebreathing followed by a maximal end-inspiratory apnea. In women, baseline MSNA was greater in the midluteal (ML) than early-follicular (EF) phase of the menstrual cycle. Baseline MSNA burst incidence was greater in men than women, while burst frequency and total MSNA were similar between men and women only in the ML phase. Chemoreflex activation evoked graded increases in MSNA burst frequency, amplitude, and total activity in all participants. In women, this sympathoexcitation was greater in the EF than ML phase. The sympathoexcitatory response to chemoreflex stimulation of the EF phase in women was also greater than in men. Nonetheless, changes in total peripheral resistance were similar between sexes and menstrual cycle phases. This indicates that neurovascular transduction was attenuated during the EF phase during chemoreflex activation, thereby offsetting the exaggerated sympathoexcitation. Chemoreflex-induced increases in mean arterial pressure were similar across sexes and menstrual cycle phases. During acute chemoreflex stimulation, reduced neurovascular transduction could provide a mechanism by which apnea-associated morbidity might be attenuated in women relative to men.
Collapse
Affiliation(s)
- Charlotte W Usselman
- Neurovascular Research Laboratory, School of Kinesiology, Western University, London, Ontario, Canada
| | - Tamara I Gimon
- Neurovascular Research Laboratory, School of Kinesiology, Western University, London, Ontario, Canada
| | - Chantelle A Nielson
- Neurovascular Research Laboratory, School of Kinesiology, Western University, London, Ontario, Canada
| | - Torri A Luchyshyn
- Neurovascular Research Laboratory, School of Kinesiology, Western University, London, Ontario, Canada
| | - Nicole S Coverdale
- Neurovascular Research Laboratory, School of Kinesiology, Western University, London, Ontario, Canada
| | - Stan H M Van Uum
- Department of Medicine, Western University, London, Ontario, Canada; Lawson Health Research Institute, Western University, London, Ontario, Canada; and
| | - J Kevin Shoemaker
- Neurovascular Research Laboratory, School of Kinesiology, Western University, London, Ontario, Canada; Department of Physiology and Pharmacology, Western University, London, Ontario, Canada
| |
Collapse
|
87
|
Charkoudian N, Wallin BG. Sympathetic neural activity to the cardiovascular system: integrator of systemic physiology and interindividual characteristics. Compr Physiol 2014; 4:825-50. [PMID: 24715570 DOI: 10.1002/cphy.c130038] [Citation(s) in RCA: 57] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
The sympathetic nervous system is a ubiquitous, integrating controller of myriad physiological functions. In the present article, we review the physiology of sympathetic neural control of cardiovascular function with a focus on integrative mechanisms in humans. Direct measurement of sympathetic neural activity (SNA) in humans can be accomplished using microneurography, most commonly performed in the peroneal (fibular) nerve. In humans, muscle SNA (MSNA) is composed of vasoconstrictor fibers; its best-recognized characteristic is its participation in transient, moment-to-moment control of arterial blood pressure via the arterial baroreflex. This property of MSNA contributes to its typical "bursting" pattern which is strongly linked to the cardiac cycle. Recent evidence suggests that sympathetic neural mechanisms and the baroreflex have important roles in the long term control of blood pressure as well. One of the striking characteristics of MSNA is its large interindividual variability. However, in young, normotensive humans, higher MSNA is not linked to higher blood pressure due to balancing influences of other cardiovascular variables. In men, an inverse relationship between MSNA and cardiac output is a major factor in this balance, whereas in women, beta-adrenergic vasodilation offsets the vasoconstrictor/pressor effects of higher MSNA. As people get older (and in people with hypertension) higher MSNA is more likely to be linked to higher blood pressure. Skin SNA (SSNA) can also be measured in humans, although interpretation of SSNA signals is complicated by multiple types of neurons involved (vasoconstrictor, vasodilator, sudomotor and pilomotor). In addition to blood pressure regulation, the sympathetic nervous system contributes to cardiovascular regulation during numerous other reflexes, including those involved in exercise, thermoregulation, chemoreflex regulation, and responses to mental stress.
