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Giannoni A, Borrelli C, Gentile F, Sciarrone P, Spießhöfer J, Piepoli M, Richerson GB, Floras JS, Coats AJS, Javaheri S, Emdin M, Passino C. Autonomic and respiratory consequences of altered chemoreflex function: clinical and therapeutic implications in cardiovascular diseases. Eur J Heart Fail 2023; 25:642-656. [PMID: 36907827 PMCID: PMC10989193 DOI: 10.1002/ejhf.2819] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/14/2022] [Revised: 02/10/2023] [Accepted: 02/26/2023] [Indexed: 03/14/2023] Open
Abstract
The importance of chemoreflex function for cardiovascular health is increasingly recognized in clinical practice. The physiological function of the chemoreflex is to constantly adjust ventilation and circulatory control to match respiratory gases to metabolism. This is achieved in a highly integrated fashion with the baroreflex and the ergoreflex. The functionality of chemoreceptors is altered in cardiovascular diseases, causing unstable ventilation and apnoeas and promoting sympathovagal imbalance, and it is associated with arrhythmias and fatal cardiorespiratory events. In the last few years, opportunities to desensitize hyperactive chemoreceptors have emerged as potential options for treatment of hypertension and heart failure. This review summarizes up to date evidence of chemoreflex physiology/pathophysiology, highlighting the clinical significance of chemoreflex dysfunction, and lists the latest proof of concept studies based on modulation of the chemoreflex as a novel target in cardiovascular diseases.
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Affiliation(s)
- Alberto Giannoni
- Health Science Interdisciplinary Center, Scuola Superiore Sant’Anna, Pisa, Italy
- Fondazione Toscana G. Monasterio, Pisa, Italy
| | | | - Francesco Gentile
- Health Science Interdisciplinary Center, Scuola Superiore Sant’Anna, Pisa, Italy
| | | | - Jens Spießhöfer
- Health Science Interdisciplinary Center, Scuola Superiore Sant’Anna, Pisa, Italy
- University of Aachen, Aachen, Germany
| | | | | | - John S Floras
- Division of Cardiology, Mount Sinai Hospital, University of Toronto, Ontario, Canada
| | | | - Shahrokh Javaheri
- Division of Pulmonary and Sleep Medicine, Bethesda North Hospital, Cincinnati, Ohio, Division of Pulmonary, Critical Care and Sleep Medicine, University of Cincinnati, Cincinnati, Ohio, and Division of Cardiology, The Ohio State University, Columbus, Ohio USA
| | - Michele Emdin
- Health Science Interdisciplinary Center, Scuola Superiore Sant’Anna, Pisa, Italy
- Fondazione Toscana G. Monasterio, Pisa, Italy
| | - Claudio Passino
- Health Science Interdisciplinary Center, Scuola Superiore Sant’Anna, Pisa, Italy
- Fondazione Toscana G. Monasterio, Pisa, Italy
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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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Villanueva-García D, Mota-Rojas D, Miranda-Cortés A, Ibarra-Ríos D, Casas-Alvarado A, Mora-Medina P, Martínez-Burnes J, Olmos-Hernández A, Hernández-Avalos I. Caffeine: cardiorespiratory effects and tissue protection in animal models. Exp Anim 2021; 70:431-439. [PMID: 34039788 PMCID: PMC8614017 DOI: 10.1538/expanim.20-0185] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022] Open
Abstract
OBJECTIVE The aim of this review is to analyze the cardiorespiratory and tissue-protective effects of caffeine in animal models. Peer-reviewed literature published between 1975 and 2021 was retrieved from CAB Abstracts, PubMed, ISI Web of Knowledge, and Scopus. Extracted data were analyzed to address the mechanism of action of caffeine on cardiorespiratory parameters (heart rate and rhythm), vasopressor effects, and some indices of respiratory function; we close this review by discussing the existing debate on the research carried out on the effects of caffeine on tissue protection. Adenosine acts through specific receptors and is a negative inotropic andchronotropic agent. Blockage of its cardiac receptors can cause tachycardia (with arrhythmogenic potential) due to the intense activity of β1 receptors. In terms of tissue protection, caffeine produces inhibition of hyperoxia-induced pulmonary inflammation by decreasing proinflammatory cytokine expression in animal models. CONCLUSION The protection that caffeine provides to tissues is not limited to the CNS, as studies have demonstrated that it generates attenuation of inflammatory effects in pulmonary tissue, where it inhibits the effects of some pro-inflammatory cytokines and prevents functional and structural changes.
