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O'Leary DS, Mannozzi J. Mechanisms mediating muscle metaboreflex control of cardiac output during exercise: Impaired regulation in heart failure. Exp Physiol 2024. [PMID: 38460125 DOI: 10.1113/ep091752] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2024] [Accepted: 02/19/2024] [Indexed: 03/11/2024]
Abstract
The ability to increase cardiac output during dynamic exercise is paramount for the ability to maintain workload performance. Reflex control of the cardiovascular system during exercise is complex and multifaceted involving multiple feedforward and feedback systems. One major reflex thought to mediate the autonomic adjustments to exercise is termed the muscle metaboreflex and is activated via afferent neurons within active skeletal muscle which respond to the accumulation of interstitial metabolites during exercise when blood flow and O2 delivery are insufficient to meet metabolic demands. This is one of the most powerful cardiovascular reflexes capable of eliciting profound increases in sympathetic nerve activity, arterial blood pressure, central blood volume mobilization, heart rate and cardiac output. This review summarizes the mechanisms meditating muscle metaboreflex-induced increases in cardiac output. Although much has been learned from studies using anaesthetized and/or decerebrate animals, we focus on studies in conscious animals and humans performing volitional exercise. We discuss the separate and interrelated roles of heart rate, ventricular contractility, ventricular preload and ventricular-vascular coupling as well as the interaction with other cardiovascular reflexes which modify muscle metaboreflex control of cardiac output. We discuss how these mechanisms may be altered in subjects with heart failure with reduced ejection fraction and offer suggestions for future studies.
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Affiliation(s)
- Donal S O'Leary
- Department of Physiology, Wayne State University School of Medicine, Detroit, Michigan, USA
| | - Joseph Mannozzi
- Department of Physiology, Wayne State University School of Medicine, Detroit, Michigan, USA
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Mannozzi J, Senador D, Kaur J, Gross M, McNitt M, Alvarez A, Lessanework B, O'Leary DS. Muscle metaboreflex stimulates the cardiac sympathetic afferent reflex causing positive feedback amplification of sympathetic activity: effect of heart failure. Am J Physiol Regul Integr Comp Physiol 2024; 326:R110-R120. [PMID: 38009212 PMCID: PMC11283898 DOI: 10.1152/ajpregu.00235.2023] [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: 10/19/2023] [Revised: 11/14/2023] [Accepted: 11/18/2023] [Indexed: 11/28/2023]
Abstract
Exercise intolerance is a hallmark symptom of heart failure and to a large extent stems from reductions in cardiac output that occur due to the inherent ventricular dysfunction coupled with enhanced muscle metaboreflex-induced functional coronary vasoconstriction, which limits increases in coronary blood flow. This creates a further mismatch between O2 delivery and O2 demand, which may activate the cardiac sympathetic afferent reflex (CSAR), causing amplification of the already increased sympathetic activity in a positive-feedback fashion. We used our chronically instrumented conscious canine model to evaluate if chronic ablation of afferents responsible for the CSAR would attenuate the gain of muscle metaboreflex before and after induction of heart failure. After afferent ablation, the gain of the muscle metaboreflex control of mean arterial pressure was significantly reduced before (-239.5 ± 16 to -95.2 ± 8 mmHg/L/min) and after the induction of heart failure (-185.6 ± 14 to -95.7 ± 12 mmHg/L/min). Similar results were observed for the strength (gain) of muscle metaboreflex control of heart rate, cardiac output, and ventricular contractility. Thus, we conclude that the CSAR contributes significantly to the strength of the muscle metaboreflex in normal animals with heart failure serving as an effective positive-feedback amplifier thereby further increasing sympathetic activity.NEW & NOTEWORTHY The powerful pressor responses from the CSAR arise via O2 delivery versus O2 demand imbalance. Muscle metaboreflex activation (MMA) simultaneously elicits coronary vasoconstriction (which is augmented in heart failure) and profound increases in cardiac work thereby upsetting oxygen balance. Whether MMA activates the CSAR thereby amplifying MMA responses is unknown. We observed that removal of the CSAR afferents attenuated the strength of the muscle metaboreflex in normal and subjects with heart failure.
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Affiliation(s)
- Joseph Mannozzi
- Department of Physiology, Wayne State University School of Medicine, Detroit, Michigan, United States
| | - Danielle Senador
- Department of Physiology, Wayne State University School of Medicine, Detroit, Michigan, United States
| | - Jasdeep Kaur
- Department of Kinesiology and Health Education, University of Texas at Austin, Austin, Texas, United States
| | - Matthew Gross
- Department of Physiology, Wayne State University School of Medicine, Detroit, Michigan, United States
| | - Megan McNitt
- Department of Physiology, Wayne State University School of Medicine, Detroit, Michigan, United States
| | - Alberto Alvarez
- Department of Physiology, Wayne State University School of Medicine, Detroit, Michigan, United States
| | - Beruk Lessanework
- Department of Physiology, Wayne State University School of Medicine, Detroit, Michigan, United States
| | - Donal S O'Leary
- Department of Physiology, Wayne State University School of Medicine, Detroit, Michigan, United States
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Boyes NG, Mannozzi J, Rapin N, Alvarez A, Al-Hassan MH, Lessanework B, Lahti DS, Olver TD, O'Leary DS, Tomczak CR. Augmented sympathoexcitation slows postexercise heart rate recovery. J Appl Physiol (1985) 2023; 135:1300-1311. [PMID: 37883101 DOI: 10.1152/japplphysiol.00549.2023] [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: 08/07/2023] [Revised: 09/13/2023] [Accepted: 10/23/2023] [Indexed: 10/27/2023] Open
Abstract
Slow heart rate recovery following exercise may be influenced by persistent sympathoexcitation. This study examined 1) the effect of muscle metaboreflex activation (MMA) on heart rate recovery following dynamic exercise; and 2) whether the effect of MMA on heart rate recovery is reversible by reducing sympathoexcitation [baroreflex activation via phenylephrine (PE)] in canines. Twenty-two young adults completed control and MMA protocols during cycle ergometry at 110% ventilatory threshold with 5 min recovery. Heart rate recovery kinetics [tau (τ), amplitude, end-exercise, and end-recovery heart rate] and root mean square of successive differences (RMSSD) were measured. Five chronically instrumented canines completed control, MMA (50%-60% imposed reduction in hindlimb blood flow), and MMA with end-exercise PE infusion (MMA + PE) protocols during moderate exercise (6.4 km·h-1) and 3 min recovery. Heart rate recovery kinetics and MAP were measured. MAP increased during MMA versus control in canines (P < 0.001). Heart rate recovery τ was slower during MMA versus control in humans (17% slower; P = 0.011) and canines (150% slower; P = 0.002). Heart rate recovery τ was faster during MMA + PE versus MMA (40% faster; P = 0.034) and was similar to control in canines (P = 0.426). Amplitude, end-exercise, and end-recovery heart rate were similar between conditions in humans (all P ≥ 0.122) and in canines (all P ≥ 0.084). MMA decreased RMSSD in early recovery (P = 0.004). MMA-induced sympathoexcitation slows heart rate recovery and this effect is markedly attenuated with PE. Therefore, elevated sympathoexcitation via MMA impairs heart rate recovery and inhibition of this stimulus normalizes, in part, heart rate recovery.NEW & NOTEWORTHY Augmented sympathoexcitation, via muscle metaboreflex activation, functionally slows heart rate recovery in both young healthy adults and chronically instrumented canines. Furthermore, elevated sympathoexcitation corresponded with lower parasympathetic activity, as assessed by heart rate variability, during the first 3 min of recovery. Finally, sympathoinhibition, via phenylephrine infusion, normalizes heart rate recovery during muscle metaboreflex activation.
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Affiliation(s)
- Natasha G Boyes
- College of Kinesiology, University of Saskatchewan, Saskatoon, Saskatchewan, Canada
| | - Joseph Mannozzi
- Department of Physiology, School of Medicine, Wayne State University, Detroit, Michigan, United States
| | - Nicole Rapin
- College of Kinesiology, University of Saskatchewan, Saskatoon, Saskatchewan, Canada
| | - Alberto Alvarez
- Department of Physiology, School of Medicine, Wayne State University, Detroit, Michigan, United States
| | - Mohamed-Hussein Al-Hassan
- Department of Physiology, School of Medicine, Wayne State University, Detroit, Michigan, United States
| | - Beruk Lessanework
- Department of Physiology, School of Medicine, Wayne State University, Detroit, Michigan, United States
| | - Dana S Lahti
- College of Kinesiology, University of Saskatchewan, Saskatoon, Saskatchewan, Canada
| | - T Dylan Olver
- Western College of Veterinary Medicine, University of Saskatchewan, Saskatoon, Saskatchewan, Canada
| | - Donal S O'Leary
- Department of Physiology, School of Medicine, Wayne State University, Detroit, Michigan, United States
| | - Corey R Tomczak
- College of Kinesiology, University of Saskatchewan, Saskatoon, Saskatchewan, Canada
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Mannozzi J, Al-Hassan MH, Kaur J, Lessanework B, Alvarez A, Massoud L, Aoun K, Spranger M, O'Leary DS. Blood flow restriction training activates the muscle metaboreflex during low-intensity sustained exercise. J Appl Physiol (1985) 2023; 135:260-270. [PMID: 37348015 PMCID: PMC10393340 DOI: 10.1152/japplphysiol.00274.2023] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2023] [Accepted: 06/09/2023] [Indexed: 06/24/2023] Open
Abstract
Blood flow restriction training (BFRT) employs partial vascular occlusion of exercising muscle and has been shown to increase muscle performance while using reduced workload and training time. Numerous studies have demonstrated that BFRT increases muscle hypertrophy, mitochondrial function, and beneficial vascular adaptations. However, changes in cardiovascular hemodynamics during the exercise protocol remain unknown, as most studies measured blood pressure before the onset and after the cessation of exercise. With reduced perfusion to the exercising muscle during BFRT, the resultant accumulation of metabolites within the ischemic muscle could potentially trigger a large reflex increase in blood pressure, termed the muscle metaboreflex. At low workloads, this pressor response occurs primarily via increases in cardiac output. However, when increases in cardiac output are limited (e.g., heart failure or during severe exercise), the reflex shifts to peripheral vasoconstriction as the primary mechanism to increase blood pressure, potentially increasing the risk of a cardiovascular event. Using our chronically instrumented conscious canine model, we utilized a 60% reduction in femoral blood pressure applied to the hindlimbs during steady-state treadmill exercise (3.2 km/h) to reproduce the ischemic environment observed during BFRT. We observed significant increases in heart rate (+19 ± 3 beats/min), stroke volume (+2.52 ± 1.2 mL), cardiac output (+1.21 ± 0.2 L/min), mean arterial pressure (+18.2 ± 2.4 mmHg), stroke work (+1.93 ± 0.2 L/mmHg), and nonischemic vascular conductance (+3.62 ± 1.7 mL/mmHg), indicating activation of the muscle metaboreflex.NEW & NOTEWORTHY Blood flow restriction training (BFRT) increases muscle mass, strength, and endurance. There has been minimal consideration of the reflex cardiovascular responses that could be elicited during BFRT sessions. We showed that during low-intensity exercise BFRT may trigger large reflex increases in blood pressure and sympathetic activity due to muscle metaboreflex activation. Thus, we urge caution when employing BFRT, especially in patients in whom exaggerated cardiovascular responses may occur that could cause sudden, adverse cardiovascular events.