Collapse
Affiliation(s)
- N Charkoudian
- U.S. Army Research Institute of Environmental Medicine, Natick, Massachusetts
| | | |
Collapse
|
88
|
Brooks VL, Shi Z, Holwerda SW, Fadel PJ. Obesity-induced increases in sympathetic nerve activity: sex matters. Auton Neurosci 2014; 187:18-26. [PMID: 25435000 DOI: 10.1016/j.autneu.2014.11.006] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2014] [Revised: 11/02/2014] [Accepted: 11/08/2014] [Indexed: 01/18/2023]
Abstract
Abundant evidence obtained largely from male human and animal subjects indicates that obesity increases sympathetic nerve activity (SNA), which contributes to hypertension development. However, recent studies that included women reported that the strong relationships between muscle SNA and waist circumference or body mass index (BMI) found in men are not present in overweight and obese women. A similar sex difference in the association between adiposity and hypertension development has been identified in animal models of obesity. In this brief review, we consider two possible mechanisms for this sex difference. First, visceral adiposity, leptin, insulin, and angiotensin II have been identified as potential culprits in obesity-induced sympathoexcitation in males. We explore if these factors wield the same impact in females. Second, we consider if sex differences in vascular reactivity to sympathetic activation contribute. Our survey of the literature suggests that premenopausal females may be able to resist obesity-induced sympathoexcitation and hypertension in part due to differences in adipose disposition as well as its muted inflammatory response and reduced production of pressor versus depressor components of the renin-angiotensin system. In addition, vascular responsiveness to increased SNA may be reduced. However, more importantly, we identify the urgent need for further study, not only of sex differences per se, but also of the mechanisms that may mediate these differences. This information is required not only to refine treatment options for obese premenopausal women but also to potentially reveal new therapeutic avenues in obese men and women.
Collapse
Affiliation(s)
- Virginia L Brooks
- Department of Physiology and Pharmacology, Oregon Health & Science University, Portland, OR 97239, United States.
| | - Zhigang Shi
- Department of Physiology and Pharmacology, Oregon Health & Science University, Portland, OR 97239, United States
| | - Seth W Holwerda
- Department of Medical Pharmacology and Physiology, Dalton Cardiovascular Research Center, University of Missouri, Columbia, MO 65212, United States
| | - Paul J Fadel
- Department of Medical Pharmacology and Physiology, Dalton Cardiovascular Research Center, University of Missouri, Columbia, MO 65212, United States
| |
Collapse
|
89
|
Hart ECJ, Charkoudian N. Sympathetic neural regulation of blood pressure: influences of sex and aging. Physiology (Bethesda) 2014; 29:8-15. [PMID: 24382867 DOI: 10.1152/physiol.00031.2013] [Citation(s) in RCA: 78] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
Sex and age have important influences on sympathetic neural control of blood pressure in humans. Young women are relatively protected against risk of hypertension due to greater peripheral vasodilator influences compared with young men and older people. This protective effect is lost at menopause. Older men and women have higher sympathetic nerve activity and tighter coupling between SNA and blood pressure, contributing to the increased risk of hypertension with aging.
Collapse
Affiliation(s)
- E C J Hart
- School of Physiology and Pharmacology, University of Bristol, Bristol, United Kingdom; and
| | | |
Collapse
|
90
|
Sforza E, Saint Martin M, Barthelemy JC, Roche F. Association of self-reported sleep and hypertension in non-insomniac elderly subjects. J Clin Sleep Med 2014; 10:965-71. [PMID: 25142770 DOI: 10.5664/jcsm.4026] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
OBJECTIVES Sleep duration and sleep quality play important roles in the development of hypertension (HT) in middle-aged subjects, with controversial data in elderly. In this study, we investigated the link between HT and self-reported sleep in non-insomniac elderly subjects. METHODS We examined 500 participants without insomnia complaints aged 72 ± 1 years. An extensive instrumental evaluation was carried out, including 24-h blood pressure (BP) monitoring and an assessment of nocturnal BP dipping. Sleep duration and quality were evaluated by the Pittsburgh Sleep Quality Index (PSQI). The subjects were stratified into three groups according to sleep duration: short (< 6 h), normal (> 6h to < 8 h), and long (> 8 h) sleepers. A PSQI < 5 defined good sleepers (GS, n = 252), and a PSQI > 5 (n = 248) defined poor sleepers (PS). RESULTS PS represented 50% of the subjects, more frequently females. Compared to GS, PS did not differ in terms of HT, BP, baroreflex sensitivity (BRS), and BP dipping. Short, normal, and long sleepers accounted for 28%, 42%, and 30% of subjects, with HT, BP values, BRS, and gender not differing between groups. No relationship was found between nocturnal BP values and self-reported sleep measures. Logistic regression analysis indicated that neither sleep duration nor sleep quality predicts the prevalence of HT, the body mass index being the only factor affecting this association. CLINICAL TRIAL REGISTRATION ClinicalTrials.gov identifiers NCT00759304 and NCT00766584. CONCLUSIONS In a sample of non-insomniac elderly subjects, neither sleep duration nor sleep quality affected the prevalence of HT. These data argue against a relationship between self-reported sleep duration and quality and HT in elderly without insomnia.