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Affiliation(s)
- Dina Villanueva-García
- Division of Neonatology, National Institute of Health, Hospital Infantil de México Federico Gómez
| | - Daniel Mota-Rojas
- Neurophysiology, Behavior, and Animal Welfare Assessment, Department of Animal Production and Agriculture (DPAA), Universidad Autónoma Metropolitana (UAM) Xochimilco Campus
| | - Agatha Miranda-Cortés
- Clinical Pharmacology and Veterinary Anaesthesia, Department of Biological Science, FESC, Universidad Nacional Autónoma de México (UNAM)
| | - Daniel Ibarra-Ríos
- Division of Neonatology, National Institute of Health, Hospital Infantil de México Federico Gómez
| | - Alejandro Casas-Alvarado
- Neurophysiology, Behavior, and Animal Welfare Assessment, Department of Animal Production and Agriculture (DPAA), Universidad Autónoma Metropolitana (UAM) Xochimilco Campus
| | - Patricia Mora-Medina
- Livestock Science Department, Universidad Nacional Autónoma de México (UNAM), Facultad de Estudios Superiores Cuautitlán
| | - Julio Martínez-Burnes
- Graduate and Research Department, Facultad de Medicina Veterinaria y Zootecnia, Universidad Autónoma de Tamaulipas
| | - Adriana Olmos-Hernández
- Division of Biotechnology, Department Bioterio and Experimental Surgery, Instituto Nacional de Rehabilitación-Luis Guillermo Ibarra Ibarra (INR-LGII)
| | - Ismael Hernández-Avalos
- Clinical Pharmacology and Veterinary Anaesthesia, Department of Biological Science, FESC, Universidad Nacional Autónoma de México (UNAM)
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Butenas ALE, Rollins KS, Matney JE, Williams AC, Kleweno TE, Parr SK, Hammond ST, Ade CJ, Hageman KS, Musch TI, Copp SW. No effect of endoperoxide 4 or thromboxane A 2 receptor blockade on static mechanoreflex activation in rats with heart failure. Exp Physiol 2020; 105:1840-1854. [PMID: 32954541 DOI: 10.1113/ep088835] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2020] [Accepted: 09/18/2020] [Indexed: 12/30/2022]
Abstract
NEW FINDINGS What is the central question of this study? Do endoperoxide 4 and thromboxane A2 receptors, which are receptors for cyclooxygenase products of arachidonic metabolism, on thin fibre muscle afferents play a role in the chronic mechanoreflex sensitization present in rats with heart failure with reduced ejection fraction (HF-rEF)? What is the main finding and its importance? The data do not support a role for endoperoxide 4 receptors or thromboxane A2 receptors in the chronic mechanoreflex sensitization in HF-rEF rats. ABSTRACT We investigated the role of cyclooxygenase metabolite-associated endoperoxide 4 receptors (EP4-R) and thromboxane A2 receptors (TxA2 -R) on thin fibre muscle afferents in the chronic mechanoreflex sensitization in rats with myocardial infarction-induced heart failure with reduced ejection fraction (HF-rEF). We hypothesized that injection of either the EP4-R antagonist L-161,982 (1 µg) or the TxA2 -R antagonist daltroban (80 µg) into the arterial supply of the hindlimb would reduce the increase in blood pressure and renal sympathetic nerve activity (RSNA) evoked in response to 30 s of static hindlimb skeletal muscle stretch (a model of isolated mechanoreflex activation) in decerebrate, unanaesthetized HF-rEF rats but not sham-operated control rats (SHAM). Ejection fraction was significantly reduced in HF-rEF (45 ± 11%) compared to SHAM (83 ± 6%; P < 0.01) rats. In SHAM and HF-rEF rats, we found that the EP4-R antagonist had no effect on the peak increase in mean arterial pressure (peak ΔMAP SHAM n = 6, pre: 15 ± 7, post: 15 ± 9, P = 0.99; HF-rEF n = 9, pre: 30 ± 11, post: 32 ± 15 mmHg, P = 0.84) or peak increase in RSNA (peak ΔRSNA SHAM pre: 33 ± 14, post: 47 ± 31%, P = 0.94; HF-rEF, pre: 109 ± 47, post: 139 ± 150%, P = 0.76) response to stretch. Similarly, in SHAM and HF-rEF rats, we found that the TxA2 -R antagonist had no effect on the peak ΔMAP (SHAM n = 7, pre: 13 ± 7, post: 19 ± 14, P = 0.15; HF-rEF n = 14, pre: 24 ± 13, post: 21 ± 13 mmHg, P = 0.47) or peak ΔRSNA (SHAM pre: 52 ± 43, post: 57 ± 67%, P = 0.94; HF-rEF, pre: 108 ± 93, post: 88 ± 72%, P = 0.30) response to stretch. The data do not support a role for EP4-Rs or TxA2 -Rs in the chronic mechanoreflex sensitization in HF-rEF.