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Affiliation(s)
- Joseph Mannozzi
- Department of Physiology, Wayne State University School of Medicine, Detroit, Michigan, United States
| | - Mohamed-Hussein Al-Hassan
- Department of Physiology, Wayne State University School of Medicine, Detroit, Michigan, United States
| | - Jasdeep Kaur
- Department of Kinesiology and Health Education, University of Texas at Austin, Austin, Texas, United States
| | - Beruk Lessanework
- Department of Physiology, Wayne State University School of Medicine, Detroit, Michigan, United States
| | - Alberto Alvarez
- Department of Physiology, Wayne State University School of Medicine, Detroit, Michigan, United States
| | - Louis Massoud
- Department of Physiology, Wayne State University School of Medicine, Detroit, Michigan, United States
| | - Kamel Aoun
- Department of Physiology, Wayne State University School of Medicine, Detroit, Michigan, United States
| | - Marty Spranger
- Department of Physiology, Michigan State University, East Lansing, Michigan, United States
| | - Donal S O'Leary
- Department of Physiology, Wayne State University School of Medicine, Detroit, Michigan, United States
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Ahmadian M, Williams AM, Mannozzi J, Konecny F, Hoiland RL, Wainman L, Erskine E, Duffy J, Manouchehri N, So K, Tauh K, Sala-Mercado JA, Shortt K, Fisk S, Kim KT, Streijger F, Foster GE, Kwon BK, O’Leary DS, West CR. A cross-species validation of single-beat metrics of cardiac contractility. J Physiol 2022; 600:4779-4806. [PMID: 36121759 PMCID: PMC9669232 DOI: 10.1113/jp283319] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2022] [Accepted: 09/02/2022] [Indexed: 12/24/2022] Open
Abstract
The assessment of left ventricular (LV) contractility in animal models is useful in various experimental paradigms, yet obtaining such measures is inherently challenging and surgically invasive. In a cross-species study using small and large animals, we comprehensively tested the agreement and validity of multiple single-beat surrogate metrics of LV contractility against the field-standard metrics derived from inferior vena cava occlusion (IVCO). Fifty-six rats, 27 minipigs and 11 conscious dogs underwent LV and arterial catheterization and were assessed for a range of single-beat metrics of LV contractility. All single-beat metrics were tested for the various underlying assumptions required to be considered a valid metric of cardiac contractility, including load-independency, sensitivity to inotropic stimulation, and ability to diagnose contractile dysfunction in cardiac disease. Of all examined single-beat metrics, only LV maximal pressure normalized to end-diastolic volume (EDV), end-systolic pressure normalized to EDV, and the maximal rate of rise of the LV pressure normalized to EDV showed a moderate-to-excellent agreement with their IVCO-derived reference measure and met all the underlying assumptions required to be considered as a valid cardiac contractile metric in both rodents and large-animal models. Our findings demonstrate that single-beat metrics can be used as a valid, reliable method to quantify cardiac contractile function in basic/preclinical experiments utilizing small- and large-animal models KEY POINTS: Validating and comparing indices of cardiac contractility that avoid caval occlusion would offer considerable advantages for the field of cardiovascular physiology. We comprehensively test the underlying assumptions of multiple single-beat indices of cardiac contractility in rodents and translate these findings to pigs and conscious dogs. We show that when performing caval occlusion is unfeasible, single-beat metrics can be utilized to accurately quantify cardiac inotropic function in basic and preclinical research employing various small and large animal species. We report that maximal left-ventricular (LV)-pressure normalized to end-diastolic volume (EDV), LV end-systolic pressure normalized to EDV and the maximal rate of rise of the LV pressure waveform normalized to EDV are the best three single-beat metrics to measure cardiac inotropic function in both small- and large-animal models.
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Affiliation(s)
- Mehdi Ahmadian
- School of Kinesiology, Faculty of Education, University of British Columbia, Vancouver, BC, Canada
- International Collaboration on Repair Discoveries, University of British Columbia, Vancouver, BC, Canada
- Centre for Chronic Disease Prevention and Management, University of British Columbia, Kelowna, BC, Canada
| | - Alexandra M. Williams
- International Collaboration on Repair Discoveries, University of British Columbia, Vancouver, BC, Canada
- Department of Cellular and Physiological Sciences, Faculty of Medicine, University of British Columbia, Vancouver, BC, Canada
| | - Joseph Mannozzi
- Department of Physiology, School of Medicine, Wayne State University, Detroit, MI 48009
| | - Filip Konecny
- Transonic Scisense Inc., London, ON, Canada
- MaRS Centre Toronto Medical Discovery Tower, 3rd Floor, 101 College Street, M5G 1L7, Toronto, Ontario, Canada
| | - Ryan L. Hoiland
- International Collaboration on Repair Discoveries, University of British Columbia, Vancouver, BC, Canada
- Department of Cellular and Physiological Sciences, Faculty of Medicine, University of British Columbia, Vancouver, BC, Canada
- Department of Anesthesiology, Pharmacology and Therapeutics, Faculty of Medicine, Vancouver General Hospital, 899 West 12th Avenue, University of British Columbia, Vancouver, BC, Canada, V5Z 1M9
| | - Liisa Wainman
- International Collaboration on Repair Discoveries, University of British Columbia, Vancouver, BC, Canada
- Centre for Chronic Disease Prevention and Management, University of British Columbia, Kelowna, BC, Canada
- Department of Cellular and Physiological Sciences, Faculty of Medicine, University of British Columbia, Vancouver, BC, Canada
| | - Erin Erskine
- International Collaboration on Repair Discoveries, University of British Columbia, Vancouver, BC, Canada
- Centre for Chronic Disease Prevention and Management, University of British Columbia, Kelowna, BC, Canada
- Department of Cellular and Physiological Sciences, Faculty of Medicine, University of British Columbia, Vancouver, BC, Canada
| | - Jennifer Duffy
- International Collaboration on Repair Discoveries, University of British Columbia, Vancouver, BC, Canada
- Centre for Chronic Disease Prevention and Management, University of British Columbia, Kelowna, BC, Canada
- Department of Cellular and Physiological Sciences, Faculty of Medicine, University of British Columbia, Vancouver, BC, Canada
| | - Neda Manouchehri
- International Collaboration on Repair Discoveries, University of British Columbia, Vancouver, BC, Canada
| | - Kitty So
- International Collaboration on Repair Discoveries, University of British Columbia, Vancouver, BC, Canada
| | - Keerit Tauh
- International Collaboration on Repair Discoveries, University of British Columbia, Vancouver, BC, Canada
| | | | - Katelyn Shortt
- International Collaboration on Repair Discoveries, University of British Columbia, Vancouver, BC, Canada
| | - Shera Fisk
- International Collaboration on Repair Discoveries, University of British Columbia, Vancouver, BC, Canada
| | - Kyoung-Tae Kim
- International Collaboration on Repair Discoveries, University of British Columbia, Vancouver, BC, Canada
- Department of Neurosurgery, School of Medicine, Kyungpook National University Hospital, Daegu, South Korea
| | - Femke Streijger
- International Collaboration on Repair Discoveries, University of British Columbia, Vancouver, BC, Canada
| | - Glen E. Foster
- Centre for Heart, Lung, & Vascular Health, School of Health and Exercise Sciences, University of British Columbia Okanagan, 3333 University Way, Kelowna, BC, V1V1V7
| | - Brian K. Kwon
- International Collaboration on Repair Discoveries, University of British Columbia, Vancouver, BC, Canada
| | - Donal S. O’Leary
- Department of Physiology, School of Medicine, Wayne State University, Detroit, MI 48009
| | - Christopher R. West
- International Collaboration on Repair Discoveries, University of British Columbia, Vancouver, BC, Canada
- Centre for Chronic Disease Prevention and Management, University of British Columbia, Kelowna, BC, Canada
- Department of Cellular and Physiological Sciences, Faculty of Medicine, University of British Columbia, Vancouver, BC, Canada
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White AJ, Boulet LM, Shafer BM, Vermeulen TD, Atwater TL, Stembridge M, Ainslie PN, Wilson RJA, Day TA, Foster GE. The coronary vascular response to the metaboreflex at low-altitude and during acute and prolonged high-altitude in males. J Appl Physiol (1985) 2022; 132:1327-1337. [PMID: 35482323 DOI: 10.1152/japplphysiol.00018.2022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Myocardial oxygen delivery is primarily regulated through changes in vascular tone to match increased metabolic demands. In males, activation of the muscle metaboreflex during acute isocapnic hypoxia results in a paradoxical coronary vasoconstriction. Whether coronary blood velocity is reduced by metaboreflex activation following travel and/or adaptation to high-altitude is unknown. This study determined if the response of the coronary vasculature to muscle metaboreflex activation at low-altitude differs from acute (1/2 days) and prolonged (8/9 days) high-altitude. Healthy males (n=16) were recruited and performed isometric handgrip exercise (30 % max) followed by post-exercise circulatory occlusion (PECO) to isolate the muscle metaboreflex at low-altitude and following acute and prolonged high-altitude (3,800 m). Mean left anterior descending coronary artery blood velocity (LADvmean, transthoracic Doppler echocardiography), heart rate, mean arterial pressure (MAP), ventilation, and respired gases were assessed during baseline and PECO at all time-points. Coronary vascular conductance index (CVCi) was calculated as LADVmean/MAP. The change in LADvmean (acute altitude: -1.7 ± 3.9 cm/s, low-altitude: 2.6 ± 3.4 cm/s, P = 0.01) and CVCi (acute altitude: -0.05 ± 0.04 cm/s/mmHg, low-altitude: -0.01 ± 0.03 cm/s/mmHg, P = 0.005) induced by PECO differed significantly between acute high-altitude and low-altitude. The change in LADVmean and CVCi induced by PECO following prolonged high-altitude was not different from low-altitude. Our results suggest that coronary vasoconstriction with metaboreflex activation in males is greatest following acute ascent to high-altitude and restored to low-altitude levels following 8-9 days of acclimatization.
