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McMillan NJ, Jacob DW, Shariffi B, Harper JL, Foster GE, Manrique-Acevedo C, Padilla J, Limberg JK. Effect of acute intranasal insulin administration on muscle sympathetic nerve activity in healthy young adults. Am J Physiol Heart Circ Physiol 2024; 327:H000. [PMID: 38787381 DOI: 10.1152/ajpheart.00253.2024] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/22/2024] [Revised: 05/14/2024] [Accepted: 05/23/2024] [Indexed: 05/25/2024]
Abstract
Systemic insulin increases muscle sympathetic nerve activity (MSNA) via both central actions within the brainstem and peripheral activation of the arterial baroreflex. Augmented MSNA during hyperinsulinemia likely restrains peripheral vasodilation and contributes to the maintenance of blood pressure (BP). However, in the absence of insulin action within the peripheral vasculature, whether central insulin stimulation increases MSNA and influences peripheral hemodynamics in humans remains unknown. Herein, we hypothesized intranasal insulin administration would increase MSNA and BP in healthy young adults. Participants were assigned to time control [TC, n = 13 (5 females/8 males), 28 ± 1 yr] or 160 IU of intranasal insulin administered over 5 min [n = 15 (5 females/10 males), 26 ± 2 yr]; five (1 female/4 males) participants completed both conditions. MSNA (fibular microneurography), BP (finger photoplethysmography), and leg blood flow (LBF, femoral Doppler ultrasound) were assessed at baseline, and 15 and 30 min following insulin administration. Leg vascular conductance [LVC = (LBF ÷ mean BP) × 100] was calculated. Venous insulin and glucose concentrations remained unchanged throughout (P > 0.05). Following intranasal insulin administration, MSNA (burst frequency; baseline = 100%; minute 15, 121 ± 8%; minute 30, 118 ± 6%; P = 0.009, n = 7) and mean BP (baseline = 100%; minute 15, 103 ± 1%; minute 30, 102 ± 1%; P = 0.003) increased, whereas LVC decreased (baseline = 100%; minute 15, 93 ± 3%; minute 30, 99 ± 3%; P = 0.03). In contrast, MSNA, mean BP, and LVC were unchanged in TC participants (P > 0.05). We provide the first evidence that intranasal insulin administration in healthy young adults acutely increases MSNA and BP and decreases LVC. These results enhance mechanistic understanding of the sympathetic and peripheral hemodynamic response to insulin.NEW & NOTEWORTHY Systemic insulin increases muscle sympathetic nerve activity (MSNA) via central actions within the brainstem and peripheral activation of the arterial baroreflex. In the absence of peripheral insulin action, whether central insulin stimulation increases MSNA and influences peripheral hemodynamics in humans was unknown. We provide the first evidence that intranasal insulin administration increases MSNA and blood pressure and reduces leg vascular conductance. These results enhance mechanistic understanding of the sympathetic and hemodynamic response to insulin.
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Affiliation(s)
- Neil J McMillan
- Department of Nutrition and Exercise Physiology, University of Missouri, Columbia, Missouri, United States
- NextGen Precision Health, University of Missouri, Columbia, Missouri, United States
| | - Dain W Jacob
- Department of Nutrition and Exercise Physiology, University of Missouri, Columbia, Missouri, United States
| | - Brian Shariffi
- Department of Nutrition and Exercise Physiology, University of Missouri, Columbia, Missouri, United States
| | - Jennifer L Harper
- Department of Nutrition and Exercise Physiology, University of Missouri, Columbia, Missouri, United States
| | - Glen E Foster
- School of Health and Exercise Sciences, Centre for Heart, Lung, and Vascular Health, University of British Columbia, Kelowna, Canada
| | - Camila Manrique-Acevedo
- NextGen Precision Health, University of Missouri, Columbia, Missouri, United States
- Division of Endocrinology, Diabetes and Metabolism, Department of Medicine, University of Missouri, Columbia, Missouri, United States
- Research Services, Harry S. Truman Memorial Veterans Hospital, Columbia, Missouri, United States
| | - Jaume Padilla
- Department of Nutrition and Exercise Physiology, University of Missouri, Columbia, Missouri, United States
- NextGen Precision Health, University of Missouri, Columbia, Missouri, United States
- Research Services, Harry S. Truman Memorial Veterans Hospital, Columbia, Missouri, United States
| | - Jacqueline K Limberg
- Department of Nutrition and Exercise Physiology, University of Missouri, Columbia, Missouri, United States
- Dalton Cardiovascular Research Center, University of Missouri, Columbia, Missouri, United States
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Graybeal AJ, Compton AT, Swafford SH, Brandner CF, Thorsen T, Renna ME, Stavres J. Measurements of Abdominal Obesity are Associated with Metabolic Syndrome Severity Independent of Hypertensive Phenotype in White but not Black Young Adults. J Racial Ethn Health Disparities 2024:10.1007/s40615-024-02051-8. [PMID: 38902464 DOI: 10.1007/s40615-024-02051-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2024] [Revised: 05/30/2024] [Accepted: 06/07/2024] [Indexed: 06/22/2024]
Abstract
PURPOSE This study sought to determine if metabolic syndrome severity (MetSindex) was differentially associated with abdominal obesity based on waist circumference (WC) site and the presentation of hypertensive phenotypes in a group of young White and Black adults. METHODS A total of 139 young adult (22.5 ± 3.3 years) non-Hispanic White (n = 73) and non-Hispanic Black (n = 66) males and females (M 53, 86 F) completed this cross-sectional evaluation. Participants had their WC measured at three distinct locations along the abdomen which were used to calculate waist-to-hip and waist-to-height ratios. Systolic (SBP) and diastolic blood pressure (DBP) were collected and used to calculate mean arterial pressure (MAP). In addition to traditional metabolic syndrome (MetS) risk factors, BP values were individually used to produce three separate MetSindex scores representing three specific hypertensive phenotypes (MetSSBP, MetSDBP, MetSMAP), and each of these were evaluated against each abdominal obesity estimate. RESULTS MetSDBP and MetSSBP were significantly higher than all other indices for females (all p ≤ 0.002) and males (all p < 0.001), respectively. MetSDBP was significantly higher than MetSMAP for White females (p = 0.039), and MetSSBP was significantly higher than MetSDBP and MetSMAP (both p < 0.001) for Black males. Standalone and joint estimates of abdominal obesity were uniquely associated with MetSindex across hypertensive phenotypes for White, but not Black males and females. CONCLUSIONS Specific hypertensive phenotypes may differentially determine MetSindex, but these estimates are not associated with abdominal obesity in young Black adults regardless of measurement location. Healthcare professionals should address this disparity by providing more comprehensive MetS screening procedures for young Black adults. CLINICAL TRIALS REGISTRATION NCT05885672.
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Affiliation(s)
- Austin J Graybeal
- School of Kinesiology and Nutrition, College of Education and Human Sciences, University of Southern Mississippi, Hattiesburg, MS, 39406, USA.
| | - Abby T Compton
- School of Kinesiology and Nutrition, College of Education and Human Sciences, University of Southern Mississippi, Hattiesburg, MS, 39406, USA
| | - Sydney H Swafford
- School of Kinesiology and Nutrition, College of Education and Human Sciences, University of Southern Mississippi, Hattiesburg, MS, 39406, USA
| | - Caleb F Brandner
- Department of Kinesiology and Health, Iowa State University, Ames, IA, 50011, USA
| | - Tanner Thorsen
- School of Kinesiology and Nutrition, College of Education and Human Sciences, University of Southern Mississippi, Hattiesburg, MS, 39406, USA
| | - Megan E Renna
- School of Psychology, College of Education and Human Sciences, University of Southern Mississippi, Hattiesburg, MS, 39406, USA
| | - Jon Stavres
- School of Kinesiology and Nutrition, College of Education and Human Sciences, University of Southern Mississippi, Hattiesburg, MS, 39406, USA
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Hanson BE, Lee JF, Garten RS, O'Keefe ZB, Layec G, Ruple BA, Wray DW, Richardson RS, Trinity JD. Acute sympathetic activation blunts the hyperemic and vasodilatory response to passive leg movement. RESEARCH SQUARE 2024:rs.3.rs-4356062. [PMID: 38765959 PMCID: PMC11100891 DOI: 10.21203/rs.3.rs-4356062/v1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2024]
Abstract
Heightened muscle sympathetic nerve activity (MSNA) contributes to impaired vasodilatory capacity and vascular dysfunction associated with aging and cardiovascular disease. The contribution of elevated MSNA to the vasodilatory response during passive leg movement (PLM) has not been adequately addressed. This study sought to test the hypothesis that elevated MSNA diminishes the vasodilatory response to PLM in healthy young males (n = 11, 25 ± 2 year). Post exercise circulatory occlusion (PECO) following 2 min of isometric handgrip (HG) exercise performed at 25% (ExPECO 25%) and 40% (ExPECO 40%) of maximum voluntary contraction was used to incrementally engage the metaboreceptors and augment MSNA. Control trials were performed without PECO (ExCON 25% and ExCON 40%) to account for changes due to HG exercise. PLM was performed 2 min after the cessation of exercise and central and peripheral hemodynamics were assessed. MSNA was directly recorded by microneurography in the peroneal nerve (n = 8). Measures of MSNA (i.e., burst incidences) increased during ExPECO 25% (+ 15 ± 5 burst/100 bpm) and ExPECO 40% (+ 22 ± 4 burst/100 bpm) and returned to pre-HG levels during ExCON trials. Vasodilation, assessed by the change in leg vascular conductance during PLM, was reduced by 16% and 44% during ExPECO 25% and ExPECO 40%, respectively. These findings indicate that elevated MSNA attenuates the vasodilatory response to PLM and that the magnitude of reduction in vasodilation during PLM is graded in relation to the degree of sympathoexcitation.
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Desai SA, Mirza UA, Mueller PJ. Influence of sex and sedentary conditions on sympathetic burst characteristics in prepubertal, postpubertal, and young adult rats. J Appl Physiol (1985) 2024; 136:1170-1181. [PMID: 38511214 DOI: 10.1152/japplphysiol.00649.2023] [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: 09/08/2023] [Revised: 03/07/2024] [Accepted: 03/15/2024] [Indexed: 03/22/2024] Open
Abstract
Recent evidence indicates that sex-based differences in cardiovascular disease (CVD) begin early in life, particularly when associated with risk factors such as a sedentary lifestyle. CVD is associated with elevated sympathetic nerve activity (SNA), quantified as increased SNA burst activity in humans. Whether burst characteristics are influenced by sex or sedentary conditions at younger ages is unknown. The purpose of our study is to compare SNA bursts in active and sedentary female and male rats at ages including prepuberty and young adulthood. We hypothesized that burst characteristics and blood pressure are higher under sedentary conditions and lower in female rats compared with males. We analyzed splanchnic SNA (SpSNA) recordings from Inactin-anesthetized male and female rats at 4-, 8-, and 16-wk of age. Physically active and sedentary rats were each housed in separate, environmentally controlled chambers where physically active rats had free access to an in-cage running wheel. Sympathetic bursts were obtained by rectifying and integrating the raw SpSNA signal. Burst frequency, burst height, and burst width were calculated using the Peak Parameters extension in LabChart. Our results showed that sedentary conditions produced a greater burst width in 8- and 16-wk-old rats compared with 4-wk-old rats in both males and females (P < 0.001 for both). Burst frequency and incidence were both higher in 16-wk-old males compared with 16-wk-old females (P < 0.001 for both). Our results suggest that there are sedentary lifestyle- and sex-related mechanisms that impact sympathetic regulation of blood pressure at ages that range from prepuberty into young adulthood.NEW & NOTEWORTHY The mechanisms of decreased incidence of cardiovascular disease (CVD) in reproductive-age women compared with age-matched men are unknown. The strong association between elevated sympathetic activity and CVD led us to characterize splanchnic sympathetic bursts in female and male rats. Prepubescent males and females exhibited narrower sympathetic bursts, whereas young adult males had higher resting burst frequency compared with age-matched females. Sex-based regulation of sympathetic activity suggests a need for sex-dependent therapeutic strategies to combat CVD.
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Affiliation(s)
- Shivansh A Desai
- Department of Physiology, Wayne State University School of Medicine, Detroit, Michigan, United States
| | - Umme Aiman Mirza
- Department of Physiology, Wayne State University School of Medicine, Detroit, Michigan, United States
| | - Patrick J Mueller
- Department of Physiology, Wayne State University School of Medicine, Detroit, Michigan, United States
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Tahsin CT, Anselmo M, Lee E, Stokes W, Fonkoue IT, Vanden Noven ML, Carter JR, Keller-Ross ML. Sleep disturbance and sympathetic neural reactivity in postmenopausal females. Am J Physiol Heart Circ Physiol 2024; 326:H752-H759. [PMID: 38214902 PMCID: PMC11221801 DOI: 10.1152/ajpheart.00724.2023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/16/2023] [Revised: 01/02/2024] [Accepted: 01/09/2024] [Indexed: 01/13/2024]
Abstract
Sleep disturbance, one of the most common menopausal symptoms, contributes to autonomic dysfunction and is linked to hypertension and cardiovascular risk. Longitudinal studies suggest that hyperreactivity of blood pressure (BP) to a stressor can predict the future development of hypertension. It remains unknown if postmenopausal females who experience sleep disturbance (SDG) demonstrate greater hemodynamic and sympathetic neural hyperreactivity to a stressor. We hypothesized that postmenopausal females with reported sleep disturbance would exhibit increased hemodynamic and sympathetic reactivity to a stressor compared with postmenopausal females without sleep disturbance (non-SDG). Fifty-five postmenopausal females (age, 62 ± 4 yr old; SDG, n = 36; non-SDG; n = 19) completed two study visits. The Menopause-Specific Quality of Life Questionnaire (MENQOL) was used to assess the presence of sleep disturbance (MENQOL sleep scale, ≥2 units). Beat-to-beat BP (finger plethysmography), heart rate (HR; electrocardiogram), and muscle sympathetic nerve activity (MSNA; microneurography; SDG, n = 25; non-SDG, n = 15) were continuously measured during a 10-min baseline and 2-min stressor (cold pressor test; CPT) in both groups. Menopause age and body mass index were similar between groups (P > 0.05). There were no differences between resting BP, HR, or MSNA (P > 0.05). HR and BP reactivity were not different between SDG and non-SDG (P > 0.05). In contrast, MSNA reactivity had a more rapid increase in the first 30 s of the CPT in the SDG (burst incidence, Δ10.2 ± 14.8 bursts/100 hb) compared with the non-SDG (burst incidence, Δ4.0 ± 14.8 bursts/100 hb, time × group, P = 0.011). Our results demonstrate a more rapid sympathetic neural reactivity to a CPT in postmenopausal females with perceived sleep disturbance, a finding that aligns with and advances recent evidence that sleep disturbance is associated with sympathetic neural hyperactivity in postmenopausal females.NEW & NOTEWORTHY This is the first study to demonstrate that muscle sympathetic nerve activity (MSNA) to a cold pressor test is augmented in postmenopausal females with perceived sleep disturbance. The more rapid increase in MSNA reactivity during the cold pressor test in the sleep disturbance group was present despite similar increases in the perceived pain levels between groups. Baseline MSNA burst incidence and burst frequency, as well as blood pressure and heart rate, were similar between the sleep disturbance and nonsleep disturbance groups.
