1
|
Nardone M, Foster M, O'Brien MW, Coovadia Y, Xie S, Usselman CW, Kimmerly DS, Taylor CE, Millar PJ. Sympathetic determinants of resting blood pressure in males and females. Am J Physiol Heart Circ Physiol 2024; 326:H612-H622. [PMID: 38214907 DOI: 10.1152/ajpheart.00497.2023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/11/2023] [Revised: 01/08/2024] [Accepted: 01/08/2024] [Indexed: 01/13/2024]
Abstract
Discharge of postganglionic muscle sympathetic nerve activity (MSNA) is related poorly to blood pressure (BP) in adults. Whether neural measurements beyond the prevailing level of MSNA can account for interindividual differences in BP remains unclear. The current study sought to evaluate the relative contributions of sympathetic-BP transduction and sympathetic baroreflex gain on resting BP in young adults. Data were analyzed from 191 (77 females) young adults (18-39 years) who underwent continuous measurement of beat-to-beat BP (finger photoplethysmography), heart rate (electrocardiography), and fibular nerve MSNA (microneurography). Linear regression analyses were computed to determine associations between sympathetic-BP transduction (signal-averaging) or sympathetic baroreflex gain (threshold technique) and resting BP, before and after controlling for age, body mass index, and MSNA burst frequency. K-mean clustering was used to explore sympathetic phenotypes of BP control and consequential influence on resting BP. Sympathetic-BP transduction was unrelated to BP in males or females (both R2 < 0.01; P > 0.67). Sympathetic baroreflex gain was positively associated with BP in males (R2 = 0.09, P < 0.01), but not in females (R2 < 0.01; P = 0.80), before and after controlling for age, body mass index, and MSNA burst frequency. K-means clustering identified a subset of participants with average resting MSNA, yet lower sympathetic-BP transduction and lower sympathetic baroreflex gain. This distinct subgroup presented with elevated BP in males (P < 0.02), but not in females (P = 0.10). Sympathetic-BP transduction is unrelated to resting BP, while the association between sympathetic baroreflex gain and resting BP in males reveals important sex differences in the sympathetic determination of resting BP.NEW & NOTEWORTHY In a sample of 191 normotensive young adults, we confirm that resting muscle sympathetic nerve activity is a poor predictor of resting blood pressure and now demonstrate that sympathetic baroreflex gain is associated with resting blood pressure in males but not females. In contrast, signal-averaged measures of sympathetic-blood pressure transduction are unrelated to resting blood pressure. These findings highlight sex differences in the neural regulation of blood pressure.
Collapse
Affiliation(s)
- Massimo Nardone
- Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, Ontario, Canada
| | - Monique Foster
- School of Health Sciences, Western Sydney University, Sydney, New South Wales, Australia
| | - Myles W O'Brien
- Division of Kinesiology, School of Health and Human Performance, Faculty of Health, Dalhousie University, Halifax, Nova Scotia, Canada
- School of Physiotherapy (Faculty of Health) and Division of Geriatric Medicine (Faculty of Medicine), Dalhousie University, Halifax, Nova Scotia, Canada
| | - Yasmine Coovadia
- Cardiovascular Health and Autonomic Regulation Laboratory, Department of Kinesiology and Physical Education, McGill University, Montreal, Quebec, Canada
| | - Shengkun Xie
- Global Management Studies, Ted Rogers School of Management, Toronto Metropolitan University, Toronto, Ontario, Canada
| | - Charlotte W Usselman
- Cardiovascular Health and Autonomic Regulation Laboratory, Department of Kinesiology and Physical Education, McGill University, Montreal, Quebec, Canada
| | - Derek S Kimmerly
- Division of Kinesiology, School of Health and Human Performance, Faculty of Health, Dalhousie University, Halifax, Nova Scotia, Canada
| | - Chloe E Taylor
- School of Health Sciences, Western Sydney University, Sydney, New South Wales, Australia
| | - Philip J Millar
- Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, Ontario, Canada
| |
Collapse
|
2
|
Gimhani D, Shanks J, Pachen M, Chang JWH, Ramchandra R. Sympathetic transduction of cardiac sympathetic nerve activity in healthy, conscious sheep. J Physiol 2024; 602:619-632. [PMID: 38329227 DOI: 10.1113/jp285079] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2023] [Accepted: 01/16/2024] [Indexed: 02/09/2024] Open
Abstract
Sympathetic transduction is the study of how impulses of sympathetic nerve activity (SNA) affect end-organ function. Recently, the transduction of resting bursts of muscle SNA (MSNA) has been investigated and shown to have a role in the maintenance of blood pressure through changes in vascular tone in humans. In the present study, we investigate whether directly recorded resting cardiac SNA (CSNA) regulates heart rate (HR), coronary blood flow (CoBF), coronary vascular conductance (CVC), cardiac output (CO) and mean arterial pressure. Instrumentation was undertaken to record CSNA and relevant vascular variables in conscious sheep. Recordings were performed at baseline, as well as after the infusion of a β-adrenoceptor blocker (propranolol) to determine the role of β-adrenergic signalling in sympathetic transduction in the heart. The results show that after every burst of CSNA, there was a significant effect of time on HR (n = 10, ∆: +2.1 ± 1.4 beats min-1 , P = 0.002) and CO (n = 8, ∆: +100 ± 150 mL min-1 , P = 0.002) was elevated, followed by an increase in CoBF (n = 9, ∆: +0.76 mL min-1 , P = 0.001) and CVC (n = 8, ∆: +0.0038 mL min-1 mmHg-1 , P = 0.0028). The changes in HR were graded depending on the size and pattern of CSNA bursts. The HR response was significantly attenuated after the infusion of propranolol. Our study is the first to explore resting sympathetic transduction in the heart, suggesting that CSNA can dynamically change HR mediated by an action on β-adrenoceptors. KEY POINTS: Sympathetic transduction is the study of how impulses of sympathetic nerve activity (SNA) affect end-organ function. Previous studies have examined sympathetic transduction primarily in the skeletal muscle and shown that bursts of muscle SNA alter blood flow to skeletal muscle and mean arterial pressure, although this has not been examined in the heart. We investigated sympathetic transduction in the heart and show that, in the conscious condition, the size of bursts of SNA to the heart can result in incremental increases in heart rate and coronary blood flow mediated by β-adrenoceptors. The pattern of bursts of SNA to the heart also resulted in incremental increases in heart rate mediated by β-adrenoceptors. This is the first study to explore the transduction of bursts of SNA to the heart.
Collapse
Affiliation(s)
- Dilsha Gimhani
- Department of Physiology, University of Auckland, Auckland, New Zealand
| | - Julia Shanks
- Department of Physiology, University of Auckland, Auckland, New Zealand
| | - Mridula Pachen
- Department of Physiology, University of Auckland, Auckland, New Zealand
| | - Joshua W-H Chang
- Department of Physiology, University of Auckland, Auckland, New Zealand
| | - Rohit Ramchandra
- Department of Physiology, University of Auckland, Auckland, New Zealand
| |
Collapse
|
3
|
Tharpe MA, Linder BA, Babcock MC, Watso JC, Pollin KU, Hutchison ZJ, Barnett AM, Culver MN, Kavazis AN, Brian MS, Robinson AT. Adjusting for muscle strength and body size attenuates sex differences in the exercise pressor reflex in young adults. Am J Physiol Heart Circ Physiol 2023; 325:H1418-H1429. [PMID: 37861651 PMCID: PMC10907031 DOI: 10.1152/ajpheart.00151.2023] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/16/2023] [Revised: 10/03/2023] [Accepted: 10/14/2023] [Indexed: 10/21/2023]
Abstract
Females typically exhibit lower blood pressure (BP) during exercise than males. However, recent findings indicate that adjusting for maximal strength attenuates sex differences in BP during isometric handgrip (HG) exercise and postexercise ischemia (PEI; metaboreflex isolation). In addition, body size is associated with HG strength but its contribution to sex differences in exercising BP is less appreciated. Therefore, the purpose of this study was to determine whether adjusting for strength and body size would attenuate sex differences in BP during HG and PEI. We obtained beat-to-beat BP in 110 participants (36 females, 74 males) who completed 2 min of isometric HG exercise at 40% of their maximal voluntary contraction followed by 3 min of PEI. In a subset (11 females, 17 males), we collected muscle sympathetic nerve activity (MSNA). Statistical analyses included independent t tests and mixed models (sex × time) with covariate adjustment for 40% HG force, height2, and body surface area. Females exhibited a lower absolute 40% HG force than male participants (Ps < 0.001). Females exhibited lower Δsystolic, Δdiastolic, and Δmean BPs during HG and PEI than males (e.g., PEI, Δsystolic BP, 15 ± 11 vs. 23 ± 14 mmHg; P = 0.004). After covariate adjustment, sex differences in BP responses were attenuated. There were no sex differences in MSNA. In a smaller strength-matched cohort, there was no sex × time interactions for BP responses (e.g., PEI systolic BP, P = 0.539; diastolic BP, P = 0.758). Our data indicate that sex differences in exercising BP responses are attenuated after adjusting for muscle strength and body size.NEW & NOTEWORTHY When compared with young males, females typically exhibit lower blood pressure (BP) during exercise. Adjusting for maximal strength attenuates sex differences in BP during isometric handgrip (HG) exercise and postexercise ischemia (PEI), but the contribution of body size is unknown. Novel findings include adjustments for muscle strength and body size attenuate sex differences in BP reactivity during exercise and PEI, and sex differences in body size contribute to HG strength differences.
Collapse
Affiliation(s)
- McKenna A Tharpe
- Neurovascular Physiology Laboratory, School of Kinesiology, Auburn University, Auburn, Alabama, United States
| | - Braxton A Linder
- Neurovascular Physiology Laboratory, School of Kinesiology, Auburn University, Auburn, Alabama, United States
| | - Matthew C Babcock
- Department of Kinesiology and Applied Physiology, University of Delaware, Newark, Delaware, United States
- Division of Geriatric Medicine, Anschutz Medical Campus, University of Colorado Denver, Aurora, Colorado, United States
| | - Joseph C Watso
- Department of Kinesiology and Applied Physiology, University of Delaware, Newark, Delaware, United States
- Department of Nutrition and Integrative Physiology, Florida State University, Tallahassee, Florida, United States
| | - Kamila U Pollin
- Department of Kinesiology and Applied Physiology, University of Delaware, Newark, Delaware, United States
- War-Related Injury and Illness Study Center, Veterans Affairs Medical Center, Washington, District of Columbia, United States
| | - Zach J Hutchison
- Neurovascular Physiology Laboratory, School of Kinesiology, Auburn University, Auburn, Alabama, United States
| | - Alex M Barnett
- Neurovascular Physiology Laboratory, School of Kinesiology, Auburn University, Auburn, Alabama, United States
| | - Meral N Culver
- Neurovascular Physiology Laboratory, School of Kinesiology, Auburn University, Auburn, Alabama, United States
| | - Andreas N Kavazis
- Neurovascular Physiology Laboratory, School of Kinesiology, Auburn University, Auburn, Alabama, United States
| | - Michael S Brian
- Department of Kinesiology and Applied Physiology, University of Delaware, Newark, Delaware, United States
- Department of Kinesiology, University of New Hampshire, Durham, New Hampshire, United States
| | - Austin T Robinson
- Neurovascular Physiology Laboratory, School of Kinesiology, Auburn University, Auburn, Alabama, United States
- Department of Kinesiology and Applied Physiology, University of Delaware, Newark, Delaware, United States
| |
Collapse
|
4
|
Stephens BY, Young BE, Nandadeva D, Skow RJ, Greaney JL, Brothers RM, Fadel PJ. Sympathetic transduction at rest and during cold pressor test in young healthy non-Hispanic Black and White women. Am J Physiol Regul Integr Comp Physiol 2023; 325:R682-R691. [PMID: 37781734 PMCID: PMC11178294 DOI: 10.1152/ajpregu.00073.2023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2023] [Revised: 09/01/2023] [Accepted: 09/20/2023] [Indexed: 10/03/2023]
Abstract
Non-Hispanic Black (BL) individuals have the highest prevalence of hypertension and cardiovascular disease (CVD) compared with all other racial/ethnic groups. Previous work focused on racial disparities in sympathetic control and blood pressure (BP) regulation between young BL and White (WH) adults, have mainly included men. Herein, we hypothesized that BL women would exhibit augmented resting sympathetic vascular transduction and greater sympathetic and BP reactivity to cold pressor test (CPT) compared with WH women. Twenty-eight young healthy women (BL: n = 14, 22 [Formula: see text] 4 yr; WH: n = 14, 22 [Formula: see text] 4 yr) participated. Beat-to-beat BP (Finometer), common femoral artery blood flow (duplex Doppler ultrasound), and muscle sympathetic nerve activity (MSNA; microneurography) were continuously recorded. In a subset (BL n = 10, WH n = 11), MSNA and BP were recorded at rest and during a 2-min CPT. Resting sympathetic vascular transduction was quantified as changes in leg vascular conductance (LVC) and mean arterial pressure (MAP) following spontaneous bursts of MSNA using signal averaging. Sympathetic and BP reactivity were quantified as changes in MSNA and MAP during the last minute of CPT. There were no differences in nadir LVC following resting MSNA bursts between BL (-8.70 ± 3.43%) and WH women (-7.30 ± 3.74%; P = 0.394). Likewise, peak increases in MAP following MSNA bursts were not different between groups (BL: +2.80 ± 1.42 mmHg; vs. WH: +2.99 ± 1.15 mmHg; P = 0.683). During CPT, increases in MSNA and MAP were also not different between BL and WH women, with similar transduction estimates between groups (ΔMAP/ΔMSNA; P = 0.182). These findings indicate that young, healthy BL women do not exhibit exaggerated sympathetic transduction or augmented sympathetic and BP reactivity during CPT.NEW & NOTEWORTHY This study was the first to comprehensively investigate sympathetic vascular transduction and sympathetic and BP reactivity during a cold pressor test in young, healthy BL women. We demonstrated that young BL women do not exhibit exaggerated resting sympathetic vascular transduction and do not have augmented sympathetic or BP reactivity during cold stress compared with their WH counterparts. Collectively, these findings suggest that alterations in sympathetic transduction and reactivity are not apparent in young, healthy BL women.
