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McGinty SJ, Matthews EL, Greaney JL, Shoemaker JK, Wenner MM. Sympathetic baroreflex sensitivity is enhanced in postmenopausal women. J Appl Physiol (1985) 2024; 137:374-381. [PMID: 38961825 DOI: 10.1152/japplphysiol.00833.2023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2023] [Revised: 07/02/2024] [Accepted: 07/02/2024] [Indexed: 07/05/2024] Open
Abstract
The sympathetic nervous system is critical for regulating blood pressure (BP) via the arterial baroreflex and sympathetic transduction in the peripheral vasculature. These mechanisms interact, and both may be altered with aging and impacted by menopause. Although age-related decreases in sympathetic transduction have been demonstrated in women, it remains unclear whether sympathetic baroreflex sensitivity (BRS) is impaired in postmenopausal women (POST). We tested the hypothesis that sympathetic BRS would be enhanced in POST compared with premenopausal women (PRE). We examined beat-by-beat BP and muscle sympathetic nerve activity (MSNA) in 19 PRE (22 ± 2 yr, 22 ± 3 kg/m2) and 12 POST (57 ± 5 yr, 24 ± 2 kg/m2) during 10 min of rest. Spontaneous sympathetic BRS was quantified as the slope of a linear regression between MSNA burst incidence and diastolic BP. Sympathetic transduction to mean arterial pressure (MAP) for the 10 cardiac cycles following spontaneous MSNA bursts was assessed via signal averaging method. Resting MAP was similar (PRE: 82 ± 8 vs. POST: 85 ± 8 mmHg, P = 0.43), whereas resting MSNA was elevated in POST (PRE: 10 ± 6 vs. POST: 45 ± 16 bursts/100 heart beats, P < 0.0001). Spontaneous sympathetic BRS was enhanced in POST (PRE: -2.0 ± 1.2 vs. POST: -5.2 ± 1.9 bursts/beat/mmHg, P < 0.0005). Sympathetic transduction to MAP was attenuated in POST (time: P < 0.001, group: P < 0.001, interaction: P < 0.01). These data suggest that sympathetic BRS may be enhanced in POST. Consistent with recent hypotheses, enhanced sensitivity of the arterial baroreflex's neural arc may signify a compensatory response to reduced efficiency of the peripheral arterial baroreflex arc (i.e., sympathetic transduction) to preserve BP buffering capacity.NEW & NOTEWORTHY Studies examining sympathetic baroreflex function with aging remain equivocal, with some studies showing an increase, decrease, or no change in sympathetic baroreflex sensitivity (BRS) in older adults compared with younger adults. With aging, women experience unique physiological changes due to menopause that influence autonomic function. For the first time, we show that postmenopausal women exhibit a greater sympathetic BRS compared with young premenopausal women.
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Affiliation(s)
- Shane J McGinty
- Department of Kinesiology and Applied Physiology, University of Delaware, Newark, Delaware, United States
| | - Evan L Matthews
- Department of Exercise Science and Physical Education, Montclair State University, Montclair, New Jersey, United States
| | - Jody L Greaney
- Department of Health Behaviour and Nutrition Sciences, University of Delaware, Newark, Delaware, United States
| | - J Kevin Shoemaker
- Neurovascular Research Laboratory, School of Kinesiology, Western University, London, Ontario, Canada
- Department of Physiology and Pharmacology, Western University, London, Ontario, Canada
| | - Megan M Wenner
- Department of Kinesiology and Applied Physiology, University of Delaware, Newark, Delaware, United States
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2
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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.
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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
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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.
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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
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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.
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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
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Sarafis ZK, Squair JW, Barak OF, Coombs GB, Soriano JE, Larkin-Kaiser KA, Lee AHX, Hansen A, Vodopic M, Romac R, Grant C, Charbonneau R, Mijacika T, Krassioukov AV, Ainslie PN, Dujic Z, Phillips AA. Common carotid artery responses to the cold-pressor test are impaired in individuals with cervical spinal cord injury. Am J Physiol Heart Circ Physiol 2022; 323:H1311-H1322. [PMID: 36367686 DOI: 10.1152/ajpheart.00261.2022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Cervical spinal cord injury (SCI) leads to autonomic cardiovascular dysfunction that underlies the three- to fourfold elevated risk of cardiovascular disease in this population. Reduced common carotid artery (CCA) dilatory responsiveness during the cold-pressor test (CPT) is associated with greater cardiovascular disease risk and progression. The cardiovascular and CCA responses to the CPT may provide insight into cardiovascular autonomic dysfunction and cardiovascular disease risk in individuals with cervical SCI. Here, we used CPT to perturb the autonomic nervous system in 14 individuals with cervical SCI and 12 uninjured controls, while measuring cardiovascular responses and CCA diameter. The CCA diameter responses were 55% impaired in those with SCI compared with uninjured controls (P = 0.019). The CCA flow, velocity, and shear response to CPT were reduced in SCI by 100% (P < 0.001), 113% (P = 0.001), and 125% (P = 0.002), respectively. The association between mean arterial pressure and CCA dilation observed in uninjured individuals (r = 0.54, P = 0.004) was absent in the SCI group (r = 0.22, P = 0.217). Steady-state systolic blood pressure (P = 0.020), heart rate (P = 0.003), and cardiac contractility (P < 0.001) were reduced in those with cervical SCI, whereas total peripheral resistance was increased compared with uninjured controls (P = 0.042). Relative cerebral blood velocity responses to CPT were increased in the SCI group and reduced in controls (middle cerebral artery, P = 0.010; posterior cerebral artery, P = 0.026). The CCA and cardiovascular responsiveness to CPT are impaired in those with cervical SCI.NEW & NOTEWORTHY This is the first study demonstrating that CCA responses during CPT are suppressed in SCI. Specifically, CCA diameter, flow, velocity, and shear rate were reduced. The relationship between changes in MAP and CCA dilatation in response to CPT was absent in individuals with SCI, despite similar cardiovascular activation between SCI and uninjured controls. These findings support the notion of elevated cardiovascular disease risk in SCI and that the cardiovascular responses to environmental stimuli are impaired.
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Affiliation(s)
- Zoe K Sarafis
- International Collaboration on Repair Discoveries, Faculty of Medicine, University of British Columbia, Vancouver, British Columbia, Canada
| | - Jordan W Squair
- International Collaboration on Repair Discoveries, Faculty of Medicine, University of British Columbia, Vancouver, British Columbia, Canada.,RESTORE.network, Departments of Physiology and Pharmacology, Cardiac Sciences and Clinical Neurosciences, Biomedical Engineering, Libin Cardiovascular Institute of Alberta, Hotchkiss Brain Institute, University of Calgary, Calgary, Alberta, Canada.,MD/PhD Training Program, Faculty of Medicine, University of British Columbia, Vancouver, British Columbia, Canada.,Department of Experimental Medicine, Faculty of Medicine, University of British Columbia, Vancouver, British Columbia, Canada
| | - Otto F Barak
- Faculty of Medicine, University of Novi Sad, Novi Sad, Serbia
| | - Geoff B Coombs
- Centre for Heart, Lung and Vascular Health, University of British Columbia Okanagan, Kelowna, British Columbia, Canada
| | - Jan Elaine Soriano
- RESTORE.network, Departments of Physiology and Pharmacology, Cardiac Sciences and Clinical Neurosciences, Biomedical Engineering, Libin Cardiovascular Institute of Alberta, Hotchkiss Brain Institute, University of Calgary, Calgary, Alberta, Canada
| | - Kelly A Larkin-Kaiser
- RESTORE.network, Departments of Physiology and Pharmacology, Cardiac Sciences and Clinical Neurosciences, Biomedical Engineering, Libin Cardiovascular Institute of Alberta, Hotchkiss Brain Institute, University of Calgary, Calgary, Alberta, Canada
| | - Amanda H X Lee
- International Collaboration on Repair Discoveries, Faculty of Medicine, University of British Columbia, Vancouver, British Columbia, Canada.,Department of Experimental Medicine, Faculty of Medicine, University of British Columbia, Vancouver, British Columbia, Canada
| | - Alex Hansen
- Department of Sport Science, University of Innsbruck, Innsbruck, Austria
| | - Maro Vodopic
- Department of Neurology, General Hospital, Dubrovnik, Croatia
| | - Rinaldo Romac
- Department of Neurology, Clinical Hospital Center, Split, Croatia
| | - Christopher Grant
- Division of Physical Medicine and Rehabilitation, Department of Clinical Neurosciences, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada
| | - Rebecca Charbonneau
- Division of Physical Medicine and Rehabilitation, Department of Clinical Neurosciences, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada
| | - Tanja Mijacika
- Department of Integrative Physiology, University of Split School of Medicine, Split, Croatia