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Affiliation(s)
- Chowdhury Tasnova Tahsin
- Division of Rehabilitation Science, Medical School, University of Minnesota, Minneapolis, Minnesota, United States
| | - Miguel Anselmo
- Division of Rehabilitation Science, Medical School, University of Minnesota, Minneapolis, Minnesota, United States
| | - Emma Lee
- Division of Physical Therapy, Medical School, University of Minnesota, Minneapolis, Minnesota, United States
| | - William Stokes
- Division of Rehabilitation Science, Medical School, University of Minnesota, Minneapolis, Minnesota, United States
| | - Ida T Fonkoue
- Division of Rehabilitation Science, Medical School, University of Minnesota, Minneapolis, Minnesota, United States
- Division of Physical Therapy, Medical School, University of Minnesota, Minneapolis, Minnesota, United States
| | - Marnie L Vanden Noven
- Department of Exercise Science, Belmont University, Nashville, Tennessee, United States
| | - Jason R Carter
- Robbins College of Health and Human Sciences, Baylor University, Waco, Texas, United States
| | - Manda L Keller-Ross
- Division of Rehabilitation Science, Medical School, University of Minnesota, Minneapolis, Minnesota, United States
- Division of Physical Therapy, Medical School, University of Minnesota, Minneapolis, Minnesota, United States
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Nardone M, Foster M, O'Brien MW, Coovadia Y, Xie S, Usselman CW, Kimmerly DS, Taylor CE, Millar PJ. Sympathetic determinants of resting blood pressure in males and females. Am J Physiol Heart Circ Physiol 2024; 326:H612-H622. [PMID: 38214907 DOI: 10.1152/ajpheart.00497.2023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/11/2023] [Revised: 01/08/2024] [Accepted: 01/08/2024] [Indexed: 01/13/2024]
Abstract
Discharge of postganglionic muscle sympathetic nerve activity (MSNA) is related poorly to blood pressure (BP) in adults. Whether neural measurements beyond the prevailing level of MSNA can account for interindividual differences in BP remains unclear. The current study sought to evaluate the relative contributions of sympathetic-BP transduction and sympathetic baroreflex gain on resting BP in young adults. Data were analyzed from 191 (77 females) young adults (18-39 years) who underwent continuous measurement of beat-to-beat BP (finger photoplethysmography), heart rate (electrocardiography), and fibular nerve MSNA (microneurography). Linear regression analyses were computed to determine associations between sympathetic-BP transduction (signal-averaging) or sympathetic baroreflex gain (threshold technique) and resting BP, before and after controlling for age, body mass index, and MSNA burst frequency. K-mean clustering was used to explore sympathetic phenotypes of BP control and consequential influence on resting BP. Sympathetic-BP transduction was unrelated to BP in males or females (both R2 < 0.01; P > 0.67). Sympathetic baroreflex gain was positively associated with BP in males (R2 = 0.09, P < 0.01), but not in females (R2 < 0.01; P = 0.80), before and after controlling for age, body mass index, and MSNA burst frequency. K-means clustering identified a subset of participants with average resting MSNA, yet lower sympathetic-BP transduction and lower sympathetic baroreflex gain. This distinct subgroup presented with elevated BP in males (P < 0.02), but not in females (P = 0.10). Sympathetic-BP transduction is unrelated to resting BP, while the association between sympathetic baroreflex gain and resting BP in males reveals important sex differences in the sympathetic determination of resting BP.NEW & NOTEWORTHY In a sample of 191 normotensive young adults, we confirm that resting muscle sympathetic nerve activity is a poor predictor of resting blood pressure and now demonstrate that sympathetic baroreflex gain is associated with resting blood pressure in males but not females. In contrast, signal-averaged measures of sympathetic-blood pressure transduction are unrelated to resting blood pressure. These findings highlight sex differences in the neural regulation of blood pressure.
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Affiliation(s)
- Massimo Nardone
- Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, Ontario, Canada
| | - Monique Foster
- School of Health Sciences, Western Sydney University, Sydney, New South Wales, Australia
| | - Myles W O'Brien
- Division of Kinesiology, School of Health and Human Performance, Faculty of Health, Dalhousie University, Halifax, Nova Scotia, Canada
- School of Physiotherapy (Faculty of Health) and Division of Geriatric Medicine (Faculty of Medicine), Dalhousie University, Halifax, Nova Scotia, Canada
| | - Yasmine Coovadia
- Cardiovascular Health and Autonomic Regulation Laboratory, Department of Kinesiology and Physical Education, McGill University, Montreal, Quebec, Canada
| | - Shengkun Xie
- Global Management Studies, Ted Rogers School of Management, Toronto Metropolitan University, Toronto, Ontario, Canada
| | - Charlotte W Usselman
- Cardiovascular Health and Autonomic Regulation Laboratory, Department of Kinesiology and Physical Education, McGill University, Montreal, Quebec, Canada
| | - Derek S Kimmerly
- Division of Kinesiology, School of Health and Human Performance, Faculty of Health, Dalhousie University, Halifax, Nova Scotia, Canada
| | - Chloe E Taylor
- School of Health Sciences, Western Sydney University, Sydney, New South Wales, Australia
| | - Philip J Millar
- Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, Ontario, Canada
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Shafer BM, Kogan SA, McHill AW. Pressure Building Against the Clock: The Impact of Circadian Misalignment on Blood Pressure. Curr Hypertens Rep 2024; 26:31-42. [PMID: 37837518 PMCID: PMC10916535 DOI: 10.1007/s11906-023-01274-0] [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] [Accepted: 10/01/2023] [Indexed: 10/16/2023]
Abstract
PURPOSE OF REVIEW Misalignment between the endogenous biological timing system and behavioral activities (i.e., sleep/wake, eating, activity) contributes to adverse cardiovascular health. In this review, we discuss the effects of recurring circadian misalignment on blood pressure regulation and the implications for hypertension development. Additionally, we highlight emerging therapeutic approaches designed to mitigate the negative cardiovascular consequences elicited by circadian disruption. RECENT FINDINGS Circadian misalignment elicited by work schedules that require individuals to be awake during the biological night (i.e., shift work) alters 24-h blood pressure rhythms. Mechanistically, circadian misalignment appears to alter blood pressure via changes in autonomic nervous system balance, variations to sodium retention, dysregulation of endothelial vasodilatory responsiveness, and activation of proinflammatory mechanisms. Recurring circadian misalignment produced by a mismatch in sleep timing on free days vs. work days (i.e., social jetlag) appears to have no direct effects on prevailing blood pressure levels in healthy adults; though, circadian disruptions resulting from social jetlag may increase the risk of hypertension through enhanced sympathetic activation and/or obesity. Furthermore, social jetlag assessment may be a useful metric in shift work populations where the magnitude of circadian misalignment may be greater than in the general population. Circadian misalignment promotes unfavorable changes to 24-h blood pressure rhythms, most notably in shift working populations. While light therapy, melatonin supplementation, and the timing of drug administration may improve cardiovascular outcomes, interventions designed to target the effects of circadian misalignment on blood pressure regulation are warranted.
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Affiliation(s)
- Brooke M Shafer
- Sleep, Chronobiology, and Health Laboratory, School of Nursing, Oregon Health & Science University, 3455 SW US Veterans Hospital Rd, Portland, OR, 97239, USA
| | - Sophia A Kogan
- Sleep, Chronobiology, and Health Laboratory, School of Nursing, Oregon Health & Science University, 3455 SW US Veterans Hospital Rd, Portland, OR, 97239, USA
| | - Andrew W McHill
- Sleep, Chronobiology, and Health Laboratory, School of Nursing, Oregon Health & Science University, 3455 SW US Veterans Hospital Rd, Portland, OR, 97239, USA.
- Oregon Institute of Occupational Health Sciences, Oregon Health & Science University, Portland, OR, USA.
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Bigalke JA, Young BE, Cleveland EL, Fadel PJ, Carter JR. Aging and sympathetic transduction to blood pressure in humans: methodological and physiological considerations. Am J Physiol Heart Circ Physiol 2024; 326:H148-H157. [PMID: 37921667 PMCID: PMC11213475 DOI: 10.1152/ajpheart.00359.2023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/19/2023] [Revised: 10/25/2023] [Accepted: 11/01/2023] [Indexed: 11/04/2023]
Abstract
Recent reports suggest that quantification of signal-averaged sympathetic transduction is influenced by resting muscle sympathetic nerve activity (MSNA) and burst occurrence relative to the average mean arterial pressure (MAP). Herein, we asked how these findings may influence age-related reductions in sympathetic transduction. Beat-to-beat blood pressure and MSNA were recorded during 5 min of rest in 27 younger (13 females: age, 25 ± 5 yr; BMI, 25 ± 4 kg/m2) and 26 older (15 females: age, 59 ± 5 yr; BMI, 26 ± 4 kg/m2) healthy adults. All MSNA bursts were signal averaged together. Beat-to-beat MAP values were then split into low (T1), middle (T2), and high (T3) tertiles, and signal-averaged transduction was calculated within each tertile. Resting MSNA was higher in older adults and MAP was similar between groups. Older adults exhibited blunted overall MAP transduction (younger, Δ1.5 ± 0.6 vs. older, Δ0.9 ± 0.7 mmHg; P = 0.005), which was irrespective of relation to prevailing MAP. A greater proportion of bursts occurred above the average MAP in older adults (P < 0.001), and a larger proportion of these bursts were associated with depressor responses (P = 0.005). Nonetheless, assessment of bursts above the average MAP associated with pressor responses revealed similar age-associated reductions in transduction (younger, Δ2.6 ± 1.6 vs. older, Δ1.7 ± 0.8 mmHg; P = 0.016). These findings indicate an age-related increase in burst occurrence above the average resting MAP, which alone does not explain blunted transduction, thereby supporting the physiological underpinnings of age-related decrements in sympathetic transduction to blood pressure.NEW & NOTEWORTHY The current study demonstrated that aging is associated with a greater prevalence of sympathetic bursts occurring above the average blood pressure, which offers both methodologically and physiologically relevant information regarding aging and sympathetic control of blood pressure. These data support age-related reductions in sympathetic transduction via a reduced pressor response to sympathetic bursts irrespective of the prevailing absolute blood pressure value, along with increases in sympathetic outflow necessary to maintain blood pressure.
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Affiliation(s)
- Jeremy A Bigalke
- Robbins College of Health and Human Sciences, Baylor University, Waco, Texas, United States
- Department of Psychology, Montana State University, Bozeman, Montana, 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
| | - Emily L Cleveland
- Department of Microbiology and Cell Biology, Montana State University, Bozeman, Montana, United States
| | - Paul J Fadel
- Department of Kinesiology, University of Texas at Arlington, Arlington, Texas, United States
| | - Jason R Carter
- Robbins College of Health and Human Sciences, Baylor University, Waco, Texas, United States
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D'Souza AW, Hissen SL, Manabe K, Takeda R, Washio T, Coombs GB, Sanchez B, Fu Q, Shoemaker JK. Age- and sex-related differences in sympathetic vascular transduction and neurohemodynamic balance in humans. Am J Physiol Heart Circ Physiol 2023; 325:H917-H932. [PMID: 37594483 DOI: 10.1152/ajpheart.00301.2023] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/23/2023] [Revised: 08/14/2023] [Accepted: 08/15/2023] [Indexed: 08/19/2023]
Abstract
Bursts of muscle sympathetic nerve activity (MSNA) and the ensuing vasoconstriction are pivotal determinants of beat-by-beat blood pressure regulation. Although age and sex impact blood pressure regulation, how these factors affect the central and peripheral arcs of the baroreflex remains unclear. In 27 young [25 (SD 3) yr] males (YM; n = 14) and females (YF; n = 13) and 23 older [71 (SD 5) yr] males (OM; n = 11) and females (OF; n = 12), femoral artery blood flow, blood pressure, and MSNA were recorded for 10 min of supine rest. Sympathetic baroreflex sensitivity (i.e., central arc) was quantified as the relationship between diastolic blood pressure and MSNA burst incidence. Signal averaging was used to determine sympathetic vascular transduction into leg vascular conductance (LVC) for 12 cardiac cycles following MSNA bursts (i.e., peripheral arc). Older adults demonstrated attenuated sympathetic transduction into LVC (both P < 0.001) following MSNA bursts, and smaller increases in sympathetic transduction as a function of MSNA burst size and firing pattern compared with young adults (range, P = 0.004-0.032). YM (r2 = 0.36; P = 0.032) and OM (r2 = 0.51; P = 0.014) exhibited an inverse relationship between the central and peripheral arcs of the baroreflex, whereas females did not (YF, r2 = 0.03, P = 0.621; OF, r2 = 0.06, P = 0.445). MSNA burst incidence was inversely related to sympathetic transduction in YM and OF (range, P = 0.03-0.046) but not in YF or OM (range, P = 0.360-0.603). These data indicate that age is associated with attenuated sympathetic vascular transduction, whereas age- and sex-specific changes are present in the relationship between the central and peripheral arcs of the baroreflex regulation of blood pressure.NEW & NOTEWORTHY Sympathetic vascular transduction is attenuated in older compared with young adults, regardless of biological sex. Males, but not females (regardless of age), demonstrate an inverse relationship between central (sympathetic baroreflex sensitivity) and peripheral (sympathetic vascular transduction) components of the baroreflex arc. Young males and older females exhibit an inverse relationship between resting sympathetic outflow and sympathetic vascular transduction. Our results indicate that age and sex exert independent and interactive effects on sympathetic vascular transduction and sympathetic neurohemodynamic balance in humans.
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Affiliation(s)
- Andrew W D'Souza
- Neurovascular Research Laboratory, School of Kinesiology, Western University, London, Ontario, Canada
| | - Sarah L Hissen
- Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital Dallas, Dallas, Texas, United States
- Internal Medicine, The University of Texas Southwestern Medical Center, Dallas, Texas, United States
| | - Kazumasa Manabe
- Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital Dallas, Dallas, Texas, United States
- Internal Medicine, The University of Texas Southwestern Medical Center, Dallas, Texas, United States
| | - Ryosuke Takeda
- Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital Dallas, Dallas, Texas, United States
- Internal Medicine, The University of Texas Southwestern Medical Center, Dallas, Texas, United States
- Laboratory of Neuromuscular Biomechanics, School of Health and Sport Sciences, Chukyo University, Toyota, Japan
| | - Takuro Washio
- Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital Dallas, Dallas, Texas, United States
- Internal Medicine, The University of Texas Southwestern Medical Center, Dallas, Texas, United States
| | - Geoff B Coombs
- Neurovascular Research Laboratory, School of Kinesiology, Western University, London, Ontario, Canada
| | - Belinda Sanchez
- Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital Dallas, Dallas, Texas, United States
- Internal Medicine, The University of Texas Southwestern Medical Center, Dallas, Texas, United States
| | - Qi Fu
- Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital Dallas, Dallas, Texas, United States
- Internal Medicine, The University of Texas Southwestern Medical Center, Dallas, Texas, United States
| | - J Kevin Shoemaker
- Neurovascular Research Laboratory, School of Kinesiology, Western University, London, Ontario, Canada
- Department of Physiology and Pharmacology, Western University, London, Ontario, Canada
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10
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Hughes GW, Moore JP, Lord RN. Barosensory vessel mechanics and the vascular sympathetic baroreflex: Impact on blood pressure homeostasis. Exp Physiol 2023; 108:1245-1249. [PMID: 37031381 PMCID: PMC10988470 DOI: 10.1113/ep089686] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2023] [Accepted: 03/09/2023] [Indexed: 04/10/2023]
Abstract
NEW FINDINGS What is the topic of this review? We review barosensory vessel mechanics and their role in blood pressure regulation across the lifespan. What advances does it highlight? In young normotensive men, aortic unloading mechanics contribute to the resting operating point of the vascular sympathetic baroreflex; however, with advancing age, this contribution is removed. This suggests that barosensory vessel unloading mechanics are not driving the well-documented age-related increase in resting muscle sympathetic nerve activity. ABSTRACT An age-associated increase in arterial blood pressure is evident for apparently healthy humans. This is frequently attributed to stiffening of the central arteries and a concurrent increase in sympathetic outflow, potentially mediated by a reduced ability of the baroreceptive vessels to distend. This is supported, in part, by a reduced mechanical component of the vascular sympathetic baroreflex (i.e., a reduction in distension for a given pressure). Previous characterization of the mechanical component has assessed only carotid artery distension; however, evidence suggests that both the aortic and carotid baroreflexes are integral to blood pressure regulation. In addition, given that baroreceptors are located in the vessel wall, the change in wall tension, comprising diameter, pressure and vessel wall thickness, and the mechanics of this change might provide a better index of the baroreceptor stimulus than the previous method used to characterize the mechanical component that relies on diameter alone. This brief review summarizes the data using this new method of assessing barosensory vessel mechanics and their influence on the vascular sympathetic baroreflex across the lifespan.