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Affiliation(s)
- Alec L E Butenas
- Department of Kinesiology, Kansas State University, Manhattan, KS, USA
| | - Korynne S Rollins
- Department of Kinesiology, Kansas State University, Manhattan, KS, USA
| | - Jacob E Matney
- Department of Kinesiology, Kansas State University, Manhattan, KS, USA
| | - Auni C Williams
- Department of Kinesiology, Kansas State University, Manhattan, KS, USA
| | - Talyn E Kleweno
- Department of Kinesiology, Kansas State University, Manhattan, KS, USA
| | - Shannon K Parr
- Department of Kinesiology, Kansas State University, Manhattan, KS, USA
| | - Stephen T Hammond
- Department of Kinesiology, Kansas State University, Manhattan, KS, USA
| | - Carl J Ade
- Department of Kinesiology, Kansas State University, Manhattan, KS, USA
| | - Karen S Hageman
- Department of Anatomy and Physiology, Kansas State University, Manhattan, KS, USA
| | - Timothy I Musch
- Department of Kinesiology, Kansas State University, Manhattan, KS, USA.,Department of Anatomy and Physiology, Kansas State University, Manhattan, KS, USA
| | - Steven W Copp
- Department of Kinesiology, Kansas State University, Manhattan, KS, USA
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Notarius CF, Millar PJ, Keir DA, Murai H, Haruki N, O'Donnell E, Marzolini S, Oh P, Floras JS. Training heart failure patients with reduced ejection fraction attenuates muscle sympathetic nerve activation during mild dynamic exercise. Am J Physiol Regul Integr Comp Physiol 2019; 317:R503-R512. [PMID: 31365304 DOI: 10.1152/ajpregu.00104.2019] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Muscle sympathetic nerve activity (MSNA) decreases during low-intensity dynamic one-leg exercise in healthy subjects but increases in patients with heart failure with reduced ejection fraction (HFrEF). We hypothesized that increased peak oxygen uptake (V̇o2peak) after aerobic training would be accompanied by less sympathoexcitation during both mild and moderate one-leg dynamic cycling, an attenuated muscle metaboreflex, and greater skin vasodilation. We studied 27 stable, treated HFrEF patients (6 women; mean age: 65 ± 2 SE yr; mean left ventricular ejection fraction: 30 ± 1%) and 18 healthy age-matched volunteers (6 women; mean age: 57 ± 2 yr). We assessed V̇o2peak (open-circuit spirometry) and the skin microcirculatory response to reactive hyperemia (laser flowmetry). Fibular MSNA (microneurography) was recorded before and during one-leg cycling (2 min unloaded and 2 min at 50% of V̇o2peak) and, to assess the muscle metaboreflex, during posthandgrip ischemia (PHGI). HFrEF patients were evaluated before and after 6 mo of exercise-based cardiac rehabilitation. Pretraining V̇o2peak and skin vasodilatation were lower (P < 0.001) and resting MSNA higher (P = 0.01) in HFrEF than control subjects. Training improved V̇o2peak (+3.0 ± 1.0 mL·kg-1·min-1; P < 0.001) and cutaneous vasodilation and diminished resting MSNA (-6.0 ± 2.0, P = 0.01) plus exercise MSNA during unloaded (-4.0 ± 2.5, P = 0.04) but not loaded cycling (-1.0 ± 4.0 bursts/min, P = 0.34) and MSNA during PHGI (P < 0.05). In HFrEF patients, exercise training lowers MSNA at rest, desensitizes the sympathoexcitatory metaboreflex, and diminishes MSNA elicited by mild but not moderate cycling. Training-induced downregulation of resting MSNA and attenuated reflex sympathetic excitation may improve exercise capacity and survival.
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Affiliation(s)
- Catherine F Notarius
- Division of Cardiology, University Health Network and Mount Sinai Hospital, University of Toronto, Toronto, Ontario, Canada
| | - Philip J Millar
- Division of Cardiology, University Health Network and Mount Sinai Hospital, University of Toronto, Toronto, Ontario, Canada.,Department of Human Health and Nutritional Sciences, University of Guelph, Ontario, Canada
| | - Daniel A Keir
- Division of Cardiology, University Health Network and Mount Sinai Hospital, University of Toronto, Toronto, Ontario, Canada
| | - Hisayoshi Murai
- Division of Cardiology, University Health Network and Mount Sinai Hospital, University of Toronto, Toronto, Ontario, Canada
| | - Nobuhiko Haruki
- Division of Cardiology, University Health Network and Mount Sinai Hospital, University of Toronto, Toronto, Ontario, Canada
| | - Emma O'Donnell
- Division of Cardiology, University Health Network and Mount Sinai Hospital, University of Toronto, Toronto, Ontario, Canada.,School of Sport, Exercise, and Health Sciences, Loughborough University, Loughborough, United Kingdom
| | - Susan Marzolini
- Cardiovascular Prevention and Rehabilitation Program, Toronto Rehabilitation Institute, University Health Network, Toronto, Ontario, Canada
| | - Paul Oh
- Cardiovascular Prevention and Rehabilitation Program, Toronto Rehabilitation Institute, University Health Network, Toronto, Ontario, Canada
| | - John S Floras
- Division of Cardiology, University Health Network and Mount Sinai Hospital, University of Toronto, Toronto, Ontario, Canada
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Hauton D, Ray CJ. Caffeine, gravity, and baroreceptor function: the integration of diet and cardiovascular control. ADVANCES IN PHYSIOLOGY EDUCATION 2018; 42:454-461. [PMID: 29972055 DOI: 10.1152/advan.00003.2017] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
We describe a simple, cost-effective experiment to demonstrate cardiovascular integration of heart rate and blood pressure to accommodate the environmental and dietary factors of gravity and caffeine. Specific learning objectives associated with this include understanding the effects of posture on blood pressure and heart rate, coupled with the role of caffeine in modifying this response. Inclusion of ECG measurements, coupled with heart rate variability analysis, added a demonstration of the contribution made by the autonomic nervous system under these conditions. We clearly demonstrate that the cardiac work, estimated as rate-pressure product, necessary to undertake the transition from supine to standing, is fixed for a given group of subjects. However, the individual contribution of heart rate and systolic pressure to the cardiac workload is subject to the external factors of gravity and caffeine. Such an activity also demonstrates additional benefits, including unstructured teaching opportunities to augment classroom learning associated with integrative physiology and also the discussion of ethical issues with regard to human experimentation.