| | - Andrei V Krassioukov
- International Collaboration on Repair Discoveries, Faculty of Medicine, University of British Columbia, Vancouver, British Columbia, Canada.,Division of Physical Medicine and Rehabilitation, University of British Columbia, Vancouver, British Columbia, Canada.,GF Strong Rehabilitation Centre, Vancouver, British Columbia, Canada
| | - Philip N Ainslie
- Centre for Heart, Lung and Vascular Health, University of British Columbia Okanagan, Kelowna, British Columbia, Canada
| | - Zeljko Dujic
- Department of Integrative Physiology, University of Split School of Medicine, Split, Croatia
| | - Aaron A Phillips
- RESTORE.network, Departments of Physiology and Pharmacology, Cardiac Sciences and Clinical Neurosciences, Biomedical Engineering, Libin Cardiovascular Institute of Alberta, Hotchkiss Brain Institute, University of Calgary, Calgary, Alberta, Canada
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Olver TD, Badrov MB, Allen MD, Coverdale NS, Shoemaker JK. Acute changes in forearm vascular compliance during transient sympatho-excitation. Physiol Rep 2022; 10:e15256. [PMID: 35439367 PMCID: PMC9017978 DOI: 10.14814/phy2.15256] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2022] [Revised: 04/07/2022] [Accepted: 03/20/2022] [Indexed: 06/14/2023] Open
Abstract
The study of vascular regulation often omits important information about the elastic properties of arteries under conditions of pulsatile flow. The purpose of this study was to examine the relationship between muscle sympathetic nerve activity (MSNA), vascular bed compliance, and peripheral blood flow responses in humans. We hypothesized that increases in MSNA would correlate with reductions in vascular compliance, and that changes in compliance would correspond with changes in peripheral blood flow during sympatho-excitation. MSNA (microneurography), blood pressure (Finopres), and brachial artery blood flow (Doppler ultrasound), were monitored in six healthy males at baseline and during the last 15 s of voluntary end-inspiratory, expiratory apneas and 5 min of static handgrip exercise (SHG; 20% maximum voluntary contraction) and 3 min of post-exercise circulatory occlusion (SHG + PECO; measured in the non-exercising arm). A lumped Windkessel model was employed to examine vascular bed compliance. During apnea, indices of MSNA were inversely related with vascular compliance, and reductions in compliance correlated with decreased brachial blood flow rate. During SHG, despite increased MSNA, compliance also increased, but was unrelated to increases in blood flow. Neither during SHG nor PECO did indices of MSNA correlate with forearm vascular compliance nor did vascular compliance correlate with brachial flow. However, during PECO, a linear combination of blood pressure and total MSNA was correlated with vascular compliance. These data indicate the elastic components of the forearm vasculature are regulated by adrenergic and myogenic mechanisms during sympatho-excitation, but in a reflex-dependent manner.
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Affiliation(s)
- T. Dylan Olver
- Biomedical SciencesWestern College of Veterinary MedicineUniversity of SaskatchewanSaskatoonSaskatchewanCanada
| | - Mark B. Badrov
- Division of CardiologyDepartment of MedicineUniversity Health Network and Sinai HealthUniversity of TorontoTorontoOntarioCanada
| | - Matti D. Allen
- Department of Physical Medicine and RehabilitationSchool of MedicineQueen's UniversityKingstonOntarioCanada
| | - Nicole S. Coverdale
- School of Kinesiology and Health StudiesQueen’s UniversityKingstonOntarioCanada
| | - J. Kevin Shoemaker
- Neurovascular Research LaboratorySchool of KinesiologyThe University of Western OntarioLondonOntarioCanada
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Wenner MM, Greaney JL, Matthews EL, McGinty S, Kaur J, Vongpatanasin W, Fadel PJ. Influence of Age and Estradiol on Sympathetic Nerve Activity Responses to Exercise in Women. Med Sci Sports Exerc 2022; 54:408-416. [PMID: 34711708 PMCID: PMC8847319 DOI: 10.1249/mss.0000000000002823] [Citation(s) in RCA: 20] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
INTRODUCTION Postmenopausal women (PMW) display exaggerated increases in blood pressure (BP) during exercise, yet the mechanism(s) involved remain unclear. Moreover, research on the impact of menopausal changes in estradiol on cardiovascular control during exercise are limited. Herein, we tested the hypothesis that sympathetic responses during exercise are augmented in PMWcompared with young women (YW), and estradiol administration attenuates these responses. METHODS Muscle sympathetic nerve activity (MSNA) and mean arterial pressure (MAP) were measured in 13 PMW (58 ± 1 yr) and 17 YW (22 ± 1 yr) during 2 min of isometric handgrip. Separately, MSNA and BP responses were measured during isometric handgrip in six PMW (53 ± 1 yr) before and after 1 month of transdermal estradiol (100 μg·d-1). A period of postexercise ischemia (PEI) to isolate muscle metaboreflex activation followed all handgrip bouts. RESULTS Resting MAP was similar between PMW and YW, whereas MSNA was greater in PMW (23 ± 3 vs 8 ± 1 bursts per minute; P < 0.05). During handgrip, the increases in MSNA (PMW Δ16 ± 2 vs YW Δ6 ± 1 bursts per minute; P < 0.05) and MAP (PMW Δ18 ± 2 vs YW Δ12 ± 2 mm Hg; P < 0.05) were greater in PMW and remained augmented during PEI. Estradiol administration decreased resting MAP but not MSNA in PMW. Moreover, MSNA (PMW (-E2) Δ27 ± 8 bursts per minute versus PMW (+E2) Δ12 ± 5 bursts per minute; P < 0.05) and MAP (Δ31 ± 8 mm Hg vs Δ20 ± 6 mm Hg; P < 0.05) responses during handgrip were attenuated in PMW after estradiol administration. Likewise, MAP responses during PEI were lower after estradiol. CONCLUSIONS These data suggest that PMW exhibit an exaggerated MSNA and BP response to isometric exercise, due in part to heightened metaboreflex activation. Furthermore, estradiol administration attenuated BP and MSNA responses to exercise in PMW.
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Affiliation(s)
- Megan M. Wenner
- Department of Kinesiology and Applied Physiology, University of Delaware, Newark, DE
| | - Jody L. Greaney
- Department of Kinesiology, The University of Texas at Arlington, Arlington, TX
| | - Evan L. Matthews
- Department of Exercise Science and Physical Education, Montclair State University, Montclair, NJ
| | - Shane McGinty
- Department of Kinesiology and Applied Physiology, University of Delaware, Newark, DE
| | - Jasdeep Kaur
- Department of Kinesiology and Health Education, University of Texas at Austin, Austin, TX
| | | | - Paul J. Fadel
- Department of Kinesiology, The University of Texas at Arlington, Arlington, TX
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8
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Holwerda SW. Crossing the intersection of human hypertension and adrenergic vasoconstriction using innovative methods. J Hum Hypertens 2022; 36:1-2. [PMID: 34453102 DOI: 10.1038/s41371-021-00571-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2021] [Revised: 06/12/2021] [Accepted: 06/15/2021] [Indexed: 01/31/2023]
Affiliation(s)
- Seth W Holwerda
- Department of Anesthesiology, University of Kansas Medical Center, Kansas City, KS, USA.
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9
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Tymko MM, Berthelsen LF, Skow RJ, Steele AR, Fraser GM, Steinback CD. Assessing static and dynamic sympathetic transduction using microneurography. J Appl Physiol (1985) 2021; 130:1626-1634. [PMID: 33792401 DOI: 10.1152/japplphysiol.00032.2021] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
The relationship between sympathetic nerve activity and the vasculature has been of great interest due to its potential role in various cardiovascular-related diseases. This relationship, termed "sympathetic transduction," has been quantified using several different laboratory and analytical techniques. The most common method is to assess the association between relative changes in muscle sympathetic nerve activity, measured via microneurography, and physiological outcomes (e.g., blood pressure, total peripheral resistance, blood flow, etc.) in response to a sympathetic stressor (e.g., exercise, cold stress, orthostatic stress). This approach, however, comes with its own caveats. For instance, elevations in blood pressure and heart rate during a sympathetic stressor can have an independent impact on muscle sympathetic nerve activity. Another assessment of sympathetic transduction was developed by Wallin and Nerhed in 1982, where alterations in blood pressure and heart rate were assessed immediately following bursts of muscle sympathetic nerve activity at rest. This approach has since been characterized and further innovated by others, including the breakdown of consecutive burst sequences (e.g., singlet, doublet, triplet, and quadruplet), and burst height (quartile analysis) on specific vascular outcomes (e.g., blood pressure, blood flow, vascular resistance). The purpose of this review is to provide an overview of the literature that has assessed sympathetic transduction using microneurography and various sympathetic stressors (static sympathetic transduction) and using the same or similar approach established by Wallin and Nerhed at rest (dynamic neurovascular transduction). Herein, we discuss the overlapping literature between these two methodologies and highlight the key physiological questions that remain.