Collapse
|
91
|
Stölting MNL, Hefermehl LJ, Tremp M, Azzabi F, Sulser T, Eberli D. The role of donor age and gender in the success of human muscle precursor cell transplantation. J Tissue Eng Regen Med 2014; 11:447-458. [PMID: 25052735 DOI: 10.1002/term.1935] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2013] [Revised: 02/14/2014] [Accepted: 05/21/2014] [Indexed: 11/09/2022]
Abstract
Autologous cell transplantation for the treatment of muscle damage is envisioned to involve the application of muscle precursor cells (MPCs) isolated from adult skeletal muscle. At the onset of trauma, these cells are recruited to proliferate and rebuild injured muscle fibres. However, a variety of donor-specific cues may directly influence the yield and quality of cells isolated from a muscle biopsy. In this study, we isolated human MPCs and assessed the role of donor gender and age on the ability of these MPCs to form functional bioengineered muscle. We analysed the cell yield, growth and molecular expression in vitro, and the muscle tissue formation and contractility of the bioengineered muscle, from cells isolated from men and women in three different age groups: young (20-39 years), adult (40-59 years) and elderly (60-80 years). Our results suggest that human MPCs can be successfully isolated and grown from patients of all ages and both genders. However, young female donors provide fast-growing cells in vitro with an optimum contractile output in vivo and are therefore an ideal cell source for muscle reconstruction. Taken together, these findings describe the donor-related limitations of MPC transplantation and provide insights for a straightforward and unbiased clinical application of these cells for muscle reconstruction. Copyright © 2014 John Wiley & Sons, Ltd.
Collapse
Affiliation(s)
- Meline N L Stölting
- Laboratory for Urologic Tissue Engineering and Stem Cell Therapy, Division of Urology, University of Zurich, Switzerland
| | - Lukas J Hefermehl
- Laboratory for Urologic Tissue Engineering and Stem Cell Therapy, Division of Urology, University of Zurich, Switzerland
| | - Mathias Tremp
- Laboratory for Urologic Tissue Engineering and Stem Cell Therapy, Division of Urology, University of Zurich, Switzerland
| | - Fahd Azzabi
- Laboratory for Urologic Tissue Engineering and Stem Cell Therapy, Division of Urology, University of Zurich, Switzerland
| | - Tullio Sulser
- Laboratory for Urologic Tissue Engineering and Stem Cell Therapy, Division of Urology, University of Zurich, Switzerland
| | - Daniel Eberli
- Laboratory for Urologic Tissue Engineering and Stem Cell Therapy, Division of Urology, University of Zurich, Switzerland
| |
Collapse
|
92
|
La Rovere MT, Pinna GD. Beneficial effects of physical activity on baroreflex control in the elderly. Ann Noninvasive Electrocardiol 2014; 19:303-10. [PMID: 24844457 DOI: 10.1111/anec.12170] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/01/2022] Open
Abstract
The baroreflex mechanisms, by controlling autonomic outflow to the heart and circulation, contribute importantly to neural circulatory control. The main function of the baroreflex is to prevent wide fluctuations in arterial blood pressure and to maintain the physiological homeostasis under basal resting conditions and in response to acute stress. Baroreflex-mediated changes in autonomic outflow affect heart rate, myocardial contractility, and peripheral vascular resistance. The baroreflex control of heart rate is of particular interest in pathological conditions, since it has been associated with increased propensity for cardiac mortality and sudden death. Aging is associated with significant cardiovascular modifications. The changes in baroreflex function that occur with age have been systematically studied by several methodological approaches. The available evidence indicates a reduced arterial baroreflex control of heart rate favoring an increase in sympathetic and a decrease in parasympathetic drive to the heart as well as an impairment in the baroreceptor control of blood pressure. Both kinds of changes have resultant clinical implications. Exercise training can modulate the age-related decline in baroreflex function and the attending abnormalities in autonomic control, thus accounting for some of the beneficial effects of physical activity in reducing the risk of cardiovascular morbidity and mortality.