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Affiliation(s)
- Guto W. Hughes
- School of Human and Behavioural SciencesBangor UniversityBangorUK
| | | | - Rachel N. Lord
- Centre for Activity, Health and Wellbeing ResearchCardiff Metropolitan UniversityCardiffUK
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11
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Wakeham DJ, Lord RN, Talbot JS, Lodge FM, Curry BA, Dawkins TG, Simpson LL, Pugh CJA, Shave RE, Moore JP. Aortic stiffness contributes to greater pressor responses during static hand grip exercise in healthy young and middle-aged normotensive men. Auton Neurosci 2023; 248:103106. [PMID: 37473585 DOI: 10.1016/j.autneu.2023.103106] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2023] [Revised: 05/28/2023] [Accepted: 07/04/2023] [Indexed: 07/22/2023]
Abstract
Central arterial stiffness can influence exercise blood pressure (BP) by increasing the rise in arterial pressure per unit increase in aortic inflow. Whether central arterial stiffness influences the pressor response to isometric handgrip exercise (HG) and post-exercise muscle ischemia (PEMI), two common laboratory tests to study sympathetic control of BP, is unknown. We studied 46 healthy non-hypertensive males (23 young and 23 middle-aged) during HG (which increases in cardiac output [Q̇c]) and isolated metaboreflex activation PEMI (no change or decreases in Q̇c). Aortic stiffness (aortic pulse wave velocity [aPWV]; applanation tonometry via SphygmoCor) was measured during supine rest and was correlated to the pressor responses to HG and PEMI. BP (photoplethysmography) and muscle sympathetic nerve activity (MSNA) were continuously recorded at rest, during HG to fatigue (35 % maximal voluntary contraction) and 2-min of PEMI. aPWV was higher in middle-aged compared to young males (7.1 ± 0.9 vs 5.4 ± 0.7 m/s, P < 0.001). Middle-aged males also exhibited greater increases in systolic pressure (∆30 ± 11 vs 10 ± 8 mmHg) and MSNA (∆2313 ± 2006 vs 1387 ± 1482 %/min) compared to young males during HG (both, P < 0.03); with no difference in the Q̇c response (P = 0.090). Responses to PEMI were not different between groups. Sympathetic transduction during these stressors (MSNA-diastolic pressure slope) was not different between groups (P > 0.341). Middle-aged males displayed a greater increase in SBP per unit change of Q̇c during HG (∆SBP/∆Q̇c; 21 ± 18 vs 6 ± 10 mmHg/L/min, P = 0.004), with a strong and moderate relationship between the change in systolic (r = 0.53, P < 0.001) and diastolic pressure (r = 0.34, P = 0.023) and resting aPWV, respectively; with no correlation during PEMI. Central arterial stiffness can modulate pressor responses during stimuli associated with increases in cardiac output and sympathoexcitation in healthy males.
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Affiliation(s)
- Denis J Wakeham
- Cardiff School of Sport and Health Sciences, Cardiff Metropolitan University, United Kingdom.
| | - Rachel N Lord
- Cardiff School of Sport and Health Sciences, Cardiff Metropolitan University, United Kingdom
| | - Jack S Talbot
- Cardiff School of Sport and Health Sciences, Cardiff Metropolitan University, United Kingdom
| | - Freya M Lodge
- Cardiff and Vale University Health Board, University Hospital of Wales, Cardiff, United Kingdom
| | - Bryony A Curry
- Cardiff School of Sport and Health Sciences, Cardiff Metropolitan University, United Kingdom
| | - Tony G Dawkins
- Cardiff School of Sport and Health Sciences, Cardiff Metropolitan University, United Kingdom
| | - Lydia L Simpson
- Department of Sport and Exercise Sciences, Bangor University, United Kingdom; Department of Sport Science, University of Innsbruck, Austria
| | - Christopher J A Pugh
- Cardiff School of Sport and Health Sciences, Cardiff Metropolitan University, United Kingdom
| | - Rob E Shave
- Centre for Heart, Lung, and Vascular Health, University of British Columbia Okanagan, Kelowna, Canada
| | - Jonathan P Moore
- Department of Sport and Exercise Sciences, Bangor University, United Kingdom
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12
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Bock JM, Greenlund IM, Somers VK, Baker SE. Sex Differences in Neurovascular Control: Implications for Obstructive Sleep Apnea. Int J Mol Sci 2023; 24:13094. [PMID: 37685900 PMCID: PMC10487948 DOI: 10.3390/ijms241713094] [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: 07/11/2023] [Revised: 08/10/2023] [Accepted: 08/14/2023] [Indexed: 09/10/2023] Open
Abstract
Patients with obstructive sleep apnea (OSA) have a heightened risk of developing cardiovascular diseases, namely hypertension. While seminal evidence indicates a causal role for sympathetic nerve activity in the hypertensive phenotype commonly observed in patients with OSA, no studies have investigated potential sex differences in the sympathetic regulation of blood pressure in this population. Supporting this exploration are large-scale observational data, as well as controlled interventional studies in healthy adults, indicating that sleep disruption increases blood pressure to a greater extent in females relative to males. Furthermore, females with severe OSA demonstrate a more pronounced hypoxic burden (i.e., disease severity) during rapid eye movement sleep when sympathetic nerve activity is greatest. These findings would suggest that females are at greater risk for the hemodynamic consequences of OSA and related sleep disruption. Accordingly, the purpose of this review is three-fold: (1) to review the literature linking sympathetic nerve activity to hypertension in OSA, (2) to highlight recent experimental data supporting the hypothesis of sex differences in the regulation of sympathetic nerve activity in OSA, and (3) to discuss the potential sex differences in peripheral adrenergic signaling that may contribute to, or offset, cardiovascular risk in patients with OSA.
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Affiliation(s)
- Joshua M. Bock
- Department of Cardiovascular Medicine, Mayo Clinic, Rochester, MN 55901, USA; (J.M.B.)
| | - Ian M. Greenlund
- Department of Cardiovascular Medicine, Mayo Clinic, Rochester, MN 55901, USA; (J.M.B.)
| | - Virend K. Somers
- Department of Cardiovascular Medicine, Mayo Clinic, Rochester, MN 55901, USA; (J.M.B.)
| | - Sarah E. Baker
- Department of Anesthesiology and Perioperative Medicine, Mayo Clinic, Rochester, MN 55901, USA
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13
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O'Brien MW, Nardone M, Foster M, Coovadia Y, Usselman CW, Taylor CE, Millar PJ, Kimmerly DS. Higher sympathetic transduction is independently associated with greater very short-term diastolic blood pressure variability in young healthy males and females. Clin Auton Res 2023; 33:529-532. [PMID: 37243873 DOI: 10.1007/s10286-023-00949-7] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2023] [Accepted: 04/29/2023] [Indexed: 05/29/2023]
Affiliation(s)
- Myles W O'Brien
- School of Physiotherapy (Faculty of Health) and Department of Medicine (Faculty of Medicine), Dalhousie University, Halifax, NS, Canada.
- Geriatric Medicine Research, Dalhousie University and Nova Scotia Health, Halifax, NS, Canada.
| | - Massimo Nardone
- Human Cardiovascular Physiology Laboratory, Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, ON, Canada
| | - Monique Foster
- School of Health Sciences, Western Sydney University, Sydney, NSW, Australia
| | - Yasmine Coovadia
- Cardiovascular Health and Autonomic Regulation Laboratory, McGill University, Montreal, QC, Canada
| | - Charlotte W Usselman
- Cardiovascular Health and Autonomic Regulation Laboratory, McGill University, Montreal, QC, Canada
| | - Chloe E Taylor
- School of Health Sciences, Western Sydney University, Sydney, NSW, Australia
| | - Philip J Millar
- Human Cardiovascular Physiology Laboratory, Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, ON, Canada
| | - Derek S Kimmerly
- Division of Kinesiology, School of Health and Human Performance, Faculty of Health, Dalhousie University, Halifax, NS, Canada
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Lubomirov LT, Mantke R, Enzmann T, Metzler D, Korotkova T, Hescheler J, Pfitzer G, Grisk O. ROK and RSK2-kinase pathways differ between senescent human renal and mesenteric arteries. J Hypertens 2023; 41:1201-1214. [PMID: 37115907 DOI: 10.1097/hjh.0000000000003450] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/29/2023]
Abstract
OBJECTIVE Small arteries from different organs vary with regard to the mechanisms that regulate vasoconstriction. This study investigated the impact of advanced age on the regulation of vasoconstriction in isolated human small arteries from kidney cortex and periintestinal mesenteric tissue. METHODS Renal and mesenteric tissues were obtained from patients (mean age 71 ± 9 years) undergoing elective surgery. Furthermore, intrarenal and mesenteric arteries from young and aged mice were studied. Arteries were investigated by small vessel myography and western blot. RESULTS Human intrarenal arteries (h-RA) showed higher stretch-induced tone and higher reactivity to α 1 adrenergic receptor stimulation than human mesenteric arteries (h-MA). Rho-kinase (ROK) inhibition resulted in a greater decrease in Ca 2+ and depolarization-induced tone in h-RA than in h-MA. Basal and α 1 adrenergic receptor stimulation-induced phosphorylation of the regulatory light chain of myosin (MLC 20 ) was higher in h-RA than in h-MA. This was associated with higher ROK-dependent phosphorylation of the regulatory subunit of myosin light-chain-phosphatase (MLCP), MYPT1-T853. In h-RA phosphorylation of ribosomal S6-kinase II (RSK2-S227) was significantly higher than in h-MA. Stretch-induced tone and RSK2 phosphorylation was also higher in interlobar arteries (m-IAs) from aged mice than in respective vessels from young mice and in murine mesenteric arteries (m-MA) from both age groups. CONCLUSION Vasoconstriction in human intrarenal arteries shows a greater ROK-dependence than in mesenteric arteries. Activation of RSK2 may contribute to intrarenal artery tone dysregulation associated with aging. Compared with h-RA, h-MA undergo age-related remodeling leading to a reduction of the contractile response to α 1 adrenergic stimulation.
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Affiliation(s)
- Lubomir T Lubomirov
- Institute of Physiology, Brandenburg Medical School Theodor Fontane, Neuruppin
- Institute of Vegetative Physiology
- Research cluster, Molecular Mechanisms of Cardiovascular Diseases
| | - René Mantke
- General and Visceral Surgery Clinic
- Faculty of Health Brandenburg, Brandenburg Medical School Theodor Fontane, Neuruppin, Germany
| | - Thomas Enzmann
- Urology and Children Urology Clinic, University Clinics Brandenburg an der Havel
| | | | | | - Jürgen Hescheler
- Institute of Neurophysiology, Center of Physiology, University of Cologne, Cologne
| | | | - Olaf Grisk
- Institute of Physiology, Brandenburg Medical School Theodor Fontane, Neuruppin
- Research cluster, Molecular Mechanisms of Cardiovascular Diseases
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15
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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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16
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Shafer BM, Nardone M, Incognito AV, Vermeulen TD, Teixeira AL, Millar PJ, Sheel AW, West C, Ayas N, Foster GE. Acute hypoxia elicits lasting reductions in the sympathetic action potential transduction of arterial blood pressure in males. J Physiol 2023; 601:669-687. [PMID: 36542455 DOI: 10.1113/jp283979] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2022] [Accepted: 12/16/2022] [Indexed: 12/24/2022] Open
Abstract
Post-hypoxia sympathoexcitation does not elicit corresponding changes in vascular tone, suggesting diminished sympathetic signalling. Blunted sympathetic transduction following acute hypoxia, however, has not been confirmed and the effects of hypoxia on the sympathetic transduction of mean arterial pressure (MAP) as a function of action potential (AP) activity is unknown. We hypothesized that MAP changes would be blunted during acute hypoxia but restored in recovery and asynchronous APs would elicit smaller MAP changes than synchronous APs. Seven healthy males (age: 24 (3) years; BMI: 25 (3) kg/m2 ) underwent 20 min isocapnic hypoxia (PET O2 : 47 (2) mmHg) and 30 min recovery. Multi-unit microneurography (muscle sympathetic nerve activity; MSNA) and continuous wavelet transform with matched mother wavelet was used to detect sympathetic APs during baseline, hypoxia, early (first 7 min) and late (last 7 min) recovery. AP groups were classified as synchronous APs, asynchronous APs (occurring outside an MSNA burst) and no AP activity. Sympathetic transduction of MAP was quantified using signal-averaging, with ΔMAP tracked following AP group cardiac cycles. Following synchronous APs, ΔMAP was reduced in hypoxia (+1.8 (0.9) mmHg) and early recovery (+1.5 (0.7) mmHg) compared with baseline (+3.1 (2.2) mmHg). AP group-by-condition interactions show that at rest asynchronous APs attenuate MAP reductions compared with no AP activity (-0.4 (1.1) vs. -2.2 (1.2) mmHg, respectively), with no difference between AP groups in hypoxia, early or late recovery. Sympathetic transduction of MAP is blunted in hypoxia and early recovery. At rest, asynchronous sympathetic APs contribute to neural regulation of MAP by attenuating nadir pressure responses. KEY POINTS: Acute isocapnic hypoxia elicits lasting sympathoexcitation that does not correspond to parallel changes in vascular tone, suggesting blunted sympathetic transduction. Signal-averaging techniques track the magnitude and temporal cardiovascular responses following integrated muscle sympathetic nerve activity (MSNA) burst and non-burst cardiac cycles. However, this does not fully characterize the effects of sympathetic action potential (AP) activity on blood pressure control. We show that hypoxia blunts the sympathetic transduction of mean arterial pressure (MAP) following synchronous APs that form integrated MSNA bursts and that sympathetic transduction of MAP remains attenuated into early recovery. At rest, asynchronous APs attenuate the reduction in MAP compared with cardiac cycles following no AP activity, thus asynchronous sympathetic APs appear to contribute to the neural regulation of blood pressure. The results advance our understanding of sympathetic transduction of arterial pressure during and following exposure to acute isocapnic hypoxia in humans.
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Affiliation(s)
- Brooke M Shafer
- Centre for Heart, Lung, and Vascular Health, School of Health and Exercise Sciences, University of British Columbia, Kelowna, Canada
| | - Massimo Nardone
- Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, Canada
| | - Anthony V Incognito
- Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, Canada
| | - Tyler D Vermeulen
- Centre for Heart, Lung, and Vascular Health, School of Health and Exercise Sciences, University of British Columbia, Kelowna, Canada
| | - André L Teixeira
- Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, Canada
| | - Philip J Millar
- Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, Canada
| | - A William Sheel
- School of Kinesiology, University of British Columbia, Vancouver, Canada
| | - Chris West
- Faculty of Medicine, University of British Columbia, Kelowna, Canada.,International Collaboration on Repair Discoveries, University of British Columbia, Vancouver, Canada.,Centre for Chronic Disease Prevention and Management, University of British Columbia, Kelowna, Canada.,Department of Cellular and Physiological Sciences, Faculty of Medicine, University of British Columbia, Vancouver, Canada
| | - Najib Ayas
- Department of Medicine, Faculty of Medicine, University of British Columbia, Vancouver, Canada
| | - Glen E Foster
- Centre for Heart, Lung, and Vascular Health, School of Health and Exercise Sciences, University of British Columbia, Kelowna, Canada
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17
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Harvey RE, Laughlin‐Tommaso SK, Stewart EA, Limberg JK, Curry TB, Joyner MJ, Barnes JN. The relationship between muscle sympathetic nerve activity and systemic hemodynamics is altered in women with uterine fibroids. Physiol Rep 2022; 10:e15445. [PMID: 36117415 PMCID: PMC9483612 DOI: 10.14814/phy2.15445] [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: 05/25/2022] [Revised: 08/10/2022] [Accepted: 08/12/2022] [Indexed: 06/15/2023] Open
Abstract
Women with uterine fibroids (UF), benign tumors of the myometrium, have a higher prevalence of hypertension than women without UF. The cause for this relationship is unclear. Muscle sympathetic nerve activity (MSNA) is a regulator of arterial blood pressure, and it is possible that variations in MSNA predispose women with UF to develop hypertension. The purpose of this study was to assess baseline blood pressure and MSNA and the relationships between MSNA and systemic hemodynamics in women with and without UF. We measured blood pressure (brachial intra-arterial line), MSNA (microneurography), and systemic hemodynamics (total peripheral resistance and cardiac output) at rest in 14 healthy, normotensive, premenopausal women with UF (42 ± 2 years old) and 9 healthy, normotensive, premenopausal women without UF (41 ± 2 years old). Baseline blood pressure and MSNA did not differ between groups (p > 0.05 for both). In women with UF, there was a positive correlation between MSNA and total peripheral resistance (r = 0.75, p = 0.02), as well as a negative correlation between MSNA and cardiac output (r = -0.73, p = 0.03). In contrast, these relationships were not seen in women without UF (p > 0.05 for both relationships). These data suggest that autonomic interactions with systemic hemodynamics, and thus blood pressure regulation, are different in healthy women with UF compared to healthy women without UF.