Collapse
Affiliation(s)
- Brandi Y Stephens
- Department of Kinesiology, University of Texas at Arlington, Arlington, Texas, United States
| | - Benjamin E Young
- Department of Kinesiology, University of Texas at Arlington, Arlington, Texas, United States
- Department of Applied Clinical Research, University of Texas Southwestern Medical Center, Dallas, Texas, United States
| | - Damsara Nandadeva
- Department of Kinesiology, University of Texas at Arlington, Arlington, Texas, United States
- Department of Physiology, Faculty of Medicine, University of Peradeniya, Peradeniya, Sri Lanka
| | - Rachel J Skow
- Department of Kinesiology, University of Texas at Arlington, Arlington, Texas, United States
| | - Jody L Greaney
- Department of Kinesiology, University of Texas at Arlington, Arlington, Texas, United States
| | - R Matthew Brothers
- Department of Kinesiology, University of Texas at Arlington, Arlington, Texas, United States
| | - Paul J Fadel
- Department of Kinesiology, University of Texas at Arlington, Arlington, Texas, United States
| |
Collapse
|
5
|
D'Souza AW, Hissen SL, Manabe K, Takeda R, Washio T, Coombs GB, Sanchez B, Fu Q, Shoemaker JK. Age- and sex-related differences in sympathetic vascular transduction and neurohemodynamic balance in humans. Am J Physiol Heart Circ Physiol 2023; 325:H917-H932. [PMID: 37594483 DOI: 10.1152/ajpheart.00301.2023] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/23/2023] [Revised: 08/14/2023] [Accepted: 08/15/2023] [Indexed: 08/19/2023]
Abstract
Bursts of muscle sympathetic nerve activity (MSNA) and the ensuing vasoconstriction are pivotal determinants of beat-by-beat blood pressure regulation. Although age and sex impact blood pressure regulation, how these factors affect the central and peripheral arcs of the baroreflex remains unclear. In 27 young [25 (SD 3) yr] males (YM; n = 14) and females (YF; n = 13) and 23 older [71 (SD 5) yr] males (OM; n = 11) and females (OF; n = 12), femoral artery blood flow, blood pressure, and MSNA were recorded for 10 min of supine rest. Sympathetic baroreflex sensitivity (i.e., central arc) was quantified as the relationship between diastolic blood pressure and MSNA burst incidence. Signal averaging was used to determine sympathetic vascular transduction into leg vascular conductance (LVC) for 12 cardiac cycles following MSNA bursts (i.e., peripheral arc). Older adults demonstrated attenuated sympathetic transduction into LVC (both P < 0.001) following MSNA bursts, and smaller increases in sympathetic transduction as a function of MSNA burst size and firing pattern compared with young adults (range, P = 0.004-0.032). YM (r2 = 0.36; P = 0.032) and OM (r2 = 0.51; P = 0.014) exhibited an inverse relationship between the central and peripheral arcs of the baroreflex, whereas females did not (YF, r2 = 0.03, P = 0.621; OF, r2 = 0.06, P = 0.445). MSNA burst incidence was inversely related to sympathetic transduction in YM and OF (range, P = 0.03-0.046) but not in YF or OM (range, P = 0.360-0.603). These data indicate that age is associated with attenuated sympathetic vascular transduction, whereas age- and sex-specific changes are present in the relationship between the central and peripheral arcs of the baroreflex regulation of blood pressure.NEW & NOTEWORTHY Sympathetic vascular transduction is attenuated in older compared with young adults, regardless of biological sex. Males, but not females (regardless of age), demonstrate an inverse relationship between central (sympathetic baroreflex sensitivity) and peripheral (sympathetic vascular transduction) components of the baroreflex arc. Young males and older females exhibit an inverse relationship between resting sympathetic outflow and sympathetic vascular transduction. Our results indicate that age and sex exert independent and interactive effects on sympathetic vascular transduction and sympathetic neurohemodynamic balance in humans.
Collapse
Affiliation(s)
- Andrew W D'Souza
- Neurovascular Research Laboratory, School of Kinesiology, Western University, London, Ontario, Canada
| | - Sarah L Hissen
- Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital Dallas, Dallas, Texas, United States
- Internal Medicine, The University of Texas Southwestern Medical Center, Dallas, Texas, United States
| | - Kazumasa Manabe
- Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital Dallas, Dallas, Texas, United States
- Internal Medicine, The University of Texas Southwestern Medical Center, Dallas, Texas, United States
| | - Ryosuke Takeda
- Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital Dallas, Dallas, Texas, United States
- Internal Medicine, The University of Texas Southwestern Medical Center, Dallas, Texas, United States
- Laboratory of Neuromuscular Biomechanics, School of Health and Sport Sciences, Chukyo University, Toyota, Japan
| | - Takuro Washio
- Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital Dallas, Dallas, Texas, United States
- Internal Medicine, The University of Texas Southwestern Medical Center, Dallas, Texas, United States
| | - Geoff B Coombs
- Neurovascular Research Laboratory, School of Kinesiology, Western University, London, Ontario, Canada
| | - Belinda Sanchez
- Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital Dallas, Dallas, Texas, United States
- Internal Medicine, The University of Texas Southwestern Medical Center, Dallas, Texas, United States
| | - Qi Fu
- Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital Dallas, Dallas, Texas, United States
- Internal Medicine, The University of Texas Southwestern Medical Center, Dallas, Texas, United States
| | - J Kevin Shoemaker
- Neurovascular Research Laboratory, School of Kinesiology, Western University, London, Ontario, Canada
- Department of Physiology and Pharmacology, Western University, London, Ontario, Canada
| |
Collapse
|
6
|
Wan HY, Bunsawat K, Amann M. Autonomic cardiovascular control during exercise. Am J Physiol Heart Circ Physiol 2023; 325:H675-H686. [PMID: 37505474 PMCID: PMC10659323 DOI: 10.1152/ajpheart.00303.2023] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/24/2023] [Revised: 07/11/2023] [Accepted: 07/23/2023] [Indexed: 07/29/2023]
Abstract
The cardiovascular response to exercise is largely determined by neurocirculatory control mechanisms that help to raise blood pressure and modulate vascular resistance which, in concert with regional vasodilatory mechanisms, promote blood flow to active muscle and organs. These neurocirculatory control mechanisms include a feedforward mechanism, known as central command, and three feedback mechanisms, namely, 1) the baroreflex, 2) the exercise pressor reflex, and 3) the arterial chemoreflex. The hemodynamic consequences of these control mechanisms result from their influence on the autonomic nervous system and subsequent alterations in cardiac output and vascular resistance. Although stimulation of the baroreflex inhibits sympathetic outflow and facilitates parasympathetic activity, central command, the exercise pressor reflex, and the arterial chemoreflex facilitate sympathetic activation and inhibit parasympathetic drive. Despite considerable understanding of the cardiovascular consequences of each of these mechanisms in isolation, the circulatory impact of their interaction, which occurs when various control systems are simultaneously activated (e.g., during exercise at altitude), has only recently been recognized. Although aging and cardiovascular disease (e.g., heart failure, hypertension) have both been recognized to alter the hemodynamic consequences of these regulatory systems, this review is limited to provide a brief overview on the action and interaction of neurocirculatory control mechanisms in health.
Collapse
Affiliation(s)
- Hsuan-Yu Wan
- Department of Anesthesiology, University of Utah, Salt Lake City, Utah, United States
| | - Kanokwan Bunsawat
- Geriatric Research, Education, and Clinical Center, George E. Wahlen Department of Veterans Affairs Medical Center, Salt Lake City, Utah, United States
- Division of Geriatrics, Department of Internal Medicine, University of Utah, Salt Lake City, Utah, United States
| | - Markus Amann
- Department of Anesthesiology, University of Utah, Salt Lake City, Utah, United States
- Geriatric Research, Education, and Clinical Center, George E. Wahlen Department of Veterans Affairs Medical Center, Salt Lake City, Utah, United States
- Division of Geriatrics, Department of Internal Medicine, University of Utah, Salt Lake City, Utah, United States
| |
Collapse
|
7
|
O'Brien MW, Nardone M, Foster M, Coovadia Y, Usselman CW, Taylor CE, Millar PJ, Kimmerly DS. Higher sympathetic transduction is independently associated with greater very short-term diastolic blood pressure variability in young healthy males and females. Clin Auton Res 2023; 33:529-532. [PMID: 37243873 DOI: 10.1007/s10286-023-00949-7] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2023] [Accepted: 04/29/2023] [Indexed: 05/29/2023]
Affiliation(s)
- Myles W O'Brien
- School of Physiotherapy (Faculty of Health) and Department of Medicine (Faculty of Medicine), Dalhousie University, Halifax, NS, Canada.
- Geriatric Medicine Research, Dalhousie University and Nova Scotia Health, Halifax, NS, Canada.
| | - Massimo Nardone
- Human Cardiovascular Physiology Laboratory, Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, ON, Canada
| | - Monique Foster
- School of Health Sciences, Western Sydney University, Sydney, NSW, Australia
| | - Yasmine Coovadia
- Cardiovascular Health and Autonomic Regulation Laboratory, McGill University, Montreal, QC, Canada
| | - Charlotte W Usselman
- Cardiovascular Health and Autonomic Regulation Laboratory, McGill University, Montreal, QC, Canada
| | - Chloe E Taylor
- School of Health Sciences, Western Sydney University, Sydney, NSW, Australia
| | - Philip J Millar
- Human Cardiovascular Physiology Laboratory, Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, ON, Canada
| | - Derek S Kimmerly
- Division of Kinesiology, School of Health and Human Performance, Faculty of Health, Dalhousie University, Halifax, NS, Canada
| |
Collapse
|
8
|
Watso JC, Fancher IS, Gomez DH, Hutchison ZJ, Gutiérrez OM, Robinson AT. The damaging duo: Obesity and excess dietary salt contribute to hypertension and cardiovascular disease. Obes Rev 2023; 24:e13589. [PMID: 37336641 PMCID: PMC10406397 DOI: 10.1111/obr.13589] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/04/2023] [Revised: 05/08/2023] [Accepted: 05/24/2023] [Indexed: 06/21/2023]
Abstract
Hypertension is a primary risk factor for cardiovascular disease. Cardiovascular disease is the leading cause of death among adults worldwide. In this review, we focus on two of the most critical public health challenges that contribute to hypertension-obesity and excess dietary sodium from salt (i.e., sodium chloride). While the independent effects of these factors have been studied extensively, the interplay of obesity and excess salt overconsumption is not well understood. Here, we discuss both the independent and combined effects of excess obesity and dietary salt given their contributions to vascular dysfunction, autonomic cardiovascular dysregulation, kidney dysfunction, and insulin resistance. We discuss the role of ultra-processed foods-accounting for nearly 60% of energy intake in America-as a major contributor to both obesity and salt overconsumption. We highlight the influence of obesity on elevated blood pressure in the presence of a high-salt diet (i.e., salt sensitivity). Throughout the review, we highlight critical gaps in knowledge that should be filled to inform us of the prevention, management, treatment, and mitigation strategies for addressing these public health challenges.
Collapse
Affiliation(s)
- Joseph C. Watso
- Department of Nutrition and Integrative Physiology, Florida State University, Tallahassee, Florida, USA
| | - Ibra S. Fancher
- Department of Kinesiology and Applied Physiology, University of Delaware, Newark, Delaware, USA
| | - Dulce H. Gomez
- School of Kinesiology, Auburn University, Auburn, Alabama, USA
- Division of Endocrinology, Diabetes, and Hypertension, Brigham and Women’s Hospital, Boston, Massachusetts, USA
| | | | - Orlando M. Gutiérrez
- Division of Nephrology, School of Medicine, University of Alabama at Birmingham, Birmingham, Alabama, USA
| | | |
Collapse
|
9
|
Holwerda SW, Gangwish ME, Luehrs RE, Nuckols VR, Thyfault JP, Miles JM, Pierce GL. Concomitantly higher resting arterial blood pressure and transduction of sympathetic neural activity in human obesity without hypertension. J Hypertens 2023; 41:326-335. [PMID: 36583358 PMCID: PMC9812452 DOI: 10.1097/hjh.0000000000003335] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
OBJECTIVE Central (abdominal) obesity is associated with elevated adrenergic activity and arterial blood pressure (BP). Therefore, we tested the hypothesis that transduction of spontaneous muscle sympathetic nerve activity (MSNA) to BP, that is, sympathetic transduction, is augmented in abdominal obesity (increased waist circumference) and positively related to prevailing BP. METHODS Young/middle-aged obese (32 ± 7 years; BMI: 36 ± 5 kg/m2, n = 14) and nonobese (29 ± 10 years; BMI: 23 ± 4 kg/m2, n = 14) without hypertension (24-h ambulatory average BP < 130/80 mmHg) were included. MSNA (microneurography) and beat-to-beat BP (finger cuff) were measured continuously and the increase in mean arterial pressure (MAP) during 15 cardiac cycles following MSNA bursts of different patterns (single, multiples) and amplitude (quartiles) was signal-averaged over a 10 min baseline period. RESULTS MSNA burst frequency was not significantly higher in obese vs. nonobese (21 ± 3 vs. 17 ± 3 bursts/min, P = 0.34). However, resting supine BP was significantly higher in obese compared with nonobese (systolic: 127 ± 3 vs. 114 ± 3; diastolic: 76 ± 2 vs. 64 ± 1 mmHg, both P < 0.01). Importantly, obese showed greater increases in MAP following multiple MSNA bursts (P = 0.02) and MSNA bursts of higher amplitude (P = 0.02), but not single MSNA bursts (P = 0.24), compared with nonobese when adjusting for MSNA burst frequency. The increase in MAP following higher amplitude bursts among all participants was associated with higher resting supine systolic (R = 0.48; P = 0.01) and diastolic (R = 0.48; P = 0.01) BP when controlling for MSNA burst frequency, but not when also controlling for waist circumference (P > 0.05). In contrast, sympathetic transduction was not correlated with 24-h ambulatory average BP. CONCLUSION Sympathetic transduction to BP is augmented in abdominal obesity and positively related to higher resting supine BP but not 24-h ambulatory average BP.