Collapse
Affiliation(s)
- Maria Teresa La Rovere
- Department of Cardiology and Biomedical Engineering, Fondazione "Salvatore Maugeri," IRCCS, Istituto Scientifico di Montescano (Pavia), Italy
| | | |
Collapse
|
93
|
Renal Denervation for Drug-Resistant Hypertension: Suffering Its Original Sin, Seeking Redemption. Can J Cardiol 2014; 30:476-8. [DOI: 10.1016/j.cjca.2014.02.008] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2014] [Accepted: 02/15/2014] [Indexed: 12/16/2022] Open
|
94
|
Hunter SK. Sex differences in human fatigability: mechanisms and insight to physiological responses. Acta Physiol (Oxf) 2014; 210:768-89. [PMID: 24433272 DOI: 10.1111/apha.12234] [Citation(s) in RCA: 330] [Impact Index Per Article: 33.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2013] [Revised: 07/29/2013] [Accepted: 01/08/2014] [Indexed: 12/17/2022]
Abstract
Sex-related differences in physiology and anatomy are responsible for profound differences in neuromuscular performance and fatigability between men and women. Women are usually less fatigable than men for similar intensity isometric fatiguing contractions. This sex difference in fatigability, however, is task specific because different neuromuscular sites will be stressed when the requirements of the task are altered, and the stress on these sites can differ for men and women. Task variables that can alter the sex difference in fatigability include the type, intensity and speed of contraction, the muscle group assessed and the environmental conditions. Physiological mechanisms that are responsible for sex-based differences in fatigability may include activation of the motor neurone pool from cortical and subcortical regions, synaptic inputs to the motor neurone pool via activation of metabolically sensitive small afferent fibres in the muscle, muscle perfusion and skeletal muscle metabolism and fibre type properties. Non-physiological factors such as the sex bias of studying more males than females in human and animal experiments can also mask a true understanding of the magnitude and mechanisms of sex-based differences in physiology and fatigability. Despite recent developments, there is a tremendous lack of understanding of sex differences in neuromuscular function and fatigability, the prevailing mechanisms and the functional consequences. This review emphasizes the need to understand sex-based differences in fatigability to shed light on the benefits and limitations that fatigability can exert for men and women during daily tasks, exercise performance, training and rehabilitation in both health and disease.