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Affiliation(s)
- Ronée E. Harvey
- Mayo Clinic College of Medicine and ScienceMayo ClinicRochesterMinnesotaUSA
- Department of AnesthesiologyMayo ClinicRochesterMinnesotaUSA
| | | | | | - Jacqueline K. Limberg
- Department of AnesthesiologyMayo ClinicRochesterMinnesotaUSA
- Department of Nutrition and Exercise PhysiologyUniversity of MissouriColumbiaMissouriUSA
| | | | | | - Jill N. Barnes
- Department of AnesthesiologyMayo ClinicRochesterMinnesotaUSA
- Department of KinesiologyUniversity of Wisconsin‐MadisonMadisonWisconsinUSA
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18
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O'Brien MW, Schwartz BD, Petterson JL, Kimmerly DS. Comparison of signal-averaging and regression approaches to analyzing sympathetic transduction. Clin Auton Res 2022; 32:299-302. [PMID: 35727399 DOI: 10.1007/s10286-022-00874-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2022] [Accepted: 06/10/2022] [Indexed: 11/24/2022]
Abstract
PURPOSE Spontaneous sympathetic transduction reflects the vascular and/or pressor responses to bursts of muscle sympathetic nerve activity (MSNA). Separately, signal-averaging and regression-based approaches have been implemented to quantify resting sympathetic transduction. It is unknown whether the outcomes of these analytical approaches provide (dis)similar information, which is imperative for between-study comparisons and the amalgamation of results for synthesis of multiple studies (i.e., meta-analyses). We explored the diastolic blood pressure (DBP) responses to spontaneous bursts of MSNA between these two methods of analysis. METHODS Resting beat-by-beat DBP (via finger photoplethysmography) and common peroneal nerve MSNA (via microneurography) were recorded in 52 healthy, normotensive adults (age 38 ± 20 years; 19 females). For the signal-averaged method, transduction was quantified as the mean peak increase in DBP (ΔDBP) during the 12 cardiac cycles following each MSNA burst. In addition, DBP was regressed to a moving two-cardiac-cycle window of normalized relative burst height (mmHg/relative %) to provide the regression-based transduction outcome. RESULTS The signal-averaged (1.2 ± 0.7 mmHg) and regression-based approaches (0.009 ± 0.016 mmHg/%) were unrelated (ρ = 0.03, p = 0.86). Adding to the discrepancy, only the signal-averaging approach demonstrated a lower transduction in middle-aged-older males versus younger males. CONCLUSIONS The decision of which method to use when calculating sympathetic transduction influences study outcomes, with the two most common methods of determining transduction being unrelated. There are challenges of making sweeping conclusions across studies if different analysis strategies are implemented. An understanding of when to use each method is needed to adopt a harmonized approach to quantifying sympathetic transduction.
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Affiliation(s)
- Myles W O'Brien
- Autonomic Cardiovascular Control and Exercise Laboratory, Division of Kinesiology, Faculty of Health, School of Health and Human Performance, Dalhousie University, 6230 South Street, Halifax, NS, B3H 4R2, Canada.
| | - Beverly D Schwartz
- Autonomic Cardiovascular Control and Exercise Laboratory, Division of Kinesiology, Faculty of Health, School of Health and Human Performance, Dalhousie University, 6230 South Street, Halifax, NS, B3H 4R2, Canada
| | - Jennifer L Petterson
- Autonomic Cardiovascular Control and Exercise Laboratory, Division of Kinesiology, Faculty of Health, School of Health and Human Performance, Dalhousie University, 6230 South Street, Halifax, NS, B3H 4R2, Canada
| | - Derek S Kimmerly
- Autonomic Cardiovascular Control and Exercise Laboratory, Division of Kinesiology, Faculty of Health, School of Health and Human Performance, Dalhousie University, 6230 South Street, Halifax, NS, B3H 4R2, Canada
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19
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Wan HY, Weavil JC, Thurston TS, Georgescu VP, Morrissey CK, Amann M. On the hemodynamic consequence of the chemoreflex and muscle mechanoreflex interaction in women and men: two tales, one story. J Physiol 2022; 600:3671-3688. [PMID: 35710103 PMCID: PMC9378608 DOI: 10.1113/jp283051] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2022] [Accepted: 06/14/2022] [Indexed: 11/08/2022] Open
Abstract
KEY POINTS The cardiovascular response resulting from the activation of the muscle mechanoreflex (MMR), or the chemoreflex (CR), was previously shown to be different between women and men; this study focused on the hemodynamic consequence of the interaction of these two sympathoexcitatory reflexes. MMR and CR were activated by passive leg movement and exposure to hypoxia (O2 -CR), or hypercapnia (CO2 -CR), respectively. Individual and interactive reflex effects on central and peripheral hemodynamics were quantified in healthy young women and men. In men, the MMR:O2 -CR and MMR:CO2 -CR interactions restricted peripheral hemodynamics, likely by potentiating sympathetic vasoconstriction. In women, the MMR:O2 -CR interaction facilitated central and peripheral hemodynamics, likely by potentiating sympathetic vasodilation; however, the MMR:CO2 -CR interaction was simply additive for the central and peripheral hemodynamics. The interaction between the MMR and the CR exerts a profound influence on the autonomic control of cardiovascular function in humans, with the hemodynamic consequences differing between women and men. ABSTRACT The cardiovascular response resulting from the individual activation of the muscle mechanoreflex (MMR), or the chemoreflex (CR), is different between men and women. Whether the hemodynamic consequence resulting from the interaction of these sympathoexcitatory reflexes is also sex-dependent remains unknown. MMR and CR were activated by passive leg movement (LM) and exposure to hypoxia (O2 -CR), or hypercapnia (CO2 -CR), respectively. Twelve young men and 12 young women completed two experimental protocols: 1) resting in normoxia (PET O2 : ∼83mmHg, PET CO2 : ∼34mmHg), normocapnic hypoxia (PET O2 : ∼48mmHg, PET CO2 : ∼34mmHg), and hyperoxic hypercapnia (PET O2 : ∼524mmHg, PET CO2 : ∼44mmHg); 2) LM under the same gas conditions. During the MMR:O2 -CR coactivation, in men, the observed blood pressure (MAP) and cardiac output (CO) were not different (additive effect), while the observed leg blood flow (LBF) and vascular conductance (LVC) were significantly lower (hypo-additive), compared with the sum of the responses elicited by each reflex alone. In women, the observed MAP was not different (additive) while the observed CO, LBF, and LVC were significantly greater (hyper-additive), compared with the summated responses. During the MMR:CO2 -CR coactivation, in men, the observed MAP, CO, and LBF were not different (additive), while the observed LVC was significantly lower (hypo-additive), compared with the summated responses. In women, the observed MAP was significantly higher (hyper-additive), while the observed CO, LBF, and LVC were not different (additive), compared with the summated responses. The interaction of the MMR and CR has a pronounced influence on the autonomic cardiovascular control, with the hemodynamic consequences differing between men and women. Abstract figure legend The chemoreflex and the muscle mechanoreflex are sympathoexcitatory mechanisms which, via neural feedback to the cardiovascular centre in the medulla, mediate neurocirculatory responses during physical activity. The interaction of the peripheral chemoreflex and muscle mechanoreflex potentiates vasoconstriction in men, but potentiates vasodilatation in women (left panel). The interaction of the central chemoreflex and muscle mechanoreflex also potentiates vasoconstriction in men, whereas the reflex interaction is simply additive for the vasomotor tone in women (right panel). This article is protected by copyright. All rights reserved.
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Affiliation(s)
- Hsuan-Yu Wan
- Department of Anesthesiology, University of Utah, Salt Lake City, UT
| | - Joshua C Weavil
- Geriatric Research, Education, and Clinical Center, VAMC, Salt Lake City, UT
| | - Taylor S Thurston
- Department of Nutrition and Integrative Physiology, University of Utah, Salt Lake City, UT
| | - Vincent P Georgescu
- Department of Nutrition and Integrative Physiology, University of Utah, Salt Lake City, UT
| | | | - Markus Amann
- Department of Anesthesiology, University of Utah, Salt Lake City, UT.,Geriatric Research, Education, and Clinical Center, VAMC, Salt Lake City, UT.,Department of Nutrition and Integrative Physiology, University of Utah, Salt Lake City, UT
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20
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Shafer BM, Incognito AV, Vermeulen TD, Nardone M, Teixeira AL, Klassen SA, Millar PJ, Foster GE. Action potential amplitude and baroreflex resetting of action potential clusters mediate hypoxia-induced sympathetic long-term facilitation. J Physiol 2022; 600:3127-3147. [PMID: 35661360 DOI: 10.1113/jp282933] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2022] [Accepted: 05/03/2022] [Indexed: 11/08/2022] Open
Abstract
KEY POINTS Acute isocapnic hypoxia resets the arterial baroreflex and permits long-lasting sympathoexcitation called sympathetic long-term facilitation. Our understanding of sympathetic long-term facilitation following hypoxia in humans is based on multiunit muscle sympathetic nerve activity and does not fully characterize the underlying baroreflex control of sympathetic neuronal subpopulations or their discharge/recruitment strategies. We show that sympathetic long-term facilitation is mediated by baroreflex resetting of sympathetic action potential clusters to higher arterial pressure operating points, a reduction in the percentage of action potentials firing asynchronously, and a shift toward larger amplitude action potential activity. The results advance our fundamental understanding of how the sympathetic nervous system mediates sympathetic long-term facilitation following exposure to acute isocapnic hypoxia in humans. ABSTRACT Baroreflex resetting permits sympathetic long-term facilitation (sLTF) following hypoxia; however, baroreflex control of action potential (AP) clusters and AP recruitment patterns facilitating sLTF is unknown. We hypothesized that baroreflex resetting of arterial pressure operating points (OPs) of AP clusters and recruitment of large-amplitude APs would mediate sLTF following hypoxia. Eight men (age: 24 (3) yrs; BMI: 24 (3) kg/m2 ) underwent 20-min isocapnic hypoxia (PET O2 : 47 (2) mmHg) and 30-min recovery. Multi-unit microneurography (muscle sympathetic nerve activity; MSNA) and a continuous wavelet transform with matched mother wavelet was used to detect sympathetic APs during baseline, hypoxia, early (first 5-min), and late recovery (last 5-min). AP amplitude (normalized to largest baseline AP amplitude), percent APs occurring outside a MSNA burst (% asynchronous APs), and proportion of APs firing in small (1-3), medium (4-6), and large (7-10) normalized cluster sizes was calculated. Normalized clusters were used to assess baroreflex OPs and sensitivity. Hypoxia increased total MSNA activity, which remained elevated during recovery (P<0.0001). Baroreflex OPs were shifted rightward for all clusters in recovery, with no effect on slope. Compared to baseline, AP amplitude was elevated by 3 (2) % and 4 (2) % while asynchronous APs were reduced by 9 (5) % and 7 (6) % in early and late recovery, respectively. In early recovery, the proportion of APs firing in large clusters was increased compared to baseline. Hypoxia-induced sLTF is mediated by baroreflex resetting of AP clusters to higher OPs, reduced asynchronous AP firing, and increased contribution from large-amplitude APs. Abstract figure legend Eight healthy men underwent 20-min isocapnic hypoxia and 30-min recovery. The study tested the hypothesis that baroreflex resetting of arterial pressure operating points (OPs) of action potential (AP) clusters and recruitment of large-amplitude APs would mediate sympathetic long-term facilitation (sLTF) following acute hypoxic exposure. Hypoxia increased multi-unit muscle sympathetic nerve activity (MSNA; measured via microneurography), which remained elevated throughout recovery. Sympathetic APs were detected in the filtered MSNA neurogram using a continuous wavelet transform with matched mother wavelet. An effect of condition revealed that compared to baseline, AP amplitude was elevated while asynchronous APs were reduced in early and late recovery, respectively. Our findings show that AP amplitude distributions are shifting towards larger AP amplitudes in all subjects following hypoxia. Our findings indicate that hypoxia-induced sLTF is mediated by baroreflex resetting of AP clusters to higher OPs, reduced asynchronous AP firing, and increased contribution from large-amplitude APs. This article is protected by copyright. All rights reserved.
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Affiliation(s)
- Brooke M Shafer
- Centre for Heart, Lung, and Vascular Health, School of Health and Exercise Sciences, University of British Columbia, Kelowna, Canada
| | - Anthony V Incognito
- Department of Human Health and Nutritional Sciences, University of Guelph, Canada
| | - Tyler D Vermeulen
- Centre for Heart, Lung, and Vascular Health, School of Health and Exercise Sciences, University of British Columbia, Kelowna, Canada
| | - Massimo Nardone
- Department of Human Health and Nutritional Sciences, University of Guelph, Canada
| | - André L Teixeira
- Department of Human Health and Nutritional Sciences, University of Guelph, Canada
| | | | - Philip J Millar
- Department of Human Health and Nutritional Sciences, University of Guelph, Canada
| | - Glen E Foster
- Centre for Heart, Lung, and Vascular Health, School of Health and Exercise Sciences, University of British Columbia, Kelowna, Canada
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21
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Jacob DW, Voshage AM, Harper JL, Limberg JK. Effect of oral hormonal contraceptive pill use on the hemodynamic response to the cold pressor test. Am J Physiol Heart Circ Physiol 2022; 322:H1072-H1079. [PMID: 35486478 PMCID: PMC9142154 DOI: 10.1152/ajpheart.00140.2022] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/15/2022] [Revised: 04/21/2022] [Accepted: 04/22/2022] [Indexed: 11/22/2022]
Abstract
Acute increases in sympathetic nervous system activity (SNA) often elicit peripheral vasoconstriction and increases in blood pressure (BP). Given sympathetic support of BP is modulated by ovarian sex hormones (e.g., estradiol), we sought to examine the effect of menstrual cycle and oral hormonal contraceptive pill (OC) phase on the hemodynamic response to acute increases in SNA. We hypothesized sympathoexcitation via cold pressor test (CPT) would elicit greater peripheral vasoconstriction and increases BP in females with natural menstrual cycles (NC) compared with females taking OC. We further hypothesized that SNA-mediated vasoconstriction would be attenuated during the high estradiol (HE) phase versus the low estradiol (LE) phase of the menstrual/pill cycle. Female NC (n = 11, 25 ± 1 yr) and OC (n = 10, 24 ± 1 yr) participants were studied during the LE (early follicular, placebo pill) and HE (late follicular, active pill) phase of the menstrual/pill cycle. BP (finger photoplethysmography), heart rate (HR, ECG), and forearm blood flow (FBF, venous occlusion plethysmography) were measured during a 5-min baseline and a 2-min CPT. CPT elicited an increase in BP in both groups (time, P < 0.01). During CPT, OC participants exhibited greater and sustained increases in HR compared with NC participants (group × time, P < 0.01). Higher HRs were met with increases in FBF in OC participants during the CPT, which was not observed in NC participants (group × time, P < 0.01). OC participants exhibit greater increases in HR, and paradoxical vasodilation during acute sympathetic activation compared with NC participants. Group differences are unaffected by menstrual/pill phase.NEW & NOTEWORTHY Acute increases in sympathetic nervous system activity often elicit peripheral vasoconstriction and increases in blood pressure (BP). Given sympathetic support of BP is modulated by ovarian sex hormones (e.g., estradiol), we sought to examine the effect of menstrual cycle and oral hormonal contraceptive pill (OC) phase on the hemodynamic response to acute increases in sympathetic nervous system activity via the cold pressor test. We show OC participants exhibit paradoxical vasodilation during acute sympathetic activation compared with participants with natural menstrual cycles; notably, group differences were unaffected by menstrual/pill phase.