Collapse
Affiliation(s)
- Seth W. Holwerda
- Department of Anesthesiology, University of Kansas Medical Center, Kansas City, Kansas
- Department of Cell Biology and Physiology, University of Kansas Medical Center, Kansas City, Kansas
- KU Diabetes Institute, University of Kansas Medical Center, Kansas City, Kansas
- Kansas Center for Metabolism and Obesity, University of Kansas Medical Center, Kansas City, Kansas
| | - Megan E. Gangwish
- Department of Anesthesiology, University of Kansas Medical Center, Kansas City, Kansas
| | - Rachel E. Luehrs
- Department of Kinesiology, North Central College, Naperville, Illinois
| | - Virginia R. Nuckols
- Department of Health and Human Physiology, University of Iowa, Iowa City, Iowa
| | - John P. Thyfault
- Department of Cell Biology and Physiology, University of Kansas Medical Center, Kansas City, Kansas
- KU Diabetes Institute, University of Kansas Medical Center, Kansas City, Kansas
- Kansas Center for Metabolism and Obesity, University of Kansas Medical Center, Kansas City, Kansas
| | - John M. Miles
- Department of Internal Medicine-Endocrinology and Metabolism, University of Kansas Medical Center, Kansas City, Kansas
| | - Gary L. Pierce
- Department of Health and Human Physiology, University of Iowa, Iowa City, Iowa
- Department of Internal Medicine, University of Iowa, Iowa City, Iowa
| |
Collapse
|
10
|
Shafer BM, Nardone M, Incognito AV, Vermeulen TD, Teixeira AL, Millar PJ, Sheel AW, West C, Ayas N, Foster GE. Acute hypoxia elicits lasting reductions in the sympathetic action potential transduction of arterial blood pressure in males. J Physiol 2023; 601:669-687. [PMID: 36542455 DOI: 10.1113/jp283979] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2022] [Accepted: 12/16/2022] [Indexed: 12/24/2022] Open
Abstract
Post-hypoxia sympathoexcitation does not elicit corresponding changes in vascular tone, suggesting diminished sympathetic signalling. Blunted sympathetic transduction following acute hypoxia, however, has not been confirmed and the effects of hypoxia on the sympathetic transduction of mean arterial pressure (MAP) as a function of action potential (AP) activity is unknown. We hypothesized that MAP changes would be blunted during acute hypoxia but restored in recovery and asynchronous APs would elicit smaller MAP changes than synchronous APs. Seven healthy males (age: 24 (3) years; BMI: 25 (3) kg/m2 ) underwent 20 min isocapnic hypoxia (PET O2 : 47 (2) mmHg) and 30 min recovery. Multi-unit microneurography (muscle sympathetic nerve activity; MSNA) and continuous wavelet transform with matched mother wavelet was used to detect sympathetic APs during baseline, hypoxia, early (first 7 min) and late (last 7 min) recovery. AP groups were classified as synchronous APs, asynchronous APs (occurring outside an MSNA burst) and no AP activity. Sympathetic transduction of MAP was quantified using signal-averaging, with ΔMAP tracked following AP group cardiac cycles. Following synchronous APs, ΔMAP was reduced in hypoxia (+1.8 (0.9) mmHg) and early recovery (+1.5 (0.7) mmHg) compared with baseline (+3.1 (2.2) mmHg). AP group-by-condition interactions show that at rest asynchronous APs attenuate MAP reductions compared with no AP activity (-0.4 (1.1) vs. -2.2 (1.2) mmHg, respectively), with no difference between AP groups in hypoxia, early or late recovery. Sympathetic transduction of MAP is blunted in hypoxia and early recovery. At rest, asynchronous sympathetic APs contribute to neural regulation of MAP by attenuating nadir pressure responses. KEY POINTS: Acute isocapnic hypoxia elicits lasting sympathoexcitation that does not correspond to parallel changes in vascular tone, suggesting blunted sympathetic transduction. Signal-averaging techniques track the magnitude and temporal cardiovascular responses following integrated muscle sympathetic nerve activity (MSNA) burst and non-burst cardiac cycles. However, this does not fully characterize the effects of sympathetic action potential (AP) activity on blood pressure control. We show that hypoxia blunts the sympathetic transduction of mean arterial pressure (MAP) following synchronous APs that form integrated MSNA bursts and that sympathetic transduction of MAP remains attenuated into early recovery. At rest, asynchronous APs attenuate the reduction in MAP compared with cardiac cycles following no AP activity, thus asynchronous sympathetic APs appear to contribute to the neural regulation of blood pressure. The results advance our understanding of sympathetic transduction of arterial pressure during and following exposure to acute isocapnic hypoxia in humans.
Collapse
Affiliation(s)
- Brooke M Shafer
- Centre for Heart, Lung, and Vascular Health, School of Health and Exercise Sciences, University of British Columbia, Kelowna, Canada
| | - Massimo Nardone
- Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, Canada
| | - Anthony V Incognito
- Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, Canada
| | - Tyler D Vermeulen
- Centre for Heart, Lung, and Vascular Health, School of Health and Exercise Sciences, University of British Columbia, Kelowna, Canada
| | - André L Teixeira
- Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, Canada
| | - Philip J Millar
- Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, Canada
| | - A William Sheel
- School of Kinesiology, University of British Columbia, Vancouver, Canada
| | - Chris West
- Faculty of Medicine, University of British Columbia, Kelowna, Canada.,International Collaboration on Repair Discoveries, University of British Columbia, Vancouver, Canada.,Centre for Chronic Disease Prevention and Management, University of British Columbia, Kelowna, Canada.,Department of Cellular and Physiological Sciences, Faculty of Medicine, University of British Columbia, Vancouver, Canada
| | - Najib Ayas
- Department of Medicine, Faculty of Medicine, University of British Columbia, Vancouver, Canada
| | - Glen E Foster
- Centre for Heart, Lung, and Vascular Health, School of Health and Exercise Sciences, University of British Columbia, Kelowna, Canada
| |
Collapse
|
11
|
Effects of age and sex on vasomotor activity and baroreflex sensitivity during the sleep-wake cycle. Sci Rep 2022; 12:22424. [PMID: 36575245 PMCID: PMC9794808 DOI: 10.1038/s41598-022-26440-3] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2022] [Accepted: 12/14/2022] [Indexed: 12/28/2022] Open
Abstract
Cardiovascular function is related to age, sex, and state of consciousness. We hypothesized that cardiovagal baroreflex sensitivity (BRS) demonstrates different patterns in both sexes before and after 50 years of age and that these patterns are associated with patterned changes during the sleep-wake cycle. We recruited 67 healthy participants (aged 20-79 years; 41 women) and divided them into four age groups: 20-29, 30-49, 50-69, and 70-79 years. All the participants underwent polysomnography and blood pressure measurements. For each participant, we used the average of the arterial pressure variability, heart rate variability (HRV), and BRS parameters during the sleep-wake stages. BRS and HRV parameters were significantly negatively correlated with age. The BRS indexes were significantly lower in the participants aged ≥ 50 years than in those aged < 50 years, and these age-related declines were more apparent during non-rapid eye movement sleep than during wakefulness. Only BRS demonstrated a significantly negative correlation with age in participants ≥ 50 years old. Women exhibited a stronger association than men between BRS and age and an earlier decline in BRS. Changes in BRS varied with age, sex, and consciousness state, each demonstrating a specific pattern. The age of 50 years appeared to be a crucial turning point for sexual dimorphism in BRS. Baroreflex modulation of the cardiovascular system during sleep sensitively delineated the age- and sex-dependent BRS patterns, highlighting the clinical importance of our results. Our findings may aid in screening for neurocardiac abnormalities in apparently healthy individuals.
Collapse
|
12
|
Stute NL, Szeghy RE, Mackowski NS. All is fair in menstruation, POTS, and… war? J Physiol 2022; 600:4055-4057. [PMID: 35913261 DOI: 10.1113/jp283297] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Affiliation(s)
- Nina L Stute
- Signature Tracking for Optimized Nutrition and Training Lab, Air Force Research Labs, Wright Patterson Air Force Base, Dayton, OH
| | - Rachel E Szeghy
- Exercise Respiratory and Physiology Lab, Department of Health & Exercise Science, Appalachian State University, Boone, NC
| | - Nicholas S Mackowski
- Signature Tracking for Optimized Nutrition and Training Lab, Air Force Research Labs, Wright Patterson Air Force Base, Dayton, OH
| |
Collapse
|
13
|
Wan HY, Weavil JC, Thurston TS, Georgescu VP, Morrissey CK, Amann M. On the hemodynamic consequence of the chemoreflex and muscle mechanoreflex interaction in women and men: two tales, one story. J Physiol 2022; 600:3671-3688. [PMID: 35710103 PMCID: PMC9378608 DOI: 10.1113/jp283051] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2022] [Accepted: 06/14/2022] [Indexed: 11/08/2022] Open
Abstract
KEY POINTS The cardiovascular response resulting from the activation of the muscle mechanoreflex (MMR), or the chemoreflex (CR), was previously shown to be different between women and men; this study focused on the hemodynamic consequence of the interaction of these two sympathoexcitatory reflexes. MMR and CR were activated by passive leg movement and exposure to hypoxia (O2 -CR), or hypercapnia (CO2 -CR), respectively. Individual and interactive reflex effects on central and peripheral hemodynamics were quantified in healthy young women and men. In men, the MMR:O2 -CR and MMR:CO2 -CR interactions restricted peripheral hemodynamics, likely by potentiating sympathetic vasoconstriction. In women, the MMR:O2 -CR interaction facilitated central and peripheral hemodynamics, likely by potentiating sympathetic vasodilation; however, the MMR:CO2 -CR interaction was simply additive for the central and peripheral hemodynamics. The interaction between the MMR and the CR exerts a profound influence on the autonomic control of cardiovascular function in humans, with the hemodynamic consequences differing between women and men. ABSTRACT The cardiovascular response resulting from the individual activation of the muscle mechanoreflex (MMR), or the chemoreflex (CR), is different between men and women. Whether the hemodynamic consequence resulting from the interaction of these sympathoexcitatory reflexes is also sex-dependent remains unknown. MMR and CR were activated by passive leg movement (LM) and exposure to hypoxia (O2 -CR), or hypercapnia (CO2 -CR), respectively. Twelve young men and 12 young women completed two experimental protocols: 1) resting in normoxia (PET O2 : ∼83mmHg, PET CO2 : ∼34mmHg), normocapnic hypoxia (PET O2 : ∼48mmHg, PET CO2 : ∼34mmHg), and hyperoxic hypercapnia (PET O2 : ∼524mmHg, PET CO2 : ∼44mmHg); 2) LM under the same gas conditions. During the MMR:O2 -CR coactivation, in men, the observed blood pressure (MAP) and cardiac output (CO) were not different (additive effect), while the observed leg blood flow (LBF) and vascular conductance (LVC) were significantly lower (hypo-additive), compared with the sum of the responses elicited by each reflex alone. In women, the observed MAP was not different (additive) while the observed CO, LBF, and LVC were significantly greater (hyper-additive), compared with the summated responses. During the MMR:CO2 -CR coactivation, in men, the observed MAP, CO, and LBF were not different (additive), while the observed LVC was significantly lower (hypo-additive), compared with the summated responses. In women, the observed MAP was significantly higher (hyper-additive), while the observed CO, LBF, and LVC were not different (additive), compared with the summated responses. The interaction of the MMR and CR has a pronounced influence on the autonomic cardiovascular control, with the hemodynamic consequences differing between men and women. Abstract figure legend The chemoreflex and the muscle mechanoreflex are sympathoexcitatory mechanisms which, via neural feedback to the cardiovascular centre in the medulla, mediate neurocirculatory responses during physical activity. The interaction of the peripheral chemoreflex and muscle mechanoreflex potentiates vasoconstriction in men, but potentiates vasodilatation in women (left panel). The interaction of the central chemoreflex and muscle mechanoreflex also potentiates vasoconstriction in men, whereas the reflex interaction is simply additive for the vasomotor tone in women (right panel). This article is protected by copyright. All rights reserved.
Collapse
Affiliation(s)
- Hsuan-Yu Wan
- Department of Anesthesiology, University of Utah, Salt Lake City, UT
| | - Joshua C Weavil
- Geriatric Research, Education, and Clinical Center, VAMC, Salt Lake City, UT
| | - Taylor S Thurston
- Department of Nutrition and Integrative Physiology, University of Utah, Salt Lake City, UT
| | - Vincent P Georgescu
- Department of Nutrition and Integrative Physiology, University of Utah, Salt Lake City, UT
| | | | - Markus Amann
- Department of Anesthesiology, University of Utah, Salt Lake City, UT.,Geriatric Research, Education, and Clinical Center, VAMC, Salt Lake City, UT.,Department of Nutrition and Integrative Physiology, University of Utah, Salt Lake City, UT
| |
Collapse
|
14
|
Sayegh ALC, Fan JL, Vianna LC, Dawes M, Paton JFR, Fisher JP. Sex-differences in the sympathetic neurocirculatory responses to chemoreflex activation. J Physiol 2022; 600:2669-2689. [PMID: 35482235 PMCID: PMC9324851 DOI: 10.1113/jp282327] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2021] [Accepted: 04/25/2022] [Indexed: 11/08/2022] Open
Abstract
Abstract The purpose of this study was to determine whether there are sex differences in the cardiorespiratory and sympathetic neurocirculatory responses to central, peripheral, and combined central and peripheral chemoreflex activation. Ten women (29 ± 6 years, 22.8 ± 2.4 kg/m2: mean ± SD) and 10 men (30 ± 7 years, 24.8 ± 3.2 kg/m2) undertook randomized 5 min breathing trials of: room air (eucapnia), isocapnic hypoxia (10% oxygen (O2); peripheral chemoreflex activation), hypercapnic hyperoxia (7% carbon dioxide (CO2), 50% O2; central chemoreflex activation) and hypercapnic hypoxia (7% CO2, 10% O2; central and peripheral chemoreflex activation). Control trials of isocapnic hyperoxia (peripheral chemoreflex inhibition) and hypocapnic hyperoxia (central and peripheral chemoreflex inhibition) were also included. Muscle sympathetic nerve activity (MSNA; microneurography), mean arterial pressure (MAP; finger photoplethysmography) and minute ventilation (V˙E; pneumotachometer) were measured. Total MSNA (P = 1.000 and P = 0.616), MAP (P = 0.265) and V˙E (P = 0.587 and P = 0.472) were not different in men and women during eucapnia and during isocapnic hypoxia. Women exhibited attenuated increases in V˙E during hypercapnic hyperoxia (27.3 ± 6.3 vs. 39.5 ± 7.5 l/min, P < 0.0001) and hypercapnic hypoxia (40.9 ± 9.1 vs. 53.8 ± 13.3 l/min, P < 0.0001) compared with men. However, total MSNA responses were augmented in women (hypercapnic hyperoxia 378 ± 215 vs. 258 ± 107%, P = 0.017; hypercapnic hypoxia 607 ± 290 vs. 362 ± 268%, P < 0.0001). No sex differences in total MSNA, MAP or V˙E were observed during isocapnic hyperoxia and hypocapnic hyperoxia. Our results indicate that young women have augmented sympathetic responses to central chemoreflex activation, which explains the augmented MSNA response to combined central and peripheral chemoreflex activation. Key points Sex differences in the control of breathing have been well studied, but whether there are differences in the sympathetic neurocirculatory responses to chemoreflex activation between healthy women and men is incompletely understood. We observed that, compared with young men, young women displayed augmented increases in muscle sympathetic nerve activity during both hypercapnic hyperoxia (central chemoreflex activation) and hypercapnic hypoxia (central and peripheral chemoreflex activation) but had attenuated increases in minute ventilation. In contrast, no sex differences were found in either muscle sympathetic nerve activity or minute ventilation responses to isocapnic hypoxia (peripheral chemoreceptor stimulation). Young women have blunted ventilator, but augmented sympathetic responses, to central (hypercapnic hyperoxia) and combined central and peripheral chemoreflex activation (hypercapnic hypoxia), compared with young men. The possible causative association between the reduced ventilation and heightened sympathetic responses in young women awaits validation.