Collapse
Affiliation(s)
- S. K. Hunter
- Exercise Science Program; Department of Physical Therapy; Marquette University; Milwaukee WI USA
| |
Collapse
|
95
|
Credeur DP, Holwerda SW, Boyle LJ, Vianna LC, Jensen AK, Fadel PJ. Effect of aging on carotid baroreflex control of blood pressure and leg vascular conductance in women. Am J Physiol Heart Circ Physiol 2014; 306:H1417-25. [PMID: 24682393 DOI: 10.1152/ajpheart.00036.2014] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Recent work suggests that β-adrenergic vasodilation offsets α-adrenergic vasoconstriction in young women, but this effect is lost after menopause. Given these age-related vascular changes, we tested the hypothesis that older women would exhibit a greater change in vascular conductance following baroreflex perturbation compared with young women. In 10 young (21 ± 1 yr) and 10 older (62 ± 2 yr) women, mean arterial pressure (MAP; Finometer), heart rate (HR), cardiac output (CO; Modelflow), total vascular conductance (TVC), and leg vascular conductance (LVC, duplex-Doppler ultrasound) were continuously measured in response to 5-s pulses of neck suction (NS; -60 Torr) and neck pressure (NP; +40 Torr) to simulate carotid hypertension and hypotension, respectively. Following NS, decreases in MAP were similar between groups; however, MAP peak response latency was slower in older women (P < 0.05). Moreover, at the time of peak MAP, increases in LVC (young, -11.5 ± 3.9%LVC vs. older, +19.1 ± 7.0%LVC; P < 0.05) and TVC were greater in older women, whereas young women exhibited larger decreases in HR and CO (young, -10 ± 3% CO vs. older, +0.8 ± 2% CO; P < 0.05). Following NP, increases in MAP were blunted (young, +14 ± 1 mmHg vs. older, +8 ± 1 mmHg; P < 0.05) in older women, whereas MAP response latencies were similar. Interestingly, decreases in LVC and TVC were similar between groups, but HR and CO (young, +7.0 ± 2% CO vs. older, -4.0 ± 2% CO; P < 0.05) responses were attenuated in older women. These findings suggest that older women have greater reliance on vascular conductance to modulate MAP via carotid baroreflex, whereas young women rely more on cardiac responsiveness. Furthermore, older women demonstrate a blunted ability to increase MAP to hypotensive stimuli.
Collapse
Affiliation(s)
| | | | | | - Lauro C Vianna
- Department of Physiology and Pharmacology, Fluminense Federal University, Niterói, Rio de Janeiro, Brazil
| | | | - Paul J Fadel
- Departments of Medical Pharmacology and Physiology, and Dalton Cardiovascular Research Center, University of Missouri, Columbia, Missouri;
| |
Collapse
|
96
|
Liu J, Sirenko S, Juhaszova M, Sollott SJ, Shukla S, Yaniv Y, Lakatta EG. Age-associated abnormalities of intrinsic automaticity of sinoatrial nodal cells are linked to deficient cAMP-PKA-Ca(2+) signaling. Am J Physiol Heart Circ Physiol 2014; 306:H1385-97. [PMID: 24633551 DOI: 10.1152/ajpheart.00088.2014] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
A reduced sinoatrial node (SAN) functional reserve underlies the age-associated decline in heart rate acceleration in response to stress. SAN cell function involves an oscillatory coupled-clock system: the sarcoplasmic reticulum (SR), a Ca(2+) clock, and the electrogenic-sarcolemmal membrane clock. Ca(2+)-activated-calmodulin-adenylyl cyclase/CaMKII-cAMP/PKA-Ca(2+) signaling regulated by phosphodiesterase activity drives SAN cells automaticity. SR-generated local calcium releases (LCRs) activate Na(+)/Ca(2+) exchanger in the membrane clock, which initiates the action potential (AP). We hypothesize that SAN cell dysfunctions accumulate with age. We found a reduction in single SAN cell AP firing in aged (20-24 mo) vs. adult (3-4 mo) mice. The sensitivity of the SAN beating rate responses to both muscarinic and adrenergic receptor activation becomes decreased in advanced age. Additionally, age-associated coincident dysfunctions occur stemming from compromised clock functions, including a reduced SR Ca(2+) load and a reduced size, number, and duration of spontaneous LCRs. Moreover, the sensitivity of SAN beating rate to a cAMP stress induced by phosphodiesterase inhibitor is reduced, as are the LCR size, amplitude, and number in SAN cells from aged vs. adult mice. These functional changes coincide with decreased expression of crucial SR Ca(2+)-cycling proteins, including SR Ca(2+)-ATPase pump, ryanodine receptors, and Na(+)/Ca(2+) exchanger. Thus a deterioration in intrinsic Ca(2+) clock kinetics in aged SAN cells, due to deficits in intrinsic SR Ca(2+) cycling and its response to a cAMP-dependent pathway activation, is involved in the age-associated reduction in intrinsic resting AP firing rate, and in the reduction in the acceleration of heart rate during exercise.