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Affiliation(s)
- David Hauton
- Department of Physiology, Anatomy & Genetics, University of Oxford , Oxford , United Kingdom
- Chemistry Research Laboratory, Department of Chemistry, University of Oxford , Oxford , United Kingdom
| | - Clare J Ray
- Institute of Clinical Sciences, College of Medical and Dental Sciences, University of Birmingham , Birmingham , United Kingdom
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7
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Fontolliet T, Gianella P, Pichot V, Barthélémy JC, Gasche-Soccal P, Ferretti G, Lador F. Heart rate variability and baroreflex sensitivity in bilateral lung transplant recipients. Clin Physiol Funct Imaging 2018; 38:872-880. [PMID: 29316181 DOI: 10.1111/cpf.12499] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2017] [Accepted: 12/05/2017] [Indexed: 11/29/2022]
Abstract
The effects of lung afferents denervation on cardiovascular regulation can be assessed on bilateral lung transplantation patients. The high-frequency component of heart rate variability is known to be synchronous with breathing frequency. Then, if heart beat is neurally modulated by breathing frequency, we may expect disappearance of high frequency of heart rate variability in bilateral lung transplantation patients. On 11 patients and 11 matching healthy controls, we measured R-R interval (electrocardiography), blood pressure (Portapres® ) and breathing frequency (ultrasonic device) in supine rest, during 10-min free breathing, 10-min cadenced breathing (0·25 Hz) and 5-min handgrip. We analysed heart rate variability and spontaneous variability of arterial blood pressure, by power spectral analysis, and baroreflex sensitivity, by the sequence method. Concerning heart rate variability, with respect to controls, transplant recipients had lower total power and lower low- and high-frequency power. The low-frequency/high-frequency ratio was higher. Concerning systolic, diastolic and mean arterial pressure variability, transplant recipients had lower total power (only for cadenced breathing), low frequency and low-frequency/high-frequency ratio during free and cadenced breathing. Baroreflex sensitivity was decreased. Denervated lungs induced strong heart rate variability reduction. The higher low-frequency/high-frequency ratio suggested that the total power drop was mostly due to high frequency. These results support the hypothesis that neural modulation from lung afferents contributes to the high frequency of heart rate variability.
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Affiliation(s)
- Timothée Fontolliet
- Départements d'Anesthésiologie de Pharmacologie et des Soins Intensifs/des Neurosciences Fondamentales, Université de Genève, Geneva, Switzerland.,EA SNA-Epis 4607, Université Jean-Monnet, Saint-Étienne, France
| | - Pietro Gianella
- Service de Pneumologie, Département de Médecine Interne des Spécialités, Université de Genève, Geneva, Switzerland
| | - Vincent Pichot
- EA SNA-Epis 4607, Université Jean-Monnet, Saint-Étienne, France
| | | | - Paola Gasche-Soccal
- Service de Pneumologie, Département de Médecine Interne des Spécialités, Université de Genève, Geneva, Switzerland
| | - Guido Ferretti
- Départements d'Anesthésiologie de Pharmacologie et des Soins Intensifs/des Neurosciences Fondamentales, Université de Genève, Geneva, Switzerland.,Dipartimento di Medicina Molecolare e Traslazionale, Università di Brescia, Brescia, Italy
| | - Frédéric Lador
- Service de Pneumologie, Département de Médecine Interne des Spécialités, Université de Genève, Geneva, Switzerland
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Dresser GK, Urquhart BL, Proniuk J, Tieu A, Freeman DJ, Arnold JM, Bailey DG. Coffee inhibition of CYP3A4 in vitro was not translated to a grapefruit-like pharmacokinetic interaction clinically. Pharmacol Res Perspect 2017; 5. [PMID: 28971609 PMCID: PMC5625156 DOI: 10.1002/prp2.346] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2017] [Accepted: 07/24/2017] [Indexed: 11/10/2022] Open
Abstract
Grapefruit can augment oral medication bioavailability through irreversible (mechanism‐based) inhibition of intestinal CYP3A4. Supplementary data from our recent coffee–drug interaction clinical study showed some subjects had higher area under the plasma drug concentration ‐ time curve (AUC) and plasma peak drug concentration (Cmax) of the CYP3A4 probe felodipine compared to aqueous control. It was hypothesized that coffee might interact like grapefruit in responsive individuals. Beans from six geographical locations were consistently brewed into coffee that was separated chromatographically to a methanolic fraction for in vitro inhibition testing of CYP3A4 metabolism of felodipine at 1% coffee strength. The effect of simultaneous incubation and 10‐min preincubation with coffee fractions determined whether coffee had direct and mechanism‐based inhibitory activity. A subsequent five‐way randomized balanced controlled crossover clinical study evaluated the clinical pharmacokinetic interaction with single‐dose felodipine. Grapefruit juice, water, or three of the in vitro tested coffees were ingested at 300 mL alone 1 h before and then with felodipine. In vitro, all six coffees decreased felodipine metabolism for both simultaneous and preincubation exposure compared to corresponding control. Five coffees demonstrated mechanism‐based inhibition. Grapefruit increased felodipine AUC0–8 (25 vs. 13 ng.h/mL, P < 0.001) and Cmax (5.8 vs. 2.7 ng/mL, P < 0.001) and decreased dehydrofelodipine/felodipine AUC0–8 ratio (0.84 vs. 1.29, P < 0.001), while the three coffees caused no change in these parameters compared to water. Despite high in vitro potency of CYP3A4 inhibition, the coffees did not cause a clinical pharmacokinetic interaction possibly from insufficient amount of inhibitor(s) in coffee reaching intestinal CYP3A4 during the absorption phase of felodipine. The results of this study highlight the need for follow‐up clinical testing when in vitro results indicate the possibility of an interaction.