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Affiliation(s)
- Michael M Tymko
- Neurovascular Health Lab, Faculty of Kinesiology, Sport, & Recreation, University of Alberta, Edmonton, Alberta, Canada
| | - Lindsey F Berthelsen
- Neurovascular Health Lab, Faculty of Kinesiology, Sport, & Recreation, University of Alberta, Edmonton, Alberta, Canada
| | - Rachel J Skow
- Neurovascular Health Lab, Faculty of Kinesiology, Sport, & Recreation, University of Alberta, Edmonton, Alberta, Canada
| | - Andrew R Steele
- Neurovascular Health Lab, Faculty of Kinesiology, Sport, & Recreation, University of Alberta, Edmonton, Alberta, Canada
| | - Graham M Fraser
- The Division of BioMedical Sciences, Faculty of Medicine, Memorial University of Newfoundland, St. John's, Newfoundland and Labrador, Canada
| | - Craig D Steinback
- Neurovascular Health Lab, Faculty of Kinesiology, Sport, & Recreation, University of Alberta, Edmonton, Alberta, Canada
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10
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Kaur J, Barbosa TC, Nandadeva D, Young BE, Stephens BY, Brothers RM, Fadel PJ. Attenuated Rapid-Onset Vasodilation to Forearm Muscle Contraction in Black Men. Med Sci Sports Exerc 2021; 53:590-596. [PMID: 32910095 PMCID: PMC7909956 DOI: 10.1249/mss.0000000000002511] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
PURPOSE Non-Hispanic Black individuals have a blunted ability to vasodilate at rest compared with other racial groups. Limited studies have investigated blood flow responses to exercise in Black individuals. Recently, our laboratory demonstrated that Black men exhibit attenuated increases in forearm vascular conductance (FVC) during steady-state rhythmic handgrip. The mechanisms for this remain unknown. Herein, we used single muscle contractions, a modality that allows for assessment of rapid-onset vasodilation (ROV) independent of major elevations in shear stress, tissue metabolism, and systemic hemodynamics. METHODS Ten young, healthy Black and White men performed single forearm contractions at 20%, 40%, and 60% maximal voluntary contraction (MVC). In addition, cuff inflations were performed on the forearm to examine the contribution of mechanical compression to ROV. Forearm blood flow (FBF; duplex Doppler ultrasound), heart rate (ECG), and mean arterial pressure (Finometer) were continuously measured. FVC was calculated as FBF/mean arterial pressure. RESULTS Baseline FVC (White men vs Black men, 0.75 ± 0.11 vs 0.80 ± 0.09 mL·min-1·mm Hg-1; P = 0.73), FBF, and MVCs (White men vs Black men, 54 ± 2 vs 54 ± 2 kg; P = 0.95) were similar between the groups. After single contractions, both groups exhibited intensity-dependent FVC and FBF increases during ROV; however, these responses were attenuated in the Black group at all intensities (e.g., 60%MVC FVC: White men vs Black men, +371% ± 37% vs +220% ± 23% baseline; P = 0.001). FVC and FBF responses to cuff inflation alone were also attenuated in Black individuals (P < 0.001). CONCLUSIONS Collectively, these data indicate that Black men have an overall blunted ability to rapidly vasodilate compared with young White men.
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Affiliation(s)
- Jasdeep Kaur
- Department of Kinesiology, University of Texas at Arlington, Arlington, TX
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11
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Holwerda SW, Carter JR, Yang H, Wang J, Pierce GL, Fadel PJ. CORP: Standardizing methodology for assessing spontaneous baroreflex control of muscle sympathetic nerve activity in humans. Am J Physiol Heart Circ Physiol 2021; 320:H762-H771. [PMID: 33275522 PMCID: PMC8082800 DOI: 10.1152/ajpheart.00704.2020] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/26/2020] [Revised: 11/24/2020] [Accepted: 11/24/2020] [Indexed: 12/28/2022]
Abstract
The use of spontaneous bursts of muscle sympathetic nerve activity (MSNA) to assess arterial baroreflex control of sympathetic nerve activity has seen increased utility in studies of both health and disease. However, methods used for analyzing spontaneous MSNA baroreflex sensitivity are highly variable across published studies. Therefore, we sought to comprehensively examine methods of producing linear regression slopes to quantify spontaneous MSNA baroreflex sensitivity in a large cohort of subjects (n = 150) to support a standardized procedure for analysis that would allow for consistent and comparable results across laboratories. The primary results demonstrated that 1) consistency of linear regression slopes was considerably improved when the correlation coefficient was above -0.70, which is more stringent compared with commonly reported criterion of -0.50, 2) longer recording durations increased the percentage of linear regressions producing correlation coefficients above -0.70 (1 min = 15%, 2 min = 28%, 5 min = 53%, 10 min = 67%, P < 0.001) and reaching statistical significance (1 min = 40%, 2 min = 69%, 5 min = 78%, 10 min = 89%, P < 0.001), 3) correlation coefficients were improved with 3-mmHg versus 1-mmHg and 2-mmHg diastolic blood pressure (BP) bin size, and 4) linear regression slopes were reduced when the acquired BP signal was not properly aligned with the cardiac cycle triggering the burst of MSNA. In summary, these results support the use of baseline recording durations of 10 min, a correlation coefficient above -0.70 for reliable linear regressions, 3-mmHg bin size, and importance of properly time-aligning MSNA and diastolic BP. Together, these findings provide best practices for determining spontaneous MSNA baroreflex sensitivity under resting conditions for improved rigor and reproducibility of results.
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Affiliation(s)
- Seth W Holwerda
- Department of Anesthesiology, University of Kansas Medical Center, Kansas City, Kansas
| | - Jason R Carter
- Department of Health and Human Development, Montana State University, Bozeman, Montana
| | - Huan Yang
- Department of Neurology, Beth Israel Deaconess Medical Center/Harvard Medical School, Boston, Massachusetts
| | - Jing Wang
- College of Nursing, University of Texas at Arlington, Arlington, Texas
| | - Gary L Pierce
- Department of Health and Human Physiology, University of Iowa, Iowa City, Iowa
| | - Paul J Fadel
- Department of Kinesiology, University of Texas at Arlington, Arlington, Texas
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12
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Nardone M, Incognito AV, Teixeira AL, Cacoilo JA, Vianna LC, Millar PJ. Effects of muscle sympathetic burst size and burst pattern on time-to-peak sympathetic transduction. Appl Physiol Nutr Metab 2021; 46:790-796. [PMID: 33428519 DOI: 10.1139/apnm-2020-0721] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
The current study evaluated the influence of resting muscle sympathetic nerve activity (MSNA) burst size and firing pattern on time-to-peak sympathetic transduction in 36 young healthy men and women. Participants underwent a 5-10 min resting baseline with beat-to-beat measures of heart rate, mean arterial pressure (MAP), and MSNA (microneurography). Cardiac output and total vascular conductance were calculated using the Modelflow algorithm. Sympathetic transduction was quantified using the burst-triggered signal averaging technique to examine the changes in MAP, cardiac output, and total vascular conductance for 15 cardiac cycles after each MSNA burst or non-burst. A stepwise increase in the peak MAP (i.e., sympathetic transduction) was observed throughout all quartiles of normalized MSNA burst area (quartile 1 (Q1): 1.7 ± 1.3 mm Hg; Q2: 2.1 ± 1.3 mm Hg; Q3: 2.6 ± 1.4 mm Hg; Q4: 3.5 ± 1.4 mm Hg; P < 0.01). The largest quartile of normalized MSNA burst area demonstrated faster time-to-peak MAP responses (5.7 ± 2.5 s) than both Q1 (10.1 ± 3.9 s, P < 0.01) and Q2 (9.3 ± 4.1 s, P < 0.01), as well as, faster time-to-peak cardiac output and time-to-nadir total vascular conductance compared with Q1 and Q2 (All P < 0.05). Larger clusters of sympathetic bursts (i.e., triplets and ≥ quadruplets) did not have increased time-to-peak transduction compared with singlets and doublet bursts across all MSNA quartiles. These results highlight intraindividual variability in the time-course of sympathetic transduction and reveal an intrinsic property of larger sympathetic bursts to increase time-to-peak sympathetic transduction in humans. Novelty: Muscle sympathetic burst size can modulate time-to-peak sympathetic transduction in young healthy men and women. These observations appear independent of the pattern of sympathetic firing.
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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
| | - André L Teixeira
- Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, Ontario, Canada
| | - Joseph A Cacoilo
- Department of Kinesiology, University of Guelph-Humber, Toronto, Canada
| | - Lauro C Vianna
- NeurȯVAṠQ - Integrative Physiology Laboratory, Faculty of Physical Education, University of Brasília, Brasília, Distrito Federal, 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
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13
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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.