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Affiliation(s)
- Austin J White
- Centre for Heart, Lung, and Vascular Health, School of Health and Exercise Sciences, University of British Columbia, British Columbia, Kelowna, Canada
| | - Lindsey M Boulet
- Centre for Heart, Lung, and Vascular Health, School of Health and Exercise Sciences, University of British Columbia, British Columbia, Kelowna, Canada
| | - Brooke M Shafer
- Centre for Heart, Lung, and Vascular Health, School of Health and Exercise Sciences, University of British Columbia, British Columbia, Kelowna, Canada
| | - Tyler D Vermeulen
- Centre for Heart, Lung, and Vascular Health, School of Health and Exercise Sciences, University of British Columbia, British Columbia, Kelowna, Canada
| | - Taylor L Atwater
- Centre for Heart, Lung, and Vascular Health, School of Health and Exercise Sciences, University of British Columbia, British Columbia, Kelowna, Canada
| | - Mike Stembridge
- Cardiff School of Sport and Health Sciences, Cardiff Metropolitan University, Cardiff, United Kingdom
| | - Philip N Ainslie
- Centre for Heart, Lung, and Vascular Health, School of Health and Exercise Sciences, University of British Columbia, British Columbia, Kelowna, Canada
| | - Richard J A Wilson
- Department of Physiology and Pharmacology, Hotchkiss Brain Institute, Cumming School of Medicine, University of Calgary, Calgary, Canada
| | - Trevor A Day
- Department of Biology, Faculty of Science and Technology, Mount Royal University, Calgary, Alberta, Canada
| | - Glen Edward Foster
- Centre for Heart, Lung, and Vascular Health, School of Health and Exercise Sciences, University of British Columbia, British Columbia, Kelowna, Canada
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Smith JR, Joyner MJ, Curry TB, Borlaug BA, Keller-Ross ML, Van Iterson EH, Olson TP. Influence of locomotor muscle group III/IV afferents on cardiovascular and ventilatory responses in human heart failure during submaximal exercise. J Appl Physiol (1985) 2022; 132:903-914. [PMID: 35201931 PMCID: PMC8957342 DOI: 10.1152/japplphysiol.00371.2021] [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: 05/27/2021] [Revised: 02/22/2022] [Accepted: 02/22/2022] [Indexed: 11/22/2022] Open
Abstract
The purpose of this study is to determine the influence of locomotor muscle group III/IV afferent inhibition on central and peripheral hemodynamics at multiple levels of submaximal cycling exercise in patients with heart failure with reduced ejection fraction (HFrEF). Eleven patients with HFrEF and nine healthy matched controls were recruited. The participants performed a multiple stage [i.e., 30 W, 50%peak workload (WL), and a workload eliciting a respiratory exchange ratio (RER) of ∼1.0] exercise test with lumbar intrathecal fentanyl (FENT) or placebo (PLA). Cardiac output ([Formula: see text]tot) was measured via open-circuit acetylene wash-in technique and stroke volume was calculated. Leg blood flow ([Formula: see text]l) was measured via constant infusion thermodilution and leg vascular conductance (LVC) was calculated. Radial artery and femoral venous blood gases were measured. For HFrEF, stroke volume was higher at the 30 W (FENT: 110 ± 21 vs. PLA: 100 ± 18 mL), 50%peak WL (FENT: 113 ± 22 vs. PLA: 103 ± 23 mL), and RER = 1.0 (FENT: 119 ± 28 vs. PLA: 110 ± 26 mL) stages, whereas heart rate and systemic vascular resistance were lower with fentanyl than with placebo (all, P < 0.05). [Formula: see text]tot in HFrEF and [Formula: see text]tot, stroke volume, and heart rate in controls were not different between fentanyl and placebo (all, P > 0.19). During submaximal exercise, controls and patients with HFrEF exhibited increased leg vascular conductance (LVC) with fentanyl compared with placebo (all, P < 0.04), whereas no differences were present in [Formula: see text]l or O2 delivery with fentanyl (all, P > 0.20). Taken together, these findings provide support for locomotor muscle group III/IV afferents playing a role in integrative control mechanisms during submaximal cycling exercise in patients with HFrEF and older controls.NEW & NOTEWORTHY Patients with HFrEF exhibit severe exercise intolerance. One of the primary peripheral mechanisms contributing to exercise intolerance in patients with HFrEF is locomotor muscle group III/IV afferent feedback. However, it is unknown whether these afferents impact the central and peripheral responses during submaximal cycling exercise. Herein, we demonstrate that inhibition of locomotor muscle group III/IV afferent feedback elicited increases in stroke volume during submaximal exercise in HFrEF, but not in healthy controls.
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Affiliation(s)
- Joshua R Smith
- Department of Cardiovascular Medicine, Mayo Clinic, Rochester, Minnesota
| | - Michael J Joyner
- Department of Anesthesiology and Perioperative Medicine, Mayo Clinic, Rochester, Minnesota
| | - Timothy B Curry
- Department of Anesthesiology and Perioperative Medicine, Mayo Clinic, Rochester, Minnesota
| | - Barry A Borlaug
- Department of Cardiovascular Medicine, Mayo Clinic, Rochester, Minnesota
| | - Manda L Keller-Ross
- Division of Physical Therapy and Rehabilitation Sciences, University of Minnesota, Minneapolis, Minnesota
| | - Erik H Van Iterson
- Section of Preventative Cardiology and Rehabilitation, Cleveland Clinic, Cleveland, Ohio
| | - Thomas P Olson
- Department of Cardiovascular Medicine, Mayo Clinic, Rochester, Minnesota
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Mannozzi J, Kim JK, Sala-Mercado JA, Al-Hassan MH, Lessanework B, Alvarez A, Massoud L, Bhatti T, Aoun K, O’Leary DS. Arterial Baroreflex Inhibits Muscle Metaboreflex Induced Increases in Effective Arterial Elastance: Implications for Ventricular-Vascular Coupling. Front Physiol 2022; 13:841076. [PMID: 35399256 PMCID: PMC8990766 DOI: 10.3389/fphys.2022.841076] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2021] [Accepted: 02/18/2022] [Indexed: 01/19/2023] Open
Abstract
The ventricular-vascular relationship assesses the efficacy of energy transferred from the left ventricle to the systemic circulation and is quantified as the ratio of effective arterial elastance to maximal left ventricular elastance. This relationship is maintained during exercise via reflex increases in cardiovascular performance raising both arterial and ventricular elastance in parallel. These changes are, in part, due to reflexes engendered by activation of metabosensitive skeletal muscle afferents-termed the muscle metaboreflex. However, in heart failure, ventricular-vascular uncoupling is apparent and muscle metaboreflex activation worsens this relationship through enhanced systemic vasoconstriction markedly increasing effective arterial elastance which is unaccompanied by substantial increases in ventricular function. This enhanced arterial vasoconstriction is, in part, due to significant reductions in cardiac performance induced by heart failure causing over-stimulation of the metaboreflex due to under perfusion of active skeletal muscle, but also as a result of reduced baroreflex buffering of the muscle metaboreflex-induced peripheral sympatho-activation. To what extent the arterial baroreflex modifies the metaboreflex-induced changes in effective arterial elastance is unknown. We investigated in chronically instrumented conscious canines if removal of baroreflex input via sino-aortic baroreceptor denervation (SAD) would significantly enhance effective arterial elastance in normal animals and whether this would be amplified after induction of heart failure. We observed that effective arterial elastance (Ea), was significantly increased during muscle metaboreflex activation after SAD (0.4 ± 0.1 mmHg/mL to 1.4 ± 0.3 mmHg/mL). In heart failure, metaboreflex activation caused exaggerated increases in Ea and in this setting, SAD significantly increased the rise in Ea elicited by muscle metaboreflex activation (1.3 ± 0.3 mmHg/mL to 2.3 ± 0.3 mmHg/mL). Thus, we conclude that the arterial baroreflex does buffer muscle metaboreflex induced increases in Ea and this buffering likely has effects on the ventricular-vascular coupling.
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9
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Increased sympathetic tone is associated with illness burden in bipolar disorder. J Affect Disord 2022; 297:471-476. [PMID: 34715156 DOI: 10.1016/j.jad.2021.10.089] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/17/2021] [Revised: 10/12/2021] [Accepted: 10/23/2021] [Indexed: 11/24/2022]
Abstract
BACKGROUND We recently described an association between reduced heart rate variability (HRV) and illness burden in bipolar disorder (BD) using a novel Illness Burden Index (IBI). We aimed to further characterize this association by using spectral analyses to assess whether the IBI is also associated with autonomic imbalance in BD patients. METHODS In this cross-sectional study, 53 participants with BD wore a device for 24 h to assess association between HRV spectral measures and the IBI or each of its components (age of onset, number and type of previous episode(s), duration of the most severe episode, history of suicide attempts or psychotic symptoms during episodes, co-morbid psychiatric disorders, and family history). We ran both unadjusted models and models controlling for age, sex, years of education, marital status, BMI, pharmacotherapy, and baseline functional cardiovascular capacity. RESULTS HRV low-frequency (LF) normalized values were almost twice as high as published in healthy controls. Higher IBI was associated with higher LF and lower High Frequency (HF) values, resulting in a higher LF/HF ratio, indicating an increased sympathetic tone. Four individual components of the IBI were similarly associated with measures of increased sympathetic tone: earlier age of onset, number of depressive episodes, co-morbid anxiety disorders, and family history of suicide. Adjusted and unadjusted models had similar results. LIMITATIONS Our models used mean LF and HF and do not consider their dynamic variations over 24 h or phase of the illness. CONCLUSIONS Burden of illness is associated with increased sympathetic tone in patients with BD, putting them at risk for arrythmias and sudden death.
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10
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Heusch G. Coronary blood flow in heart failure: cause, consequence and bystander. Basic Res Cardiol 2022; 117:1. [PMID: 35024969 PMCID: PMC8758654 DOI: 10.1007/s00395-022-00909-8] [Citation(s) in RCA: 48] [Impact Index Per Article: 24.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/03/2021] [Revised: 12/20/2021] [Accepted: 12/21/2021] [Indexed: 01/31/2023]
Abstract
Heart failure is a clinical syndrome where cardiac output is not sufficient to sustain adequate perfusion and normal bodily functions, initially during exercise and in more severe forms also at rest. The two most frequent forms are heart failure of ischemic origin and of non-ischemic origin. In heart failure of ischemic origin, reduced coronary blood flow is causal to cardiac contractile dysfunction, and this is true for stunned and hibernating myocardium, coronary microembolization, myocardial infarction and post-infarct remodeling, possibly also for the takotsubo syndrome. The most frequent form of non-ischemic heart failure is dilated cardiomyopathy, caused by genetic mutations, myocarditis, toxic agents or sustained tachyarrhythmias, where alterations in coronary blood flow result from and contribute to cardiac contractile dysfunction. Hypertrophic cardiomyopathy is caused by genetic mutations but can also result from increased pressure and volume overload (hypertension, valve disease). Heart failure with preserved ejection fraction is characterized by pronounced coronary microvascular dysfunction, the causal contribution of which is however not clear. The present review characterizes the alterations of coronary blood flow which are causes or consequences of heart failure in its different manifestations. Apart from any potentially accompanying coronary atherosclerosis, all heart failure entities share common features of impaired coronary blood flow, but to a different extent: enhanced extravascular compression, impaired nitric oxide-mediated, endothelium-dependent vasodilation and enhanced vasoconstriction to mediators of neurohumoral activation. Impaired coronary blood flow contributes to the progression of heart failure and is thus a valid target for established and novel treatment regimens.