Collapse
Affiliation(s)
- Ana Luiza C Sayegh
- Manaaki Manawa - The Centre for Heart Research, Department of Physiology, Faculty of Medical & Health Sciences, University of Auckland, New Zealand
| | - Jui-Lin Fan
- Manaaki Manawa - The Centre for Heart Research, Department of Physiology, Faculty of Medical & Health Sciences, University of Auckland, New Zealand
| | - Lauro C Vianna
- NeuroV̇ASQ̇ - Integrative Physiology Laboratory, Faculty of Physical Education, University of Brasília, Brasília, DF, Brazil
| | - Mathew Dawes
- Department of Medicine, Faculty of Medical & Health Sciences, University of Auckland, New Zealand
| | - Julian F R Paton
- Manaaki Manawa - The Centre for Heart Research, Department of Physiology, Faculty of Medical & Health Sciences, University of Auckland, New Zealand
| | - James P Fisher
- Manaaki Manawa - The Centre for Heart Research, Department of Physiology, Faculty of Medical & Health Sciences, University of Auckland, New Zealand
| |
Collapse
|
15
|
Nardone M, Katerberg C, Teixeira AL, Lee JB, Bommarito JC, Millar PJ. Sympathetic transduction of blood pressure during graded lower body negative pressure in young healthy adults. Am J Physiol Regul Integr Comp Physiol 2022; 322:R620-R628. [DOI: 10.1152/ajpregu.00034.2022] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Sympathetic transduction of blood pressure (BP) is correlated negatively with resting muscle sympathetic nerve activity (MSNA) in cross-sectional data, but the acute effects of increasing MSNA are unclear. Sixteen (4 females) healthy adults (26±3 years) underwent continuous measurement of heart rate, BP, and MSNA at rest and during graded lower body negative pressure (LBNP) at -10, -20, and -30mmHg. Sympathetic transduction of BP was quantified in the time (signal averaging) and frequency (MSNA-BP gain) domains. The proportion of MSNA bursts firing within each tertile of BP were calculated. As expected, LBNP increased MSNA burst frequency (P<0.01) and burst amplitude (P<0.02), though the proportions of MSNA bursts firing across each BP tertile remained stable (all P>0.44). The MSNA-diastolic BP low frequency transfer function gain (P=0.25) was unchanged during LBNP; the spectral coherence was increased (P=0.03). Signal-averaged sympathetic transduction of diastolic BP was unchanged (from 2.1±1.0 at rest to 2.4±1.5, 2.2±1.3, and 2.3±1.4mmHg; P=0.43) during LBNP, but diastolic BP responses following non-burst cardiac cycles progressively decreased (from -0.8±0.4 at rest to -1.0±0.6, -1.2±0.6, and -1.6±0.9mmHg; P<0.01). As a result, the difference between MSNA burst and non-bursts diastolic BP responses was increased (from 2.9±1.4 at rest to 3.4±1.9, 3.4±1.9, and 3.9±2.1mmHg; P<0.01). In conclusion, acute increases in MSNA using LBNP did not alter traditional signal-averaged or frequency-domain measures of sympathetic transduction of BP or the proportion of MSNA bursts firing at different BP levels. The factors that determine changes in the firing of MSNA bursts relative to oscillations in BP require further investigation.
Collapse
Affiliation(s)
- Massimo Nardone
- Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, Ontario, Canada
| | - Carlin Katerberg
- Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, Ontario, Canada
| | - André L. Teixeira
- Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, Ontario, Canada
| | - Jordan B. Lee
- Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, Ontario, Canada
| | - Julian C. Bommarito
- Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, Ontario, Canada
| | - Philip J. Millar
- Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, Ontario, Canada
- Toronto General Research Institute, Toronto General Hospital, Toronto, Ontario, Canada
| |
Collapse
|
16
|
Coovadia Y, Adler TE, Martin-Arrowsmith PW, Usselman CW. Sex differences in sympathetic neuro-vascular and neuro-hemodynamic relationships during the cold pressor test. Am J Physiol Regul Integr Comp Physiol 2022; 322:R411-R420. [PMID: 35293259 DOI: 10.1152/ajpregu.00223.2021] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Muscle sympathetic nerve activity (MSNA) affects vascular resistance differently in women and men. However, whether this sex difference persists during pronounced increases in MSNA remains unclear. Therefore, the purpose of this study was to examine sex differences in neurovascular transduction during cold pressor test (CPT)-mediated sympatho-excitation. Integrated peroneal MSNA (microneurography) was measured at rest and during a 3-minute CPT in young healthy women (n=11) and men (n=10). Mean arterial pressure (MAP) was measured beat-by-beat (Finometer) and superficial femoral artery blood flow was measured using duplex ultrasound. Femoral vascular resistance (FVR) was quantified as MAP/femoral blood flow (mmHg/mL/min). Baseline MSNA was similar between women and men (14±9 vs 15±9 bursts/100hb, respectively; P=0.83), whereas MAP was lower (86±7 vs 92±4 mmHg; P=0.047), and FVR was greater in women than men (0.54±0.16 vs 0.36±0.15 mmHg/mL/min; P=0.02). CPT-induced increases in MSNA were similar between the sexes (+19±11 vs +26±14 bursts/100hb; P=0.26) while increases in MAP (+7±3 vs +10±3mmHg; P=0.03) and FVR (+3.2±18.6 vs +26.8±12.8%; P<0.01) were smaller in women than men. Within men, CPT- induced increases in MSNA predicted increases in MAP (R2=0.51, P=0.02) and FVR (R2=0.49, P=0.02). However, MSNA did not predict MAP (R2=0.11, P=0.35) or FVR (R2=0.07, P=0.46) in women. Our findings demonstrate that men experience robust CPT-induced MAP responses that are driven by both neuro-vascular (MSNA-FVR) and neuro-hemodynamic (MSNA-MAP) coupling. These relationships were not observed in women, indicating that even during pronounced increases in sympathetic outflow, MSNA is not predictive of vascular nor blood pressure outcomes in young healthy women.
Collapse
Affiliation(s)
- Yasmine Coovadia
- Cardiovascular Health and Autonomic Regulation Laboratory, McGill University, Montreal, Quebec, Canada
| | - Tessa E Adler
- Cardiovascular Health and Autonomic Regulation Laboratory, McGill University, Montreal, Quebec, Canada
| | - Patrick W Martin-Arrowsmith
- Exercise Metabolism and 6 Nutrition Research Lab, Department of Kinesiology and Physical Education, McGill University, Montreal, Quebec, Canada
| | - Charlotte W Usselman
- Cardiovascular Health and Autonomic Regulation Laboratory, McGill University, Montreal, Quebec, Canada.,McGill Research Centre for Physical Activity and Health, McGill University, Montreal, Quebec, Canada
| |
Collapse
|
17
|
Thuptimdang W, Shah P, Khaleel M, Sunwoo J, Veluswamy S, Kato RM, Coates TD, Khoo MCK. Vasoconstriction Response to Mental Stress in Sickle Cell Disease: The Role of the Cardiac and Vascular Baroreflexes. Front Physiol 2021; 12:698209. [PMID: 34803725 PMCID: PMC8599360 DOI: 10.3389/fphys.2021.698209] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2021] [Accepted: 10/15/2021] [Indexed: 11/13/2022] Open
Abstract
Recent studies have shown that individuals with sickle cell disease (SCD) exhibit greater vasoconstriction responses to physical autonomic stressors, such as heat pain and cold pain than normal individuals, but this is not the case for mental stress (MTS). We sought to determine whether this anomalous finding for MTS is related to inter-group differences in baseline cardiac and vascular autonomic function. Fifteen subjects with SCD and 15 healthy volunteers participated in three MTS tasks: N-back, Stroop, and pain anticipation (PA). R-R interval (RRI), arterial blood pressure and finger photoplethysmogram (PPG) were continuously monitored before and during these MTS tasks. The magnitude of vasoconstriction was quantified using change in PPG amplitude (PPGa) from the baseline period. To represent basal autonomic function, we assessed both cardiac and vascular arms of the baroreflex during the baseline period. Cardiac baroreflex sensitivity (BRSc) was estimated by applying both the "sequence" and "spectral" techniques to beat-to-beat measurements of systolic blood pressure and RRIs. The vascular baroreflex sensitivity (BRSv) was quantified using the same approaches, modified for application to beat-to-beat diastolic blood pressure and PPGa measurements. Baseline BRSc was not different between SCD and non-SCD subjects, was not correlated with BRSv, and was not associated with the vasoconstriction responses to MTS tasks. BRSv in both groups was correlated with mean PPGa, and since both baseline PPGa and BRSv were lower in SCD, these results suggested that the SCD subjects were in a basal state of higher sympathetically mediated vascular tone. In both groups, baseline BRSv was positively correlated with the vasoconstriction responses to N-back, Stroop, and PA. After adjusting for differences in BRSv within and between groups, we found no difference in the vasoconstriction responses to all three mental tasks between SCD and non-SCD subjects. The implications of these findings are significant in subjects with SCD since vasoconstriction reduces microvascular flow and prolongs capillary transit time, increasing the likelihood for vaso-occlusive crisis (VOC) to be triggered by exposure to stressful events.
Collapse
Affiliation(s)
- Wanwara Thuptimdang
- Department of Biomedical Engineering, University of Southern California, Los Angeles, CA, United States
| | - Payal Shah
- Hematology Section, Children's Center for Cancer, Blood Disease and Bone Marrow Transplantation, Children's Hospital Los Angeles, University of Southern California Keck School of Medicine, Los Angeles, CA, United States
| | - Maha Khaleel
- Hematology Section, Children's Center for Cancer, Blood Disease and Bone Marrow Transplantation, Children's Hospital Los Angeles, University of Southern California Keck School of Medicine, Los Angeles, CA, United States
| | - John Sunwoo
- Department of Biomedical Engineering, University of Southern California, Los Angeles, CA, United States
| | - Saranya Veluswamy
- Hematology Section, Children's Center for Cancer, Blood Disease and Bone Marrow Transplantation, Children's Hospital Los Angeles, University of Southern California Keck School of Medicine, Los Angeles, CA, United States
| | - Roberta M Kato
- Division of Pulmonology, Children's Hospital Los Angeles, University of Southern California Keck School of Medicine, Los Angeles, CA, United States
| | - Thomas D Coates
- Hematology Section, Children's Center for Cancer, Blood Disease and Bone Marrow Transplantation, Children's Hospital Los Angeles, University of Southern California Keck School of Medicine, Los Angeles, CA, United States
| | - Michael C K Khoo
- Department of Biomedical Engineering, University of Southern California, Los Angeles, CA, United States
| |
Collapse
|
18
|
Lower sympathetic transduction of blood pressure in uncontrolled hypertensives: physiological adaptation, methodological limitation, or both? J Hum Hypertens 2021; 36:423-424. [PMID: 34795392 DOI: 10.1038/s41371-021-00638-w] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2021] [Revised: 11/04/2021] [Accepted: 11/09/2021] [Indexed: 11/08/2022]
|
19
|
Nardone M, Katerberg C, Incognito AV, Teixeira AL, Vianna LC, Millar PJ. Blood pressure oscillations impact signal-averaged sympathetic transduction of blood pressure: implications for the association with resting sympathetic outflow. Am J Physiol Heart Circ Physiol 2021; 321:H798-H806. [PMID: 34506224 DOI: 10.1152/ajpheart.00422.2021] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Signal-averaged sympathetic transduction of blood pressure (BP) is inversely related to resting muscle sympathetic nerve activity (MSNA) burst frequency in healthy cohorts. Whether this represents a physiological compensatory adaptation or a methodological limitation, remains unclear. The current analysis aimed to determine the contribution of methodological limitations by evaluating the dependency of MSNA transduction at different levels of absolute BP. Thirty-six healthy participants (27 ± 7 yr, 9 females) underwent resting measures of beat-to-beat heart rate, BP, and muscle sympathetic nerve activity (MSNA). Tertiles of mean arterial pressure (MAP) were computed for each participant to identify cardiac cycles occurring below, around, and above the MAP operating pressure (OP). Changes in hemodynamic variables were computed across 15 cardiac cycles within each MAP tertile to quantify sympathetic transduction. MAP increased irrespective of sympathetic activity when initiated below the OP, but with MSNA bursts provoking larger rises (3.0 ± 0.9 vs. 2.1 ± 0.7 mmHg; P < 0.01). MAP decreased irrespective of sympathetic activity when initiated above the OP, but with MSNA bursts attenuating the drop (-1.3 ± 1.1 vs. -3.1 ± 1.2 mmHg; P < 0.01). In participants with low versus high resting MSNA (12 ± 4 vs. 32 ± 10 bursts/min), sympathetic transduction of MAP was not different when initiated by bursts below (3.2 ± 1.0 vs. 2.8 ± 0.9 mmHg; P = 0.26) and above the OP (-1.0 ± 1.3 vs. -1.6 ± 0.8 mmHg; P = 0.08); however, low resting MSNA was associated with a smaller proportion of MSNA bursts firing above the OP (15 ± 5 vs. 22 ± 5%; P < 0.01). The present analyses demonstrate that the signal-averaging technique for calculating sympathetic transduction of BP is influenced by the timing of an MSNA burst relative to cyclic oscillations in BP.NEW & NOTEWORTHY The current signal-averaging technique for calculating sympathetic transduction of blood pressure does not consider the arterial pressure at which each muscle sympathetic burst occurs. A burst firing when mean arterial pressure is above the operating pressure was associated with a decrease in blood pressure. Thus, individuals with higher muscle sympathetic nerve activity demonstrate a reduced sympathetic transduction owing to the weighted contribution of more sympathetic bursts at higher levels of arterial pressure.