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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
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14
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Peace A, Pinna V, Timmen F, Speretta G, Jones H, Lotto R, Jones I, Thijssen D. Role of Blood Pressure in Mediating Carotid Artery Dilation in Response to Sympathetic Stimulation in Healthy, Middle-Aged Individuals. Am J Hypertens 2020; 33:146-153. [PMID: 31560753 DOI: 10.1093/ajh/hpz159] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2019] [Revised: 09/07/2019] [Accepted: 09/20/2019] [Indexed: 11/14/2022] Open
Abstract
OBJECTIVES Carotid artery diameter responses to sympathetic stimulation, i.e., carotid artery reactivity (CAR), represent a novel test of vascular health and relates to cardiovascular disease (CVD)/risk. This study aims to understand the relationship between the increase in blood pressure and carotid artery diameter response during the CAR-test in healthy, middle-aged men. METHODS Sample consisted of 40 normotensive men (aged 31-59 years) with no history of CVD of currently taking medication. Noninvasive ultrasound was used to measure carotid artery diameter during the cold pressor test (CPT), with CAR% being calculated as the relative change from baseline (%). Mean arterial pressure (MAP) was measured with beat-to-beat blood pressure recording. RESULTS CAR% was 4.4 ± 5.4%, peaking at 92 ± 43 seconds. MAP increased from 88 ± 9 mmHg to 110 ± 15 mmHg, peaked at 112 ± 38 seconds, which was significantly later than the diameter peak (P = 0.04). The correlation between resting MAP and CAR% was weak (r = 0.209 P = 0.197). Tertiles based on resting MAP or MAP-increase revealed no significant differences between groups in subject characteristics including age, body mass index, or CAR% (all P > 0.05). Subgroup analysis of individuals with carotid constriction (n = 6) vs. dilation (n = 34), revealed no significant difference in resting MAP or increase in MAP (P = 0.209 and 0.272, respectively). CONCLUSION Our data suggest that the characteristic increase in MAP during the CPT does not mediate carotid artery vasomotion.
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Affiliation(s)
- Arron Peace
- Faculty of Education, Health and Community, Liverpool John Moores University, Liverpool, UK
- Research Institute for Sport and Exercise Sciences, Liverpool John Moores University, Liverpool, UK
| | - Virginia Pinna
- Research Institute for Sport and Exercise Sciences, Liverpool John Moores University, Liverpool, UK
- Department of Physiology, Radboudumc, Nijmegen, The Netherlands
- Department of Medical Sciences and Public Health, Sports Physiology Lab, University of Cagliari, Cagliari, Italy
| | - Friso Timmen
- Research Institute for Sport and Exercise Sciences, Liverpool John Moores University, Liverpool, UK
- Department of Physiology, Radboudumc, Nijmegen, The Netherlands
| | - Guillherme Speretta
- Research Institute for Sport and Exercise Sciences, Liverpool John Moores University, Liverpool, UK
- Department of Physiological Sciences, Biological Sciences Centre, Federal University of Santa Catarina (UFSC), Florianópolis, SC, Brazil
| | - Helen Jones
- Research Institute for Sport and Exercise Sciences, Liverpool John Moores University, Liverpool, UK
| | - Robyn Lotto
- Faculty of Education, Health and Community, Liverpool John Moores University, Liverpool, UK
| | - Ian Jones
- Faculty of Education, Health and Community, Liverpool John Moores University, Liverpool, UK
| | - Dick Thijssen
- Research Institute for Sport and Exercise Sciences, Liverpool John Moores University, Liverpool, UK
- Department of Physiology, Radboudumc, Nijmegen, The Netherlands
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15
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Limberg JK, Casey DP, Trinity JD, Nicholson WT, Wray DW, Tschakovsky ME, Green DJ, Hellsten Y, Fadel PJ, Joyner MJ, Padilla J. Assessment of resistance vessel function in human skeletal muscle: guidelines for experimental design, Doppler ultrasound, and pharmacology. Am J Physiol Heart Circ Physiol 2019; 318:H301-H325. [PMID: 31886718 DOI: 10.1152/ajpheart.00649.2019] [Citation(s) in RCA: 84] [Impact Index Per Article: 16.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
The introduction of duplex Doppler ultrasound almost half a century ago signified a revolutionary advance in the ability to assess limb blood flow in humans. It is now widely used to assess blood flow under a variety of experimental conditions to study skeletal muscle resistance vessel function. Despite its pervasive adoption, there is substantial variability between studies in relation to experimental protocols, procedures for data analysis, and interpretation of findings. This guideline results from a collegial discussion among physiologists and pharmacologists, with the goal of providing general as well as specific recommendations regarding the conduct of human studies involving Doppler ultrasound-based measures of resistance vessel function in skeletal muscle. Indeed, the focus is on methods used to assess resistance vessel function and not upstream conduit artery function (i.e., macrovasculature), which has been expertly reviewed elsewhere. In particular, we address topics related to experimental design, data collection, and signal processing as well as review common procedures used to assess resistance vessel function, including postocclusive reactive hyperemia, passive limb movement, acute single limb exercise, and pharmacological interventions.
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Affiliation(s)
- Jacqueline K Limberg
- Department of Nutrition and Exercise Physiology, University of Missouri, Columbia, Missouri
| | - Darren P Casey
- Department of Physical Therapy and Rehabilitation Science, Carver College of Medicine, University of Iowa, Iowa City, Iowa.,François M. Abboud Cardiovascular Research Center, Carver College of Medicine, University of Iowa, Iowa City, Iowa.,Fraternal Order of Eagles Diabetes Research, Carver College of Medicine, University of Iowa, Iowa City, Iowa
| | - Joel D Trinity
- Geriatric Research, Education, and Clinical Center, Veterans Affairs Medical Center, Salt Lake City, Utah.,Department of Internal Medicine, Division of Geriatrics, University of Utah, Salt Lake City, Utah.,Department of Nutrition and Integrative Physiology, University of Utah, Salt Lake City, Utah
| | | | - D Walter Wray
- Geriatric Research, Education, and Clinical Center, Veterans Affairs Medical Center, Salt Lake City, Utah.,Department of Internal Medicine, Division of Geriatrics, University of Utah, Salt Lake City, Utah.,Department of Nutrition and Integrative Physiology, University of Utah, Salt Lake City, Utah
| | - Michael E Tschakovsky
- School of Kinesiology and Health Studies, Queen's University, Kingston, Ontario, Canada
| | - Daniel J Green
- School of Human Sciences (Exercise and Sport Science), University of Western Australia, Perth, Western Australia, Australia
| | - Ylva Hellsten
- Department of Nutrition, Exercise and Sports, University of Copenhagen, Copenhagen, Denmark
| | - Paul J Fadel
- Department of Kinesiology, University of Texas at Arlington, Arlington, Texas
| | | | - Jaume Padilla
- Department of Nutrition and Exercise Physiology, University of Missouri, Columbia, Missouri.,Dalton Cardiovascular Research Center, University of Missouri, Columbia, Missouri
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16
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Nardone M, Miner S, McCarthy M, Ardern CI, Edgell H. Noninvasive Microvascular Indices Reveal Peripheral Vascular Abnormalities in Patients With Suspected Coronary Microvascular Dysfunction. Can J Cardiol 2019; 36:1289-1297. [PMID: 32553821 DOI: 10.1016/j.cjca.2019.12.003] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2019] [Revised: 12/03/2019] [Accepted: 12/03/2019] [Indexed: 12/27/2022] Open
Abstract
BACKGROUND Reactive hyperemia peripheral arterial tonometry and flow-mediated dilation are common noninvasive measures of peripheral vascular function. However, their relationship with the coronary circulation, particularly in coronary microvascular dysfunction (CMD), is unclear. Therefore, the purpose of this study is to compare these noninvasive measurements with coronary microvascular function after endothelial-independent, endothelial-dependent, and sympathetically mediated pharmacologic hyperemia. METHODS Forty-seven patients with suspected CMD completed peripheral and coronary assessments. The reactive hyperemia index was collected using the EndoPAT2000 device, whereas a subset of patients (n = 28) completed brachial artery flow-mediated dilation using duplex ultrasound. Coronary microvascular function was quantified using the resistance and flow responses to intravenous adenosine (140 μg/kg/min), dobutamine (40 μg/kg/min), and intracoronary acetylcholine (100 μg). Abnormal coronary microvascular responses to adenosine and/or acetylcholine were used to define CMD. RESULTS The reactive hyperemia index (No CMD: 0.85 ± 0.23 vs CMD: 0.61 ± 0.26, P < 0.05) and flow-mediated dilation (No CMD: 7.2 ± 2.3 vs CMD: 4.8 ± 3.1; P < 0.05) were attenuated in patients with CMD. Whereas the reactive hyperemia index was correlated with the resistance and flow responses to dobutamine (ρ = -0.44 and ρ = 0.39, respectively; P < 0.05), flow-mediated dilation was correlated with the resistance responses to both adenosine (ρ = -0.48; P < 0.05) and acetylcholine (ρ = -0.66; P < 0.05). Lastly, the reactive hyperemia index and flow-mediated dilation had sensitivities of 80% and 69% and specificities of 71% and 93%, respectively, for identifying patients with CMD. CONCLUSIONS Peripheral vascular function is attenuated in CMD, and noninvasive measurements are associated with coronary responses to pharmaceutical stimulation.