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Affiliation(s)
- Dain W Jacob
- Department of Nutrition and Exercise Physiology, University of Missouri, Columbia, Missouri
| | - Aaron M Voshage
- Department of Nutrition and Exercise Physiology, University of Missouri, Columbia, Missouri
| | - Jennifer L Harper
- Department of Nutrition and Exercise Physiology, University of Missouri, Columbia, Missouri
| | - Jacqueline K Limberg
- Department of Nutrition and Exercise Physiology, University of Missouri, Columbia, Missouri
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22
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Greaney JL, Darling AM, Mogle J, Saunders EFH. Microvascular β-Adrenergic Receptor-Mediated Vasodilation Is Attenuated in Adults With Major Depressive Disorder. Hypertension 2022; 79:1091-1100. [PMID: 35232218 PMCID: PMC9010365 DOI: 10.1161/hypertensionaha.122.18985] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
BACKGROUND Major depressive disorder (MDD) is associated with sympathetic overactivity and alterations in peripheral adrenergic receptor function; however, no studies have directly assessed vasoconstrictor responsiveness in adults with MDD. We tested the hypotheses that β-adrenergic receptor-mediated vasodilation would be blunted in adults with MDD compared with healthy nondepressed adults (HA) and would functionally contribute to exaggerated norepinephrine-induced vasoconstriction. METHODS In 13 HA (8 female; 24±4 years) and in 12 adults with MDD (8 female; 22±3 yrs), red blood cell flux was measured during graded intradermal microdialysis perfusion of the β-adrenergic receptor agonist isoproterenol (10-10 to 10-4 mol/L) and, separately, during the perfusion of norepinephrine (10-12 to 10-2 mol/L), alone and in combination with the β-adrenergic receptor antagonist propranolol (2 mmol/L). Nonadrenergic vasoconstriction was assessed via perfusion of angiotensin II (10-12 to 10-4 mol/L). RESULTS Isoproterenol-induced vasodilation was blunted in adults with MDD (188.9±70.1 HA versus 128.3±39.4 au MDD, P=0.025). Net norepinephrine-induced vasoconstriction was exaggerated in adults with MDD (-0.16±0.54 HA versus -0.75±0.56 au MDD, P=0.014); however, there were no group differences in angiotensin II-induced vasoconstriction. Propranolol potentiated norepinephrine-induced vasoconstriction in HA (-0.16±0.54 norepinephrine versus -1.60±1.40 au propranolol, P<0.01) but had no effect in adults with MDD (-0.75±0.56 norepinephrine versus -1.58±1.56 au propranolol, P=0.08). CONCLUSIONS β-adrenergic receptor-mediated microvascular vasodilation was blunted in adults with MDD and contributed to exaggerated adrenergic vasoconstriction. The relative loss of the vasoprotective effect of β-adrenergic receptor-mediated vasodilation may contribute to increased peripheral resistance, thereby driving the development of hypertension in adults with MDD.
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Affiliation(s)
- Jody L. Greaney
- Department of Kinesiology, The University of Texas at Arlington, Arlington, TX
| | - Ashley M. Darling
- Department of Kinesiology, The University of Texas at Arlington, Arlington, TX
| | - Jacqueline Mogle
- Edna Bennett Pierce Prevention Research Center, The Pennsylvania State University, University Park, PA
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23
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Nardone M, Katerberg C, Teixeira AL, Lee JB, Bommarito JC, Millar PJ. Sympathetic transduction of blood pressure during graded lower body negative pressure in young healthy adults. Am J Physiol Regul Integr Comp Physiol 2022; 322:R620-R628. [DOI: 10.1152/ajpregu.00034.2022] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Sympathetic transduction of blood pressure (BP) is correlated negatively with resting muscle sympathetic nerve activity (MSNA) in cross-sectional data, but the acute effects of increasing MSNA are unclear. Sixteen (4 females) healthy adults (26±3 years) underwent continuous measurement of heart rate, BP, and MSNA at rest and during graded lower body negative pressure (LBNP) at -10, -20, and -30mmHg. Sympathetic transduction of BP was quantified in the time (signal averaging) and frequency (MSNA-BP gain) domains. The proportion of MSNA bursts firing within each tertile of BP were calculated. As expected, LBNP increased MSNA burst frequency (P<0.01) and burst amplitude (P<0.02), though the proportions of MSNA bursts firing across each BP tertile remained stable (all P>0.44). The MSNA-diastolic BP low frequency transfer function gain (P=0.25) was unchanged during LBNP; the spectral coherence was increased (P=0.03). Signal-averaged sympathetic transduction of diastolic BP was unchanged (from 2.1±1.0 at rest to 2.4±1.5, 2.2±1.3, and 2.3±1.4mmHg; P=0.43) during LBNP, but diastolic BP responses following non-burst cardiac cycles progressively decreased (from -0.8±0.4 at rest to -1.0±0.6, -1.2±0.6, and -1.6±0.9mmHg; P<0.01). As a result, the difference between MSNA burst and non-bursts diastolic BP responses was increased (from 2.9±1.4 at rest to 3.4±1.9, 3.4±1.9, and 3.9±2.1mmHg; P<0.01). In conclusion, acute increases in MSNA using LBNP did not alter traditional signal-averaged or frequency-domain measures of sympathetic transduction of BP or the proportion of MSNA bursts firing at different BP levels. The factors that determine changes in the firing of MSNA bursts relative to oscillations in BP require further investigation.
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Affiliation(s)
- Massimo Nardone
- Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, Ontario, Canada
| | - Carlin Katerberg
- Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, Ontario, Canada
| | - André L. Teixeira
- Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, Ontario, Canada
| | - Jordan B. Lee
- Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, Ontario, Canada
| | - Julian C. Bommarito
- Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, Ontario, Canada
| | - Philip J. Millar
- Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, Ontario, Canada
- Toronto General Research Institute, Toronto General Hospital, Toronto, Ontario, Canada
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24
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Coovadia Y, Adler TE, Martin-Arrowsmith PW, Usselman CW. Sex differences in sympathetic neuro-vascular and neuro-hemodynamic relationships during the cold pressor test. Am J Physiol Regul Integr Comp Physiol 2022; 322:R411-R420. [PMID: 35293259 DOI: 10.1152/ajpregu.00223.2021] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Muscle sympathetic nerve activity (MSNA) affects vascular resistance differently in women and men. However, whether this sex difference persists during pronounced increases in MSNA remains unclear. Therefore, the purpose of this study was to examine sex differences in neurovascular transduction during cold pressor test (CPT)-mediated sympatho-excitation. Integrated peroneal MSNA (microneurography) was measured at rest and during a 3-minute CPT in young healthy women (n=11) and men (n=10). Mean arterial pressure (MAP) was measured beat-by-beat (Finometer) and superficial femoral artery blood flow was measured using duplex ultrasound. Femoral vascular resistance (FVR) was quantified as MAP/femoral blood flow (mmHg/mL/min). Baseline MSNA was similar between women and men (14±9 vs 15±9 bursts/100hb, respectively; P=0.83), whereas MAP was lower (86±7 vs 92±4 mmHg; P=0.047), and FVR was greater in women than men (0.54±0.16 vs 0.36±0.15 mmHg/mL/min; P=0.02). CPT-induced increases in MSNA were similar between the sexes (+19±11 vs +26±14 bursts/100hb; P=0.26) while increases in MAP (+7±3 vs +10±3mmHg; P=0.03) and FVR (+3.2±18.6 vs +26.8±12.8%; P<0.01) were smaller in women than men. Within men, CPT- induced increases in MSNA predicted increases in MAP (R2=0.51, P=0.02) and FVR (R2=0.49, P=0.02). However, MSNA did not predict MAP (R2=0.11, P=0.35) or FVR (R2=0.07, P=0.46) in women. Our findings demonstrate that men experience robust CPT-induced MAP responses that are driven by both neuro-vascular (MSNA-FVR) and neuro-hemodynamic (MSNA-MAP) coupling. These relationships were not observed in women, indicating that even during pronounced increases in sympathetic outflow, MSNA is not predictive of vascular nor blood pressure outcomes in young healthy women.
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Affiliation(s)
- Yasmine Coovadia
- Cardiovascular Health and Autonomic Regulation Laboratory, McGill University, Montreal, Quebec, Canada
| | - Tessa E Adler
- Cardiovascular Health and Autonomic Regulation Laboratory, McGill University, Montreal, Quebec, Canada
| | - Patrick W Martin-Arrowsmith
- Exercise Metabolism and 6 Nutrition Research Lab, Department of Kinesiology and Physical Education, McGill University, Montreal, Quebec, Canada
| | - Charlotte W Usselman
- Cardiovascular Health and Autonomic Regulation Laboratory, McGill University, Montreal, Quebec, Canada.,McGill Research Centre for Physical Activity and Health, McGill University, Montreal, Quebec, Canada
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25
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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: 14] [Impact Index Per Article: 7.0] [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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26
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Petterson JL, O'Brien MW, Ramsay DJ, Johnston W, O'Neill CD, Dogra S, Mekari S, Floras JS, Kimmerly DS. Sympathetic neurohemodynamic transduction is attenuated in older males independent of aerobic fitness. Clin Auton Res 2022; 32:73-76. [PMID: 35024990 DOI: 10.1007/s10286-021-00845-y] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2021] [Accepted: 12/14/2021] [Indexed: 11/28/2022]
Affiliation(s)
- Jennifer L Petterson
- Autonomic Cardiovascular Control and Exercise Laboratory, Division of Kinesiology, School of Health and Human Performance, Faculty of Health, Dalhousie University, 6230 South Street, Halifax, NS, B3H 4R2, Canada
| | - Myles W O'Brien
- Autonomic Cardiovascular Control and Exercise Laboratory, Division of Kinesiology, School of Health and Human Performance, Faculty of Health, Dalhousie University, 6230 South Street, Halifax, NS, B3H 4R2, Canada
| | - Diane J Ramsay
- Autonomic Cardiovascular Control and Exercise Laboratory, Division of Kinesiology, School of Health and Human Performance, Faculty of Health, Dalhousie University, 6230 South Street, Halifax, NS, B3H 4R2, Canada
| | - William Johnston
- Autonomic Cardiovascular Control and Exercise Laboratory, Division of Kinesiology, School of Health and Human Performance, Faculty of Health, Dalhousie University, 6230 South Street, Halifax, NS, B3H 4R2, Canada
| | - Carley D O'Neill
- Exercise Physiology and Cardiovascular Health Lab, University of Ottawa Heart Institute, Ottawa, ON, Canada.,Department of Family Medicine, Université de Sherbrooke, Sherbrooke, QC, Canada
| | - Shilpa Dogra
- Health and Human Performance Laboratory, Faculty of Health Sciences, University of Ontario Institute of Technology, Oshawa, ON, Canada.,Department of Family Medicine, Université de Sherbrooke, Sherbrooke, QC, Canada
| | - Said Mekari
- Department of Family Medicine, Université de Sherbrooke, Sherbrooke, QC, Canada
| | - John S Floras
- University Health Network and Mount Sinai Hospital Division of Cardiology, Department of Medicine, University of Toronto and the Toronto General Research Institute, University Health Network, Toronto, ON, Canada
| | - Derek S Kimmerly
- Autonomic Cardiovascular Control and Exercise Laboratory, Division of Kinesiology, School of Health and Human Performance, Faculty of Health, Dalhousie University, 6230 South Street, Halifax, NS, B3H 4R2, Canada.
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27
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Kobetic MD, Burchell AE, Ratcliffe LEK, Neumann S, Adams ZH, Nolan R, Nightingale AK, Paton JFR, Hart EC. Sympathetic-transduction in untreated hypertension. J Hum Hypertens 2022; 36:24-31. [PMID: 34453103 PMCID: PMC8766277 DOI: 10.1038/s41371-021-00578-5] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2019] [Revised: 04/28/2021] [Accepted: 07/07/2021] [Indexed: 01/31/2023]
Abstract
Transduction of muscle sympathetic nerve activity (MSNA) into vascular tone varies with age and sex. Older normotensive men have reduced sympathetic transduction so that a given level of MSNA causes less arteriole vasoconstriction. Whether sympathetic transduction is altered in hypertension (HTN) is not known. We investigated whether sympathetic transduction is impaired in untreated hypertensive men compared to normotensive controls. Eight untreated hypertensive men and 10 normotensive men (age 50 ± 15 years vs. 45 ± 12 years (mean ± SD); p = 0.19, body mass index (BMI) 24.7 ± 2.7 kg/m2 vs. 26.0 ± 4.2 kg/m2; p = 0.21) were recruited. MSNA was recorded from the peroneal nerve using microneurography; beat-to-beat blood pressure (BP; Finapres) and heart rate (ECG) were recorded simultaneously at rest for 10 min. Sympathetic-transduction was quantified using a previously described method. The relationship between MSNA burst area and subsequent diastolic BP was measured for each participant with the slope of the regression indicating sympathetic transduction. MSNA was higher in the hypertensive group compared to normotensives (73 ± 17 bursts/100 heartbeats vs. 49 ± 19 bursts/100 heart bursts; p = 0.007). Sympathetic-transduction was lower in the hypertensive versus normotensive group (0.04%/mmHg/s vs. 0.11%/mmHg/s, respectively; R = 0.622; p = 0.006). In summary, hypertensive men had lower sympathetic transduction compared to normotensive individuals suggesting that higher levels of MSNA are needed to cause the same level of vasoconstrictor tone.