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Affiliation(s)
- Gerd Heusch
- grid.5718.b0000 0001 2187 5445Institute for Pathophysiology, West German Heart and Vascular Center, University of Essen Medical School, University of Duisburg-Essen, Hufelandstr. 55, 45147 Essen, Germany
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11
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Mannozzi J, Al-Hassan MH, Lessanework B, Alvarez A, Senador D, O'Leary DS. Chronic ablation of TRPV1-sensitive skeletal muscle afferents attenuates the muscle metaboreflex. Am J Physiol Regul Integr Comp Physiol 2021; 321:R385-R395. [PMID: 34259041 DOI: 10.1152/ajpregu.00129.2021] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Exercise intolerance is a hallmark symptom of cardiovascular disease and likely occurs via enhanced activation of muscle metaboreflex-induced vasoconstriction of the heart and active skeletal muscle which, thereby limits cardiac output and peripheral blood flow. Muscle metaboreflex vasoconstrictor responses occur via activation of metabolite-sensitive afferent fibers located in ischemic active skeletal muscle, some of which express transient receptor potential vanilloid 1 (TRPV1) cation channels. Local cardiac and intrathecal administration of an ultrapotent noncompetitive, dominant negative agonist resiniferatoxin (RTX) can ablate these TRPV1-sensitive afferents. This technique has been used to attenuate cardiac sympathetic afferents and nociceptive pain. We investigated whether intrathecal administration (L4-L6) of RTX (2 µg/kg) could chronically attenuate subsequent muscle metaboreflex responses elicited by reductions in hindlimb blood flow during mild exercise (3.2 km/h) in chronically instrumented conscious canines. RTX significantly attenuated metaboreflex-induced increases in mean arterial pressure (27 ± 5.0 mmHg vs. 6 ± 8.2 mmHg), cardiac output (1.40 ± 0.2 L/min vs. 0.28 ± 0.1 L/min), and stroke work (2.27 ± 0.2 L·mmHg vs. 1.01 ± 0.2 L·mmHg). Effects were maintained until 78 ± 14 days post-RTX at which point the efficacy of RTX injection was tested by intra-arterial administration of capsaicin (20 µg/kg). A significant reduction in the mean arterial pressure response (+45.7 ± 6.5 mmHg pre-RTX vs. +19.7 ± 3.1 mmHg post-RTX) was observed. We conclude that intrathecal administration of RTX can chronically attenuate the muscle metaboreflex and could potentially alleviate enhanced sympatho-activation observed in cardiovascular disease states.
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Affiliation(s)
- Joseph Mannozzi
- Department of Physiology, Wayne State University School of Medicine, Detroit, Michigan
| | | | - Beruk Lessanework
- Department of Physiology, Wayne State University School of Medicine, Detroit, Michigan
| | - Alberto Alvarez
- Department of Physiology, Wayne State University School of Medicine, Detroit, Michigan
| | - Danielle Senador
- Department of Physiology, Wayne State University School of Medicine, Detroit, Michigan
| | - Donal S O'Leary
- Department of Physiology, Wayne State University School of Medicine, Detroit, Michigan
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12
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Tan LC, Zhang WY, Zuo YD, Chen HY, Jiang CL. Anesthetic management of a child with double outlet right ventricle and severe polycythemia: A case report. World J Clin Cases 2021; 9:2634-2640. [PMID: 33889630 PMCID: PMC8040181 DOI: 10.12998/wjcc.v9.i11.2634] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/07/2020] [Revised: 01/13/2021] [Accepted: 02/10/2021] [Indexed: 02/06/2023] Open
Abstract
BACKGROUND Double outlet right ventricle (DORV) is a rare and complex congenital heart defect, and the surgical repairs vary with type and pathophysiology consequences. Due to prolonged progressive hypoxemia, severe polycythemia is common in patients with DORV, which ultimately leads to coagulation dysfunction and increases the risk of thrombosis and infarction. Consequently, the anesthetic management is challenging and how to manage severe polycythemia and avoid hypoxia-related complications in such patients is of great significance.
CASE SUMMARY Herein, we report the anesthetic management of a 10-year-old female patient with a DORV. She lived in the low-oxygen Qinghai-Tibet Plateau, and presented with severe polycythemia (hemoglobin, 24.8 g/dL; hematocrit, 75%). She underwent a modified Fontan surgery, which was satisfactory and without any perioperative complications. Our anesthetic management highlights the importance of perioperative hemodilution in decreasing the risk of thromboembolism and the importance of correcting coagulopathy in preventing hemorrhage.
CONCLUSION Anesthetic management is challenging in rare cyanotic congenital heart disease patients with severe polycythemia. It is important to adopt perioperative hemodilution and correction of coagulopathy in preventing thrombosis and hemorrhage.
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Affiliation(s)
- Ling-Can Tan
- Department of Anesthesiology, West China Hospital, Sichuan University and The Research Units of West China (2018RU012), Chinese Academy of Medical Sciences, Chengdu 610041, Sichuan Province, China
| | - Wei-Yi Zhang
- Department of Anesthesiology, West China Hospital, Sichuan University and The Research Units of West China (2018RU012), Chinese Academy of Medical Sciences, Chengdu 610041, Sichuan Province, China
| | - Yi-Ding Zuo
- Department of Anesthesiology, West China Hospital, Sichuan University and The Research Units of West China (2018RU012), Chinese Academy of Medical Sciences, Chengdu 610041, Sichuan Province, China
| | - Hong-Yang Chen
- Department of Anesthesiology, West China Hospital, Sichuan University and The Research Units of West China (2018RU012), Chinese Academy of Medical Sciences, Chengdu 610041, Sichuan Province, China
| | - Chun-Ling Jiang
- Department of Anesthesiology, West China Hospital, Sichuan University and The Research Units of West China (2018RU012), Chinese Academy of Medical Sciences, Chengdu 610041, Sichuan Province, China
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13
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Mannozzi J, Massoud L, Kaur J, Coutsos M, O'Leary DS. Ventricular contraction and relaxation rates during muscle metaboreflex activation in heart failure: are they coupled? Exp Physiol 2020; 106:401-411. [PMID: 33226720 DOI: 10.1113/ep089053] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2020] [Accepted: 11/18/2020] [Indexed: 01/08/2023]
Abstract
NEW FINDINGS What is the central question of this study? Does the muscle metaboreflex affect the ratio of left ventricular contraction/relaxation rates and does heart failure impact this relationship. What is the main finding and its importance? The effect of muscle metaboreflex activation on the ventricular relaxation rate was significantly attenuated in heart failure. Heart failure attenuates the exercise and muscle metaboreflex-induced changes in the contraction/relaxation ratio. In heart failure, the reduced ability to raise cardiac output during muscle metaboreflex activation may not solely be due to attenuation of ventricular contraction but also alterations in ventricular relaxation and diastolic function. ABSTRACT The relationship between contraction and relaxation rates of the left ventricle varies with exercise. In in vitro models, this ratio was shown to be relatively unaltered by changes in sarcomere length, frequency of stimulation, and β-adrenergic stimulation. We investigated whether the ratio of contraction to relaxation rate is maintained in the whole heart during exercise and muscle metaboreflex activation and whether heart failure alters these relationships. We observed that in healthy subjects the ratio of contraction to relaxation increases from rest to exercise as a result of a higher increase in contraction relative to relaxation. During muscle metaboreflex activation the ratio of contraction to relaxation is significantly reduced towards 1.0 due to a large increase in relaxation rate matching contraction rate. In heart failure, contraction and relaxation rates are significantly reduced, and increases during exercise are attenuated. A significant increase in the ratio was observed from rest to exercise although baseline ratio values were significantly reduced close to 1.0 when compared to healthy subjects. There was no significant change observed between exercise and muscle metaboreflex activation nor was the ratio during muscle metaboreflex activation significantly different between heart failure and control. We conclude that heart failure reduces the muscle metaboreflex gain and contraction and relaxation rates. Furthermore, we observed that the ratio of the contraction and relaxation rates during muscle metaboreflex activation is not significantly different between control and heart failure, but significant changes in the ratio in healthy subjects due to increased relaxation rate were abolished in heart failure.
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Affiliation(s)
- Joseph Mannozzi
- Department of Physiology, Wayne State University School of Medicine, Detroit, MI, USA
| | - Louis Massoud
- Department of Physiology, Wayne State University School of Medicine, Detroit, MI, USA
| | - Jasdeep Kaur
- Department of Physiology, Wayne State University School of Medicine, Detroit, MI, USA
| | - Matthew Coutsos
- Department of Physiology, Wayne State University School of Medicine, Detroit, MI, USA
| | - Donal S O'Leary
- Department of Physiology, Wayne State University School of Medicine, Detroit, MI, USA
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14
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Grotle AK, Macefield VG, Farquhar WB, O'Leary DS, Stone AJ. Recent advances in exercise pressor reflex function in health and disease. Auton Neurosci 2020; 228:102698. [PMID: 32861944 DOI: 10.1016/j.autneu.2020.102698] [Citation(s) in RCA: 47] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2020] [Revised: 07/01/2020] [Accepted: 07/02/2020] [Indexed: 01/11/2023]
Abstract
Autonomic alterations at the onset of exercise are critical to redistribute cardiac output towards the contracting muscles while preventing a fall in arterial pressure due to excessive vasodilation within the contracting muscles. Neural mechanisms responsible for these adjustments include central command, the exercise pressor reflex, and arterial and cardiopulmonary baroreflexes. The exercise pressor reflex evokes reflex increases in sympathetic activity to the heart and systemic vessels and decreases in parasympathetic activity to the heart, which increases blood pressure (BP), heart rate, and total peripheral resistance through vasoconstriction of systemic vessels. In this review, we discuss recent advancements in our understanding of exercise pressor reflex function in health and disease. Specifically, we discuss emerging evidence suggesting that sympathetic vasoconstrictor drive to the contracting and non-contracting skeletal muscle is differentially controlled by central command and the metaboreflex in healthy conditions. Further, we discuss evidence from animal and human studies showing that cardiovascular diseases, including hypertension, diabetes, and heart failure, lead to an altered exercise pressor reflex function. We also provide an update on the mechanisms thought to underlie this altered exercise pressor reflex function in each of these diseases. Although these mechanisms are complex, multifactorial, and dependent on the etiology of the disease, there is a clear consensus that several mechanisms are involved. Ultimately, approaches targeting these mechanisms are clinically significant as they provide alternative therapeutic strategies to prevent adverse cardiovascular events while also reducing symptoms of exercise intolerance.
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Affiliation(s)
- Ann-Katrin Grotle
- Department of Kinesiology and Health Education, The University of Texas at Austin, Austin, TX, United States of America
| | | | - William B Farquhar
- Department of Kinesiology and Applied Physiology, University of Delaware, Newark, DE, United States of America
| | - Donal S O'Leary
- Department of Physiology, Wayne State University School of Medicine, Detroit, MI, United States of America
| | - Audrey J Stone
- Department of Kinesiology and Health Education, The University of Texas at Austin, Austin, TX, United States of America.
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15
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Mannozzi J, Kaur J, Spranger MD, Al-Hassan MH, Lessanework B, Alvarez A, Chung CS, O'Leary DS. Muscle metaboreflex-induced increases in effective arterial elastance: effect of heart failure. Am J Physiol Regul Integr Comp Physiol 2020; 319:R1-R10. [PMID: 32348680 DOI: 10.1152/ajpregu.00040.2020] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Dynamic exercise elicits robust increases in sympathetic activity in part due to muscle metaboreflex activation (MMA), a pressor response triggered by activation of skeletal muscle afferents. MMA during dynamic exercise increases arterial pressure by increasing cardiac output via increases in heart rate, ventricular contractility, and central blood volume mobilization. In heart failure, ventricular function is compromised, and MMA elicits peripheral vasoconstriction. Ventricular-vascular coupling reflects the efficiency of energy transfer from the left ventricle to the systemic circulation and is calculated as the ratio of effective arterial elastance (Ea) to left ventricular maximal elastance (Emax). The effect of MMA on Ea in normal subjects is unknown. Furthermore, whether muscle metaboreflex control of Ea is altered in heart failure has not been investigated. We utilized two previously published methods of evaluating Ea [end-systolic pressure/stroke volume (EaPV)] and [heart rate × vascular resistance (EaZ)] during rest, mild treadmill exercise, and MMA (induced via partial reductions in hindlimb blood flow imposed during exercise) in chronically instrumented conscious canines before and after induction of heart failure via rapid ventricular pacing. In healthy animals, MMA elicits significant increases in effective arterial elastance and stroke work that likely maintains ventricular-vascular coupling. In heart failure, Ea is high, and MMA-induced increases are exaggerated, which further exacerbates the already uncoupled ventricular-vascular relationship, which likely contributes to the impaired ability to raise stroke work and cardiac output during exercise in heart failure.