Collapse
Affiliation(s)
- Jie Liu
- Laboratory of Cardiovascular Science, Intramural Research Program, National Institute on Aging, National Institutes of Health, Baltimore, Maryland; and Department of Physiology, University of Sydney, Sydney, New South Wales, Australia
| | - Syevda Sirenko
- Laboratory of Cardiovascular Science, Intramural Research Program, National Institute on Aging, National Institutes of Health, Baltimore, Maryland; and
| | - Magdalena Juhaszova
- Laboratory of Cardiovascular Science, Intramural Research Program, National Institute on Aging, National Institutes of Health, Baltimore, Maryland; and
| | - Steven J Sollott
- Laboratory of Cardiovascular Science, Intramural Research Program, National Institute on Aging, National Institutes of Health, Baltimore, Maryland; and
| | - Shweta Shukla
- Laboratory of Cardiovascular Science, Intramural Research Program, National Institute on Aging, National Institutes of Health, Baltimore, Maryland; and
| | - Yael Yaniv
- Laboratory of Cardiovascular Science, Intramural Research Program, National Institute on Aging, National Institutes of Health, Baltimore, Maryland; and
| | - Edward G Lakatta
- Laboratory of Cardiovascular Science, Intramural Research Program, National Institute on Aging, National Institutes of Health, Baltimore, Maryland; and
| |
Collapse
|
97
|
Relationship of muscle sympathetic nerve activity to insulin sensitivity. Clin Auton Res 2014; 24:77-85. [PMID: 24577625 DOI: 10.1007/s10286-014-0235-0] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2013] [Accepted: 02/11/2014] [Indexed: 02/08/2023]
Abstract
PURPOSE An association between insulin resistance and activation of the sympathetic nervous system has been reported in previous studies. However, potential interactions between insulin sensitivity and sympathetic neural mechanisms in healthy people remain poorly understood. We conducted a study to determine the relationship between sympathetic activity and insulin resistance in young, healthy humans. METHODS Thirty-seven healthy adults (18-35 years, BMI <28 kg m(-2)) were studied. Resting muscle sympathetic nerve activity (MSNA) was measured with microneurography and insulin sensitivity of glucose and free fatty acid metabolism was measured during a hyperinsulinemic-euglycemic clamp with two levels of insulin. RESULTS During lower doses of insulin, we found a small association between lower insulin sensitivity and higher MSNA (P < 0.05) but age was a cofactor in this relationship. Overall, we found no difference in insulin sensitivity between groups of low and high MSNA, but when women were analyzed separately, insulin sensitivity was lower in the high MSNA group compared with the low MSNA group of women. CONCLUSIONS These data suggest that MSNA and insulin sensitivity are only weakly associated with young healthy individuals and that age and sex may be important modifiers of this relationship.
Collapse
|
98
|
Nannapaneni S, Ramar K. Periodic limb movements during sleep and their effect on the cardiovascular system: is there a final answer? Sleep Med 2014; 15:379-84. [PMID: 24656911 DOI: 10.1016/j.sleep.2013.12.014] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/11/2013] [Revised: 12/04/2013] [Accepted: 12/11/2013] [Indexed: 10/25/2022]
Abstract
Periodic limb movements during sleep (PLMS) is a sleep-related movement disorder characterized by repetitive limb movements during sleep, seen predominantly in the legs but also occasionally involving the arms. These movements may be associated with arousals that can lead to increases in sympathetic tone, resulting in tachycardia and elevated systolic blood pressure. Chronic sustained tachycardia and elevated systolic blood pressure are known to be associated with the development of arrhythmias, hypertension, left ventricular hypertrophy, and congestive heart failure. However, the data are not entirely clear on whether untreated PLMS is associated with these cardiovascular risks. This review examines the current evidence on whether PLMS has any effect on the cardiovascular system.
Collapse
Affiliation(s)
- Srikant Nannapaneni
- Division of Pulmonary and Critical Care Medicine, Mayo Clinic, Rochester, MN, USA.