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Affiliation(s)
- Massimo Nardone
- School of Kinesiology and Health Science, York University, Toronto, Ontario, Canada
| | - Steven Miner
- School of Kinesiology and Health Science, York University, Toronto, Ontario, Canada; Southlake Regional Health Centre, Newmarket, Ontario, Canada
| | - Mary McCarthy
- Southlake Regional Health Centre, Newmarket, Ontario, Canada
| | - Chris I Ardern
- School of Kinesiology and Health Science, York University, Toronto, Ontario, Canada
| | - Heather Edgell
- School of Kinesiology and Health Science, York University, Toronto, Ontario, Canada; Southlake Regional Health Centre, Newmarket, Ontario, Canada.
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17
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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.
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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
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18
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Young BE, Holwerda SW, Vranish JR, Keller DM, Fadel PJ. Sympathetic Transduction in Type 2 Diabetes Mellitus. Hypertension 2019; 74:201-207. [PMID: 31188673 DOI: 10.1161/hypertensionaha.119.12928] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Approximately 60% of patients with type 2 diabetes mellitus (T2D) develop hypertension. Recent work also indicates greater blood pressure (BP) excursions throughout the day in T2D. Collectively, these findings suggest altered BP control in T2D. Although muscle sympathetic nerve activity (MSNA) recordings in T2D have provided equivocal results, quantification of MSNA alone does not account for ensuing vasoconstriction and BP responses elicited by MSNA. Thus, we tested the hypothesis that patients with T2D exhibit enhanced sympathetic transduction to BP. MSNA (microneurography) and beat-to-beat BP (Finometer) were measured at rest in 21 T2D and 13 age-matched and body mass index-matched control subjects and, signal-averaging was performed to quantify the mean arterial pressure and total vascular conductance responses to spontaneous bursts of MSNA. The peak mean arterial pressure and total vascular conductance responses to spontaneous MSNA were similar between T2D and control (both P>0.05). However, further analysis, separating T2D into those taking statins (n=13, T2D +statin) and not taking statins (n=8, T2D -statin), indicated that T2D -statin patients (4.2±0.6 mm Hg) exhibited greater peak mean arterial pressure responses compared with both T2D +statin patients (2.5±0.3 mm Hg, P=0.01) and control (control: 2.8±0.3 mm Hg, P=0.02). Likewise, nadir total vascular conductance responses to spontaneous MSNA bursts were greater in T2D -statin patients (T2D -statin: -3.3±0.6 mL/(min·mm Hg), T2D +statin: -1.6±0.3 mL/(min·mm Hg), P=0.03; control -2.2±0.3 mL/(min·mm Hg), P=0.08). Notably, T2D +statin patients exhibited similar peak mean arterial pressure and total vascular conductance responses to MSNA compared with control. Collectively, these findings demonstrate, for the first time, that patients with T2D exhibit augmented sympathetic transduction and this effect seems to be offset by statin therapy.
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Affiliation(s)
- Benjamin E Young
- From the Department of Kinesiology, University of Texas at Arlington (B.E.Y., D.M.K., P.J.F.)
| | - Seth W Holwerda
- Department of Health and Human Physiology, University of Iowa (S.W.H.)
| | - Jennifer R Vranish
- Department of Integrative Physiology and Health Science, Alma College, MI (J.R.V.)
| | - David M Keller
- From the Department of Kinesiology, University of Texas at Arlington (B.E.Y., D.M.K., P.J.F.)
| | - Paul J Fadel
- From the Department of Kinesiology, University of Texas at Arlington (B.E.Y., D.M.K., P.J.F.)
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19
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Kaur J, Vranish JR, Barbosa TC, Washio T, Young BE, Stephens BY, Brothers RM, Ogoh S, Fadel PJ. Regulation of Regional Cerebral Blood Flow During Graded Reflex-Mediated Sympathetic Activation via Lower Body Negative Pressure. J Appl Physiol (1985) 2018; 125:1779-1786. [PMID: 30188801 PMCID: PMC10392631 DOI: 10.1152/japplphysiol.00623.2018] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The role of the sympathetic nervous system in cerebral blood flow (CBF) regulation remains unclear. Previous studies have primarily measured middle cerebral artery blood velocity to assess CBF. Recently, there has been a transition towards measuring internal carotid artery (ICA) and vertebral artery (VA) blood flow using duplex Doppler ultrasound. Given that the VA supplies autonomic control centers in the brainstem, we hypothesized that graded sympathetic activation via lower body negative pressure (LBNP) would reduce ICA but not VA blood flow. ICA and VA blood flow were measured during two protocols: Protocol-1, low-to-moderate LBNP (-10, -20, -30, -40 Torr) and Protocol-2, moderate-to-high LBNP (-30, -50, -70 Torr). ICA and VA blood flow, diameter, and blood velocity were unaffected up to -40 LBNP. However, -50 and -70 LBNP evoked reductions in ICA and VA blood flow (e.g., -70 LBNP: %∆VA-baseline= -27.6±3.0) that were mediated by decreases in both diameter and velocity (e.g., -70 LBNP: %∆VA-baseline diameter= -7.5±1.9 and %∆VA-baseline velocity= -13.6±1.7), which were comparable between vessels. Since hyperventilation during -70 LBNP reduced PETCO2, this decrease in PETCO2 was matched via voluntary hyperventilation. Reductions in ICA and VA blood flow during hyperventilation alone were significantly smaller than during -70 LBNP and were primarily mediated by decreases in velocity (%∆VA-baseline velocity= -8.6±2.4; %∆VA-baseline diameter= -0.05±0.56). These data demonstrate that both ICA and VA were unaffected by low-to-moderate sympathetic activation, whereas robust reflex-mediated sympatho-excitation caused similar magnitudes of vasoconstriction in both arteries. Thus, contrary to our hypothesis, the ICA was not preferentially vasoconstricted by sympathetic activation.
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Affiliation(s)
- Jasdeep Kaur
- Department of Kinesiology, University of Texas at Arlington, United States
| | - Jennifer R Vranish
- Department of Kinesiology, University of Texas at Arlington, United States
| | - Thales C Barbosa
- Department of Kinesiology, University of Texas at Arlington, United States
| | - Takuro Washio
- Department of Biomedical Engineering, Toyo University
| | | | | | | | - Shigehiko Ogoh
- Department of Biomedical Engineering, Toyo University, Japan
| | - Paul J Fadel
- Department of Kinesiology, University of Texas at Arlington, United States
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20
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Holwerda SW, Luehrs RE, Gremaud AL, Wooldridge NA, Stroud AK, Fiedorowicz JG, Abboud FM, Pierce GL. Relative burst amplitude of muscle sympathetic nerve activity is an indicator of altered sympathetic outflow in chronic anxiety. J Neurophysiol 2018. [PMID: 29537916 DOI: 10.1152/jn.00064.2018] [Citation(s) in RCA: 40] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Relative burst amplitude of muscle sympathetic nerve activity (MSNA) is an indicator of augmented sympathetic outflow and contributes to greater vasoconstrictor responses. Evidence suggests anxiety-induced augmentation of relative MSNA burst amplitude in patients with panic disorder; thus we hypothesized that acute stress would result in augmented relative MSNA burst amplitude and vasoconstriction in individuals with chronic anxiety. Eighteen participants with chronic anxiety (ANX; 8 men, 10 women, 32 ± 2 yr) and 18 healthy control subjects with low or no anxiety (CON; 8 men, 10 women, 39 ± 3 yr) were studied. Baseline MSNA and 24-h blood pressure were similar between ANX and CON ( P > 0.05); however, nocturnal systolic blood pressure % dipping was blunted among ANX ( P = 0.02). Relative MSNA burst amplitude was significantly greater among ANX compared with CON immediately preceding (anticipation) and during physiological stress [2-min cold pressor test; ANX: 73 ± 5 vs. CON: 59 ± 3% arbitrary units (AU), P = 0.03] and mental stress (4-min mental arithmetic; ANX: 65 ± 3 vs. CON: 54 ± 3% AU, P = 0.02). Increases in MSNA burst frequency, incidence, and total activity in response to stress were not augmented among ANX compared with CON ( P > 0.05), and reduction in brachial artery conductance during cold stress was similar between ANX and CON ( P = 0.92). Relative MSNA burst amplitude during mental stress was strongly correlated with state ( P < 0.01) and trait ( P = 0.01) anxiety (State-Trait Anxiety Inventory), independent of age, sex, and body mass index. Thus in response to acute stress, both mental and physiological, individuals with chronic anxiety demonstrate selective augmentation in relative MSNA burst amplitude, indicating enhanced sympathetic drive in a population with higher risk for cardiovascular disease. NEW & NOTEWORTHY Relative burst amplitude of muscle sympathetic nerve activity in response to acute mental and physiological stress is selectively augmented in individuals with chronic anxiety, which is a prevalent condition that is associated with the development of cardiovascular disease. Augmented sympathetic burst amplitude occurs with chronic anxiety in the absence of common comorbidities. These findings provide important insight into the relation between anxiety, acute stress and sympathetic activation.