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Affiliation(s)
- Joseph Mannozzi
- Department of Physiology, Wayne State University School of Medicine, Detroit, Michigan
| | - Jasdeep Kaur
- Department of Physiology, Wayne State University School of Medicine, Detroit, Michigan
| | - Marty D Spranger
- Department of Physiology, Wayne State University School of Medicine, Detroit, Michigan
| | | | - Beruk Lessanework
- Department of Physiology, Wayne State University School of Medicine, Detroit, Michigan
| | - Alberto Alvarez
- Department of Physiology, Wayne State University School of Medicine, Detroit, Michigan
| | - Charles S Chung
- Department of Physiology, Wayne State University School of Medicine, Detroit, Michigan
| | - Donal S O'Leary
- Department of Physiology, Wayne State University School of Medicine, Detroit, Michigan
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16
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O'Leary DS, Senador D, Augustyniak RA. Muscle metaboreflex-induced central blood volume mobilization in heart failure. Am J Physiol Heart Circ Physiol 2019; 316:H1047-H1052. [PMID: 30822120 DOI: 10.1152/ajpheart.00805.2018] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Underperfusion of active skeletal muscle causes metabolites to accumulate and stimulate group III and IV skeletal muscle afferents, which triggers a powerful pressor response termed the muscle metaboreflex. Muscle metaboreflex activation (MMA) during submaximal dynamic exercise in healthy individuals increases arterial pressure mainly via substantial increases in cardiac output (CO). The increases in CO occur via the combination of tachycardia and increased ventricular contractility. Importantly, MMA also elicits substantial central blood volume mobilization, which allows the ventricular responses to sustain the increases in CO. Otherwise preload would fall and the increases in CO could not be maintained. In subjects with systolic heart failure (HF), the ability to increase CO during exercise and MMA is markedly reduced, which has been attributed to impaired ventricular contractility. Whether the ability to maintain preload during MMA in HF is preserved is unknown. Using a conscious chronically instrumented canine model, we observed that MMA in HF is able to raise central blood volume similarly as in normal subjects. Therefore, the loss of the ability to raise CO during MMA in HF is not because of the loss of the ability to mobilize blood volume centrally. NEW & NOTEWORTHY In normal subjects during dynamic exercise muscle metaboreflex activation elicits large increases in cardiac output that occur via increases in heart rate, ventricular contractility, and, importantly, marked central blood volume mobilization that acts to maintain ventricular preload, thereby allowing the changes in cardiac function to maintain the increases in cardiac output. In subjects with heart failure, the ability to raise cardiac output during muscle metaboreflex activation is impaired. We investigated whether this is because of the inability to maintain ventricular preload. We found that this reflex is still able to elicit large increases in central blood volume, and therefore the limited ability to raise cardiac output likely stems from ventricular dysfunction and not the ability to maintain preload.
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Affiliation(s)
- Donal S O'Leary
- Department of Physiology, Wayne State University School of Medicine , Detroit, Michigan
| | - Danielle Senador
- Department of Physiology, Wayne State University School of Medicine , Detroit, Michigan
| | - Robert A Augustyniak
- Department of Physiology, Wayne State University School of Medicine , Detroit, Michigan
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17
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Hoye NA, Wilson LC, Jardine DL, Walker RJ. Sympathetic overactivity in dialysis patients-Underappreciated and clinically consequential. Semin Dial 2018; 32:255-265. [PMID: 30461070 DOI: 10.1111/sdi.12756] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Cardiovascular morbidity and mortality remain frustratingly common in dialysis patients. A dearth of established evidence-based treatment calls for alternative therapeutic avenues to be embraced. Sympathetic hyperactivity, predominantly due to afferent nerve signaling from the diseased native kidneys, has been established to be prognostic in the dialysis population for over 15 years. Despite this, tangible therapeutic interventions have, to date, been unsuccessful and the outlook for patients remains poor. This narrative review summarizes established experimental and clinical data, highlighting recent developments, and proposes why interventions to ameliorate sympathetic hyperactivity may well be beneficial for this high-risk population.
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Affiliation(s)
- Neil A Hoye
- Department of Renal Medicine, South Tees Hospitals NHS Foundation Trust, Middlesbrough, UK
| | - Luke C Wilson
- Department of Medicine, Dunedin School of Medicine, University of Otago, Dunedin, Otago, New Zealand
| | - David L Jardine
- Department of Medicine, University of Otago, Christchurch, Otago, New Zealand
| | - Robert J Walker
- Department of Medicine, Dunedin School of Medicine, University of Otago, Dunedin, Otago, New Zealand
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18
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Kaur J, Krishnan AC, Senador D, Alvarez A, Hanna HW, O'Leary DS. Altered arterial baroreflex-muscle metaboreflex interaction in heart failure. Am J Physiol Heart Circ Physiol 2018; 315:H1383-H1392. [PMID: 30074841 PMCID: PMC6297818 DOI: 10.1152/ajpheart.00338.2018] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/30/2018] [Revised: 07/30/2018] [Accepted: 07/30/2018] [Indexed: 11/22/2022]
Abstract
Two powerful reflexes controlling cardiovascular function during exercise are the muscle metaboreflex and arterial baroreflex. In heart failure (HF), the strength and mechanisms of these reflexes are altered. Muscle metaboreflex activation (MMA) in normal subjects increases mean arterial pressure (MAP) primarily via increases in cardiac output (CO), whereas in HF the mechanism shifts to peripheral vasoconstriction. Baroreceptor unloading increases MAP via peripheral vasoconstriction, and this pressor response is blunted in HF. Baroreceptor unloading during MMA in normal animals elicits an enormous pressor response via combined increases in CO and peripheral vasoconstriction. The mode of interaction between these reflexes is intimately dependent on the parameter (e.g., MAP and CO) being investigated. The interaction between the two reflexes when activated simultaneously during dynamic exercise in HF is unknown. We activated the muscle metaboreflex in chronically instrumented dogs during mild exercise (via graded reductions in hindlimb blood flow) followed by baroreceptor unloading [via bilateral carotid occlusion (BCO)] before and after induction of HF. We hypothesized that BCO during MMA in HF would cause a smaller increase in MAP and a larger vasoconstriction of ischemic hindlimb vasculature, which would attenuate the restoration of blood flow to ischemic muscle observed in normal dogs. We observed that BCO during MMA in HF increases MAP by substantial vasoconstriction of all vascular beds, including ischemic active muscle, and that all cardiovascular responses, except ventricular function, exhibit occlusive interaction. We conclude that vasoconstriction of ischemic active skeletal muscle in response to baroreceptor unloading during MMA attenuates restoration of hindlimb blood flow. NEW & NOTEWORTHY We found that baroreceptor unloading during the muscle metaboreflex in heart failure results in occlusive interaction (except for ventricular function) with significant vasoconstriction of all vascular beds. In addition, restoration of blood flow to ischemic active muscle, via preferentially larger vasoconstriction of nonischemic beds, is significantly attenuated in heart failure.
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Affiliation(s)
- Jasdeep Kaur
- Department of Physiology and Cardiovascular Research Institute, Wayne State University School of Medicine , Detroit, Michigan
| | - Abhinav C Krishnan
- Department of Physiology and Cardiovascular Research Institute, Wayne State University School of Medicine , Detroit, Michigan
| | - Danielle Senador
- Department of Physiology and Cardiovascular Research Institute, Wayne State University School of Medicine , Detroit, Michigan
| | - Alberto Alvarez
- Department of Physiology and Cardiovascular Research Institute, Wayne State University School of Medicine , Detroit, Michigan
| | - Hanna W Hanna
- Department of Physiology and Cardiovascular Research Institute, Wayne State University School of Medicine , Detroit, Michigan
| | - Donal S O'Leary
- Department of Physiology and Cardiovascular Research Institute, Wayne State University School of Medicine , Detroit, Michigan
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Magnani S, Roberto S, Sainas G, Milia R, Palazzolo G, Cugusi L, Pinna V, Doneddu A, Kakhak SAH, Tocco F, Mercuro G, Crisafulli A. Metaboreflex-mediated hemodynamic abnormalities in individuals with coronary artery disease without overt signs or symptoms of heart failure. Am J Physiol Heart Circ Physiol 2017; 314:H452-H463. [PMID: 29127237 DOI: 10.1152/ajpheart.00436.2017] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
This study was devised to investigate the effect of coronary artery disease (CAD) without overt signs of heart failure on the cardiovascular responses to muscle metaboreflex activation. We hypothesized that any CAD-induced preclinical systolic and/or diastolic dysfunction could impair hemodynamic response to the metaboreflex test. Twelve men diagnosed with CAD without any sign or symptoms of heart failure and 11 age-matched healthy control (CTL) subjects participated in the study. Subjects performed a postexercise muscle ischemia (PEMI) test to activate the metaboreflex. They also performed a control exercise recovery test to compare data from the PEMI test. The main results were that the CAD group reached a similar mean arterial blood pressure response as the CTL group during PEMI. However, the mechanism by which this response was achieved was different between groups. In particular, CAD achieved the target mean arterial blood pressure by increasing systemic vascular resistance (+383.8 ± 256.6 vs. +91.2 ± 293.5 dyn·s-1·cm-5 for the CAD and CTL groups, respectively), the CTL group by increasing cardiac preload (-0.92 ± 8.53 vs. 5.34 ± 4.29 ml in end-diastolic volume for the CAD and CTL groups, respectively), which led to an enhanced stroke volume and cardiac output. Furthermore, the ventricular filling rate response was higher in the CTL group than in the CAD group during PEMI ( P < 0.05 for all comparisons). This study confirms that diastolic function is pivotal for normal hemodynamics during the metaboreflex. Moreover, it provides evidence that early signs of diastolic impairment attributable to CAD can be detected by the metaboreflex test. NEW & NOTEWORTHY Individuals suffering from coronary artery disease without overt signs of heart failure may show early signs of diastolic dysfunction, which can be detected by the metaboreflex test. During the metaboreflex, these subjects show impaired preload and stroke volume responses and exaggerated vasoconstriction compared with controls.