Collapse
Affiliation(s)
- Massimo Nardone
- Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, Ontario, Canada
| | - Carlin Katerberg
- Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, Ontario, Canada
| | - Anthony V Incognito
- Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, Ontario, Canada
| | - André L Teixeira
- Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, Ontario, Canada
| | - Lauro C Vianna
- NeuroV̇ASQ̇-Integrative Physiology Laboratory, Faculty of Physical Education, University of Brasilia, Brasilia, Federal District, Brazil
| | - Philip J Millar
- Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, Ontario, Canada.,Toronto General Research Institute, Toronto General Hospital, Toronto, Ontario, Canada
| |
Collapse
|
20
|
Nardone M, Incognito AV, Kathia MM, Omazic LJ, Lee JB, Teixeira AL, Xie S, Vianna LC, Millar PJ. Signal-averaged resting sympathetic transduction of blood pressure: is it time to account for prevailing muscle sympathetic burst frequency? Am J Physiol Regul Integr Comp Physiol 2021; 321:R484-R494. [PMID: 34287075 DOI: 10.1152/ajpregu.00131.2021] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Calculating the blood pressure (BP) response to a burst of muscle sympathetic nerve activity (MSNA), termed sympathetic transduction, may be influenced by an individual's resting burst frequency. We examined the relationships between sympathetic transduction and MSNA in 107 healthy males and females and developed a normalized sympathetic transduction metric to incorporate resting MSNA. Burst-triggered signal-averaging was used to calculate the peak diastolic BP response following each MSNA burst (sympathetic transduction of BP) and following incorporation of MSNA burst cluster patterns and amplitudes (sympathetic transduction slope). MSNA burst frequency was negatively correlated with sympathetic transduction of BP (r=-0.42; P<0.01) and the sympathetic transduction slope (r=-0.66; P<0.01), independent of sex. MSNA burst amplitude was unrelated to sympathetic transduction of BP in males (r=0.04; P=0.78), but positively correlated in females (r=0.44; P<0.01) and with the sympathetic transduction slope in all participants (r=0.42; P<0.01). To control for MSNA, the linear regression slope of the log-log relationship between sympathetic transduction and MSNA burst frequency was used as a correction exponent. In sub-analysis of males (38±10 vs. 14±4bursts/min) and females (28±5 vs. 12±4bursts/min) with high vs. low MSNA, sympathetic transduction of BP and sympathetic transduction slope were lower in participants with high MSNA (all P<0.05). In contrast, normalized sympathetic transduction of BP and normalized sympathetic transduction slope were similar in males and females with high vs. low MSNA (all P>0.22). We propose that incorporating MSNA burst frequency into the calculation of sympathetic transduction will allow comparisons between participants with varying levels of resting MSNA.
Collapse
Affiliation(s)
- Massimo Nardone
- Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, Ontario, Canada
| | - Anthony V Incognito
- Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, Ontario, Canada
| | | | - Lucas Joseph Omazic
- Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, Ontario, Canada
| | - Jordan B Lee
- Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, Ontario, Canada
| | - André L Teixeira
- Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, Ontario, Canada
| | - Shengkun Xie
- Global Management Studies, Ted Rogers School of Management, Ryerson University, Toronto, Ontario, Canada
| | - Lauro C Vianna
- NeuroVASQ - Integrative Physiology Laboratory, Faculty of Physical Education, University of Brasilia, Brazil
| | - Philip J Millar
- Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, Ontario, Canada.,Toronto General Research Institute, Toronto General Hospital, Toronto, Ontario, Canada
| |
Collapse
|
21
|
O'Brien MW, Ramsay DJ, O'Neill CD, Petterson JL, Dogra S, Mekary S, Kimmerly DS. Aerobic fitness is inversely associated with neurohemodynamic transduction and blood pressure variability in older adults. GeroScience 2021; 43:2737-2748. [PMID: 34056679 DOI: 10.1007/s11357-021-00389-z] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2021] [Accepted: 05/20/2021] [Indexed: 10/21/2022] Open
Abstract
Higher aerobic fitness is independently associated with better cardiovascular health in older adults. The transduction of muscle sympathetic nerve activity (MSNA) into mean arterial pressure (MAP) responses provides important insight regarding beat-by-beat neural circulatory control. Aerobic fitness is negatively associated with peak MAP responses to spontaneous MSNA in young males. Whether this relationship exists in older adults is known. We tested the hypothesis that aerobic fitness was inversely related to sympathetic neurohemodynamic transduction and blood pressure variability (BPV) in older adults. Relative peak oxygen consumption (V̇O2peak, indirect calorimetry) was assessed in 22 older adults (13 males, 65 ± 5 years, 36.3 ± 11.5 ml/kg/min). Peroneal MSNA (microneurography) and arterial pressure (finger photoplethysmography) were recorded during ≥ 10-min of rest. BPV was assessed using the average real variability index. MAP was tracked for 12 cardiac cycles following heartbeats associated with MSNA bursts (i.e., peak ΔMAP). Peak ΔMAP responses (0.9 ± 0.6 mmHg) were negatively associated (all, P < 0.04) with resting burst frequency (30 ± 11 bursts/min; R = -0.47) and burst incidence (54 ± 22 bursts/100 heartbeats; R = -0.51), but positively associated with BPV (ρ = 0.47). V̇O2peak was inversely related to the pressor responses to spontaneous bursts (R = -0.47, P = 0.03) and BPV (ρ = -0.54, P = 0.01), positively related to burst incidence (R = 0.42, P = 0.05), but unrelated to MSNA burst frequency (P = 0.20). The V̇O2peak-BPV relationship remained after controlling for burst frequency, peak ΔMAP, age, and sex. Lower V̇O2peak was associated with augmented neurohemodynamic transduction and BPV in older adults. These negative hemodynamic outcomes highlight the importance of higher aerobic fitness with ageing for optimal cardiovascular health.
Collapse
Affiliation(s)
- Myles W O'Brien
- Autonomic Cardiovascular Control and Exercise Laboratory, Division of Kinesiology, School of Health and Human Performance, Faculty of Health, Dalhousie University, 6230 South Street, Halifax, NS, B3H 4R2, Canada
| | - Diane J Ramsay
- Autonomic Cardiovascular Control and Exercise Laboratory, Division of Kinesiology, School of Health and Human Performance, Faculty of Health, Dalhousie University, 6230 South Street, Halifax, NS, B3H 4R2, Canada
| | - Carley D O'Neill
- Exercise Physiology and Cardiovascular Health Lab, University of Ottawa Heart Institute, Ottawa, ON, Canada.,School of Kinesiology, Acadia University, Wolfville, NS, Canada
| | - Jennifer L Petterson
- Autonomic Cardiovascular Control and Exercise Laboratory, Division of Kinesiology, School of Health and Human Performance, Faculty of Health, Dalhousie University, 6230 South Street, Halifax, NS, B3H 4R2, Canada
| | - Shilpa Dogra
- School of Kinesiology, Acadia University, Wolfville, NS, Canada.,Health and Human Performance Laboratory, Faculty of Health Sciences, University of Ontario Institute of Technology, Oshawa, ON, Canada
| | - Said Mekary
- School of Kinesiology, Acadia University, Wolfville, NS, Canada
| | - Derek S Kimmerly
- Autonomic Cardiovascular Control and Exercise Laboratory, Division of Kinesiology, School of Health and Human Performance, Faculty of Health, Dalhousie University, 6230 South Street, Halifax, NS, B3H 4R2, Canada.
| |
Collapse
|
22
|
Hockin BCD, Tang EZ, Lloyd MG, Claydon VE. Forearm vascular resistance responses to the Valsalva maneuver in healthy young and older adults. Clin Auton Res 2021; 31:737-753. [PMID: 34014418 DOI: 10.1007/s10286-021-00810-9] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2020] [Accepted: 05/03/2021] [Indexed: 11/25/2022]
Abstract
PURPOSE Effective end-organ peripheral vascular resistance responses are critical to blood pressure control while upright, and prevention of syncope (fainting). The Valsalva maneuver (VM) induces blood pressure decreases that evoke baroreflex-mediated vasoconstriction. We characterized beat-to-beat forearm vascular resistance (FVR) responses to the VM in healthy adults, evaluated the impact of age and sex on these responses, and investigated their association with orthostatic tolerance (OT; susceptibility to syncope). We hypothesized that individuals with smaller FVR responses would be more susceptible to syncope. METHODS Healthy young (N = 36; 19 women; age 25.4 ± 4.6 years) and older (N = 21; 12 women; age 62.4 ± 9.6 years) adults performed a supine 40 mmHg, 20 s VM. Graded 60° head-up-tilt with combined lower body negative pressure continued to presyncope was used to determine OT. Non-invasive beat-to-beat blood pressure and heart rate (finger plethysmography) were recorded continuously. FVR was calculated as mean arterial pressure (MAP) divided by brachial blood flow velocity (Doppler ultrasound) relative to baseline. RESULTS The VM produces a distinctive FVR pattern that peaks (+137.1 ± 11.6%) in phase 2B (17.5 ± 0.3 s) as the baroreflex responds to low-pressure perturbations. This response increased with age overall (p < 0.001) and within male (p = 0.030) and female subgroups (p < 0.001). Maximum FVR during the VM was significantly correlated with maximal tilt FVR (r = 0.364; p = 0.0153) and with OT when expressed relative to the MAP decrease in phase 2A (Max FVR (%)/MAP2A-1; r = 0.337; p = 0.0206). CONCLUSION This is the first characterization of FVR responses to the VM. The VM elicits large baroreflex-mediated increases in FVR; small FVR responses to the VM may indicate susceptibility to syncope.
Collapse
Affiliation(s)
- Brooke C D Hockin
- Department of Biomedical Physiology and Kinesiology, Simon Fraser University, Burnaby, BC, V5A 1S6, Canada.,International Collaboration On Repair and Discoveries (ICORD), University of British Columbia, Vancouver, BC, Canada
| | - Eileen Z Tang
- Department of Biomedical Physiology and Kinesiology, Simon Fraser University, Burnaby, BC, V5A 1S6, Canada.,International Collaboration On Repair and Discoveries (ICORD), University of British Columbia, Vancouver, BC, Canada
| | - Matthew G Lloyd
- Department of Biomedical Physiology and Kinesiology, Simon Fraser University, Burnaby, BC, V5A 1S6, Canada.,International Collaboration On Repair and Discoveries (ICORD), University of British Columbia, Vancouver, BC, Canada
| | - Victoria E Claydon
- Department of Biomedical Physiology and Kinesiology, Simon Fraser University, Burnaby, BC, V5A 1S6, Canada. .,International Collaboration On Repair and Discoveries (ICORD), University of British Columbia, Vancouver, BC, Canada.
| |
Collapse
|
23
|
O'Brien MW, Petterson JL, Kimmerly DS. An open-source program to analyze spontaneous sympathetic neurohemodynamic transduction. J Neurophysiol 2021; 125:972-976. [PMID: 33596745 DOI: 10.1152/jn.00002.2021] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
The sympathetic nervous system is important for the beat-by-beat regulation of arterial blood pressure and the control of blood flow to various organs. Microneurographic recordings of pulse-synchronous muscle sympathetic nerve activity (MSNA) are used by numerous laboratories worldwide. The transduction of hemodynamic and vascular responses elicited by spontaneous bursts of MSNA provides novel, mechanistic insight into sympathetic neural control of the circulation. Although some of these laboratories have developed in-house software programs to analyze these sympathetic transduction responses, they are not openly available and most require higher level programming skills and/or costly platforms. In the present paper, we present an open-source, Microsoft Excel-based analysis program designed to examine the pressor and/or vascular responses to spontaneous resting bursts of MSNA, including across longer, continuous MSNA burst sequences, as well as following heartbeats not associated with MSNA bursts. An Excel template with embedded formulas is provided. Detailed written and video-recorded instructions are provided to help facilitate the user and promote its implementation among the research community. Open science activities such as the dissemination of analytical programs and instructions may assist other laboratories in their pursuit to answer novel and impactful research questions regarding sympathetic neural control strategies in human health and disease.NEW & NOTEWORTHY The pressor responses to spontaneous bursts of muscle sympathetic nerve activity provide important information regarding sympathetic regulation of the circulation. Many laboratories worldwide quantify sympathetic neurohemodynamic transduction using in-house, customized software requiring high-level programming skills and/or costly computer programs. To overcome these barriers, this study presents a simple, open-source, Microsoft Excel-based analysis program along with video instructions to assist researchers without the necessary resources to quantify sympathetic neurohemodynamic transduction.
Collapse
Affiliation(s)
- Myles W O'Brien
- Autonomic Cardiovascular Control and Exercise Laboratory, Division of Kinesiology, Faculty of Health, School of Health and Human Performance, Dalhousie University, Halifax, Nova Scotia, Canada
| | - Jennifer L Petterson
- Autonomic Cardiovascular Control and Exercise Laboratory, Division of Kinesiology, Faculty of Health, School of Health and Human Performance, Dalhousie University, Halifax, Nova Scotia, Canada
| | - Derek S Kimmerly
- Autonomic Cardiovascular Control and Exercise Laboratory, Division of Kinesiology, Faculty of Health, School of Health and Human Performance, Dalhousie University, Halifax, Nova Scotia, Canada
| |
Collapse
|
24
|
Young BE, Greaney JL, Keller DM, Fadel PJ. Sympathetic transduction in humans: recent advances and methodological considerations. Am J Physiol Heart Circ Physiol 2021; 320:H942-H953. [PMID: 33416453 DOI: 10.1152/ajpheart.00926.2020] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Ever since their origin more than one half-century ago, microneurographic recordings of sympathetic nerve activity have significantly advanced our understanding of the generation and regulation of central sympathetic outflow in human health and disease. For example, it is now appreciated that a myriad of disease states exhibit chronic sympathetic overactivity, a significant predictor of cardiovascular morbidity and mortality. Although microneurographic recordings allow for the direct quantification of sympathetic outflow, they alone do not provide information with respect to the ensuing sympathetically mediated vasoconstriction and blood pressure (BP) response. Therefore, the study of vascular and/or BP responses to sympathetic outflow (i.e., sympathetic transduction) has now emerged as an area of growing interest within the field of neural cardiovascular control in human health and disease. To date, studies have primarily examined sympathetic transduction under two distinct paradigms: when reflexively evoking sympatho-excitation through the induction of a laboratory stressor (i.e., sympathetic transduction during stress) and/or following spontaneous bursts of sympathetic outflow occurring under resting conditions (i.e., sympathetic transduction at rest). The purpose of this brief review is to highlight how our physiological understanding of sympathetic transduction has been advanced by these studies and to evaluate the primary analytical techniques developed to study sympathetic transduction in humans. We also discuss the framework by which the assessment of sympathetic transduction during stress reflects a fundamentally different process relative to sympathetic transduction at rest and why findings from investigations using these different techniques should be interpreted as such and not necessarily be considered one and the same.