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Affiliation(s)
- Seth W Holwerda
- Department of Health and Human Physiology, University of Iowa , Iowa City, Iowa.,Abboud Cardiovascular Research Center, University of Iowa , Iowa City, Iowa
| | - Rachel E Luehrs
- Department of Health and Human Physiology, University of Iowa , Iowa City, Iowa
| | - Allene L Gremaud
- Department of Health and Human Physiology, University of Iowa , Iowa City, Iowa
| | - Nealy A Wooldridge
- Department of Health and Human Physiology, University of Iowa , Iowa City, Iowa
| | - Amy K Stroud
- Department of Psychiatry, University of Iowa , Iowa City, Iowa
| | - Jess G Fiedorowicz
- Department of Psychiatry, University of Iowa , Iowa City, Iowa.,Department of Epidemiology, University of Iowa , Iowa City, Iowa.,Department of Internal Medicine, University of Iowa , Iowa City, Iowa.,Abboud Cardiovascular Research Center, University of Iowa , Iowa City, Iowa
| | - Francois M Abboud
- Department of Internal Medicine, University of Iowa , Iowa City, Iowa.,Department of Molecular Physiology and Biophysics, University of Iowa , Iowa City, Iowa.,Abboud Cardiovascular Research Center, University of Iowa , Iowa City, Iowa
| | - Gary L Pierce
- Department of Health and Human Physiology, University of Iowa , Iowa City, Iowa.,Abboud Cardiovascular Research Center, University of Iowa , Iowa City, Iowa.,Fraternal Order of Eagles Diabetes Research Center, University of Iowa , Iowa City, Iowa
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21
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Credeur DP, Reynolds LJ, Holwerda SW, Vranish JR, Young BE, Wang J, Thyfault JP, Fadel PJ. Influence of physical inactivity on arterial compliance during a glucose challenge. Exp Physiol 2018; 103:483-494. [PMID: 29315921 DOI: 10.1113/ep086713] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2017] [Accepted: 01/05/2018] [Indexed: 12/26/2022]
Abstract
NEW FINDINGS What is the central question of this study? To understand better the effects of acute hyperglycaemia on arterial stiffness in healthy young individuals, we assessed arterial stiffness in physically active men before and after reduced ambulatory physical activity to decrease insulin sensitivity. What is the main finding and its importance? During an oral glucose tolerance test, we identified an increase in leg arterial stiffness (i.e. reduced femoral artery compliance) only when subjects were inactive for 5 days (<5000 steps day-1 ) and not when they were engaging in regular physical activity (>10,000 steps day-1 ). These results demonstrate the deleterious consequence of acute reductions in daily physical activity on the response of the peripheral vasculature to acute hyperglycaemia. ABSTRACT Acute hyperglycaemia has been shown to augment indices of arterial stiffness in patients with insulin resistance and other co-morbidities; however, conflicting results exist in healthy young individuals. We examined whether acute hyperglycaemia after an oral glucose tolerance test (OGTT) increases arterial stiffness in healthy active men before and after reduced ambulatory physical activity to decrease insulin sensitivity. High-resolution arterial diameter traces acquired from Doppler ultrasound allowed an arterial blood pressure (BP) waveform to be obtained from the diameter trace within a cardiac cycle. In 24 subjects, this method demonstrated sufficient agreement with the traditional approach for assessing arterial compliance using applanation tonometry. In 10 men, continuous recordings of femoral and brachial artery diameter and beat-to-beat BP (Finometer) were acquired at rest, 60 and 120 min of an OGTT before and after 5 days of reduced activity (from >10,000 to <5000 steps day-1 ). Compliance and β-stiffness were quantified. Before the reduction in activity, the OGTT had no effect on arterial compliance or β-stiffness. However, after the reduction in activity, femoral compliance was decreased (rest, 0.10 ± 0.03 mm2 mmHg-1 versus 120 min OGTT, 0.06 ± 0.02 mm2 mmHg-1 ; P < 0.001) and femoral β-stiffness increased (rest, 8.7 ± 2.7 a.u. versus 120 min OGTT, 15.3 ± 6.5 a.u.; P < 0.001) during OGTT, whereas no changes occurred in brachial artery compliance (P = 0.182) or stiffness (P = 0.892). Insulin sensitivity (Matsuda index) was decreased after the reduction in activity (P = 0.002). In summary, in young healthy men the femoral artery becomes susceptible to acute hyperglycaemia after 5 days of reduced activity and the resultant decrease in insulin sensitivity, highlighting the strong influence of daily physical activity levels on vascular physiology.
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Affiliation(s)
- Daniel P Credeur
- School of Kinesiology, University of Southern Mississippi, Hattiesburg, MS, USA
| | - Leryn J Reynolds
- Department of Human Movement Sciences, Old Dominion University, Norfolk, VA, USA
| | - Seth W Holwerda
- Department of Health and Human Physiology, University of Iowa, Iowa City, IA, USA
| | - Jennifer R Vranish
- Department of Kinesiology, University of Texas at Arlington, Arlington, TX, USA
| | - Benjamin E Young
- Department of Kinesiology, University of Texas at Arlington, Arlington, TX, USA
| | - Jing Wang
- College of Nursing, University of Texas at Arlington, Arlington, TX, USA
| | - John P Thyfault
- Department of Molecular and Integrative Physiology, University of Kansas Medical Center, Kansas City, KS, USA
| | - Paul J Fadel
- Department of Kinesiology, University of Texas at Arlington, Arlington, TX, USA
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22
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Vranish JR, Holwerda SW, Young BE, Credeur DP, Patik JC, Barbosa TC, Keller DM, Fadel PJ. Exaggerated Vasoconstriction to Spontaneous Bursts of Muscle Sympathetic Nerve Activity in Healthy Young Black Men. Hypertension 2017; 71:192-198. [PMID: 29203629 DOI: 10.1161/hypertensionaha.117.10229] [Citation(s) in RCA: 72] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2017] [Revised: 09/05/2017] [Accepted: 09/22/2017] [Indexed: 12/16/2022]
Abstract
Blacks have the highest prevalence of hypertension, putting them at greater risk of cardiovascular disease and death. Previous studies have reported that, relative to whites, healthy black men have augmented pressor responses to sympathoexcitatory stressors. Although important, these studies do not inform about the resting state and the influence of spontaneous changes in resting muscle sympathetic nerve activity (MSNA). Likewise, little is known about the transduction of MSNA into a vascular response at rest on a beat-to-beat basis. Accordingly, we tested the hypothesis that relative to whites, blacks would exhibit greater vasoconstriction and pressor responses following spontaneous bursts of MSNA. Mean arterial pressure, common femoral artery blood flow, and MSNA were continuously recorded during 20 minutes of supine rest in 35 young healthy men (17 blacks and 18 whites). Signal averaging was used to characterize changes in leg vascular conductance, total vascular conductance, and mean arterial pressure following spontaneous MSNA bursts. Blacks demonstrated significantly greater decreases in leg vascular conductance (blacks: -15.0±1.0%; whites: -11.5±1.2%; P=0.042) and total vascular conductance (blacks: -8.6±0.9%; whites: -5.1±0.4%; P=0.001) following MSNA bursts, which resulted in greater mean arterial pressure increases (blacks: +5.2±0.6 mm Hg; whites: +3.9±0.3 mm Hg; P=0.04). These exaggerated responses in blacks compared with whites were present whether MSNA bursts occurred in isolation (singles) or in combination (multiples) and were graded with increases in burst height. Collectively, these findings suggest that healthy young black men exhibit augmented sympathetic vascular transduction at rest and provide novel insight into potential mechanism(s) by which this population may develop hypertension later in life.