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Affiliation(s)
- Sara Magnani
- Department of Medical Sciences and Public Health, University of Cagliari , Cagliari , Italy
| | - Silvana Roberto
- Department of Medical Sciences and Public Health, University of Cagliari , Cagliari , Italy
| | - Gianmarco Sainas
- Department of Medical Sciences and Public Health, University of Cagliari , Cagliari , Italy
| | - Raffaele Milia
- Department of Medical Sciences and Public Health, University of Cagliari , Cagliari , Italy
| | - Girolamo Palazzolo
- Department of Medical Sciences and Public Health, University of Cagliari , Cagliari , Italy
| | - Lucia Cugusi
- Department of Medical Sciences and Public Health, University of Cagliari , Cagliari , Italy
| | - Virginia Pinna
- Department of Medical Sciences and Public Health, University of Cagliari , Cagliari , Italy
| | - Azzurra Doneddu
- Department of Medical Sciences and Public Health, University of Cagliari , Cagliari , Italy
| | | | - Filippo Tocco
- Department of Medical Sciences and Public Health, University of Cagliari , Cagliari , Italy
| | - Giuseppe Mercuro
- Department of Medical Sciences and Public Health, University of Cagliari , Cagliari , Italy
| | - Antonio Crisafulli
- Department of Medical Sciences and Public Health, University of Cagliari , Cagliari , Italy
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Kaur J, Senador D, Krishnan AC, Hanna HW, Alvarez A, Machado TM, O'Leary DS. Muscle metaboreflex-induced vasoconstriction in the ischemic active muscle is exaggerated in heart failure. Am J Physiol Heart Circ Physiol 2017; 314:H11-H18. [PMID: 28939649 DOI: 10.1152/ajpheart.00375.2017] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
When oxygen delivery to active muscle is insufficient to meet the metabolic demand during exercise, metabolites accumulate and stimulate skeletal muscle afferents, inducing a reflex increase in blood pressure, termed the muscle metaboreflex. In healthy individuals, muscle metaboreflex activation (MMA) during submaximal exercise increases arterial pressure primarily via an increase in cardiac output (CO), as little peripheral vasoconstriction occurs. This increase in CO partially restores blood flow to ischemic muscle. However, we recently demonstrated that MMA induces sympathetic vasoconstriction in ischemic active muscle, limiting the ability of the metaboreflex to restore blood flow. In heart failure (HF), increases in CO are limited, and metaboreflex-induced pressor responses occur predominantly via peripheral vasoconstriction. In the present study, we tested the hypothesis that vasoconstriction of ischemic active muscle is exaggerated in HF. Changes in hindlimb vascular resistance [femoral arterial pressure ÷ hindlimb blood flow (HLBF)] were observed during MMA (via graded reductions in HLBF) during mild exercise with and without α1-adrenergic blockade (prazosin, 50 µg/kg) before and after induction of HF. In normal animals, initial HLBF reductions caused metabolic vasodilation, while reductions below the metaboreflex threshold elicited reflex vasoconstriction, in ischemic active skeletal muscle, which was abolished after α1-adrenergic blockade. Metaboreflex-induced vasoconstriction of ischemic active muscle was exaggerated after induction of HF. This heightened vasoconstriction impairs the ability of the metaboreflex to restore blood flow to ischemic muscle in HF and may contribute to the exercise intolerance observed in these patients. We conclude that sympathetically mediated vasoconstriction of ischemic active muscle during MMA is exaggerated in HF. NEW & NOTEWORTHY We found that muscle metaboreflex-induced vasoconstriction of the ischemic active skeletal muscle from which the reflex originates is exaggerated in heart failure. This results in heightened metaboreflex activation, which further amplifies the reflex-induced vasoconstriction of the ischemic active skeletal muscle and contributes to exercise intolerance in patients.
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Affiliation(s)
- Jasdeep Kaur
- Department of Physiology and Cardiovascular Research Institute, Wayne State University School of Medicine , Detroit, Michigan
| | - Danielle Senador
- Department of Physiology and Cardiovascular Research Institute, Wayne State University School of Medicine , Detroit, Michigan
| | - Abhinav C Krishnan
- Department of Physiology and Cardiovascular Research Institute, Wayne State University School of Medicine , Detroit, Michigan
| | - Hanna W Hanna
- Department of Physiology and Cardiovascular Research Institute, Wayne State University School of Medicine , Detroit, Michigan
| | - Alberto Alvarez
- Department of Physiology and Cardiovascular Research Institute, Wayne State University School of Medicine , Detroit, Michigan
| | - Tiago M Machado
- Department of Physiology and Cardiovascular Research Institute, Wayne State University School of Medicine , Detroit, Michigan
| | - Donal S O'Leary
- Department of Physiology and Cardiovascular Research Institute, Wayne State University School of Medicine , Detroit, Michigan
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Kaur J, Young BE, Fadel PJ. Sympathetic Overactivity in Chronic Kidney Disease: Consequences and Mechanisms. Int J Mol Sci 2017; 18:ijms18081682. [PMID: 28767097 PMCID: PMC5578072 DOI: 10.3390/ijms18081682] [Citation(s) in RCA: 79] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2017] [Revised: 07/20/2017] [Accepted: 07/28/2017] [Indexed: 12/19/2022] Open
Abstract
The incidence of chronic kidney disease (CKD) is increasing worldwide, with more than 26 million people suffering from CKD in the United States alone. More patients with CKD die of cardiovascular complications than progress to dialysis. Over 80% of CKD patients have hypertension, which is associated with increased risk of cardiovascular morbidity and mortality. Another common, perhaps underappreciated, feature of CKD is an overactive sympathetic nervous system. This elevation in sympathetic nerve activity (SNA) not only contributes to hypertension but also plays a detrimental role in the progression of CKD independent of any increase in blood pressure. Indeed, high SNA is associated with poor prognosis and increased cardiovascular morbidity and mortality independent of its effect on blood pressure. This brief review will discuss some of the consequences of sympathetic overactivity and highlight some of the potential pathways contributing to chronically elevated SNA in CKD. Mechanisms leading to chronic sympathoexcitation in CKD are complex, multifactorial and to date, not completely understood. Identification of the mechanisms and/or signals leading to sympathetic overactivity in CKD are crucial for development of effective therapeutic targets to reduce the increased cardiovascular risk in this patient group.
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Affiliation(s)
- Jasdeep Kaur
- Department of Kinesiology, University of Texas at Arlington, Arlington, TX 76019, USA.
| | - Benjamin E Young
- Department of Kinesiology, University of Texas at Arlington, Arlington, TX 76019, USA.
| | - Paul J Fadel
- Department of Kinesiology, University of Texas at Arlington, Arlington, TX 76019, USA.
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Abstract
The heart is uniquely responsible for providing its own blood supply through the coronary circulation. Regulation of coronary blood flow is quite complex and, after over 100 years of dedicated research, is understood to be dictated through multiple mechanisms that include extravascular compressive forces (tissue pressure), coronary perfusion pressure, myogenic, local metabolic, endothelial as well as neural and hormonal influences. While each of these determinants can have profound influence over myocardial perfusion, largely through effects on end-effector ion channels, these mechanisms collectively modulate coronary vascular resistance and act to ensure that the myocardial requirements for oxygen and substrates are adequately provided by the coronary circulation. The purpose of this series of Comprehensive Physiology is to highlight current knowledge regarding the physiologic regulation of coronary blood flow, with emphasis on functional anatomy and the interplay between the physical and biological determinants of myocardial oxygen delivery. © 2017 American Physiological Society. Compr Physiol 7:321-382, 2017.
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Affiliation(s)
- Adam G Goodwill
- Department of Cellular and Integrative Physiology, Indiana University School of Medicine, Indianapolis, IN
| | - Gregory M Dick
- California Medical Innovations Institute, 872 Towne Center Drive, Pomona, CA
| | - Alexander M Kiel
- Department of Cellular and Integrative Physiology, Indiana University School of Medicine, Indianapolis, IN
- Weldon School of Biomedical Engineering, Purdue University, 206 S Martin Jischke Drive, Lafayette, IN
| | - Johnathan D Tune
- Department of Cellular and Integrative Physiology, Indiana University School of Medicine, Indianapolis, IN
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Spranger MD, Kaur J, Sala-Mercado JA, Krishnan AC, Abu-Hamdah R, Alvarez A, Machado TM, Augustyniak RA, O'Leary DS. Exaggerated coronary vasoconstriction limits muscle metaboreflex-induced increases in ventricular performance in hypertension. Am J Physiol Heart Circ Physiol 2016; 312:H68-H79. [PMID: 27769997 DOI: 10.1152/ajpheart.00417.2016] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/08/2016] [Revised: 10/18/2016] [Accepted: 10/18/2016] [Indexed: 02/07/2023]
Abstract
Increases in myocardial oxygen consumption during exercise mainly occur via increases in coronary blood flow (CBF) as cardiac oxygen extraction is high even at rest. However, sympathetic coronary constrictor tone can limit increases in CBF. Increased sympathetic nerve activity (SNA) during exercise likely occurs via the action of and interaction among activation of skeletal muscle afferents, central command, and resetting of the arterial baroreflex. As SNA is heightened even at rest in subjects with hypertension (HTN), we tested whether HTN causes exaggerated coronary vasoconstriction in canines during mild treadmill exercise with muscle metaboreflex activation (MMA; elicited by reducing hindlimb blood flow by ~60%) thereby limiting increases in CBF and ventricular performance. Experiments were repeated after α1-adrenergic blockade (prazosin; 75 µg/kg) and in the same animals following induction of HTN (modified Goldblatt 2K1C model). HTN increased mean arterial pressure from 97.1 ± 2.6 to 132.1 ± 5.6 mmHg at rest and MMA-induced increases in CBF, left ventricular dP/dtmax, and cardiac output were markedly reduced to only 32 ± 13, 26 ± 11, and 28 ± 12% of the changes observed in control. In HTN, α1-adrenergic blockade restored the coronary vasodilation and increased in ventricular function to the levels observed when normotensive. We conclude that exaggerated MMA-induced increases in SNA functionally vasoconstrict the coronary vasculature impairing increases in CBF, which limits oxygen delivery and ventricular performance in HTN. NEW & NOTEWORTHY We found that metaboreflex-induced increases in coronary blood flow and ventricular contractility are attenuated in hypertension. α1-Adrenergic blockade restored these parameters toward normal levels. These findings indicate that the primary mechanism mediating impaired metaboreflex-induced increases in ventricular function in hypertension is accentuated coronary vasoconstriction.