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Affiliation(s)
- George K Dresser
- Lawson Health Research Institute, London Health Sciences Centre, Western University, London, Ontario, Canada.,Department of Medicine, Schulich School of Medicine & Dentistry, Western University, London, Ontario, Canada
| | - Brad L Urquhart
- Department of Physiology & Pharmacology, Schulich School of Medicine & Dentistry, Western University, London, Ontario, Canada
| | - Julianne Proniuk
- Department of Physiology & Pharmacology, Schulich School of Medicine & Dentistry, Western University, London, Ontario, Canada
| | - Alvin Tieu
- Department of Physiology & Pharmacology, Schulich School of Medicine & Dentistry, Western University, London, Ontario, Canada
| | - David J Freeman
- Department of Medicine, Schulich School of Medicine & Dentistry, Western University, London, Ontario, Canada.,Department of Physiology & Pharmacology, Schulich School of Medicine & Dentistry, Western University, London, Ontario, Canada
| | - John Malcolm Arnold
- Department of Medicine, Schulich School of Medicine & Dentistry, Western University, London, Ontario, Canada
| | - David G Bailey
- Lawson Health Research Institute, London Health Sciences Centre, Western University, London, Ontario, Canada.,Department of Medicine, Schulich School of Medicine & Dentistry, Western University, London, Ontario, Canada
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Bailey DG, Dresser GK, Urquhart BL, Freeman DJ, Arnold JM. Coffee-Antihypertensive Drug Interaction: A Hemodynamic and Pharmacokinetic Study With Felodipine. Am J Hypertens 2016; 29:1386-1393. [PMID: 27481881 DOI: 10.1093/ajh/hpw081] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2016] [Accepted: 07/12/2016] [Indexed: 11/12/2022] Open
Abstract
OBJECTIVES A period of abstinence from coffee to permit caffeine elimination appears to enable increased blood pressure on subsequent exposure. We hypothesized that this would offset the antihypertensive effect of the dihydropyridine calcium channel blocker felodipine. METHODS A randomized, single-dose, crossover study assessed hemodynamic and pharmacokinetic effects following 2 days without coffee and caffeine-containing foods. Consistently brewed black coffee (2×300ml), felodipine maximum recommended dose (10mg), and coffee plus felodipine were tested in middle-aged normotensive subjects. RESULTS Pretreatment plasma caffeine concentrations were unquantifiable. After coffee, blood pressure changes (mm Hg) averaged over study hours 1-4 were increased for brachial systolic (7.6, P < 0.001) and diastolic (4.9, P < 0.001) and aortic systolic (7.4, P < 0.001), pulse (3.0, P < 0.05) and augmentation (1.4, P < 0.05) relative to baseline. After coffee plus felodipine, they were higher for brachial systolic (4.0, P < 0.05) and diastolic (3.9, P < 0.001) and aortic systolic (4.6, P < 0.05) compared to felodipine alone. The pressor effects of coffee and its modulation by felodipine were variable among individuals. Coffee containing caffeine (127mg) caused maximum pressor effect. Caffeine and felodipine pharmacokinetics were similar for coffee and felodipine given alone or in combination indicating an interaction having a pharmacodynamic basis. Plasma felodipine concentration-diastolic blood pressure reduction relationship shifted with coffee such that doubling the felodipine concentration would eliminate the pressor effect. However, this may increase the risk of adverse drug events particularly during the timeframe without coffee. CONCLUSION Intermittent coffee ingestion might complicate hypertension diagnosis and management for many individuals.
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Affiliation(s)
- David G Bailey
- Lawson Health Research Institute, London Health Sciences Centre, Western University, London, Ontario, Canada
- Department of Medicine, Schulich School of Medicine and Dentistry, Western University, London, Ontario, Canada
| | - George K Dresser
- Lawson Health Research Institute, London Health Sciences Centre, Western University, London, Ontario, Canada
- Department of Medicine, Schulich School of Medicine and Dentistry, Western University, London, Ontario, Canada
| | | | - David J Freeman
- Department of Medicine, Schulich School of Medicine and Dentistry, Western University, London, Ontario, Canada
- Department of Physiology and Pharmacology, Schulich School of Medicine and Dentistry, Western University, London, Ontario, Canada
| | - John Malcolm Arnold
- Department of Medicine, Schulich School of Medicine and Dentistry, Western University, London, Ontario, Canada
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10
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Senden PJ, Sabelis LWE, Zonderland ML, van de Kolk R, Meiss L, de Vries WR, Bol E, Mosterd WL. Determinants of maximal exercise performance in chronic heart failure. ACTA ACUST UNITED AC 2016; 11:41-7. [PMID: 15167205 DOI: 10.1097/01.hjr.0000116825.84388.eb] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
BACKGROUND Chronic heart failure (CHF) is characterized by symptoms like fatigue, dyspnoea and limited exercise performance. It has been postulated that maximal exercise performance (Wmax) is predominantly limited by skeletal muscle function and less by heart function. AIM To study the interrelation between most relevant muscle and anthropometrical variables and Wmax in CHF patients in order to develop a model that describes the impact of these variables for maximal exercise performance. DESIGN In 77 patients with CHF Wmax was assessed by incremental cycle ergometry until exhaustion (20 Watt/3 min). Peak torque (strength) and total work (endurance) for the quadriceps and hamstrings were assessed by isokinetic dynamometry. Isometric strength was measured by hand dynamometry. Relevant muscle areas were calculated by computerized tomography scan. RESULTS Significant correlations between Wmax and isokinetic muscle parameters (peak torque and total work) ranged from 0.41-0.65 (P<0.01). Other significant relationships (P<0.01) with Wmax were obtained for age (r=-0.22), gender (r=0.45), fat free mass (FFM) (r=0.51), quadriceps muscle area (r=0.73), hamstrings muscle area (r=0.50), upper leg muscle function (i.e., a combination of muscle strength and muscle endurance) (r=0.71) and isometric strength (r=0.63). Multiple regression analysis showed that upper leg muscle function and quadriceps muscle area could predict 57% of the variance in Wmax. CONCLUSION Muscle strength and muscle endurance, combined with quadriceps muscle area are the main predictors of maximal exercise performance in patients with CHF.