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Affiliation(s)
- Jennifer R Vranish
- From the Department of Kinesiology, University of Texas at Arlington (J.R.V., B.E.Y., J.C.P., T.C.B., D.M.K., P.J.F.); School of Kinesiology, University of Southern Mississippi, Hattiesburg (D.P.C.); and Department of Health and Human Physiology, University of Iowa, Iowa City (S.W.H.)
| | - Seth W Holwerda
- From the Department of Kinesiology, University of Texas at Arlington (J.R.V., B.E.Y., J.C.P., T.C.B., D.M.K., P.J.F.); School of Kinesiology, University of Southern Mississippi, Hattiesburg (D.P.C.); and Department of Health and Human Physiology, University of Iowa, Iowa City (S.W.H.)
| | - Benjamin E Young
- From the Department of Kinesiology, University of Texas at Arlington (J.R.V., B.E.Y., J.C.P., T.C.B., D.M.K., P.J.F.); School of Kinesiology, University of Southern Mississippi, Hattiesburg (D.P.C.); and Department of Health and Human Physiology, University of Iowa, Iowa City (S.W.H.)
| | - Daniel P Credeur
- From the Department of Kinesiology, University of Texas at Arlington (J.R.V., B.E.Y., J.C.P., T.C.B., D.M.K., P.J.F.); School of Kinesiology, University of Southern Mississippi, Hattiesburg (D.P.C.); and Department of Health and Human Physiology, University of Iowa, Iowa City (S.W.H.)
| | - Jordan C Patik
- From the Department of Kinesiology, University of Texas at Arlington (J.R.V., B.E.Y., J.C.P., T.C.B., D.M.K., P.J.F.); School of Kinesiology, University of Southern Mississippi, Hattiesburg (D.P.C.); and Department of Health and Human Physiology, University of Iowa, Iowa City (S.W.H.)
| | - Thales C Barbosa
- From the Department of Kinesiology, University of Texas at Arlington (J.R.V., B.E.Y., J.C.P., T.C.B., D.M.K., P.J.F.); School of Kinesiology, University of Southern Mississippi, Hattiesburg (D.P.C.); and Department of Health and Human Physiology, University of Iowa, Iowa City (S.W.H.)
| | - David M Keller
- From the Department of Kinesiology, University of Texas at Arlington (J.R.V., B.E.Y., J.C.P., T.C.B., D.M.K., P.J.F.); School of Kinesiology, University of Southern Mississippi, Hattiesburg (D.P.C.); and Department of Health and Human Physiology, University of Iowa, Iowa City (S.W.H.)
| | - Paul J Fadel
- From the Department of Kinesiology, University of Texas at Arlington (J.R.V., B.E.Y., J.C.P., T.C.B., D.M.K., P.J.F.); School of Kinesiology, University of Southern Mississippi, Hattiesburg (D.P.C.); and Department of Health and Human Physiology, University of Iowa, Iowa City (S.W.H.).
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23
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Vranish JR, Young BE, Kaur J, Patik JC, Padilla J, Fadel PJ. Influence of sex on microvascular and macrovascular responses to prolonged sitting. Am J Physiol Heart Circ Physiol 2017; 312:H800-H805. [PMID: 28130340 DOI: 10.1152/ajpheart.00823.2016] [Citation(s) in RCA: 72] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/14/2016] [Revised: 01/13/2017] [Accepted: 01/20/2017] [Indexed: 11/22/2022]
Abstract
Increased daily sitting time is associated with greater cardiovascular risk, and, on average, women are more sedentary than men. Recent reports have demonstrated that prolonged sitting reduces lower leg microvascular (reactive hyperemia) and macrovascular [flow-mediated dilation (FMD)] vasodilator function. However, these studies have predominately included men, and the effects of sitting in young women are largely unexplored. This becomes important given known sex differences in vascular function. Thus, herein, we assessed popliteal artery reactive hyperemia and FMD before and after a 3-h sitting period in healthy young women (n = 12) and men (n = 8). In addition, resting popliteal artery hemodynamics (duplex Doppler ultrasound) and calf circumference were measured before, during, and after sitting. Resting popliteal artery shear rate was reduced to a similar extent in both groups during the sitting period (women: -48.5 ± 8.4 s-1 and men: -52.9 ± 12.3 s-1, P = 0.45). This was accompanied by comparable increases in calf circumference in men and women (P = 0.37). After the sitting period, popliteal artery FMD was significantly reduced in men (PreSit: 5.5 ± 0.9% and PostSit: 1.6 ± 0.4%, P < 0.001) but not women (PreSit: 4.4 ± 0.6% and PostSit: 3.6 ± 0.6%, P = 0.29). In contrast, both groups demonstrated similar reductions in hyperemic blood flow area under the curve (women: -28,860 ± 5,742 arbitrary units and men: -28,691 ± 9,685 arbitrary units, P = 0.99), indicating impaired microvascular reactivity after sitting. These findings indicate that despite comparable reductions in shear rate during 3 h of uninterrupted sitting, macrovascular function appears protected in some young women but the response was variable, whereas men exhibited more consistent reductions in FMD. In contrast, the leg microvasculature is susceptible to similar sitting-induced impairments in men and women.NEW & NOTEWORTHY We demonstrate that leg macrovascular function was consistently reduced in young men but not young women after prolonged sitting. In contrast, both men and women exhibited similar reductions in leg microvascular reactivity after sitting. These data demonstrate, for the first time, sex differences in vascular responses to prolonged sitting.
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Affiliation(s)
- Jennifer R Vranish
- Department of Kinesiology, University of Texas at Arlington, Arlington, Texas; and
| | - Benjamin E Young
- Department of Kinesiology, University of Texas at Arlington, Arlington, Texas; and
| | - Jasdeep Kaur
- Department of Kinesiology, University of Texas at Arlington, Arlington, Texas; and
| | - Jordan C Patik
- Department of Kinesiology, University of Texas at Arlington, Arlington, Texas; and
| | - Jaume Padilla
- Nutrition and Exercise Physiology, University of Missouri, Columbia, Missouri
| | - Paul J Fadel
- Department of Kinesiology, University of Texas at Arlington, Arlington, Texas; and
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24
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Greaney JL, Matthews EL, Wenner MM. Sympathetic reactivity in young women with a family history of hypertension. Am J Physiol Heart Circ Physiol 2015; 308:H816-22. [PMID: 25681430 DOI: 10.1152/ajpheart.00867.2014] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/02/2014] [Accepted: 02/11/2015] [Indexed: 11/22/2022]
Abstract
Young adults with a family history of hypertension (+FH) have increased risk of developing hypertension. Furthermore, the blood pressure (BP) response to sympathoexcitatory stimuli in young adults can predict the future development of hypertension. Therefore, we hypothesized young women with a +FH would have exaggerated cardiovascular and sympathetic reactivity compared with young women without a family history of hypertension (-FH). Beat-by-beat mean arterial pressure (MAP) and muscle sympathetic nerve activity (MSNA) were measured in 14 women +FH (22 ± 1 yr, 21 ± 1 kg/m(2), MAP 80 ± 2 mmHg) and 15 women -FH (22 ± 1 yr, 22 ± 1 kg/m(2), MAP 78 ± 2 mmHg) during acute sympathoexcitatory maneuvers: cold pressor test, 2 min of isometric handgrip (HG) exercise at 30% of maximal voluntary contraction, and 3 min of postexercise ischemia (PEI; isolated activation of the skeletal muscle metaboreflex). During cold pressor test, the increase in BP was greater in women +FH (ΔMAP: +FH 16 ± 2 vs. -FH 11 ± 1 mmHg, P < 0.05), which was accompanied by an exaggerated increase in MSNA (ΔMSNA: +FH 17 ± 2 vs. -FH 8 ± 2 burst/min, P < 0.05). The increase in BP was greater in +FH during the last minute of HG (ΔMAP: +FH 23 ± 3 vs. -FH 12 ± 1 mmHg, P < 0.05) and during PEI (ΔMAP: +FH 17 ± 3 vs. -FH 9 ± 2 mmHg, P < 0.05). Similarly, the increase in MSNA was greater in +FH during both HG (ΔMSNA: +FH 12 ± 2 vs. -FH 6 ± 2 burst/min, P < 0.05) and PEI (ΔMSNA: +FH 16 ± 2 vs. -FH 4 ± 2 burst/min, P < 0.05). These data demonstrate that +FH women have greater BP and sympathetic reactivity compared with -FH women.