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Affiliation(s)
- Marty D Spranger
- Department of Physiology and Cardiovascular Research Institute, Wayne State University School of Medicine, Detroit, Michigan
| | - Jasdeep Kaur
- Department of Physiology and Cardiovascular Research Institute, Wayne State University School of Medicine, Detroit, Michigan
| | - Javier A Sala-Mercado
- Department of Physiology and Cardiovascular Research Institute, Wayne State University School of Medicine, Detroit, Michigan
| | - Abhinav C Krishnan
- Department of Physiology and Cardiovascular Research Institute, Wayne State University School of Medicine, Detroit, Michigan
| | - Rania Abu-Hamdah
- Department of Physiology and Cardiovascular Research Institute, Wayne State University School of Medicine, Detroit, Michigan
| | - Alberto Alvarez
- Department of Physiology and Cardiovascular Research Institute, Wayne State University School of Medicine, Detroit, Michigan
| | - Tiago M Machado
- Department of Physiology and Cardiovascular Research Institute, Wayne State University School of Medicine, Detroit, Michigan
| | - Robert A Augustyniak
- Department of Physiology and Cardiovascular Research Institute, Wayne State University School of Medicine, Detroit, Michigan
| | - Donal S O'Leary
- Department of Physiology and Cardiovascular Research Institute, Wayne State University School of Medicine, Detroit, Michigan
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24
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Ardell JL, Andresen MC, Armour JA, Billman GE, Chen PS, Foreman RD, Herring N, O'Leary DS, Sabbah HN, Schultz HD, Sunagawa K, Zucker IH. Translational neurocardiology: preclinical models and cardioneural integrative aspects. J Physiol 2016; 594:3877-909. [PMID: 27098459 DOI: 10.1113/jp271869] [Citation(s) in RCA: 102] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2016] [Accepted: 03/14/2016] [Indexed: 12/15/2022] Open
Abstract
Neuronal elements distributed throughout the cardiac nervous system, from the level of the insular cortex to the intrinsic cardiac nervous system, are in constant communication with one another to ensure that cardiac output matches the dynamic process of regional blood flow demand. Neural elements in their various 'levels' become differentially recruited in the transduction of sensory inputs arising from the heart, major vessels, other visceral organs and somatic structures to optimize neuronal coordination of regional cardiac function. This White Paper will review the relevant aspects of the structural and functional organization for autonomic control of the heart in normal conditions, how these systems remodel/adapt during cardiac disease, and finally how such knowledge can be leveraged in the evolving realm of autonomic regulation therapy for cardiac therapeutics.
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Affiliation(s)
- J L Ardell
- University of California - Los Angeles (UCLA) Cardiac Arrhythmia Center, David Geffen School of Medicine, Los Angeles, CA, USA.,UCLA Neurocardiology Research Center of Excellence, David Geffen School of Medicine, Los Angeles, CA, USA
| | - M C Andresen
- Department of Physiology and Pharmacology, Oregon Health and Science University, Portland, OR, USA
| | - J A Armour
- University of California - Los Angeles (UCLA) Cardiac Arrhythmia Center, David Geffen School of Medicine, Los Angeles, CA, USA.,UCLA Neurocardiology Research Center of Excellence, David Geffen School of Medicine, Los Angeles, CA, USA
| | - G E Billman
- Department of Physiology and Cell Biology, The Ohio State University, Columbus, OH, USA
| | - P-S Chen
- The Krannert Institute of Cardiology and Division of Cardiology, Department of Medicine, Indiana University School of Medicine, Indianapolis, IN, USA
| | - R D Foreman
- Department of Physiology, University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA
| | - N Herring
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, UK
| | - D S O'Leary
- Department of Physiology, Wayne State University, Detroit, MI, USA
| | - H N Sabbah
- Department of Medicine, Henry Ford Hospital, Detroit, MI, USA
| | - H D Schultz
- Cellular and Integrative Physiology, University of Nebraska Medical Center, Omaha, NE, USA
| | - K Sunagawa
- Department of Cardiovascular Medicine, Kyushu University, Fukuoka, Japan
| | - I H Zucker
- Cellular and Integrative Physiology, University of Nebraska Medical Center, Omaha, NE, USA
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Spranger MD, Krishnan AC, Levy PD, O'Leary DS, Smith SA. Blood flow restriction training and the exercise pressor reflex: a call for concern. Am J Physiol Heart Circ Physiol 2015; 309:H1440-52. [PMID: 26342064 PMCID: PMC7002872 DOI: 10.1152/ajpheart.00208.2015] [Citation(s) in RCA: 136] [Impact Index Per Article: 15.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/20/2015] [Accepted: 08/31/2015] [Indexed: 02/07/2023]
Abstract
Blood flow restriction (BFR) training (also known as Kaatsu training) is an increasingly common practice employed during resistance exercise by athletes attempting to enhance skeletal muscle mass and strength. During BFR training, blood flow to the exercising muscle is mechanically restricted by placing flexible pressurizing cuffs around the active limb proximal to the working muscle. This maneuver results in the accumulation of metabolites (e.g., protons and lactic acid) in the muscle interstitium that increase muscle force and promote muscle growth. Therefore, the premise of BFR training is to simulate and receive the benefits of high-intensity resistance exercise while merely performing low-intensity resistance exercise. This technique has also been purported to provide health benefits to the elderly, individuals recovering from joint injuries, and patients undergoing cardiac rehabilitation. Since the seminal work of Alam and Smirk in the 1930s, it has been well established that reductions in blood flow to exercising muscle engage the exercise pressor reflex (EPR), a reflex that significantly contributes to the autonomic cardiovascular response to exercise. However, the EPR and its likely contribution to the BFR-mediated cardiovascular response to exercise is glaringly missing from the scientific literature. Inasmuch as the EPR has been shown to generate exaggerated increases in sympathetic nerve activity in disease states such as hypertension (HTN), heart failure (HF), and peripheral artery disease (PAD), concerns are raised that BFR training can be used safely for the rehabilitation of patients with cardiovascular disease, as has been suggested. Abnormal BFR-induced and EPR-mediated cardiovascular complications generated during exercise could precipitate adverse cardiovascular or cerebrovascular events (e.g., cardiac arrhythmia, myocardial infarction, stroke and sudden cardiac death). Moreover, although altered EPR function in HTN, HF, and PAD underlies our concern for the widespread implementation of BFR, use of this training mechanism may also have negative consequences in the absence of disease. That is, even normal, healthy individuals performing resistance training exercise with BFR are potentially at increased risk for deleterious cardiovascular events. This review provides a brief yet detailed overview of the mechanisms underlying the autonomic cardiovascular response to exercise with BFR. A more complete understanding of the consequences of BFR training is needed before this technique is passively explored by the layman athlete or prescribed by a health care professional.
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Affiliation(s)
- Marty D Spranger
- Department of Physiology, Michigan State University, East Lansing, Michigan; Department of Physiology, Wayne State University School of Medicine, Detroit, Michigan; Cardiovascular Research Institute, Wayne State University School of Medicine, Detroit, Michigan;
| | - Abhinav C Krishnan
- Department of Physiology, Wayne State University School of Medicine, Detroit, Michigan; Cardiovascular Research Institute, Wayne State University School of Medicine, Detroit, Michigan
| | - Phillip D Levy
- Department of Physiology, Wayne State University School of Medicine, Detroit, Michigan; Department of Emergency Medicine, Wayne State University School of Medicine, Detroit, Michigan
| | - Donal S O'Leary
- Department of Physiology, Wayne State University School of Medicine, Detroit, Michigan; Cardiovascular Research Institute, Wayne State University School of Medicine, Detroit, Michigan
| | - Scott A Smith
- Department of Health Care Sciences, University of Texas Southwestern Medical Center, Dallas, Texas; Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, Texas
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26
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Michelini LC, O'Leary DS, Raven PB, Nóbrega ACL. Neural control of circulation and exercise: a translational approach disclosing interactions between central command, arterial baroreflex, and muscle metaboreflex. Am J Physiol Heart Circ Physiol 2015; 309:H381-92. [PMID: 26024683 PMCID: PMC4631530 DOI: 10.1152/ajpheart.00077.2015] [Citation(s) in RCA: 69] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/02/2015] [Accepted: 05/18/2015] [Indexed: 01/13/2023]
Abstract
The last 100 years witnessed a rapid and progressive development of the body of knowledge concerning the neural control of the cardiovascular system in health and disease. The understanding of the complexity and the relevance of the neuroregulatory system continues to evolve and as a result raises new questions. The purpose of this review is to articulate results from studies involving experimental models in animals as well as in humans concerning the interaction between the neural mechanisms mediating the hemodynamic responses during exercise. The review describes the arterial baroreflex, the pivotal mechanism controlling mean arterial blood pressure and its fluctuations along with the two main activation mechanisms to exercise: central command (parallel activation of central somatomotor and autonomic descending pathways) and the muscle metaboreflex, the metabolic component of exercise pressor reflex (feedback from ergoreceptors within contracting skeletal muscles). In addition, the role of the cardiopulmonary baroreceptors in modulating the resetting of arterial baroreflex is identified, and the mechanisms in the central nervous system involved with the resetting of baroreflex function during dynamic exercise are also described. Approaching a very relevant clinical condition, the review also presents the concept that the impaired arterial baroreflex function is an integral component of the metaboreflex-mediated exaggerated sympathetic tone in subjects with heart failure. This increased sympathetic activity has a major role in causing the depressed ventricular function observed during submaximal dynamic exercise in these patients. The potential contribution of a metaboreflex arising from respiratory muscles is also considered.
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Affiliation(s)
- Lisete C Michelini
- Department of Physiology and Biophysics, Biomedical Sciences Institute, University of São Paulo, São Paulo, Brazil
| | - Donal S O'Leary
- Department of Physiology, Wayne State University School of Medicine, Detroit, Michigan
| | - Peter B Raven
- Department of Integrative Physiology, University of North Texas Health Science Center, Fort Worth, Texas; and
| | - Antonio C L Nóbrega
- Department of Physiology and Pharmacology, Fluminense Federal University, Niteroi, Brazil
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27
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Spranger MD, Kaur J, Sala-Mercado JA, Machado TM, Krishnan AC, Alvarez A, O'Leary DS. Attenuated muscle metaboreflex-induced pressor response during postexercise muscle ischemia in renovascular hypertension. Am J Physiol Regul Integr Comp Physiol 2015; 308:R650-8. [PMID: 25632024 DOI: 10.1152/ajpregu.00464.2014] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2014] [Accepted: 01/27/2015] [Indexed: 11/22/2022]
Abstract
During dynamic exercise, muscle metaboreflex activation (MMA; induced via partial hindlimb ischemia) markedly increases mean arterial pressure (MAP), and MAP is sustained when the ischemia is maintained following the cessation of exercise (postexercise muscle ischemia, PEMI). We previously reported that the sustained pressor response during PEMI in normal individuals is driven by a sustained increase in cardiac output (CO) with no peripheral vasoconstriction. However, we have recently shown that the rise in CO with MMA is significantly blunted in hypertension (HTN). The mechanisms sustaining the pressor response during PEMI in HTN are unknown. In six chronically instrumented canines, hemodynamic responses were observed during rest, mild exercise (3.2 km/h), MMA, and PEMI in the same animals before and after the induction of HTN [Goldblatt two kidney, one clip (2K1C)]. In controls, MAP, CO and HR increased with MMA (+52 ± 6 mmHg, +2.1 ± 0.3 l/min, and +37 ± 7 beats per minute). After induction of HTN, MAP at rest increased from 97 ± 3 to 130 ± 4 mmHg, and the metaboreflex responses were markedly attenuated (+32 ± 5 mmHg, +0.6 ± 0.2 l/min, and +11 ± 3 bpm). During PEMI in HTN, HR and CO were not sustained, and MAP fell to normal recovery levels. We conclude that the attenuated metaboreflex-induced HR, CO, and MAP responses are not sustained during PEMI in HTN.