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Affiliation(s)
- Peter J Senden
- Department of Cardiology, University Medical Centre Utrecht, The Netherlands.
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11
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Caffeine intake inverts the effect of adenosine on myocardial perfusion during stress as measured by T1 mapping. Int J Cardiovasc Imaging 2016; 32:1545-53. [PMID: 27473274 PMCID: PMC5021723 DOI: 10.1007/s10554-016-0949-2] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/10/2016] [Accepted: 07/22/2016] [Indexed: 11/08/2022]
Abstract
Caffeine intake before adenosine stress myocardial perfusion imaging may cause false negative findings. We hypothesized that the antagonistic effect of caffeine can be measured by T1 relaxation times in rest and adenosine stress cardiac magnetic resonance imaging (CMR), as T1 mapping techniques are sensitive to changes in myocardial blood volume. We prospectively analyzed 105 consecutive patients with adenosine stress perfusion CMR on a 1.5-T MRI system. Rest and stress T1 mapping was performed using Modified Look-Locker Inversion recovery. T1 reactivity was defined as difference in T1rest and T1stress (∆T1). Fifteen patients drank coffee within 4 h of CMR (<4H caffeine group), and 10 patients had coffee the day before (>8H caffeine group). Comparison was made to patients without self-reported coffee intake: 50 with normal CMR (control group), 18 with myocardial ischemia, and 12 with myocardial infarction. The national review board approved the study; all patients gave written informed consent. The <4H caffeine group showed inverted ∆T1 of −7.8 % (T1rest 975 ± 42 ms, T1stress 898 ± 51 ms, p < 0.0005). The >8H caffeine group showed reduced T1 reactivity (1.8 %; T1rest 979 ms, T1stress 997 ms) compared to the controls (4.3 %; T1rest 977 ± 40 ms, T1stress 1018 ± 40 ms), p < 0.0005. Ischemic and infarcted myocardium showed minimal T1 reactivity (0.2 and 0.3 %, respectively). Caffeine intake inverts the adenosine effect during stress perfusion CMR as measured by T1 mapping. T1 reactivity can assess the adequacy of adenosine-induced stress in perfusion CMR.
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12
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Floras JS, Ponikowski P. The sympathetic/parasympathetic imbalance in heart failure with reduced ejection fraction. Eur Heart J 2015; 36:1974-82b. [PMID: 25975657 DOI: 10.1093/eurheartj/ehv087] [Citation(s) in RCA: 168] [Impact Index Per Article: 18.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/29/2015] [Accepted: 03/06/2015] [Indexed: 12/20/2022] Open
Abstract
Cardiovascular autonomic imbalance, a cardinal phenotype of human heart failure, has adverse implications for symptoms during wakefulness and sleep; for cardiac, renal, and immune function; for exercise capacity; and for lifespan and mode of death. The objectives of this Clinical Review are to summarize current knowledge concerning mechanisms for disturbed parasympathetic and sympathetic circulatory control in heart failure with reduced ejection fraction and its clinical and prognostic implications; to demonstrate the patient-specific nature of abnormalities underlying this common phenotype; and to illustrate how such variation provides opportunities to improve or restore normal sympathetic/parasympathetic balance through personalized drug or device therapy.
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Affiliation(s)
- John S Floras
- University Health Network and Mount Sinai Hospital Division of Cardiology, University of Toronto, Suite 1614, 600 University Avenue, Toronto, Ontario, Canada M5G 1X5
| | - Piotr Ponikowski
- Department for Heart Disease, Medical University, Clinical Military Hospital, Wroclaw, Poland
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13
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Jammes Y, Joulia F, Steinberg JG, Ravailhe S, Delpierre S, Condo J, Guieu R, Delliaux S. Endogenous adenosine release is involved in the control of heart rate in rats. Can J Physiol Pharmacol 2015. [PMID: 26222197 DOI: 10.1139/cjpp-2015-0042] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Intravenous (i.v.) injections of adenosine exert marked effects on heart rate (HR) and arterial blood pressure (BP), but the role of an endogenous adenosine release by vagal stimulation has not been evaluated. In anaesthetized rats, we examined HR and BP changes induced by 1 min electrical vagal stimulation in the control condition, and then after i.v. injections of (i) atropine, (ii) propranolol, (iii) caffeine, (iv) 8 cyclopentyl-1,3-dipropylxanthine (DPCPX), or (v) dipyridamole to increase the plasma concentration of adenosine (APC). APC was measured by chromatography in the arterial blood before and at the end of vagal stimulation. The decrease in HR in the controls during vagal stimulation was markedly attenuated, but persisted after i.v. injections of atropine and propranolol. When first administered, DPCPX modestly but significantly reduced the HR response to vagal stimulation, but this disappeared after i.v. caffeine administration. Both the HR and BP responses were significantly accentuated after i.v. injection of dipyridamole. Vagal stimulation induced a significant increase in APC, proportional to the magnitude of HR decrease. Our data suggest that the inhibitory effects of electrical vagal stimulations on HR and BP were partly mediated through the activation of A1 and A2 receptors by an endogenous adenosine release. Our experimental data could help to understand the effects of ischemic preconditioning, which are partially mediated by adenosine.