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Affiliation(s)
- Matthew D. Kobetic
- grid.5337.20000 0004 1936 7603School of Physiology, Pharmacology, and Neuroscience, Clinical Research and Imaging Centre, University of Bristol, Bristol, UK
| | - Amy E. Burchell
- grid.5337.20000 0004 1936 7603Cardionomics Research Group, Bristol Heart Institute, University Hospitals Bristol NHS Foundation Trust, University of Bristol, Bristol, UK
| | - Laura E. K. Ratcliffe
- grid.415953.f0000 0004 0400 1537Department of Nephrology, Lister Hospital, East and North Hertfordshire NHS Trust, Hertfordshire, UK
| | - Sandra Neumann
- grid.5337.20000 0004 1936 7603School of Physiology, Pharmacology, and Neuroscience, Clinical Research and Imaging Centre, University of Bristol, Bristol, UK ,grid.5337.20000 0004 1936 7603Cardionomics Research Group, Bristol Heart Institute, University Hospitals Bristol NHS Foundation Trust, University of Bristol, Bristol, UK
| | - Zoe H. Adams
- grid.5337.20000 0004 1936 7603School of Physiology, Pharmacology, and Neuroscience, Clinical Research and Imaging Centre, University of Bristol, Bristol, UK ,grid.5337.20000 0004 1936 7603Cardionomics Research Group, Bristol Heart Institute, University Hospitals Bristol NHS Foundation Trust, University of Bristol, Bristol, UK
| | - Regina Nolan
- grid.5337.20000 0004 1936 7603Cardionomics Research Group, Bristol Heart Institute, University Hospitals Bristol NHS Foundation Trust, University of Bristol, Bristol, UK
| | - Angus K. Nightingale
- grid.5337.20000 0004 1936 7603School of Physiology, Pharmacology, and Neuroscience, Clinical Research and Imaging Centre, University of Bristol, Bristol, UK ,grid.5337.20000 0004 1936 7603Cardionomics Research Group, Bristol Heart Institute, University Hospitals Bristol NHS Foundation Trust, University of Bristol, Bristol, UK
| | - Julian F. R. Paton
- grid.5337.20000 0004 1936 7603School of Physiology, Pharmacology, and Neuroscience, Clinical Research and Imaging Centre, University of Bristol, Bristol, UK ,grid.5337.20000 0004 1936 7603Cardionomics Research Group, Bristol Heart Institute, University Hospitals Bristol NHS Foundation Trust, University of Bristol, Bristol, UK
| | - Emma C. Hart
- grid.5337.20000 0004 1936 7603School of Physiology, Pharmacology, and Neuroscience, Clinical Research and Imaging Centre, University of Bristol, Bristol, UK ,grid.5337.20000 0004 1936 7603Cardionomics Research Group, Bristol Heart Institute, University Hospitals Bristol NHS Foundation Trust, University of Bristol, Bristol, UK
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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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Limberg JK, Johansson RE, Carter KJ, Peltonen GL, Harrell JW, Kellawan JM, Eldridge MW, Sebranek JJ, Walker BJ, Schrage WG. Preserved β-adrenergic-mediated vasodilation in skeletal muscle of young adults with obesity despite shifts in cyclooxygenase and nitric oxide synthase. Am J Physiol Heart Circ Physiol 2022; 322:H25-H35. [PMID: 34738833 PMCID: PMC8698505 DOI: 10.1152/ajpheart.00449.2021] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Central adiposity is associated with greater sympathetic support of blood pressure. β-adrenergic receptors (β-AR) buffer sympathetically mediated vasoconstriction and β-AR-mediated vasodilation is attenuated in preclinical models of obesity. With this information, we hypothesized β-AR vasodilation would be lower in obese compared with normal weight adults. Because β-AR vasodilation in normal weight adults is limited by cyclooxygenase (COX) restraint of nitric oxide synthase (NOS), we further explored the contributions of COX and NOS to β-AR vasodilation in this cohort. Forearm blood flow (FBF, Doppler ultrasound) and mean arterial blood pressure (MAP, brachial arterial catheter) were measured and forearm vascular conductance (FVC) was calculated (FVC = FBF/MAP). The rise in FVC from baseline (ΔFVC) was quantified during graded brachial artery infusion of isoproterenol (Iso, 1-12 ng/100 g/min) in normal weight (n = 36) and adults with obesity (n = 22) (18-40 yr old). In a subset of participants, Iso-mediated vasodilation was examined before and during inhibition of NOS [NG-monomethyl-l-arginine (l-NMMA)], COX (ketorolac), and NOS + COX (l-NMMA + ketorolac). Iso-mediated increases in FVC did not differ between groups (P = 0.57). l-NMMA attenuated Iso-mediated ΔFVC in normal weight (P = 0.03) but not adults with obesity (P = 0.27). In normal weight adults, ketorolac increased Iso-mediated ΔFVC (P < 0.01) and this response was lost with concurrent l-NMMA (P = 0.67). In contrast, neither ketorolac (P = 0.81) nor ketorolac + l-NMMA (P = 0.40) altered Iso-mediated ΔFVC in adults with obesity. Despite shifts in COX and NOS, β-AR vasodilation is preserved in young adults with obesity. These data highlight the presence of a compensatory shift in microvascular control mechanisms in younger humans with obesity.NEW & NOTEWORTHY We examined β-adrenergic receptor-mediated vasodilation in skeletal muscle of humans with obesity and normal weight. Results show that despite shifts in the contribution of cyclooxygenase and nitric oxide synthase, β-adrenergic-mediated vasodilation is relatively preserved in young, otherwise healthy adults with obesity. These data highlight the presence of subclinical changes in microvascular control mechanisms early in the obesity process and suggest duration of obesity and/or the addition of primary aging may be necessary for overt dysfunction.
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Affiliation(s)
- Jacqueline K. Limberg
- 1Department of Nutrition and Exercise Physiology, University of Missouri, Columbia, Missouri,2Department of Kinesiology, University of Wisconsin, Madison, Wisconsin
| | | | - Katrina J. Carter
- 2Department of Kinesiology, University of Wisconsin, Madison, Wisconsin
| | - Garrett L. Peltonen
- 2Department of Kinesiology, University of Wisconsin, Madison, Wisconsin,3School of Nursing and Kinesiology, Western New Mexico University, Silver City, New Mexico
| | - John W. Harrell
- 2Department of Kinesiology, University of Wisconsin, Madison, Wisconsin,4711th Human Performance Wing, Air Force Research Laboratory, Wright-Patterson Air Force Base, Ohio
| | - J. Mikhail Kellawan
- 2Department of Kinesiology, University of Wisconsin, Madison, Wisconsin,5Department of Health and Exercise Science, University of Oklahoma, Norman, Oklahoma
| | - Marlowe W. Eldridge
- 2Department of Kinesiology, University of Wisconsin, Madison, Wisconsin,6Department of Pediatrics, University of Wisconsin, Madison, Wisconsin
| | - Joshua J. Sebranek
- 7Department of Anesthesiology, University of Wisconsin, Madison, Wisconsin
| | - Benjamin J. Walker
- 7Department of Anesthesiology, University of Wisconsin, Madison, Wisconsin
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Lower sympathetic transduction of blood pressure in uncontrolled hypertensives: physiological adaptation, methodological limitation, or both? J Hum Hypertens 2021; 36:423-424. [PMID: 34795392 DOI: 10.1038/s41371-021-00638-w] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2021] [Revised: 11/04/2021] [Accepted: 11/09/2021] [Indexed: 11/08/2022]
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31
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Shafer BM, Incognito AV, Vermeulen TD, Nardone M, Teixeira AL, Benbaruj J, Millar PJ, Foster GE. Muscle Metaboreflex Control of Sympathetic Activity Is Preserved after Acute Intermittent Hypercapnic Hypoxia. Med Sci Sports Exerc 2021; 53:2233-2244. [PMID: 34081056 DOI: 10.1249/mss.0000000000002716] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
PURPOSE In normotensive patients with obstructive sleep apnea (OSA), the muscle sympathetic nerve activity (MSNA) response to exercise is increased while metaboreflex control of MSNA is decreased. We tested the hypotheses that acute intermittent hypercapnic hypoxia (IHH) in males free from OSA and associated comorbidities would augment the MSNA response to exercise but attenuate the change in MSNA during metaboreflex activation. METHODS Thirteen healthy males (age = 24 ± 4 yr) were exposed to 40 min of IHH. Before and after IHH, the pressor response to exercise was studied during 2 min of isometric handgrip exercise (at 30% maximal voluntary contraction), whereas the metaboreflex was studied during 4 min of postexercise circulatory occlusion (PECO). Mean arterial pressure (MAP), heart rate (HR), and fibular MSNA were recorded continuously. MSNA was quantified as burst frequency (BF) and total activity (TA). Mixed effects linear models were used to compare the exercise pressor and metaboreflex before and after IHH. RESULTS As expected, IHH led to significant increases in MSNA BF, TA, and MAP at baseline and throughout exercise and PECO. However, during handgrip exercise, the change from baseline in MAP, HR, MSNA BF, and TA was similar before and after IHH (All P > 0.31). During PECO, the change from baseline in MSNA BF and TA was similar after IHH, whereas the change from baseline in MAP (Δ14 mm Hg, 95% CI = 7-19, vs Δ16 mm Hg, 95% CI = 10-21; P < 0.01) was modestly increased. CONCLUSION After acute IHH, MSNA response to handgrip exercise and metaboreflex activation were preserved in healthy young males despite overall increases in resting MSNA and MAP. Chronic IHH and comorbidities often associated with OSA may be required to modulate the exercise pressor reflex and metaboreflex.
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Affiliation(s)
- Brooke M Shafer
- Centre for Heart, Lung, and Vascular Health, School of Health and Exercise Sciences, University of British Columbia, Kelowna, British Columbia, CANADA
| | - Anthony V Incognito
- Department of Human Health and Nutritional Sciences, University of Guelph, Ontario, CANADA
| | - Tyler D Vermeulen
- Centre for Heart, Lung, and Vascular Health, School of Health and Exercise Sciences, University of British Columbia, Kelowna, British Columbia, CANADA
| | - Massimo Nardone
- Department of Human Health and Nutritional Sciences, University of Guelph, Ontario, CANADA
| | - André L Teixeira
- Department of Human Health and Nutritional Sciences, University of Guelph, Ontario, CANADA
| | - Jenna Benbaruj
- Centre for Heart, Lung, and Vascular Health, School of Health and Exercise Sciences, University of British Columbia, Kelowna, British Columbia, CANADA
| | - Philip J Millar
- Department of Human Health and Nutritional Sciences, University of Guelph, Ontario, CANADA
| | - Glen E Foster
- Centre for Heart, Lung, and Vascular Health, School of Health and Exercise Sciences, University of British Columbia, Kelowna, British Columbia, CANADA
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Nardone M, Katerberg C, Incognito AV, Teixeira AL, Vianna LC, Millar PJ. Blood pressure oscillations impact signal-averaged sympathetic transduction of blood pressure: implications for the association with resting sympathetic outflow. Am J Physiol Heart Circ Physiol 2021; 321:H798-H806. [PMID: 34506224 DOI: 10.1152/ajpheart.00422.2021] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Signal-averaged sympathetic transduction of blood pressure (BP) is inversely related to resting muscle sympathetic nerve activity (MSNA) burst frequency in healthy cohorts. Whether this represents a physiological compensatory adaptation or a methodological limitation, remains unclear. The current analysis aimed to determine the contribution of methodological limitations by evaluating the dependency of MSNA transduction at different levels of absolute BP. Thirty-six healthy participants (27 ± 7 yr, 9 females) underwent resting measures of beat-to-beat heart rate, BP, and muscle sympathetic nerve activity (MSNA). Tertiles of mean arterial pressure (MAP) were computed for each participant to identify cardiac cycles occurring below, around, and above the MAP operating pressure (OP). Changes in hemodynamic variables were computed across 15 cardiac cycles within each MAP tertile to quantify sympathetic transduction. MAP increased irrespective of sympathetic activity when initiated below the OP, but with MSNA bursts provoking larger rises (3.0 ± 0.9 vs. 2.1 ± 0.7 mmHg; P < 0.01). MAP decreased irrespective of sympathetic activity when initiated above the OP, but with MSNA bursts attenuating the drop (-1.3 ± 1.1 vs. -3.1 ± 1.2 mmHg; P < 0.01). In participants with low versus high resting MSNA (12 ± 4 vs. 32 ± 10 bursts/min), sympathetic transduction of MAP was not different when initiated by bursts below (3.2 ± 1.0 vs. 2.8 ± 0.9 mmHg; P = 0.26) and above the OP (-1.0 ± 1.3 vs. -1.6 ± 0.8 mmHg; P = 0.08); however, low resting MSNA was associated with a smaller proportion of MSNA bursts firing above the OP (15 ± 5 vs. 22 ± 5%; P < 0.01). The present analyses demonstrate that the signal-averaging technique for calculating sympathetic transduction of BP is influenced by the timing of an MSNA burst relative to cyclic oscillations in BP.NEW & NOTEWORTHY The current signal-averaging technique for calculating sympathetic transduction of blood pressure does not consider the arterial pressure at which each muscle sympathetic burst occurs. A burst firing when mean arterial pressure is above the operating pressure was associated with a decrease in blood pressure. Thus, individuals with higher muscle sympathetic nerve activity demonstrate a reduced sympathetic transduction owing to the weighted contribution of more sympathetic bursts at higher levels of arterial pressure.
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Affiliation(s)
- Massimo Nardone
- Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, Ontario, Canada
| | - Carlin Katerberg
- Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, Ontario, Canada
| | - Anthony V Incognito
- Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, Ontario, Canada
| | - André L Teixeira
- Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, Ontario, Canada
| | - Lauro C Vianna
- NeuroV̇ASQ̇-Integrative Physiology Laboratory, Faculty of Physical Education, University of Brasilia, Brasilia, Federal District, Brazil
| | - Philip J Millar
- Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, Ontario, Canada.,Toronto General Research Institute, Toronto General Hospital, Toronto, Ontario, Canada
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Steele AR, Skow RJ, Fraser GM, Berthelsen LF, Steinback CD. Sympathetic neurovascular transduction following acute hypoxia. Clin Auton Res 2021; 31:755-765. [PMID: 34528146 DOI: 10.1007/s10286-021-00824-3] [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: 06/22/2021] [Accepted: 08/18/2021] [Indexed: 01/29/2023]
Abstract
PURPOSE Following an acute exposure to hypoxia, sympathetic nerve activity remains elevated. However, this elevated sympathetic nerve activity does not elicit a parallel increase in vascular resistance suggesting a blunted sympathetic signaling [i.e. blunted sympathetic neurovascular transduction (sNVT)]. Therefore, we sought to quantify spontaneous sympathetic bursts and related changes in total peripheral resistance following hypoxic exposure. We hypothesized that following hypoxia sNVT would be blunted. METHODS Nine healthy participants (n = 6 men; mean age 25 ± 2 years) were recruited. We collected data on muscle sympathetic nerve activity (MSNA) using microneurography and beat-by-beat total peripheral resistance (TPR) via finger photoplethysmography at baseline, during acute hypoxia and during two periods of recovery (recovery period 1, 0-10 min post hypoxia; recovery period 2, 10-20 min post hypoxia). MSNA burst sequences (i.e. singlets, doublets, triplets and quads+) were identified and coupled to changes in TPR over 15 cardiac cycles as an index of sNVT for burst sequences. A sNVT slope for each participant was calculated from the slope of the relationship between TPR plotted against normalized burst amplitude. RESULTS The sNVT slope was blunted during hypoxia [Δ 0.0044 ± 0.0014 (mmHg/L/min)/(a.u.)], but unchanged following termination of hypoxia [recovery 1, Δ 0.031 ± 0.0019 (mmHg/L/min)/(a.u.); recovery 2, Δ 0.0038 ± 0.0014 (mmHg/L/min)/(a.u.) compared to baseline (Δ 0.038 ± 0.0015 (L/min/mmHg)/(a.u.)] (main effect of group p = 0.012). CONCLUSIONS Contrary to our hypothesis, we have demonstrated that systemic sNVT is unchanged following hypoxia in young healthy adults.
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Affiliation(s)
- Andrew R Steele
- Neurovascular Health Lab, Faculty of Kinesiology, Sport, and Recreation, , University of Alberta, 1-059D Li Ka Shing Centre for Health Research Innovation, Edmonton, AB, Canada, T6G 2E1
| | - Rachel J Skow
- Neurovascular Health Lab, Faculty of Kinesiology, Sport, and Recreation, , University of Alberta, 1-059D Li Ka Shing Centre for Health Research Innovation, Edmonton, AB, Canada, T6G 2E1
- Women and Children's Health Research Institute, University of Alberta, Edmonton, AB, Canada
- Alberta Diabetes Institute, University of Alberta, Edmonton, AB, Canada
- Neuroscience and Mental Health Institute, University of Alberta, Edmonton, AB, Canada
| | - Graham M Fraser
- Division of BioMedical Sciences, Faculty of Medicine, Memorial University of Newfoundland, St. John's, NL, Canada
| | - Lindsey F Berthelsen
- Neurovascular Health Lab, Faculty of Kinesiology, Sport, and Recreation, , University of Alberta, 1-059D Li Ka Shing Centre for Health Research Innovation, Edmonton, AB, Canada, T6G 2E1
| | - Craig D Steinback
- Neurovascular Health Lab, Faculty of Kinesiology, Sport, and Recreation, , University of Alberta, 1-059D Li Ka Shing Centre for Health Research Innovation, Edmonton, AB, Canada, T6G 2E1.
- Women and Children's Health Research Institute, University of Alberta, Edmonton, AB, Canada.
- Alberta Diabetes Institute, University of Alberta, Edmonton, AB, Canada.
- Neuroscience and Mental Health Institute, University of Alberta, Edmonton, AB, Canada.