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Affiliation(s)
- Marty D Spranger
- Department of Physiology and Cardiovascular Research Institute, Wayne State University School of Medicine, Detroit, Michigan
| | - Jasdeep Kaur
- Department of Physiology and Cardiovascular Research Institute, Wayne State University School of Medicine, Detroit, Michigan
| | - Javier A Sala-Mercado
- Department of Physiology and Cardiovascular Research Institute, Wayne State University School of Medicine, Detroit, Michigan
| | - Tiago M Machado
- Department of Physiology and Cardiovascular Research Institute, Wayne State University School of Medicine, Detroit, Michigan
| | - Abhinav C Krishnan
- Department of Physiology and Cardiovascular Research Institute, Wayne State University School of Medicine, Detroit, Michigan
| | - Alberto Alvarez
- Department of Physiology and Cardiovascular Research Institute, Wayne State University School of Medicine, Detroit, Michigan
| | - Donal S O'Leary
- Department of Physiology and Cardiovascular Research Institute, Wayne State University School of Medicine, Detroit, Michigan
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McNulty CL, Moody WE, Wagenmakers AJ, Fisher JP. Effect of muscle metaboreflex activation on central hemodynamics and cardiac function in humans. Appl Physiol Nutr Metab 2014; 39:861-70. [DOI: 10.1139/apnm-2013-0414] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
We sought to determine how the mode of muscle metaboreflex activation influences the central hemodynamic response and cardiac inotropic and lusotropic function in healthy humans. Ten healthy males performed (i) isometric handgrip (IHG) with and without post-exercise ischemia (PEI) to examine the influence of isolated muscle metaboreflex activation and (ii) rhythmic handgrip (RHG) with and without ischemia to examine the influence of enhanced muscle metaboreflex activation. Heart rate (HR) and blood pressure (BP) were continuously monitored. Stroke volume (SV, Doppler echocardiography) was measured, cardiac output (CO = HR × SV) and total peripheral resistance (TPR = mean BP/CO) calculated, and indices of left ventricular systolic and diastolic function were obtained (tissue Doppler imaging). During isolated muscle metaboreflex activation with PEI following IHG, mean BP (+23 ± 3 mm Hg) and TPR were elevated from baseline (p < 0.05), whereas HR, SV, and CO were unchanged. Enhanced muscle metaboreceptor activation during ischemic RHG augmented the increase in mean BP, CO, and HR (p < 0.05 ischemic vs. free-flow RHG), whereas SV and TPR were unchanged from baseline. Neither isolated (PEI) nor enhanced muscle metaboreflex activation altered left ventricular systolic function (systolic myocardial velocity), but left atrial systolic function (late diastolic myocardial velocity) was enhanced. These findings indicate that the mode of muscle metaboreceptor activation (during vs. post handgrip) determines whether the resultant pressor response is flow (CO) or vasoconstriction (TPR) mediated, and that although left ventricular systolic function is unchanged, enhanced left atrial systolic function likely aids the preservation of SV during muscle metaboreflex engagement.
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Affiliation(s)
- Clare L. McNulty
- School of Sport, Exercise and Rehabilitation Sciences, College of Life and Environmental Sciences, University of Birmingham, Edgbaston, Birmingham, B15 2TT, England
| | - William E. Moody
- Department of Cardiovascular Sciences, College of Medicine and Dentistry, University of Birmingham, Edgbaston, Birmingham, B15 2TT, UK
| | - Anton J.M. Wagenmakers
- Research Institute for Sport and Exercise Sciences, Liverpool John Moores University, Liverpool, L3 3AF, UK
| | - James P. Fisher
- School of Sport, Exercise and Rehabilitation Sciences, College of Life and Environmental Sciences, University of Birmingham, Edgbaston, Birmingham, B15 2TT, England
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30
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Nobrega ACL, O'Leary D, Silva BM, Marongiu E, Piepoli MF, Crisafulli A. Neural regulation of cardiovascular response to exercise: role of central command and peripheral afferents. BIOMED RESEARCH INTERNATIONAL 2014; 2014:478965. [PMID: 24818143 PMCID: PMC4000959 DOI: 10.1155/2014/478965] [Citation(s) in RCA: 118] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/25/2013] [Accepted: 02/04/2014] [Indexed: 12/12/2022]
Abstract
During dynamic exercise, mechanisms controlling the cardiovascular apparatus operate to provide adequate oxygen to fulfill metabolic demand of exercising muscles and to guarantee metabolic end-products washout. Moreover, arterial blood pressure is regulated to maintain adequate perfusion of the vital organs without excessive pressure variations. The autonomic nervous system adjustments are characterized by a parasympathetic withdrawal and a sympathetic activation. In this review, we briefly summarize neural reflexes operating during dynamic exercise. The main focus of the present review will be on the central command, the arterial baroreflex and chemoreflex, and the exercise pressure reflex. The regulation and integration of these reflexes operating during dynamic exercise and their possible role in the pathophysiology of some cardiovascular diseases are also discussed.
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Affiliation(s)
- Antonio C. L. Nobrega
- Department of Physiology and Pharmacology, Fluminense Federal University, Niterói, RJ, Brazil
| | - Donal O'Leary
- Department of Physiology, Wayne State University School of Medicine, Detroit, MI, USA
| | - Bruno Moreira Silva
- Section of Exercise Physiology, Department of Physiology, Federal University of São Paulo, SP, Brazil
| | - Elisabetta Marongiu
- Sports Physiology laboratory Lab., Department of Medical Sciences, University of Cagliari, Italy
| | - Massimo F. Piepoli
- Heart Failure Unit, Cardiac Department, Guglielmo da Saliceto Polichirurgico Hospital, Piacenza, Italy
| | - Antonio Crisafulli
- Sports Physiology laboratory Lab., Department of Medical Sciences, University of Cagliari, Italy
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Sala-Mercado JA, Spranger MD, Abu-Hamdah R, Kaur J, Coutsos M, Stayer D, Augustyniak RA, O'Leary DS. Attenuated muscle metaboreflex-induced increases in cardiac function in hypertension. Am J Physiol Heart Circ Physiol 2013; 305:H1548-54. [PMID: 24014673 DOI: 10.1152/ajpheart.00478.2013] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Sympathoactivation may be excessive during exercise in subjects with hypertension, leading to increased susceptibility to adverse cardiovascular events, including arrhythmias, infarction, stroke, and sudden cardiac death. The muscle metaboreflex is a powerful cardiovascular reflex capable of eliciting marked increases in sympathetic activity during exercise. We used conscious, chronically instrumented dogs trained to run on a motor-driven treadmill to investigate the effects of hypertension on the mechanisms of the muscle metaboreflex. Experiments were performed before and 30.9 ± 4.2 days after induction of hypertension, which was induced via partial, unilateral renal artery occlusion. After induction of hypertension, resting mean arterial pressure was significantly elevated from 98.2 ± 2.6 to 141.9 ± 7.4 mmHg. The hypertension was caused by elevated total peripheral resistance. Although cardiac output was not significantly different at rest or during exercise after induction of hypertension, the rise in cardiac output with muscle metaboreflex activation was significantly reduced in hypertension. Metaboreflex-induced increases in left ventricular function were also depressed. These attenuated cardiac responses caused a smaller metaboreflex-induced rise in mean arterial pressure. We conclude that the ability of the muscle metaboreflex to elicit increases in cardiac function is impaired in hypertension, which may contribute to exercise intolerance.
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Affiliation(s)
- Javier A Sala-Mercado
- Department of Physiology and The Cardiovascular Research Institute, Wayne State University School of Medicine, Detroit, Michigan
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Ichinose M, Maeda S, Kondo N, Nishiyasu T. Blood pressure regulation II: what happens when one system must serve two masters--oxygen delivery and pressure regulation? Eur J Appl Physiol 2013; 114:451-65. [PMID: 23846841 DOI: 10.1007/s00421-013-2691-y] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2013] [Accepted: 07/02/2013] [Indexed: 11/30/2022]
Abstract
During high-intensity dynamic exercise, O2 delivery to active skeletal muscles is enhanced through marked increases in both cardiac output and skeletal muscle blood flow. When the musculature is vigorously engaged in exercise, the human heart lacks the pumping capacity to meet the blood flow demands of both the skeletal muscles and other organs such as the brain. Vasoconstriction must therefore be induced through activation of sympathetic nervous activity to maintain blood flow to the brain and to produce the added driving pressure needed to increase flow to the skeletal muscles. In this review, we first briefly summarize the local vascular and neural control mechanisms operating during high-intensity exercise. This is followed by a review of the major neural mechanisms regulating blood pressure during high-intensity exercise, focusing mainly on the integrated activities of the arterial baroreflex and muscle metaboreflex. In high cardiac output situations, such as during high-intensity dynamic exercise, small changes in total peripheral resistance can induce large changes in blood pressure, which means that rapid and fine regulation is necessary to avoid unacceptable drops in blood pressure. To accomplish this rapid regulation, arterial baroreflex function may be modulated in various ways through activation of the muscle metaboreflex and/or other neural mechanisms. Moreover, this modulation of the arterial baroreflex may change over the time course of an exercise bout, or to accommodate changes in exercise intensity. Within this model, integration of arterial baroreflex modulation with other neural mechanisms plays an important role in cardiovascular control during high-intensity exercise.
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Affiliation(s)
- Masashi Ichinose
- Human Integrative Physiology Laboratory, School of Business Administration, Meiji University, Tokyo, Japan
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Heinonen I, Wendelin-Saarenhovi M, Kaskinoro K, Knuuti J, Scheinin M, Kalliokoski KK. Inhibition of α-adrenergic tone disturbs the distribution of blood flow in the exercising human limb. Am J Physiol Heart Circ Physiol 2013; 305:H163-72. [PMID: 23666670 DOI: 10.1152/ajpheart.00925.2012] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
The role of neuronal regulation of human cardiovascular function remains incompletely elucidated, especially during exercise. Here we, by positron emission tomography, monitored tissue-specific blood flow (BF) changes in nine healthy young men during femoral arterial infusions of norepinephrine (NE) and phentolamine. At rest, the α-adrenoceptor agonist NE reduced BF by ~40%, similarly in muscles (from 3.2 ± 1.9 to 1.4 ± 0.3 ml·min(-1)·100 g(-1) in quadriceps femoris muscle), bone (from 1.1 ± 0.4 to 0.5 ± 0.2 ml·min(-1)·100 g(-1)) and adipose tissue (AT) (from 1.2 ± 0.7 to 0.7 ± 0.3 ml·min(-1)·100 g(-1)). During exercise, NE reduced exercising muscle BF by ~16%. BF in AT was reduced similarly as rest. The α-adrenoceptor antagonist phentolamine increased BF similarly in the different muscles and other tissues of the limb at rest. During exercise, BF in inactive muscle was increased 3.4-fold by phentolamine compared with exercise without drug, but BF in exercising muscles was not influenced. Bone and AT (P = 0.055) BF were also increased by phentolamine in the exercise condition. NE increased and phentolamine decreased oxygen extraction in the limb during exercise. We conclude that inhibition of α-adrenergic tone markedly disturbs the distribution of BF and oxygen extraction in the exercising human limb by increasing BF especially around inactive muscle fibers. Moreover, although marked functional sympatholysis also occurs during exercise, the arterial NE infusion that mimics the exaggerated sympathetic nerve activity commonly seen in patients with cardiovascular disease was still capable of directly limiting BF in the exercising leg muscles.
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Affiliation(s)
- Ilkka Heinonen
- Turku PET Centre, University of Turku and Turku University Hospital, Turku, Finland.
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