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Affiliation(s)
- Yves Jammes
- Aix-Marseille University, UMR MD2, 13015 Marseille, France.,Aix-Marseille University, UMR MD2, 13015 Marseille, France
| | - Fabrice Joulia
- Aix-Marseille University, UMR MD2, 13015 Marseille, France.,Aix-Marseille University, UMR MD2, 13015 Marseille, France
| | - Jean Guillaume Steinberg
- Aix-Marseille University, UMR MD2, 13015 Marseille, France.,Aix-Marseille University, UMR MD2, 13015 Marseille, France
| | - Sylvie Ravailhe
- Aix-Marseille University, UMR MD2, 13015 Marseille, France.,Aix-Marseille University, UMR MD2, 13015 Marseille, France
| | - Stéphane Delpierre
- Aix-Marseille University, UMR MD2, 13015 Marseille, France.,Aix-Marseille University, UMR MD2, 13015 Marseille, France
| | - Jocelyne Condo
- Aix-Marseille University, UMR MD2, 13015 Marseille, France.,Aix-Marseille University, UMR MD2, 13015 Marseille, France
| | - Regis Guieu
- Aix-Marseille University, UMR MD2, 13015 Marseille, France.,Aix-Marseille University, UMR MD2, 13015 Marseille, France
| | - Stéphane Delliaux
- Aix-Marseille University, UMR MD2, 13015 Marseille, France.,Aix-Marseille University, UMR MD2, 13015 Marseille, France
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14
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Notarius CF, Millar PJ, Murai H, Morris BL, Marzolini S, Oh P, Floras JS. Divergent muscle sympathetic responses to dynamic leg exercise in heart failure and age-matched healthy subjects. J Physiol 2014; 593:715-22. [PMID: 25398528 DOI: 10.1113/jphysiol.2014.281873] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2014] [Accepted: 11/03/2014] [Indexed: 01/12/2023] Open
Abstract
KEY POINTS People with diminished ventricular contraction who develop heart failure have higher sympathetic nerve firing rates at rest compared with healthy individuals of a similar age and this is associated with less exercise capacity. During handgrip exercise, sympathetic nerve activity to muscle is higher in patients with heart failure but the response to leg exercise is unknown because its recording requires stillness. We measured sympathetic activity from one leg while the other leg cycled at a moderate level and observed a decrease in nerve firing rate in healthy subjects but an increase in subjects with heart failure. Because these nerves release noradrenaline, which can restrict muscle blood flow, this observation helps explain the limited exercise capacity of patients with heart failure. Lower nerve traffic during exercise was associated with greater peak oxygen uptake, suggesting that if exercise training attenuated sympathetic outflow functional capacity in heart failure would improve. ABSTRACT The reflex fibular muscle sympathetic nerve (MSNA) response to dynamic handgrip exercise is elicited at a lower threshold in heart failure with reduced ejection fraction (HFrEF). The present aim was to test the hypothesis that the contralateral MSNA response to mild to moderate dynamic one-legged exercise is augmented in HFrEF relative to age- and sex-matched controls. Heart rate (HR), blood pressure and MSNA were recorded in 16 patients with HFrEF (left ventricular ejection fraction = 31 ± 2%; age 62 ± 3 years, mean ± SE) and 13 healthy control subjects (56 ± 2 years) before and during 2 min of upright one-legged unloaded cycling followed by 2 min at 50% of peak oxygen uptake (V̇O2,peak). Resting HR and blood pressure were similar between groups whereas MSNA burst frequency was higher (50.0 ± 2.0 vs. 42.3 ± 2.7 bursts min(-1), P = 0.03) and V̇O2,peak lower (18.0 ± 2.0 vs. 32.6 ± 2.8 ml kg(-1) min(-1), P < 0.001) in HFrEF. Exercise increased HR (P < 0.001) with no group difference (P = 0.1). MSNA burst frequency decreased during mild to moderate dynamic exercise in the healthy controls but increased in HFrEF (-5.5 ± 2.0 vs. 6.9 ± 1.8 bursts min(-1), P < 0.001). Exercise capacity correlated inversely with MSNA burst frequency at 50% V̇O2,peak (n = 29; r = -0.64; P < 0.001). At the same relative workload, one-legged dynamic exercise elicited a fall in MSNA burst frequency in healthy subjects but sympathoexcitation in HFrEF, a divergence probably reflecting between-group differences in reflexes engaged by cycling. This finding, coupled with an inverse relationship between MSNA burst frequency during loaded cycling and subjects' V̇O2,peak, is consistent with a neurogenic determinant of exercise capacity in HFrEF.
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Affiliation(s)
- Catherine F Notarius
- University Health Network and Mount Sinai Hospital Division of Cardiology, University of Toronto, Toronto, Ontario, Canada
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15
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Abstract
Heart failure (HF) is a syndrome characterized by upregulation of the sympathetic nervous system and abnormal responsiveness of the parasympathetic nervous system. Studies in the 1980s and 1990s demonstrated that inhibition of the renin-angiotensin-aldosterone system with angiotensin-converting enzyme inhibitors improved symptoms and mortality in HF resulting from systolic dysfunction, thus providing a framework to consider the use of β-blockers for HF therapy, contrary to the prevailing wisdom of the time. Against this backdrop, this article reviews the contemporary understanding of the sympathetic nervous system and the failing heart.