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Affiliation(s)
- Jody L Greaney
- Department of Kinesiology and Applied Physiology, University of Delaware, Newark, Delaware; and Department of Kinesiology, Noll Laboratory, The Pennsylvania State University, University Park, Pennsylvania
| | - Evan L Matthews
- Department of Kinesiology and Applied Physiology, University of Delaware, Newark, Delaware; and
| | - Megan M Wenner
- Department of Kinesiology and Applied Physiology, University of Delaware, Newark, Delaware; and
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25
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Credeur DP, Holwerda SW, Restaino RM, King PM, Crutcher KL, Laughlin MH, Padilla J, Fadel PJ. Characterizing rapid-onset vasodilation to single muscle contractions in the human leg. J Appl Physiol (1985) 2014; 118:455-64. [PMID: 25539935 DOI: 10.1152/japplphysiol.00785.2014] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Rapid-onset vasodilation (ROV) following single muscle contractions has been examined in the forearm of humans, but has not yet been characterized in the leg. Given known vascular differences between the arm and leg, we sought to characterize ROV following single muscle contractions in the leg. Sixteen healthy men performed random ordered single contractions at 5, 10, 20, 40, and 60% of their maximum voluntary contraction (MVC) using isometric knee extension made with the leg above and below heart level, and these were compared with single isometric contractions of the forearm (handgrip). Single thigh cuff compressions (300 mmHg) were utilized to estimate the mechanical contribution to leg ROV. Continuous blood flow was determined by duplex-Doppler ultrasound and blood pressure via finger photoplethysmography (Finometer). Single isometric knee extensor contractions produced intensity-dependent increases in peak leg vascular conductance that were significantly greater than the forearm in both the above- and below-heart level positions (e.g., above heart level: leg 20% MVC, +138 ± 28% vs. arm 20% MVC, +89 ± 17%; P < 0.05). Thigh cuff compressions also produced a significant hyperemic response, but these were brief and smaller in magnitude compared with single isometric contractions in the leg. Collectively, these data demonstrate the presence of a rapid and robust vasodilation to single muscle contractions in the leg that is largely independent of mechanical factors, thus establishing the leg as a viable model to study ROV in humans.
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Affiliation(s)
- Daniel P Credeur
- Department of Medical Pharmacology and Physiology, University of Missouri, Columbia, Missouri
| | - Seth W Holwerda
- Department of Medical Pharmacology and Physiology, University of Missouri, Columbia, Missouri
| | - Robert M Restaino
- Department of Medical Pharmacology and Physiology, University of Missouri, Columbia, Missouri
| | - Phillip M King
- Department of Medical Pharmacology and Physiology, University of Missouri, Columbia, Missouri
| | - Kiera L Crutcher
- Department of Medical Pharmacology and Physiology, University of Missouri, Columbia, Missouri
| | - M Harold Laughlin
- Department of Medical Pharmacology and Physiology, University of Missouri, Columbia, Missouri; Department of Biomedical Sciences, University of Missouri, Columbia, Missouri; Dalton Cardiovascular Research Center, University of Missouri, Columbia, Missouri
| | - Jaume Padilla
- Dalton Cardiovascular Research Center, University of Missouri, Columbia, Missouri; Department of Nutrition and Exercise Physiology, University of Missouri, Columbia, Missouri; and Department of Child Health, University of Missouri, Columbia, Missouri
| | - Paul J Fadel
- Department of Medical Pharmacology and Physiology, University of Missouri, Columbia, Missouri; Dalton Cardiovascular Research Center, University of Missouri, Columbia, Missouri;
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26
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Fairfax ST, Padilla J, Vianna LC, Holwerda SW, Davis MJ, Fadel PJ. Myogenic responses occur on a beat-to-beat basis in the resting human limb. Am J Physiol Heart Circ Physiol 2014; 308:H59-67. [PMID: 25362138 DOI: 10.1152/ajpheart.00609.2014] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
Investigations of human myogenic responses typically use maneuvers that evoke robust changes in transmural pressure. Although this strategy has demonstrated peripheral myogenic responsiveness in the limbs, particularly in glabrous skin of the hand or foot, it has not considered the potential influence of the myogenic mechanism in beat-to-beat blood flow (BF) control during unprovoked rest. In the present study, we examined the interactions of spontaneous beat-to-beat mean arterial pressure (MAP; Finapres) with BF (Doppler ultrasound) supplying the forearm (brachial artery), lower leg (popliteal artery), and hand (ulnar artery) during 10 min of supine rest in healthy young men. Cross-correlation analyses revealed a negative association between MAP and BF, which was more prominent in the forearm than lower leg. The strongest correlation resulted when a -2-heart beat offset of MAP was applied (R=-0.53±0.04 in the forearm and -0.23±0.05 in the leg, P<0.05), suggesting an ∼2-s delay from instances of high/low MAP to low/high BF. Negatively associated episodes (high MAP/low BF and low MAP/high BF) outnumbered positively associated data (P<0.05). BF during low MAP values was greater than the steady-state average BF and vice versa. Wrist and ankle occlusion blunted the strength of correlations, homogenized the incidence of MAP and BF pairings, and reduced the magnitude of deviation from steady-state values. In contrast, these relationships were matched or accentuated for hand BF. Overall, these results suggest that myogenic responses are present and occur rapidly in human limbs during rest, overwhelm perfusion pressure gradient influences, and are primarily mediated by the distal limb circulation.
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Affiliation(s)
- Seth T Fairfax
- Department of Biomedical Sciences, University of Missouri, Columbia, Missouri
| | - Jaume Padilla
- Department of Nutrition and Exercise Physiology, University of Missouri, Columbia, Missouri; Department of Child Health, University of Missouri, Columbia, Missouri; Dalton Cardiovascular Research Center, University of Missouri, Columbia, Missouri
| | - Lauro C Vianna
- Department of Physical Education, University of Brasilia, Brasilia, Brazil
| | - Seth W Holwerda
- Department of Medical Pharmacology and Physiology, University of Missouri, Columbia, Missouri; and
| | - Michael J Davis
- Dalton Cardiovascular Research Center, University of Missouri, Columbia, Missouri; Department of Medical Pharmacology and Physiology, University of Missouri, Columbia, Missouri; and
| | - Paul J Fadel
- Dalton Cardiovascular Research Center, University of Missouri, Columbia, Missouri; Department of Medical Pharmacology and Physiology, University of Missouri, Columbia, Missouri; and
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27
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Greaney JL, Stanhewicz AE, Kenney WL, Alexander LM. Muscle sympathetic nerve activity during cold stress and isometric exercise in healthy older adults. J Appl Physiol (1985) 2014; 117:648-57. [PMID: 25103970 DOI: 10.1152/japplphysiol.00516.2014] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
Cardiovascular mortality increases in cold weather in older adults, and physical activity may impart even greater cardiovascular risk than cold exposure alone. Human aging is associated with exaggerated pressor responses to whole body cooling; however, the sympathetic response to cold stress alone and in combination with isometric exercise is unknown. We hypothesized that cold stress would 1) increase muscle sympathetic nerve activity (MSNA) and 2) augment the MSNA response to isometric handgrip in older adults. Whole body cooling (water-perfused suit) was conducted in 11 young (23 ± 1 yr) and 12 healthy older adults (60 ± 2 yr). Blood pressure (BP; Finometer) and MSNA (microneurography) were measured throughout cooling and during isometric handgrip at 30% maximal voluntary contraction performed at a mean skin temperature (Tsk) of 34 and 30.5°C. MSNA was greater in older adults at Tsk = 34.0°C and throughout cooling (P < 0.05). MSNA increased during cooling in older, but not young, adults (young: Δ0 ± 1 vs. older: Δ8 ± 1 bursts/min; P < 0.05). The cooling-induced increase in BP was greater in older adults (P < 0.05). During handgrip, the increases in MSNA and BP were not different between conditions in either young (Δ14 ± 2 Tsk 34°C vs. Δ12 ± 3 Tsk 30.5°C bursts/min; Δ20 ± 3 Tsk 34°C vs. Δ19 ± 3 Tsk 30.5°C mmHg; both P > 0.05) or older adults (Δ12 ± 1 Tsk 34°C vs. Δ8 ± 1 Tsk 30.5°C bursts/min; Δ18 ± 3 Tsk 34°C vs. Δ17 ± 2 Tsk 30.5°C mmHg; both P > 0.05). In summary, MSNA increased during cold stress in older, but not young, adults. Furthermore, concomitant cold stress did not alter the sympathetic responses to isometric exercise in either age group, suggesting preserved sympathetic responsiveness during exercise in the cold in healthy aging.
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Affiliation(s)
- Jody L Greaney
- Department of Kinesiology, Noll Laboratory, The Pennsylvania State University, University Park, Pennsylvania
| | - Anna E Stanhewicz
- Department of Kinesiology, Noll Laboratory, The Pennsylvania State University, University Park, Pennsylvania
| | - W Larry Kenney
- Department of Kinesiology, Noll Laboratory, The Pennsylvania State University, University Park, Pennsylvania
| | - Lacy M Alexander
- Department of Kinesiology, Noll Laboratory, The Pennsylvania State University, University Park, Pennsylvania
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