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Holwerda SW. Flattening the sympathetic-vascular transduction curve. Am J Physiol Regul Integr Comp Physiol 2021; 321:R482-R483. [PMID: 34378407 PMCID: PMC8579908 DOI: 10.1152/ajpregu.00191.2021] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2021] [Revised: 08/08/2021] [Accepted: 08/09/2021] [Indexed: 11/22/2022]
Affiliation(s)
- Seth W Holwerda
- Department of Anesthesiology, University of Kansas Medical Center, Kansas City, Kansas
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35
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Klassen SA, Joyner MJ, Baker SE. The impact of ageing and sex on sympathetic neurocirculatory regulation. Semin Cell Dev Biol 2021; 116:72-81. [PMID: 33468420 PMCID: PMC8282778 DOI: 10.1016/j.semcdb.2021.01.001] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2020] [Revised: 12/30/2020] [Accepted: 01/04/2021] [Indexed: 02/07/2023]
Abstract
The sympathetic nervous system represents a critical mechanism for homoeostatic blood pressure regulation in humans. This review focuses on age-related alterations in neurocirculatory regulation in men and women by highlighting human studies that examined the relationship between muscle sympathetic nerve activity (MSNA) acquired by microneurography and circulatory variables (e.g., blood pressure, vascular resistance). We frame this review with epidemiological evidence highlighting sex-specific patterns in age-related blood pressure increases in developed nations. Indeed, young women exhibit lower blood pressure than men, but women demonstrate larger blood pressure increases with age, such that by about age 60 years, blood pressure is greater in women. Sympathetic neurocirculatory mechanisms contribute to sex differences in blood pressure rises with age. Muscle sympathetic nerve activity increases with age in both sexes, but women demonstrate greater age-related increases. The circulatory adjustments imposed by MSNA - referred to as neurovascular transduction or autonomic (sympathetic) support of blood pressure - differ in men and women. For example, whereas young men demonstrate a positive relationship between resting MSNA and vascular resistance, this relationship is absent in young women due to beta-2 adrenergic vasodilation, which offsets alpha-adrenergic vasoconstriction. However, post-menopausal women demonstrate a positive relationship between MSNA and vascular resistance due to a decline in beta-2 adrenergic vasodilatory mechanisms. Emerging data suggest that greater aerobic fitness appears to modulate neurocirculatory regulation, at least in young, healthy men and women. This review also highlights recent advances in microneurographic recordings of sympathetic action potential discharge, which may nuance our understanding of age-related alterations in sympathetic neurocirculatory regulation in humans.
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Affiliation(s)
- Stephen A Klassen
- Human and Integrative Physiology and Clinical Pharmacology Laboratory, Department of Anesthesiology and Perioperative Medicine, Mayo Clinic, Rochester, MN, USA
| | - Michael J Joyner
- Human and Integrative Physiology and Clinical Pharmacology Laboratory, Department of Anesthesiology and Perioperative Medicine, Mayo Clinic, Rochester, MN, USA
| | - Sarah E Baker
- Human and Integrative Physiology and Clinical Pharmacology Laboratory, Department of Anesthesiology and Perioperative Medicine, Mayo Clinic, Rochester, MN, USA.
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36
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Bigalke JA, Greenlund IM, Nicevski JR, Smoot CA, Oosterhoff B, John-Henderson NA, Carter JR. Blunted heart rate recovery to spontaneous nocturnal arousals in short-sleeping adults. Am J Physiol Heart Circ Physiol 2021; 321:H558-H566. [PMID: 34328345 DOI: 10.1152/ajpheart.00329.2021] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Chronic insufficient sleep is a common occurrence around the world and results in numerous physiological detriments and consequences, including cardiovascular complications. The purpose of the present study was to assess the relationship between habitual total sleep time (TST) measured objectively via at-home actigraphy and heart rate (HR) reactivity to nocturnal cortical arousals. We hypothesized that short habitual TST would be associated with exaggerated cardiac reactivity to nocturnal cortical arousals. Participants included 35 healthy individuals [20 men, 15 women, age: 24 ± 1 yr, body mass index (BMI): 27 ± 1 kg/m2], and were split using a median analysis into short-sleeping (SS; n = 17) and normal-sleeping (NS; n = 18) adults based on a minimum of 7 days of at-home actigraphy testing. All participants underwent a full overnight laboratory polysomnography (PSG) testing session, including continuous HR (electrocardiogram, ECG) sampling. HR reactivities to all spontaneous cortical arousals were assessed for 30 cardiac cycles following the onset of the arousal in all participants. Baseline HR was not significantly different between groups (P > 0.05). Spontaneous nocturnal arousal elicited an augmented HR response in the SS group, specifically during the recovery period [F(5.261,163.08) = 3.058, P = 0.01, ηp2 = 0.09]. There were no significant differences in HR reactivity between sexes [F(3.818,118.368) = 1.191, P = 0.318]. These findings offer evidence of nocturnal cardiovascular dysregulation in habitual short sleepers, independent from any diagnosed sleep disorders.NEW & NOTEWORTHY Short habitual sleep is associated with poor cardiovascular outcomes, but mechanisms remain equivocal. The present study used objectively measured habitual sleep via wrist actigraphy, and reports that habitual short sleepers have augmented heart rate recovery responses to spontaneous arousals as determined by gold-standard polysomnography. There were no reported sex differences. The augmented heart rate recovery to spontaneous cortical arousals may be an important mechanism contributing to the associations between insufficient sleep and cardiovascular risk.
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Affiliation(s)
- Jeremy A Bigalke
- Department of Health and Human Development, Montana State University, Bozeman, Montana.,Department of Psychology, Montana State University, Bozeman, Montana.,Department of Kinesiology and Integrative Physiology, Michigan Technological University, Houghton, Michigan
| | - Ian M Greenlund
- Department of Health and Human Development, Montana State University, Bozeman, Montana.,Department of Psychology, Montana State University, Bozeman, Montana.,Department of Kinesiology and Integrative Physiology, Michigan Technological University, Houghton, Michigan
| | - Jennifer R Nicevski
- Department of Health and Human Development, Montana State University, Bozeman, Montana
| | - Carl A Smoot
- Department of Health and Human Development, Montana State University, Bozeman, Montana
| | | | | | - Jason R Carter
- Department of Health and Human Development, Montana State University, Bozeman, Montana.,Department of Psychology, Montana State University, Bozeman, Montana
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37
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Nardone M, Incognito AV, Kathia MM, Omazic LJ, Lee JB, Teixeira AL, Xie S, Vianna LC, Millar PJ. Signal-averaged resting sympathetic transduction of blood pressure: is it time to account for prevailing muscle sympathetic burst frequency? Am J Physiol Regul Integr Comp Physiol 2021; 321:R484-R494. [PMID: 34287075 DOI: 10.1152/ajpregu.00131.2021] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Calculating the blood pressure (BP) response to a burst of muscle sympathetic nerve activity (MSNA), termed sympathetic transduction, may be influenced by an individual's resting burst frequency. We examined the relationships between sympathetic transduction and MSNA in 107 healthy males and females and developed a normalized sympathetic transduction metric to incorporate resting MSNA. Burst-triggered signal-averaging was used to calculate the peak diastolic BP response following each MSNA burst (sympathetic transduction of BP) and following incorporation of MSNA burst cluster patterns and amplitudes (sympathetic transduction slope). MSNA burst frequency was negatively correlated with sympathetic transduction of BP (r=-0.42; P<0.01) and the sympathetic transduction slope (r=-0.66; P<0.01), independent of sex. MSNA burst amplitude was unrelated to sympathetic transduction of BP in males (r=0.04; P=0.78), but positively correlated in females (r=0.44; P<0.01) and with the sympathetic transduction slope in all participants (r=0.42; P<0.01). To control for MSNA, the linear regression slope of the log-log relationship between sympathetic transduction and MSNA burst frequency was used as a correction exponent. In sub-analysis of males (38±10 vs. 14±4bursts/min) and females (28±5 vs. 12±4bursts/min) with high vs. low MSNA, sympathetic transduction of BP and sympathetic transduction slope were lower in participants with high MSNA (all P<0.05). In contrast, normalized sympathetic transduction of BP and normalized sympathetic transduction slope were similar in males and females with high vs. low MSNA (all P>0.22). We propose that incorporating MSNA burst frequency into the calculation of sympathetic transduction will allow comparisons between participants with varying levels of resting MSNA.
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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
| | | | - Lucas Joseph Omazic
- Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, Ontario, Canada
| | - Jordan B Lee
- Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, Ontario, Canada
| | - André L Teixeira
- Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, Ontario, Canada
| | - Shengkun Xie
- Global Management Studies, Ted Rogers School of Management, Ryerson University, Toronto, Ontario, Canada
| | - Lauro C Vianna
- NeuroVASQ - Integrative Physiology Laboratory, Faculty of Physical Education, University of Brasilia, Brazil
| | - Philip J Millar
- Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, Ontario, Canada.,Toronto General Research Institute, Toronto General Hospital, Toronto, Ontario, Canada
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38
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Matus LN, Flessland OD, Mueller PJ. Sex-dependent development of enhanced sympathoexcitation in sedentary versus physically active rats. J Physiol 2021; 599:4101-4116. [PMID: 34258769 DOI: 10.1113/jp281757] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2021] [Accepted: 07/07/2021] [Indexed: 11/08/2022] Open
Abstract
KEY POINTS The rostral ventrolateral medulla (RVLM) may contribute to sex-based differences in cardiovascular disease (CVD) based on overactivation of the sympathetic nervous system observed in sedentary male rats; however, the added influence of the reproductive cycle in females is currently unknown. To our knowledge this is the first study to demonstrate greater increases in sympathetic nerve activity in response to direct activation of the RVLM in female versus male rats prior to the onset of the reproductive cycle, which persisted after the onset of the reproductive cycle. Lower resting blood pressures in females also suggest peripheral adaptations contribute to sex-based differences in CVD. Sedentary versus physically active conditions appear to promote higher resting sympathetic outflow independent of age and sex. Our results demonstrate the importance of examining sedentary conditions in the context of sex differences and the reproductive cycle in contributing to sympathetic overactivity associated with cardiovascular disease. ABSTRACT Female reproductive hormones are considered cardioprotective based on higher risks of cardiovascular disease (CVD) in post- versus pre-menopausal women. Similarly, based on epidemiological studies, a sedentary lifestyle is also a major risk factor for CVD. The mechanisms by which sedentary conditions contribute to CVD, and their influences in the presence and absence of female reproductive hormones are unknown. We hypothesized that sexually immature male and female rats would have similar centrally mediated regulation of blood pressure, but upon sexual maturation, female rats would have lower resting blood pressure and centrally-mediated sympathoexcitation compared to age-matched males. We also predicted resting sympathetic activity would increase upon exposure to sedentary versus active conditions (voluntary wheel running) in males but not in females. We recorded splanchnic sympathetic nerve activity (SSNA) and blood pressure in 4-, 8- and 16-week-old male and female rats under Inactin anaesthesia before and during microinjections of glutamate (1-100 mM) into the rostral ventrolateral medulla (RVLM). Four-week-old female rats had lower resting blood pressure and greater sympathoexcitation following activation of the RVLM, as did 8- and 16-week-old female rats, independent of age or activity condition. Sedentary animals had higher baseline SSNA compared to active animals, independent of sex or age. Our results reveal a complex influence of the interactions between the female reproductive cycle and sedentary conditions. They also demonstrate the importance of examining sedentary conditions in the context of sex- and female reproductive cycle-dependent incidences of cardiovascular disease.
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Affiliation(s)
- Lyndsey N Matus
- Department of Physiology, Wayne State University School of Medicine, 540 E. Canfield, Detroit, MI, 48201, USA
| | - Olivia D Flessland
- Department of Physiology, Wayne State University School of Medicine, 540 E. Canfield, Detroit, MI, 48201, USA
| | - Patrick J Mueller
- Department of Physiology, Wayne State University School of Medicine, 540 E. Canfield, Detroit, MI, 48201, USA
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O'Brien MW, Ramsay DJ, O'Neill CD, Petterson JL, Dogra S, Mekary S, Kimmerly DS. Aerobic fitness is inversely associated with neurohemodynamic transduction and blood pressure variability in older adults. GeroScience 2021; 43:2737-2748. [PMID: 34056679 DOI: 10.1007/s11357-021-00389-z] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2021] [Accepted: 05/20/2021] [Indexed: 10/21/2022] Open
Abstract
Higher aerobic fitness is independently associated with better cardiovascular health in older adults. The transduction of muscle sympathetic nerve activity (MSNA) into mean arterial pressure (MAP) responses provides important insight regarding beat-by-beat neural circulatory control. Aerobic fitness is negatively associated with peak MAP responses to spontaneous MSNA in young males. Whether this relationship exists in older adults is known. We tested the hypothesis that aerobic fitness was inversely related to sympathetic neurohemodynamic transduction and blood pressure variability (BPV) in older adults. Relative peak oxygen consumption (V̇O2peak, indirect calorimetry) was assessed in 22 older adults (13 males, 65 ± 5 years, 36.3 ± 11.5 ml/kg/min). Peroneal MSNA (microneurography) and arterial pressure (finger photoplethysmography) were recorded during ≥ 10-min of rest. BPV was assessed using the average real variability index. MAP was tracked for 12 cardiac cycles following heartbeats associated with MSNA bursts (i.e., peak ΔMAP). Peak ΔMAP responses (0.9 ± 0.6 mmHg) were negatively associated (all, P < 0.04) with resting burst frequency (30 ± 11 bursts/min; R = -0.47) and burst incidence (54 ± 22 bursts/100 heartbeats; R = -0.51), but positively associated with BPV (ρ = 0.47). V̇O2peak was inversely related to the pressor responses to spontaneous bursts (R = -0.47, P = 0.03) and BPV (ρ = -0.54, P = 0.01), positively related to burst incidence (R = 0.42, P = 0.05), but unrelated to MSNA burst frequency (P = 0.20). The V̇O2peak-BPV relationship remained after controlling for burst frequency, peak ΔMAP, age, and sex. Lower V̇O2peak was associated with augmented neurohemodynamic transduction and BPV in older adults. These negative hemodynamic outcomes highlight the importance of higher aerobic fitness with ageing for optimal cardiovascular health.
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Affiliation(s)
- Myles W O'Brien
- Autonomic Cardiovascular Control and Exercise Laboratory, Division of Kinesiology, School of Health and Human Performance, Faculty of Health, Dalhousie University, 6230 South Street, Halifax, NS, B3H 4R2, Canada
| | - Diane J Ramsay
- Autonomic Cardiovascular Control and Exercise Laboratory, Division of Kinesiology, School of Health and Human Performance, Faculty of Health, Dalhousie University, 6230 South Street, Halifax, NS, B3H 4R2, Canada
| | - Carley D O'Neill
- Exercise Physiology and Cardiovascular Health Lab, University of Ottawa Heart Institute, Ottawa, ON, Canada.,School of Kinesiology, Acadia University, Wolfville, NS, Canada
| | - Jennifer L Petterson
- Autonomic Cardiovascular Control and Exercise Laboratory, Division of Kinesiology, School of Health and Human Performance, Faculty of Health, Dalhousie University, 6230 South Street, Halifax, NS, B3H 4R2, Canada
| | - Shilpa Dogra
- School of Kinesiology, Acadia University, Wolfville, NS, Canada.,Health and Human Performance Laboratory, Faculty of Health Sciences, University of Ontario Institute of Technology, Oshawa, ON, Canada
| | - Said Mekary
- School of Kinesiology, Acadia University, Wolfville, NS, Canada
| | - Derek S Kimmerly
- Autonomic Cardiovascular Control and Exercise Laboratory, Division of Kinesiology, School of Health and Human Performance, Faculty of Health, Dalhousie University, 6230 South Street, Halifax, NS, B3H 4R2, Canada.