Collapse
Affiliation(s)
- Benjamin E Young
- Department of Kinesiology, University of Texas at Arlington, Arlington, Texas
| | - Jody L Greaney
- Department of Kinesiology, University of Texas at Arlington, Arlington, Texas
| | - David M Keller
- Department of Kinesiology, University of Texas at Arlington, Arlington, Texas
| | - Paul J Fadel
- Department of Kinesiology, University of Texas at Arlington, Arlington, Texas
| |
Collapse
|
25
|
Greenlund IM, Smoot CA, Carter JR. Sex differences in blood pressure responsiveness to spontaneous K-complexes during stage II sleep. J Appl Physiol (1985) 2020; 130:491-497. [PMID: 33300855 DOI: 10.1152/japplphysiol.00825.2020] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
K-complexes are a key marker of nonrapid eye movement sleep, specifically during stages II sleep. Recent evidence suggests the heart rate responses to a K-complexes may differ between men and women. The purpose of this study was to compare beat-to-beat blood pressure responses to K-complexes in men and women. We hypothesized that the pressor response following a spontaneous K-complex would be augmented in men compared with women. Ten men [age: 23 ± 2 yr, body mass index (BMI): 28 ± 4 kg/m2] and ten women (age: 23 ± 5 yr, BMI: 25 ± 4 kg/m2) were equipped with overnight finger plethysmography and standard 10-lead polysomnography. Hemodynamic responses to a spontaneous K-complex during stable stage II sleep were quantified for 10 consecutive cardiac cycles, and measurements included systolic arterial pressure (SAP), diastolic arterial pressure (DAP), and heart rate. K-complex elicited greater pressor responses in men when blood pressures were expressed as SAP (cardiac cycle × sex: P = 0.007) and DAP (cardiac cycle × sex: P = 0.004). Heart rate trended to be different between men and women (cardiac cycle × sex: P = 0.078). These findings suggest a divergent pressor response between men and women following a spontaneous K-complex during normal stage II sleep. These findings could contribute to sex-specific differences in cardiovascular risk that exist between men and women.NEW & NOTEWORTHY K-complexes during stage II sleep have been shown to elicit acute increases in blood pressure and heart rate, but the role of sex (i.e., male vs. female) in this response is unclear. In the present study, we demonstrate that the pressor response following spontaneous K-complexes were augmented in men compared to age-matched women. The augmented blood pressure reactivity to spontaneous K-complexes during stage II sleep in men advance the field of cardiovascular sex differences, with implications for nocturnal blood pressure control.
Collapse
Affiliation(s)
- Ian M Greenlund
- Department of Health and Human Development, Montana State University, Bozeman, Montana.,Department of Psychology, Montana State University, Bozeman, Montana.,Department of Kinesiology and Integrative Physiology, Michigan Technological University, Houghton, Michigan
| | - Carl A Smoot
- Department of Kinesiology and Integrative Physiology, Michigan Technological University, Houghton, Michigan
| | - Jason R Carter
- Department of Health and Human Development, Montana State University, Bozeman, Montana.,Department of Psychology, Montana State University, Bozeman, Montana.,Department of Kinesiology and Integrative Physiology, Michigan Technological University, Houghton, Michigan
| |
Collapse
|
26
|
Huang CC, Chung CM, Leu HB, Huang PH, Wu TC, Lin LY, Lin SJ, Pan WH, Chen JW. Sex difference in sympathetic nervous system activity and blood pressure in hypertensive patients. J Clin Hypertens (Greenwich) 2020; 23:137-146. [PMID: 33190416 PMCID: PMC8029801 DOI: 10.1111/jch.14098] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2020] [Revised: 10/18/2020] [Accepted: 10/20/2020] [Indexed: 12/28/2022]
Abstract
Increased sympathetic nervous system (SNS) activity leads to increased risk of cardiovascular morbidity and mortality. This study investigated whether there were sex differences in SNS activity among Chinese patients with hypertension. Ethnic Chinese non‐diabetic hypertensive patients aged 20–50 years were enrolled in Taiwan. A total of 970 hypertensive patients (41.0 ± 7.2 years) completed the study, 664 men and 306 women. They received comprehensive evaluations including office blood pressure (BP) measurement, 24‐h ambulatory BP monitoring, and 24‐h urine sampling assayed for catecholamine excretion. Compared to women, men were younger, had higher body mass index (BMI), office systolic BP (SBP), office diastolic BP (DBP), 24‐h ambulatory BP, and 24‐h urine catecholamine excretion. In men, 24‐h urine total catecholamine levels were correlated with 24‐h SBP (r = 0.103, p = .008) and 24‐h DBP (r = 0.083, p = .033). In women, however, there was no correlation between 24‐h urine total catecholamine levels and 24‐h ambulatory BP. Multivariate linear regression indicated that being male (β = 1.65, 95% confidence interval [CI] 0.01–3.29, p = .048) and 24‐h urine total catecholamine (β = 5.03, 95% CI 0.62–9.44, p = .025) were both independently associated with 24‐h SBP; being male was independently associated with 24‐h DBP (β = 3.55, 95% CI 2.26–4.85, p < .001). In conclusion, Chinese men with hypertension had higher SNS activity than women, and SNS activity was independently associated with 24‐h ambulatory BP in men rather than in women. These findings suggest that different hypertensive treatment strategies should be considered according to patient sex.
Collapse
Affiliation(s)
- Chin-Chou Huang
- Division of Cardiology, Department of Medicine, Taipei Veterans General Hospital, Taipei, Taiwan.,Department of Medical Education, Taipei Veterans General Hospital, Taipei, Taiwan.,Faculty of Medicine, National Yang-Ming University, Taipei, Taiwan.,Institute of Pharmacology, National Yang-Ming University, Taipei, Taiwan.,Cardiovascular Research Center, National Yang-Ming University, Taipei, Taiwan
| | - Chia-Min Chung
- Environment-Omics-Disease Research Centre, China Medical University Hospital, Taichung, Taiwan.,Graduate Institute of Clinical Medical Science, China Medical University, Taichung, Taiwan
| | - Hsin-Bang Leu
- Division of Cardiology, Department of Medicine, Taipei Veterans General Hospital, Taipei, Taiwan.,Faculty of Medicine, National Yang-Ming University, Taipei, Taiwan.,Cardiovascular Research Center, National Yang-Ming University, Taipei, Taiwan.,Healthcare and Management Center, Taipei Veterans General Hospital, Taipei, Taiwan
| | - Po-Hsun Huang
- Division of Cardiology, Department of Medicine, Taipei Veterans General Hospital, Taipei, Taiwan.,Cardiovascular Research Center, National Yang-Ming University, Taipei, Taiwan.,Department of Critical Care Medicine, Taipei Veterans General Hospital, Taipei, Taiwan.,Institute of Clinical Medicine, National Yang-Ming University, Taipei, Taiwan
| | - Tao-Cheng Wu
- Division of Cardiology, Department of Medicine, Taipei Veterans General Hospital, Taipei, Taiwan.,Faculty of Medicine, National Yang-Ming University, Taipei, Taiwan.,Cardiovascular Research Center, National Yang-Ming University, Taipei, Taiwan
| | - Liang-Yu Lin
- Faculty of Medicine, National Yang-Ming University, Taipei, Taiwan.,Cardiovascular Research Center, National Yang-Ming University, Taipei, Taiwan.,Division of Endocrinology and Metabolism, Department of Medicine, Taipei Veterans General Hospital, Taipei, Taiwan
| | - Shing-Jong Lin
- Division of Cardiology, Department of Medicine, Taipei Veterans General Hospital, Taipei, Taiwan.,Cardiovascular Research Center, National Yang-Ming University, Taipei, Taiwan.,Institute of Clinical Medicine, National Yang-Ming University, Taipei, Taiwan.,Taipei Heart Institute, Taipei Medical University, Taipei, Taiwan
| | - Wen-Harn Pan
- Institute of Biomedical Sciences, Academia Sinica, Taipei, Taiwan.,Institute of Epidemiology, School of Public Health, National Taiwan University, Taipei, Taiwan
| | - Jaw-Wen Chen
- Division of Cardiology, Department of Medicine, Taipei Veterans General Hospital, Taipei, Taiwan.,Institute of Pharmacology, National Yang-Ming University, Taipei, Taiwan.,Cardiovascular Research Center, National Yang-Ming University, Taipei, Taiwan.,Healthcare and Management Center, Taipei Veterans General Hospital, Taipei, Taiwan
| |
Collapse
|
27
|
Hong MH, Jin XJ, Yoon JJ, Lee YJ, Oh HC, Lee HS, Kim HY, Kang DG. Antihypertensive Effects of Gynura divaricata (L.) DC in Rats with Renovascular Hypertension. Nutrients 2020; 12:E3321. [PMID: 33138042 PMCID: PMC7692656 DOI: 10.3390/nu12113321] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2020] [Revised: 10/19/2020] [Accepted: 10/22/2020] [Indexed: 12/15/2022] Open
Abstract
Gynura divaricata (L.) DC (Compositae) (GD) could be found in various parts of Asia. It has been used as a traditional medicine to treat diabetes, high blood pressure, and other diseases, but its effects have not yet been scientifically confirmed. Therefore, we aimed at determining whether GD could affect renal function regulation, blood pressure, and the renin-angiotensin-aldosterone system (RAAS). Cardio-renal syndrome (CRS) is a disease caused by the interaction between the kidney and the cardiovascular system, where the acute or chronic dysfunction in one organ might induce acute or chronic dysfunction of the other. This study investigated whether GD could improve cardio-renal mutual in CRS type 4 model animals, two-kidney one-clip (2K1C) renal hypertensive rats. The experiments were performed on the following six experimental groups: control rats (CONT); 2K1C rats (negative control); OMT (Olmetec, 10 mg/kg/day)-treated 2K1C rats (positive control); and 2K1C rats treated with GD extracts in three different doses (50, 100, and 200 mg/kg/day) for three weeks by oral intake. Each group consisted of 10 rats. We measured the systolic blood pressure weekly using the tail-cuff method. Urine was also individually collected from the metabolic cage to investigate the effect of GD on the kidney function, monitoring urine volume, electrolyte, osmotic pressure, and creatinine levels from the collected urine. We observed that kidney weight and urine volume, which would both display typically increased values in non-treated 2K1C animals, significantly decreased following the GD treatment (###p < 0.001 vs. 2K1C). Osmolality and electrolytes were measured in the urine to determine how renal excretory function, which is reduced in 2K1C rats, could be affected. We found that the GD treatment improved renal excretory function. Moreover, using periodic acid-Schiff staining, we confirmed that the GD treatment significantly reduced fibrosis, which is typically increased in 2K1C rats. Thus, we confirmed that the GD treatment improved kidney function in 2K1C rats. Meanwhile, we conducted blood pressure and vascular relaxation studies to determine if the GD treatment could improve cardiovascular function in 2K1C rats. The heart weight percentages of the left atrium and ventricle were significantly lower in GD-treated 2K1C rats than in non-treated 2K1C rats. These results showed that GD treatment reduced cardiac hypertrophy in 2K1C rats. Furthermore, the acetylcholine-, sodium nitroprusside-, and atrial natriuretic peptide-mediated reduction of vasodilation in 2K1C rat aortic rings was also ameliorated by GD treatment (GD 200 mg/kg/day; p < 0.01, p < 0.05, and p < 0.05 vs. 2K1C for vasodilation percentage in case of each compound). The mRNA expression in the 2K1C rat heart tissue showed that the GD treatment reduced brain-type natriuretic peptide and troponin T levels (p < 0.001 and p < 0.001 vs. 2K1C). In conclusion, this study showed that GD improved the cardiovascular and renal dysfunction observed in an innovative hypertension model, highlighting the potential of GD as a therapeutic agent for hypertension. These findings indicate that GD shows beneficial effects against high blood pressure by modulating the RAAS in the cardio-renal syndrome. Thus, it should be considered an effective traditional medicine in hypertension treatment.
Collapse
Affiliation(s)
- Mi Hyeon Hong
- College of Oriental Medicine and Professional Graduate School of Oriental Medicine, Wonkwang University, Iksan, Jeonbuk 54538, Korea; (M.H.H.); (X.J.J.); (J.J.Y.); (Y.J.L.); (H.S.L.)
- Hanbang Cardio-renal Research Center & Professional Graduate School of Oriental Medicine, Wonkwang University, Iksan, Jeonbuk 54538, Korea
| | - Xian Jun Jin
- College of Oriental Medicine and Professional Graduate School of Oriental Medicine, Wonkwang University, Iksan, Jeonbuk 54538, Korea; (M.H.H.); (X.J.J.); (J.J.Y.); (Y.J.L.); (H.S.L.)
| | - Jung Joo Yoon
- College of Oriental Medicine and Professional Graduate School of Oriental Medicine, Wonkwang University, Iksan, Jeonbuk 54538, Korea; (M.H.H.); (X.J.J.); (J.J.Y.); (Y.J.L.); (H.S.L.)
- Hanbang Cardio-renal Research Center & Professional Graduate School of Oriental Medicine, Wonkwang University, Iksan, Jeonbuk 54538, Korea
| | - Yun Jung Lee
- College of Oriental Medicine and Professional Graduate School of Oriental Medicine, Wonkwang University, Iksan, Jeonbuk 54538, Korea; (M.H.H.); (X.J.J.); (J.J.Y.); (Y.J.L.); (H.S.L.)
- Hanbang Cardio-renal Research Center & Professional Graduate School of Oriental Medicine, Wonkwang University, Iksan, Jeonbuk 54538, Korea
| | - Hyun Cheol Oh
- College of Pharmacy, Wonkwang University, Iksan 54538, Korea;
| | - Ho Sub Lee
- College of Oriental Medicine and Professional Graduate School of Oriental Medicine, Wonkwang University, Iksan, Jeonbuk 54538, Korea; (M.H.H.); (X.J.J.); (J.J.Y.); (Y.J.L.); (H.S.L.)
- Hanbang Cardio-renal Research Center & Professional Graduate School of Oriental Medicine, Wonkwang University, Iksan, Jeonbuk 54538, Korea
| | - Hye Yoom Kim
- College of Oriental Medicine and Professional Graduate School of Oriental Medicine, Wonkwang University, Iksan, Jeonbuk 54538, Korea; (M.H.H.); (X.J.J.); (J.J.Y.); (Y.J.L.); (H.S.L.)
- Hanbang Cardio-renal Research Center & Professional Graduate School of Oriental Medicine, Wonkwang University, Iksan, Jeonbuk 54538, Korea
| | - Dae Gill Kang
- College of Oriental Medicine and Professional Graduate School of Oriental Medicine, Wonkwang University, Iksan, Jeonbuk 54538, Korea; (M.H.H.); (X.J.J.); (J.J.Y.); (Y.J.L.); (H.S.L.)
- Hanbang Cardio-renal Research Center & Professional Graduate School of Oriental Medicine, Wonkwang University, Iksan, Jeonbuk 54538, Korea
| |
Collapse
|
28
|
O'Brien MW, Ramsay D, Johnston W, Kimmerly DS. Aerobic fitness and sympathetic responses to spontaneous muscle sympathetic nerve activity in young males. Clin Auton Res 2020; 31:253-261. [PMID: 33034876 DOI: 10.1007/s10286-020-00734-w] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2020] [Accepted: 09/18/2020] [Indexed: 01/29/2023]
Abstract
PURPOSE Lower aerobic fitness increases the risk of developing hypertension. Muscle sympathetic nerve activity (MSNA) is important for the beat-by-beat regulation of blood pressure. Whether the cardiovascular consequences of lower aerobic fitness are due to augmented transduction of MSNA into vascular responses is unclear. We tested the hypothesis that aerobic fitness is inversely related to peak increases in total peripheral resistance (TPR) and mean arterial pressure (MAP) in response to spontaneous MSNA bursts in young males. METHODS Relative peak oxygen consumption (VO2peak, indirect calorimetry) was assessed in 18 young males (23 ± 3 years; 41 ± 8 ml/kg/min). MSNA (microneurography), cardiac intervals (electrocardiogram) and arterial pressure (finger photoplethysmography) were recorded continuously during supine rest. Stroke volume and cardiac output (CO) were estimated via the ModelFlow method. TPR was calculated as MAP/CO. Changes in TPR and MAP were tracked for 12 cardiac cycles following heartbeats associated with or without spontaneous bursts of MSNA. RESULTS Overall, aerobic fitness was inversely correlated to the peak ΔTPR (0.8 ± 0.7 mmHg/l/min; R = - 0.61, P = 0.007) and ΔMAP (2.3 ± 0.8 mmHg; R = - 0.69, P < 0.001), but not with the peak ΔCO (0.2 ± 0.1 l/min; P = 0.50), MSNA burst frequency (14 ± 5 bursts/min; P = 0.43) or MSNA relative burst amplitude (65 ± 12%; P = 0.13). Heartbeats without an associated burst of MSNA did not increase TPR, MAP or CO. CONCLUSION Although unrelated to traditional MSNA characteristics, aerobic fitness was inversely associated with spontaneous sympathetic neurovascular transduction in young males. This may be a potential mechanism by which aerobic fitness modulates the regulation of arterial blood pressure through the sympathetic nervous system.