| | - Kannan Ramar
- Center for Sleep Medicine, Mayo Clinic, Rochester, MN, USA
| |
Collapse
|
99
|
Ferrara N, Komici K, Corbi G, Pagano G, Furgi G, Rengo C, Femminella GD, Leosco D, Bonaduce D. β-adrenergic receptor responsiveness in aging heart and clinical implications. Front Physiol 2014; 4:396. [PMID: 24409150 PMCID: PMC3885807 DOI: 10.3389/fphys.2013.00396] [Citation(s) in RCA: 93] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2013] [Accepted: 12/17/2013] [Indexed: 12/24/2022] Open
Abstract
Elderly healthy individuals have a reduced exercise tolerance and a decreased left ventricle inotropic reserve related to increased vascular afterload, arterial-ventricular load mismatching, physical deconditioning and impaired autonomic regulation (the so called "β-adrenergic desensitization"). Adrenergic responsiveness is altered with aging and the age-related changes are limited to the β-adrenergic receptor density reduction and to the β-adrenoceptor-G-protein(s)-adenylyl cyclase system abnormalities, while the type and level of abnormalities change with species and tissues. Epidemiological studies have shown an high incidence and prevalence of heart failure in the elderly and a great body of evidence correlate the changes of β-adrenergic system with heart failure pathogenesis. In particular it is well known that: (a) levels of cathecolamines are directly correlated with mortality and functional status in heart failure, (b) β1-adrenergic receptor subtype is down-regulated in heart failure, (c) heart failure-dependent cardiac adrenergic responsiveness reduction is related to changes in G proteins activity. In this review we focus on the cardiovascular β-adrenergic changes involvement in the aging process and on similarities and differences between aging heart and heart failure.
Collapse
Affiliation(s)
- Nicola Ferrara
- Department of Translational Medical Sciences, University of Naples “Federico II”Naples, Italy
- “S. Maugeri” Foundation, Scientific Institute of Telese Terme (BN), IRCCSTelese Terme, Italy
| | - Klara Komici
- Department of Translational Medical Sciences, University of Naples “Federico II”Naples, Italy
| | - Graziamaria Corbi
- Department of Medicine and Health Sciences, University of MoliseCampobasso, Italy
| | - Gennaro Pagano
- Department of Translational Medical Sciences, University of Naples “Federico II”Naples, Italy
| | - Giuseppe Furgi
- “S. Maugeri” Foundation, Scientific Institute of Telese Terme (BN), IRCCSTelese Terme, Italy
| | - Carlo Rengo
- Department of Translational Medical Sciences, University of Naples “Federico II”Naples, Italy
- “S. Maugeri” Foundation, Scientific Institute of Telese Terme (BN), IRCCSTelese Terme, Italy
| | - Grazia D. Femminella
- Department of Translational Medical Sciences, University of Naples “Federico II”Naples, Italy
| | - Dario Leosco
- Department of Translational Medical Sciences, University of Naples “Federico II”Naples, Italy
| | - Domenico Bonaduce
- Department of Translational Medical Sciences, University of Naples “Federico II”Naples, Italy
| |
Collapse
|
100
|
Maranon RO, Lima R, Mathbout M, do Carmo JM, Hall JE, Roman RJ, Reckelhoff JF. Postmenopausal hypertension: role of the sympathetic nervous system in an animal model. Am J Physiol Regul Integr Comp Physiol 2013; 306:R248-56. [PMID: 24381180 DOI: 10.1152/ajpregu.00490.2013] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
In postmenopausal women the mechanisms responsible for hypertension have not been completely elucidated, and there are no gender-specific guidelines for women despite studies showing that blood pressure is not as well controlled to goal in women as in men. In the present study we tested the hypotheses that the sympathetic nervous system and the renal sympathetic nerves contribute to hypertension in aging female rats, that sympathetic activation may be mediated by the melanocortin 3/4 receptor (MC3/4R), and that MC3/4R activation may be due to increases in leptin. α-1, β-1,2-Adrenergic blockade reduced blood pressure in both young (3-4 mo) and old (18-19 mo) female spontaneously hypertensive rats (SHR). Renal denervation attenuated the hypertension more in old females than young females. MC3/4R antagonism with SHU-9119 given intracerebroventricularly had no effect on blood pressure in either young or old females but significantly reduced blood pressure in old males. Plasma leptin levels were similar in old male and female SHR and in old versus young females. These data suggest that the hypertension in old female SHR is in part due to activation of the sympathetic nervous system, that the renal nerves contribute to the hypertension, and that the mechanism responsible for sympathetic activation in old females is independent of the MC3/4R.
Collapse
|