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40
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Hockin BCD, Tang EZ, Lloyd MG, Claydon VE. Forearm vascular resistance responses to the Valsalva maneuver in healthy young and older adults. Clin Auton Res 2021; 31:737-753. [PMID: 34014418 DOI: 10.1007/s10286-021-00810-9] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2020] [Accepted: 05/03/2021] [Indexed: 11/25/2022]
Abstract
PURPOSE Effective end-organ peripheral vascular resistance responses are critical to blood pressure control while upright, and prevention of syncope (fainting). The Valsalva maneuver (VM) induces blood pressure decreases that evoke baroreflex-mediated vasoconstriction. We characterized beat-to-beat forearm vascular resistance (FVR) responses to the VM in healthy adults, evaluated the impact of age and sex on these responses, and investigated their association with orthostatic tolerance (OT; susceptibility to syncope). We hypothesized that individuals with smaller FVR responses would be more susceptible to syncope. METHODS Healthy young (N = 36; 19 women; age 25.4 ± 4.6 years) and older (N = 21; 12 women; age 62.4 ± 9.6 years) adults performed a supine 40 mmHg, 20 s VM. Graded 60° head-up-tilt with combined lower body negative pressure continued to presyncope was used to determine OT. Non-invasive beat-to-beat blood pressure and heart rate (finger plethysmography) were recorded continuously. FVR was calculated as mean arterial pressure (MAP) divided by brachial blood flow velocity (Doppler ultrasound) relative to baseline. RESULTS The VM produces a distinctive FVR pattern that peaks (+137.1 ± 11.6%) in phase 2B (17.5 ± 0.3 s) as the baroreflex responds to low-pressure perturbations. This response increased with age overall (p < 0.001) and within male (p = 0.030) and female subgroups (p < 0.001). Maximum FVR during the VM was significantly correlated with maximal tilt FVR (r = 0.364; p = 0.0153) and with OT when expressed relative to the MAP decrease in phase 2A (Max FVR (%)/MAP2A-1; r = 0.337; p = 0.0206). CONCLUSION This is the first characterization of FVR responses to the VM. The VM elicits large baroreflex-mediated increases in FVR; small FVR responses to the VM may indicate susceptibility to syncope.
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Affiliation(s)
- Brooke C D Hockin
- Department of Biomedical Physiology and Kinesiology, Simon Fraser University, Burnaby, BC, V5A 1S6, Canada.,International Collaboration On Repair and Discoveries (ICORD), University of British Columbia, Vancouver, BC, Canada
| | - Eileen Z Tang
- Department of Biomedical Physiology and Kinesiology, Simon Fraser University, Burnaby, BC, V5A 1S6, Canada.,International Collaboration On Repair and Discoveries (ICORD), University of British Columbia, Vancouver, BC, Canada
| | - Matthew G Lloyd
- Department of Biomedical Physiology and Kinesiology, Simon Fraser University, Burnaby, BC, V5A 1S6, Canada.,International Collaboration On Repair and Discoveries (ICORD), University of British Columbia, Vancouver, BC, Canada
| | - Victoria E Claydon
- Department of Biomedical Physiology and Kinesiology, Simon Fraser University, Burnaby, BC, V5A 1S6, Canada. .,International Collaboration On Repair and Discoveries (ICORD), University of British Columbia, Vancouver, BC, Canada.
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Low ventilatory responsiveness to transient hypoxia or breath-holding predicts fast marathon performance in healthy middle-aged and older men. Sci Rep 2021; 11:10255. [PMID: 33986451 PMCID: PMC8119959 DOI: 10.1038/s41598-021-89766-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2021] [Accepted: 04/23/2021] [Indexed: 02/03/2023] Open
Abstract
The aim of this study was to test the utility of haemodynamic and autonomic variables (e.g. peripheral chemoreflex sensitivity [PCheS], blood pressure variability [BPV]) for the prediction of individual performance (marathon time and VO2max) in older men. The post-competition vasodilation and sympathetic vasomotor tone predict the marathon performance in younger men, but their prognostic relevance in older men remains unknown. The peripheral chemoreflex restrains exercise-induced vasodilation via sympathetically-mediated mechanism, what makes it a plausible candidate for the individual performance marker. 23 men aged ≥ 50 year competing in the Wroclaw Marathon underwent an evaluation of: resting haemodynamic parameters, PCheS with two methods: transient hypoxia and breath-holding test (BHT), cardiac barosensitivity, heart rate variability (HRV) and BPV, plasma renin and aldosterone, VO2max in a cardiopulmonary exercise test (CPET). All tests were conducted twice: before and after the race, except for transient hypoxia and CPET which were performed once, before the race. Fast marathon performance and high VO2max were correlated with: low ventilatory responsiveness to hypoxia (r = - 0.53, r = 0.67, respectively) and pre-race BHT (r = - 0.47, r = 0.51, respectively), (1) greater SD of beat-to-beat SBP (all p < 0.05). Fast performance was related with an enhanced pre-race vascular response to BHT (r = - 0.59, p = 0.005). The variables found by other studies to predict the marathon performance in younger men: post-competition vasodilation, sympathetic vasomotor tone (LF-BPV) and HRV were not associated with the individual performance in our population. The results suggest that PCheS (ventilatory response) predicts individual performance (marathon time and VO2max) in men aged ≥ 50 yeat. Although cause-effect relationship including the role of peripheral chemoreceptors in restraining the post-competition vasodilation via the sympathetic vasoconstrictor outflow may be hypothesized to underline these findings, the lack of correlation between individual performance and both, the post-competition vasodilation and the sympathetic vasomotor tone argues against such explanation. Vascular responsiveness to breath-holding appears to be of certain value for predicting individual performance in this population, however.
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Ferri R, Silvani A, Mogavero MP, Rundo F, Bruni O, Picchietti DL, DelRosso LM. Heart rate changes associated with the different types of leg movements during sleep in children, adolescents and adults with restless legs syndrome. J Sleep Res 2021; 30:e13379. [PMID: 33960046 DOI: 10.1111/jsr.13379] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2021] [Revised: 02/24/2021] [Accepted: 04/14/2021] [Indexed: 11/30/2022]
Abstract
The objective of this study was to describe in detail the heart rate changes accompanying short-interval leg movements during sleep, periodic leg movements during sleep, and isolated leg movements during sleep in children and adolescents with restless legs syndrome, and to compare them with the same findings in adults with restless legs syndrome. We analysed time series of R-R intervals synchronized to the onset of short-interval leg movements during sleep, periodic leg movements during sleep or isolated leg movements during sleep that entailed an arousal during non-rapid-eye-movement sleep. We assessed cardiac activation based on the heart rate changes with respect to baseline during non-rapid-eye-movement sleep without leg movements. All types of leg movements recorded during sleep were accompanied by important heart rate changes also in children, with an overall impact similar to that observed in adults. In all age groups, heart rate changes accompanying short-interval leg movements during sleep were constituted by a tachycardia, without a subsequent relative bradycardia, that was instead evident for periodic leg movements during sleep and isolated leg movements during sleep. Moreover, an age-related decline of the relative bradycardia following the heart rate increase, in association with periodic leg movements during sleep and isolated leg movements during sleep, was observed. Our findings show that important heart rate changes accompany all leg movements during sleep at all ages in restless legs syndrome, with significant age-related differences. This information represents an important contribution to the ongoing scientific debate on the possibility and opportunity to treat periodic leg movements during sleep.
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Affiliation(s)
- Raffaele Ferri
- Sleep Research Centre, Department of Neurology I.C., Oasi Research Institute - IRCCS, Troina, Italy
| | - Alessandro Silvani
- Department of Biomedical and Neuromotor Sciences (DIBINEM), University of Bologna, Bologna, Italy
| | - Maria P Mogavero
- Istituti Clinici Scientifici Maugeri, IRCCS, Scientific Institute of Pavia, Pavia, Italy
| | - Francesco Rundo
- Sleep Research Centre, Department of Neurology I.C., Oasi Research Institute - IRCCS, Troina, Italy
| | - Oliviero Bruni
- Department of Social and Developmental Psychology, Sapienza University, Rome, Italy
| | - Daniel L Picchietti
- University of Illinois School of Medicine, Carle Illinois College of Medicine, and Carle Foundation Hospital, Urbana, IL, USA
| | - Lourdes M DelRosso
- Seattle Children's Hospital and University of Washington, Seattle, WA, USA
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43
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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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Steele AR, Berthelsen LF, Fraser GM, Phillips DB, Fuhr DP, Wong EYL, Stickland MK, Steinback CD. Blunted sympathetic neurovascular transduction is associated to the severity of obstructive sleep apnea. Clin Auton Res 2021; 31:443-451. [DOI: 10.1007/s10286-021-00784-8] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2020] [Accepted: 01/28/2021] [Indexed: 01/09/2023]
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45
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Stute NL, Koopmans PJ. Pushing the needle forward on the relationship between autoimmunity and autonomic dysfunction. J Physiol 2021; 599:1039-1040. [PMID: 33442880 DOI: 10.1113/jp281197] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Affiliation(s)
- Nina L Stute
- Department of Health & Exercise Science, Appalachian State University, Boone, NC, USA
| | - P J Koopmans
- Department of Health & Exercise Science, Appalachian State University, Boone, NC, USA
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46
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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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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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Hanson BE, Joyner MJ, Casey DP. Sex-related differences in rapid-onset vasodilation: impact of aging. J Appl Physiol (1985) 2021; 130:206-214. [PMID: 33119464 DOI: 10.1152/japplphysiol.00663.2020] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Rapid-onset vasodilation (ROV) in response to a single muscle contraction is attenuated with aging. Moreover, sex-related differences in muscle blood flow and vasodilation during dynamic exercise have been observed in young and older adults. The purpose of the present study was to explore if sex-related differences in ROV exist in young (n = 36, 25 ± 1 yr) and older (n = 32, 66 ± 1 yr) adults. Subjects performed single forearm contractions at 10%, 20%, and 40% maximal voluntary contraction. Brachial artery blood velocity and diameter were measured with Doppler ultrasound, and forearm vascular conductance (mL·min-1·100 mmHg-1) was calculated from blood flow (mL·min-1) and mean arterial pressure (mmHg) and used as a measure of ROV. Peak ROV was attenuated in women across all relative intensities in the younger and older groups (P < 0.05). In a subset of subjects with similar absolute workloads (∼5 kg and ∼11 kg), age-related differences in ROV were observed among both women and men (P < 0.05). However, only older women demonstrated an attenuated peak ROV compared with men (91 ± 6 vs. 121 ± 11 mL·min-1·100 mmHg-1, P < 0.05), a difference not observed in the young group (134 ± 8 vs. 154 ± 11 mL·min-1·100 mmHg-1, P = 0.15). Additionally, examining the slope of peak ROV across contraction intensities indicated a blunted response in older women compared with their younger counterparts (P < 0.05), with no differences observed between older and young men (P = 0.38). Our data suggest that sex-related differences in the rapid vasodilatory response to single muscle contractions exist in older but not young adults, such that older women have a blunted response compared with older men.NEW & NOTEWORTHY While rapid-onset vasodilation (ROV) has been shown to decrease in older individuals, it is unclear if sex contributes to the decline with aging. We sought to identify if sex-related differences exist in the ROV response to single forearm contractions in young and older adults. Our data suggest sex-related differences are present among older but not young individuals, with women having an attenuated response. These data indicate sex plays a role in decreased vasodilation with aging.
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Affiliation(s)
- Brady E Hanson
- Department of Physical Therapy and Rehabilitation Science, Carver College of Medicine, University of Iowa, Iowa City, Iowa
| | - Michael J Joyner
- Department of Anesthesiology and Perioperative Medicine, Mayo Clinic, Rochester, Minnesota
| | - Darren P Casey
- Department of Physical Therapy and Rehabilitation Science, Carver College of Medicine, 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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49
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Greenlund IM, Smoot CA, Carter JR. Sex differences in blood pressure responsiveness to spontaneous K-complexes during stage II sleep. J Appl Physiol (1985) 2020; 130:491-497. [PMID: 33300855 DOI: 10.1152/japplphysiol.00825.2020] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
K-complexes are a key marker of nonrapid eye movement sleep, specifically during stages II sleep. Recent evidence suggests the heart rate responses to a K-complexes may differ between men and women. The purpose of this study was to compare beat-to-beat blood pressure responses to K-complexes in men and women. We hypothesized that the pressor response following a spontaneous K-complex would be augmented in men compared with women. Ten men [age: 23 ± 2 yr, body mass index (BMI): 28 ± 4 kg/m2] and ten women (age: 23 ± 5 yr, BMI: 25 ± 4 kg/m2) were equipped with overnight finger plethysmography and standard 10-lead polysomnography. Hemodynamic responses to a spontaneous K-complex during stable stage II sleep were quantified for 10 consecutive cardiac cycles, and measurements included systolic arterial pressure (SAP), diastolic arterial pressure (DAP), and heart rate. K-complex elicited greater pressor responses in men when blood pressures were expressed as SAP (cardiac cycle × sex: P = 0.007) and DAP (cardiac cycle × sex: P = 0.004). Heart rate trended to be different between men and women (cardiac cycle × sex: P = 0.078). These findings suggest a divergent pressor response between men and women following a spontaneous K-complex during normal stage II sleep. These findings could contribute to sex-specific differences in cardiovascular risk that exist between men and women.NEW & NOTEWORTHY K-complexes during stage II sleep have been shown to elicit acute increases in blood pressure and heart rate, but the role of sex (i.e., male vs. female) in this response is unclear. In the present study, we demonstrate that the pressor response following spontaneous K-complexes were augmented in men compared to age-matched women. The augmented blood pressure reactivity to spontaneous K-complexes during stage II sleep in men advance the field of cardiovascular sex differences, with implications for nocturnal blood pressure control.
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Affiliation(s)
- Ian M Greenlund
- Department of Health and Human Development, Montana State University, Bozeman, Montana.,Department of Psychology, Montana State University, Bozeman, Montana.,Department of Kinesiology and Integrative Physiology, Michigan Technological University, Houghton, Michigan
| | - Carl A Smoot
- Department of Kinesiology and Integrative Physiology, Michigan Technological University, Houghton, Michigan
| | - Jason R Carter
- Department of Health and Human Development, Montana State University, Bozeman, Montana.,Department of Psychology, Montana State University, Bozeman, Montana.,Department of Kinesiology and Integrative Physiology, Michigan Technological University, Houghton, Michigan
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50
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Abstract
PURPOSE OF THE REVIEW This review summarizes sex-related changes in the heart and vasculature that occur with aging, both in the presence and absence of cardiovascular disease (CVD). RECENT FINDINGS In the presence of CVD risk factors and/or overt CVD, sex-specific changes in the number of cardiomyocytes, extent of the myocardial extracellular matrix, and myocellular hypertrophy promote unique patterns of LV remodeling in men and women. In addition, age- and sex-specific vascular stiffening is also well established, driven by changes in endothelial dysfunction, elastin-collagen content, microvascular dysfunction, and neurohormonal signaling. Together, these changes in LV chamber geometry and morphology, coupled with heightened vascular stiffness, appear to drive both age-related increases in systolic function and declines in diastolic function, particularly in postmenopausal women. Accordingly, estrogen has been implicated as a key mediator, given its direct vasodilating properties, association with nitric oxide excretion, and involvement in myocellular Ca2+ handling, mitochondrial energy production, and oxidative stress. The culmination of the abovementioned sex-specific cardiac and vascular changes across the lifespan provides important insight into heart failure development, particularly of the preserved ejection fraction variety, while offering promise for future preventive strategies and therapeutic approaches.
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Affiliation(s)
- Andrew Oneglia
- Applied Physiology and Advanced Imaging Lab, University of Texas at Arlington, 655 West Mitchell St, Arlington, TX, 76010, USA
| | - Michael D Nelson
- Applied Physiology and Advanced Imaging Lab, University of Texas at Arlington, 655 West Mitchell St, Arlington, TX, 76010, USA
- Barbra Streisand Women's Heart Center, Smidt Heart Institute, Cedars-Sinai Medical Center, 127 S San Vicente Blvd, AHSP Suite A3206, Los Angeles, CA, 90048, USA
| | - C Noel Bairey Merz
- Barbra Streisand Women's Heart Center, Smidt Heart Institute, Cedars-Sinai Medical Center, 127 S San Vicente Blvd, AHSP Suite A3206, Los Angeles, CA, 90048, USA.
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