Collapse
Affiliation(s)
- Myles W O'Brien
- Autonomic Cardiovascular Control and Exercise Laboratory, Division of Kinesiology, School of Health and Human Performance, Faculty of Health, Dalhousie University, 6230 South Street, Halifax, NS, B3H 4R2, Canada
| | - Diane Ramsay
- Autonomic Cardiovascular Control and Exercise Laboratory, Division of Kinesiology, School of Health and Human Performance, Faculty of Health, Dalhousie University, 6230 South Street, Halifax, NS, B3H 4R2, Canada
| | - William Johnston
- Autonomic Cardiovascular Control and Exercise Laboratory, Division of Kinesiology, School of Health and Human Performance, Faculty of Health, Dalhousie University, 6230 South Street, Halifax, NS, B3H 4R2, Canada
| | - Derek S Kimmerly
- Autonomic Cardiovascular Control and Exercise Laboratory, Division of Kinesiology, School of Health and Human Performance, Faculty of Health, Dalhousie University, 6230 South Street, Halifax, NS, B3H 4R2, Canada.
| |
Collapse
|
29
|
Jacob DW, Ott EP, Baker SE, Scruggs ZM, Ivie CL, Harper JL, Manrique-Acevedo CM, Limberg JK. Sex differences in integrated neurocardiovascular control of blood pressure following acute intermittent hypercapnic hypoxia. Am J Physiol Regul Integr Comp Physiol 2020; 319:R626-R636. [PMID: 32966122 DOI: 10.1152/ajpregu.00191.2020] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Repetitive hypoxic apneas, similar to those observed in sleep apnea, result in resetting of the sympathetic baroreflex to higher blood pressures (BP). This baroreflex resetting is associated with hypertension in preclinical models of sleep apnea (intermittent hypoxia, IH); however, the majority of understanding comes from males. There are data to suggest that female rats exposed to IH do not develop high BP. Clinical data further support sex differences in the development of hypertension in sleep apnea, but mechanistic data are lacking. Here we examined sex-related differences in the effect of IH on sympathetic control of BP in humans. We hypothesized that after acute IH we would observe a rise in muscle sympathetic nerve activity (MSNA) and arterial BP in young men (n = 30) that would be absent in young women (n = 19). BP and MSNA were measured during normoxic rest before and after 30 min of IH. Baroreflex sensitivity (modified Oxford) was evaluated before and after IH. A rise in mean BP following IH was observed in men (+2.0 ± 0.7 mmHg, P = 0.03), whereas no change was observed in women (-2.7 ± 1.2 mmHg, P = 0.11). The elevation in MSNA following IH was not different between groups (4.7 ± 1.1 vs. 3.8 ± 1.2 bursts/min, P = 0.65). Sympathetic baroreflex sensitivity did not change after IH in either group (P > 0.05). Our results support sex-related differences in the effect of IH on neurovascular control of BP and show that any BP-raising effects of IH are absent in young women. These data enhance our understanding of sex-specific mechanisms that may contribute to BP changes in sleep apnea.
Collapse
Affiliation(s)
- Dain W Jacob
- Department of Nutrition and Exercise Physiology, University of Missouri, Columbia, Missouri
| | - Elizabeth P Ott
- Department of Nutrition and Exercise Physiology, University of Missouri, Columbia, Missouri
| | - Sarah E Baker
- Department of Anesthesiology, Mayo Clinic, Rochester, Minnesota
| | | | - Clayton L Ivie
- Department of Nutrition and Exercise Physiology, University of Missouri, Columbia, Missouri
| | - Jennifer L Harper
- Department of Nutrition and Exercise Physiology, University of Missouri, Columbia, Missouri
| | - Camila M Manrique-Acevedo
- Department of Medicine, University of Missouri, Columbia, Missouri.,Research Service, Harry S. Truman Memorial Veterans' Hospital, Columbia, Missouri.,Dalton Cardiovascular Research Center, University of Missouri, Columbia, Missouri
| | - Jacqueline K Limberg
- Department of Nutrition and Exercise Physiology, University of Missouri, Columbia, Missouri.,Department of Anesthesiology, Mayo Clinic, Rochester, Minnesota
| |
Collapse
|
30
|
Hissen SL, Taylor CE. Sex differences in vascular transduction of sympathetic nerve activity. Clin Auton Res 2020; 30:381-392. [PMID: 32865664 DOI: 10.1007/s10286-020-00722-0] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2020] [Accepted: 08/18/2020] [Indexed: 12/21/2022]
Abstract
PURPOSE Sympathetic vasoconstriction plays a major role in the beat-to-beat control of blood pressure. To be effective and thus avoid dangerously high or low blood pressures, this mechanism relies upon transduction of sympathetic nerve activity at the level of the vasculature. However, recent evidence suggests that considerable variability exists in beat-to-beat vascular transduction, particularly between the sexes. METHODS We reviewed the methods available for quantifying beat-to-beat transduction of muscle sympathetic nerve activity (MSNA) and explored the recent evidence for sex differences in vascular transduction. We paid specific attention to relationships between vascular transduction and factors such as resting levels of sympathetic nerve activity and baroreflex sensitivity. RESULTS There are two dominant methods now available for the quantification of beat-to-beat transduction of muscle sympathetic nerve activity at rest. Whilst there is some evidence to suggest that young females exhibit lower levels of vascular transduction, results vary depending on the method used and the direction of change in MSNA. Evidence suggests that compensatory relationships may exist between key components of neurovascular control, such as vascular transduction and resting levels of MSNA. Also consistent is the presence of such relationships in young males but not young females. CONCLUSION The lack of significant relationships in young females may reflect the influence of vasodilator mechanisms that counteract sympathetic vasoconstriction. The assessment of vascular transduction following MSNA bursts and non-bursts in males and females, both young and older, may help to gain a mechanistic understanding of the prevalence of hypotensive and hypertensive disorders across the lifespan.
Collapse
Affiliation(s)
- Sarah L Hissen
- Institute for Exercise and Environmental Medicine at Texas Health Presbyterian Hospital Dallas, Dallas, TX, USA
- The University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Chloe E Taylor
- School of Health Sciences, Western Sydney University, Campbelltown Campus, Locked Bag 1797, Penrith, Sydney, NSW, 2751, Australia.
- School of Medicine, Western Sydney University, Sydney, Australia.
| |
Collapse
|
31
|
Coovadia Y, Adler TE, Steinback CD, Fraser GM, Usselman CW. Sex differences in dynamic blood pressure regulation: beat-by-beat responses to muscle sympathetic nerve activity. Am J Physiol Heart Circ Physiol 2020; 319:H531-H538. [PMID: 32734818 DOI: 10.1152/ajpheart.00245.2020] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
It has been suggested that sex differences in acute blood pressure fluctuations occur during the periods of time between bursts of muscle sympathetic nerve activity. Therefore, we tested the hypothesis that men experience more dynamic changes in mean arterial pressure (Finometer MIDI) than women during acute sympathoinhibition (i.e., slow breathing) in which bursts of sympathetic activity occur more infrequently than at rest. We tested healthy women (n = 9) and men (n = 9) of similar age (22 ± 2 vs. 23 ± 3 yr, P = 0.6). Custom software was used to calculate beat-by-beat changes in blood pressure following sympathetic burst and nonburst sequences (recorded using microneurography) during 10 min of supine rest and a 15-min bout of slow breathing. During slow breathing following nonburst sequences, women demonstrated smaller overall reductions in mean arterial pressure compared with men over the subsequent 15 cardiac cycles (P < 0.01). In addition, following a burst of sympathetic activity, women experienced greater overall increases in mean arterial pressure compared with men over the following 15 cardiac cycles (P < 0.01). Despite these differences, the peak and nadir changes in arterial pressure following burst and nonburst sequences were not different between the sexes (P = 0.45 and P = 0.48, burst and nonburst sequences, respectively). As such, these data suggest that women respond to a burst of sympathetic activity with more sustained increases in blood pressure than men, coupled with improved maintenance of blood pressure during acute periods of sympathetic quiescence. In other words, these findings suggest that men rely more on frequent bursts of sympathetic activity to acutely regulate arterial pressure than women.NEW & NOTEWORTHY We demonstrate that during acute sympathoinhibition, women demonstrate more sustained increases in blood pressure following sympathetic bursts of activity than men. Likewise, during prolonged sympathetic quiescence, blood pressure is less labile in women than men. This suggests that lower overall blood pressure in young women may not be mediated by smaller beat-by-beat changes in blood pressure in response to sympathetic outflow but may instead be mediated by a lower frequency of sympathetic bursts.
Collapse
Affiliation(s)
- Yasmine Coovadia
- Cardiovascular Health and Autonomic Regulation Laboratory, Department of Kinesiology and Physical Education, McGill University, Montreal, Quebec, Canada
| | - Tessa E Adler
- Cardiovascular Health and Autonomic Regulation Laboratory, Department of Kinesiology and Physical Education, McGill University, Montreal, Quebec, Canada
| | - Craig D Steinback
- Neurovascular Health Laboratory, Program for Pregnancy and Postpartum Health, Faculty of Physical Education and Recreation, University of Alberta, Edmonton, Alberta, Canada.,Women and Children's Health Research Institute, University of Alberta, Edmonton, Alberta, Canada
| | - Graham M Fraser
- Division of BioMedical Sciences, Faculty of Medicine, Memorial University of Newfoundland, St. John's, Newfoundland and Labrador
| | - Charlotte W Usselman
- Cardiovascular Health and Autonomic Regulation Laboratory, Department of Kinesiology and Physical Education, McGill University, Montreal, Quebec, Canada.,McGill Research Centre for Physical Activity and Health, McGill University, Montreal, Quebec, Canada
| |
Collapse
|
32
|
Takeda R, Stickford AS, Best SA, Yoo JK, Fu Q. Salt intake impacts sympathetic neural control but not morning blood pressure surge in premenopausal women with a history of normal pregnancy. Am J Physiol Heart Circ Physiol 2020; 319:H571-H581. [PMID: 32734815 DOI: 10.1152/ajpheart.00197.2020] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Salt intake may alter blood pressure (BP) regulation, but no study has investigated the impact of salt reduction versus salt loading on morning blood pressure surge (MBPS) and sympathetic neural control in premenopausal women with a history of normal pregnancy. Nine healthy women (42 ± 3 yr; mean ± SD) were given a low-salt diet (LS; 50 mEq sodium/day) and high-salt diet (HS; 250 mEq sodium/day) for 1 wk each (~2 mo apart with the order randomized), while water intake was ad libitum. Ambulatory BP at 24 h was measured, and the percent change in blood volume (BV) was calculated following LS and HS. MBPS was defined as the morning systolic BP (averaged for 2 h after wake-up) minus the lowest nocturnal systolic BP. Beat-by-beat BP, heart rate, and muscle sympathetic nerve activity (MSNA) were measured during supine rest. Signal averaging was used to characterize changes in beat-by-beat mean arterial pressure and total vascular conductance following spontaneous MSNA bursts to assess sympathetic vascular transduction. Ambulatory BP and MBPS (32 ± 7 vs. 26 ± 12 mmHg, P = 0.208) did not differ between LS and HS. From LS to HS, BV increased by 4.3 ± 3.7% (P = 0.008). MSNA (30 ± 20 vs. 18 ± 13 bursts/100 heartbeats, P = 0.005) was higher, whereas sympathetic vascular transduction was lower in LS than HS (both, P < 0.01). Changes in MSNA from LS to HS were correlated to percent changes in BV (r = -0.673; P = 0.047). Thus, salt intake affects sympathetic neural control but not MBPS in premenopausal women with a history of normal pregnancy. The underlying mechanisms remain unknown; however, alterations in sympathetic vascular transduction may, in part, contribute.NEW & NOTEWORTHY This is the first study to demonstrate that MBPS and ambulatory BP were not affected by salt intake despite a significant change in sympathetic outflow in healthy premenopausal women with a history of normal pregnancy. This may be due to compensatory adaptations in MSNA and sympathetic vascular transduction during salt reduction versus salt loading.
Collapse
Affiliation(s)
- Ryosuke Takeda
- Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital Dallas, Dallas, Texas.,University of Texas Southwestern Medical Center, Dallas, Texas
| | - Abigail S Stickford
- Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital Dallas, Dallas, Texas.,University of Texas Southwestern Medical Center, Dallas, Texas
| | - Stuart A Best
- Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital Dallas, Dallas, Texas.,University of Texas Southwestern Medical Center, Dallas, Texas
| | - Jeung-Ki Yoo
- Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital Dallas, Dallas, Texas.,University of Texas Southwestern Medical Center, Dallas, Texas
| | - Qi Fu
- Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital Dallas, Dallas, Texas.,University of Texas Southwestern Medical Center, Dallas, Texas
| |
Collapse
|
33
|
Keller-Ross ML, Cunningham HA, Carter JR. Impact of age and sex on neural cardiovascular responsiveness to cold pressor test in humans. Am J Physiol Regul Integr Comp Physiol 2020; 319:R288-R295. [PMID: 32697654 DOI: 10.1152/ajpregu.00045.2020] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Prior longitudinal work suggests that blood pressure (BP) reactivity to the cold pressor test (CPT) helps predict hypertension; yet the impact of age and sex on hemodynamic and neural responsiveness to CPT remains equivocal. Forty-three young (21 ± 1yr, means ± SE) men (YM, n = 20) and women (YW, n = 23) and 16 older (60 ± 1yr) men (OM, n = 9) and women (OW, n = 7) participated in an experimental visit where continuous BP (finger plethysmography) and muscle sympathetic nerve activity (MSNA; microneurography) were recorded during a 3- to 5-min baseline and 2-min CPT. Baseline mean arterial pressure (MAP) was greater in OM than in YM (92 ± 4 vs. 77 ± 1 mmHg, P < 0.01), but similar in women (P = 0.12). Baseline MSNA incidence was greater in OM [69 ± 6 bursts/100 heartbeats (hb)] than in OW (44 ± 7 bursts/100 hb, P = 0.02) and lower in young adults (YM: 17 ± 3 vs. YW: 16 ± 2 bursts/100 hb, P < 0.01), but similar across the sexes (P = 0.83). However, when exposed to the CPT, MSNA increased more rapidly in OW (Δ43 ± 6 bursts/100 hb; group × time, P = 0.01) compared with OM (Δ15 ± 3 bursts/100 hb) but was not different between YW (Δ30 ± 3 bursts/100 hb) and YM (Δ33 ± 4 bursts/100 hb, P = 1.0). There were no differences in MAP with CPT between groups (group × time, P = 0.33). These findings suggest that OW demonstrate a more rapid initial rise in MSNA responsiveness to a CPT compared with OM. This greater sympathetic reactivity in OW may be a contributing mechanism to the increased hypertension risk in postmenopausal women.
Collapse
Affiliation(s)
- M L Keller-Ross
- Department of Rehabilitation Medicine, Divisions of Physical Therapy and Rehabilitation Science, Medical School, University of Minnesota, Minneapolis, Minnesota
| | - H A Cunningham
- Department of Kinesiology and Integrative Physiology, Michigan Technological University, Houghton, Michigan
| | - J R Carter
- Department of Kinesiology and Integrative Physiology, Michigan Technological University, Houghton, Michigan.,Department of Health and Human Development, Montana State University - Bozeman, Bozeman, Montana
| |
Collapse
|
34
|
Engelland RE, Hemingway HW, Tomasco OG, Olivencia-Yurvati AH, Romero SA. Neural control of blood pressure is altered following isolated leg heating in aged humans. Am J Physiol Heart Circ Physiol 2020; 318:H976-H984. [PMID: 32142377 DOI: 10.1152/ajpheart.00019.2020] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
There is a sustained reduction in arterial blood pressure that occurs in aged adults following exposure to acute leg heating. We tested the hypothesis that acute leg heating would decrease arterial blood pressure in aged adults secondary to sympathoinhibition. We exposed 13 young and 10 aged adults to 45 min of leg heating. Muscle sympathetic nerve activity (radial nerve) was measured before leg heating (preheat) and 30 min after (recovery) and is expressed as burst frequency. Neurovascular transduction was examined by assessing the slope of the relation between muscle sympathetic nerve activity and leg vascular conductance measured at rest and during isometric handgrip exercise performed to fatigue. Arterial blood pressure was well maintained in young adults (preheat, 86 ± 6 mmHg vs. recovery, 88 ± 7 mmHg; P = 0.4) due to increased sympathetic nerve activity (preheat, 16 ± 7 bursts/min vs. recovery, 22 ± 10 bursts/min; P < 0.01). However, in aged adults, sympathetic nerve activity did not differ from preheat (37 ± 5 bursts/min) to recovery (33 ± 6 bursts/min, P = 0.1), despite a marked reduction in arterial blood pressure (preheat, 101 ± 7 mmHg vs. recovery, 94 ± 6 mmHg; P < 0.01). Neurovascular transduction did not differ from preheat to recovery for either age group (P ≥ 0.1). The reduction in arterial blood pressure that occurs in aged adults following exposure to acute leg heating is mediated, in part, by a sympathoinhibitory effect that alters the compensatory neural response to hypotension.NEW & NOTEWORTHY There is a sustained reduction in arterial blood pressure that occurs in aged adults following exposure to acute leg heating. However, the neurovascular mechanisms mediating this response remain unknown. Our findings demonstrate for the first time that this reduction in arterial blood pressure is mediated, in part, by a sympathoinhibitory effect that alters the compensatory neural response to hypotension in aged adults.
Collapse
Affiliation(s)
- Rachel E Engelland
- Department of Physiology and Anatomy, Human Vascular Physiology Laboratory, University of North Texas Health Science Center, Ft. Worth, Texas
| | - Holden W Hemingway
- Department of Physiology and Anatomy, Human Vascular Physiology Laboratory, University of North Texas Health Science Center, Ft. Worth, Texas
| | - Olivia G Tomasco
- Department of Physiology and Anatomy, Human Vascular Physiology Laboratory, University of North Texas Health Science Center, Ft. Worth, Texas
| | - Albert H Olivencia-Yurvati
- Department of Physiology and Anatomy, Human Vascular Physiology Laboratory, University of North Texas Health Science Center, Ft. Worth, Texas.,Department of Surgery, University of North Texas Health Science Center, Ft. Worth, Texas
| | - Steven A Romero
- Department of Physiology and Anatomy, Human Vascular Physiology Laboratory, University of North Texas Health Science Center, Ft. Worth, Texas
| |
Collapse
|
35
|
Hissen SL, Macefield VG, Brown R, Taylor CE. Sympathetic baroreflex sensitivity is inversely related to vascular transduction in men but not women. Am J Physiol Heart Circ Physiol 2019; 317:H1203-H1209. [PMID: 31675259 DOI: 10.1152/ajpheart.00501.2019] [Citation(s) in RCA: 32] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Sympathetic baroreflex sensitivity (BRS) is a measure of how effectively the baroreflex buffers beat-to-beat changes in blood pressure through the modulation of muscle sympathetic nerve activity (MSNA). However, current methods of assessment do not take into account the transduction of sympathetic nerve activity at the level of the vasculature, which is known to vary between individuals. In this study we tested the hypothesis that there is an inverse relationship between sympathetic BRS and vascular transduction. In 38 (18 men) healthy adults, continuous measurements of blood pressure, MSNA and superficial femoral artery diameter and blood flow (Doppler ultrasound) were recorded during 10 min of rest. Spontaneous sympathetic BRS was quantified as the relationship between diastolic pressure and MSNA burst incidence. Vascular transduction was quantified by plotting the changes in leg vascular conductance for 10 cardiac cycles following each burst of MSNA, and taking the nadir. In men, sympathetic BRS was inversely related to vascular transduction (r = -0.49; P = 0.04). However, this relationship was not present in women (r = -0.17; P = 0.47). To conclude, an interaction exists between sympathetic BRS and vascular transduction in healthy men, such that men with high sympathetic BRS have low vascular transduction and vice versa. This may be to ensure that blood pressure is regulated effectively, although further research is needed to explore what mechanisms are involved and examine why this relationship was not apparent in women.NEW & NOTEWORTHY Evidence suggests that compensatory interactions exist between factors involved in cardiovascular control. This study was the first to demonstrate an inverse relationship between sympathetic BRS and beat-to-beat vascular transduction. Those with low sympathetic BRS had high vascular transduction and vice versa. However, this interaction was present in young men but not women.
Collapse
Affiliation(s)
- Sarah L Hissen
- School of Science and Health, Western Sydney University, Sydney, Australia
| | - Vaughan G Macefield
- School of Medicine, Western Sydney University, Sydney, Australia.,Neuroscience Research Australia, Sydney, Australia.,Baker Heart and Diabetes Institute, Melbourne, Australia
| | - Rachael Brown
- School of Medicine, Western Sydney University, Sydney, Australia.,Neuroscience Research Australia, Sydney, Australia
| | - Chloe E Taylor
- School of Science and Health, Western Sydney University, Sydney, Australia.,School of Medicine, Western Sydney University, Sydney, Australia
| |
Collapse
|
36
|
Alula KM, Biltz R, Xu H, Garver H, Laimon-Thomson EL, Fink GD, Galligan JJ. Effects of high-fat diet on sympathetic neurotransmission in mesenteric arteries from Dahl salt-sensitive rat. Auton Neurosci 2019; 222:102599. [PMID: 31731103 DOI: 10.1016/j.autneu.2019.102599] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2019] [Revised: 10/18/2019] [Accepted: 10/29/2019] [Indexed: 12/19/2022]
Abstract
Obesity hypertension is driven by sympathetic neurotransmission to the heart and blood vessels. We tested the hypothesis that high-fat diet (HFD)-induced hypertension is driven by sympathetic neurotransmission to mesenteric arteries (MA) in male but not female Dahl salt-sensitive (Dahl ss) rat. Rats were fed a control diet (CD; 10 kcal% from fat) or HFD (60 kcal% from fat) beginning at 3 weeks (wk) of age; measurements were made at 10-, 17- and 24-wk. Body weight increased with HFD, age and sex. Mean arterial pressure (MAP) was higher in HFD versus CD rats from both sexes at 17- and 24-wk. MA constriction measured using pressure myography, and electrical field stimulation (EFS, 0.2-30 Hz) was greater in HFD versus CD in males at 17-wk; this was not due to changes in α2 autoreceptor or norepinephrine transporter (NET) function. Prazosin (α1-AR antagonist) and suramin (P2 receptor antagonist) inhibited neurogenic MA constriction equally in all groups. Arterial reactivity to exogenous norepinephrine (NE; 10-8 - 10-5 M) was lower in HFD versus CD at 10-wk in males. Female MA reactivity to exogenous ATP was lower at 24-weeks compared to earlier time points. HFD did not affect tyrosine hydroxylase (TH) or the vesicular nucleotide transporter (VNUT) nerve density in MA from both sexes. NE content was lower in MA but higher in plasma at 24-wk compared to 10- and 17-wk in both sexes. In conclusion, HFD-induced hypertension is not driven by increased sympathetic neurotransmission to MA in male and female Dahl ss rats.
Collapse
Affiliation(s)
- Kibrom M Alula
- Department of Pharmacology and Toxicology, Michigan State University, East Lansing, MI 48824, USA
| | - Rebecca Biltz
- The Neuroscience Program, Michigan State University, East Lansing, MI 48824, USA
| | - Hui Xu
- Department of Pharmacology and Toxicology, Michigan State University, East Lansing, MI 48824, USA; The Neuroscience Program, Michigan State University, East Lansing, MI 48824, USA
| | - Hannah Garver
- Department of Pharmacology and Toxicology, Michigan State University, East Lansing, MI 48824, USA
| | - Erinn L Laimon-Thomson
- Department of Pharmacology and Toxicology, Michigan State University, East Lansing, MI 48824, USA
| | - Gregory D Fink
- Department of Pharmacology and Toxicology, Michigan State University, East Lansing, MI 48824, USA; The Neuroscience Program, Michigan State University, East Lansing, MI 48824, USA
| | - James J Galligan
- Department of Pharmacology and Toxicology, Michigan State University, East Lansing, MI 48824, USA; The Neuroscience Program, Michigan State University, East Lansing, MI 48824, USA.
| |
Collapse
|
37
|
Watso JC, Robinson AT, Babcock MC, Migdal KU, Wenner MM, Stocker SD, Farquhar WB. Short-term water deprivation does not increase blood pressure variability or impair neurovascular function in healthy young adults. Am J Physiol Regul Integr Comp Physiol 2019; 318:R112-R121. [PMID: 31617739 DOI: 10.1152/ajpregu.00149.2019] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
High dietary salt increases arterial blood pressure variability (BPV) in salt-resistant, normotensive rodents and is thought to result from elevated plasma [Na+] sensitizing central sympathetic networks. Our purpose was to test the hypothesis that water deprivation (WD)-induced elevations in serum [Na+] augment BPV via changes in baroreflex function and sympathetic vascular transduction in humans. In a randomized crossover fashion, 35 adults [17 female/18 male, age: 25 ± 4 yr, systolic/diastolic blood pressure (BP): 107 ± 11/60 ± 7 mmHg, body mass index: 23 ± 3 kg/m2] completed two hydration protocols: a euhydration control condition (CON) and a stepwise reduction in water intake over 3 days, concluding with 16 h of WD. We assessed blood and urine electrolyte concentrations and osmolality, resting muscle sympathetic nerve activity (MSNA; peroneal microneurography; 18 paired recordings), beat-to-beat BP (photoplethysmography), common femoral artery blood flow (Doppler ultrasound), and heart rate (single-lead ECG). A subset of participants (n = 25) underwent ambulatory BP monitoring during day 3 of each protocol. We calculated average real variability as an index of BPV. WD increased serum [Na+] (141.0 ± 2.3 vs. 142.1 ± 1.7 mmol/L, P < 0.01) and plasma osmolality (288 ± 4 vs. 292 ± 5 mosmol/kg H2O, P < 0.01). However, WD did not increase beat-to-beat (1.9 ± 0.4 vs. 1.8 ± 0.4 mmHg, P = 0.24) or ambulatory daytime (9.6 ± 2.1 vs. 9.4 ± 3.3 mmHg, P = 0.76) systolic BPV. Additionally, sympathetic baroreflex sensitivity (P = 0.20) and sympathetic vascular transduction were not different after WD (P = 0.17 for peak Δmean BP following spontaneous MSNA bursts). These findings suggest that, despite modestly increasing serum [Na+], WD does not affect BPV, arterial baroreflex function, or sympathetic vascular transduction in healthy young adults.
Collapse
Affiliation(s)
- Joseph C Watso
- Department of Kinesiology and Applied Physiology, University of Delaware, Newark, Delaware
| | - Austin T Robinson
- Department of Kinesiology and Applied Physiology, University of Delaware, Newark, Delaware
| | - Matthew C Babcock
- Department of Kinesiology and Applied Physiology, University of Delaware, Newark, Delaware
| | - Kamila U Migdal
- 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
| | - Sean D Stocker
- Department of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania
| | - William B Farquhar
- Department of Kinesiology and Applied Physiology, University of Delaware, Newark, Delaware
| |
Collapse
|
38
|
Hydration Status and Cardiovascular Function. Nutrients 2019; 11:nu11081866. [PMID: 31405195 PMCID: PMC6723555 DOI: 10.3390/nu11081866] [Citation(s) in RCA: 54] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2019] [Revised: 07/30/2019] [Accepted: 08/08/2019] [Indexed: 02/07/2023] Open
Abstract
Hypohydration, defined as a state of low body water, increases thirst sensations, arginine vasopressin release, and elicits renin–angiotensin–aldosterone system activation to replenish intra- and extra-cellular fluid stores. Hypohydration impairs mental and physical performance, but new evidence suggests hypohydration may also have deleterious effects on cardiovascular health. This is alarming because cardiovascular disease is the leading cause of death in the United States. Observational studies have linked habitual low water intake with increased future risk for adverse cardiovascular events. While it is currently unclear how chronic reductions in water intake may predispose individuals to greater future risk for adverse cardiovascular events, there is evidence that acute hypohydration impairs vascular function and blood pressure (BP) regulation. Specifically, acute hypohydration may reduce endothelial function, increase sympathetic nervous system activity, and worsen orthostatic tolerance. Therefore, the purpose of this review is to present the currently available evidence linking acute hypohydration with altered vascular function and BP regulation.
Collapse
|