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Affiliation(s)
- David Y Zhang
- Section of Cardiology, Department of Medicine, University of Chicago, 5841 S. Maryland Ave, Chicago, IL 60637, USA
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16
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Wijeysundera HC, Parmar G, Rongen GA, Floras JS. Reflex systemic sympatho-neural response to brachial adenosine infusion in treated heart failure. Eur J Heart Fail 2014; 13:475-81. [DOI: 10.1093/eurjhf/hfr005] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Affiliation(s)
- Harindra C. Wijeysundera
- Mount Sinai Hospital and University Health Network Division of Cardiology, Faculty of Medicine; University of Toronto; Toronto ON Canada
- Sunnybrook Health Sciences Centre Division of Cardiology, Faculty of Medicine; University of Toronto; Suite A209D, 2075 Bayview Avenue Toronto ON Canada M4N 3M5
| | - Gurpreet Parmar
- Mount Sinai Hospital and University Health Network Division of Cardiology, Faculty of Medicine; University of Toronto; Toronto ON Canada
| | - Gerard A. Rongen
- Department of Pharmacology-Toxicology and General Internal Medicine; Nijmegen Netherlands
| | - John S. Floras
- Mount Sinai Hospital and University Health Network Division of Cardiology, Faculty of Medicine; University of Toronto; Toronto ON Canada
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17
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Notarius CF, Floras JS. Caffeine Enhances Heart Rate Variability in Middle-Aged Healthy, But Not Heart Failure Subjects. JOURNAL OF CAFFEINE RESEARCH 2012; 2:77-82. [PMID: 24761268 DOI: 10.1089/jcr.2012.0010] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
BACKGROUND In chronic heart failure (CHF) due to left ventricular dysfunction, diminished heart rate variability (HRV) is an independent predictor of poor prognosis. Caffeine has been shown to increase HRV in young healthy subjects. Such an increase may be of potential benefit to patients with CHF. OBJECTIVE We hypothesized that intravenous infusion of caffeine would increase HRV in CHF, and in age-matched healthy control subjects. METHODS On two separate days, 11 patients (1F) with CHF (age=51.3±4.6 years; left ventricular ejection fraction=18.6±2.7%; mean±standard error) and 10 healthy control subjects (age=48.0±4.0) according to a double-blind randomization design, received either saline or caffeine (4 mg/kg) infusion. We assessed HRV over 7 minutes of supine rest (fast Fourier Transform analysis) to determine total spectral power as well as its high-frequency (HF) (0.15-0.50 Hz) and low-frequency (LF) (0.05-0.15 Hz) components, and recorded muscle sympathetic nerve activity (MSNA) directly from the peroneal nerve (microneurography). RESULTS In healthy control subjects, compared with saline, caffeine reduced both heart rate and sympathetic nerve traffic (p≤0.003) and increased the ratio of HF/total power (p≤0.05). Baseline LF power and the ratio LF/HF were significantly lower in CHF compared with controls (p=0.02), but caffeine had no effect on any element of HRV. CONCLUSIONS Caffeine increases cardiac vagal heart rate modulation and reduces MSNA in middle-aged healthy subjects, but not in those with CHF.
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Affiliation(s)
- Catherine F Notarius
- Division of Cardiology, University Health Network and Mount Sinai Hospital, University of Toronto , Toronto, ON, Canada
| | - John S Floras
- Division of Cardiology, University Health Network and Mount Sinai Hospital, University of Toronto , Toronto, ON, Canada
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18
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Riksen NP, Rongen GA. Targeting adenosine receptors in the development of cardiovascular therapeutics. Expert Rev Clin Pharmacol 2012; 5:199-218. [PMID: 22390562 DOI: 10.1586/ecp.12.8] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Adenosine receptor stimulation has negative inotropic and dromotropic actions, reduces cardiac ischemia-reperfusion injury and remodeling, and prevents cardiac arrhythmias. In the vasculature, adenosine modulates vascular tone, reduces infiltration of inflammatory cells and generation of foam cells, and may prevent the development of atherosclerosis as a result. Modulation of insulin sensitivity may further add to the anti-atherosclerotic properties of adenosine signaling. In the kidney, adenosine plays an important role in tubuloglomerular feedback and modulates tubular sodium reabsorption. The challenge is to take advantage of the beneficial actions of adenosine signaling while preventing its potential adverse effects, such as salt retention and sympathoexcitation. Drugs that interfere with adenosine formation and elimination or drugs that allosterically enhance specific adenosine receptors seem to be most promising to meet this challenge.
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Affiliation(s)
- Niels P Riksen
- Department of Pharmacology-Toxicology 149 and Internal Medicine 463, Radboud University Nijmegen Medical Centre, PO Box 9101, 6500 HB Nijmegen, The Netherlands
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19
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Fordy GR, Marshall JM. Breathing 40% O2can attenuate postcontraction hyperaemia or muscle fatigue caused by static forearm contraction, depending on timing. Exp Physiol 2012; 97:362-74. [DOI: 10.1113/expphysiol.2011.060632] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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20
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McGowan CL, Notarius CF, McReynolds A, Morris BL, Kimmerly DS, Picton PE, Floras JS. Effect of angiotensin AT1 receptor blockade on sympathetic responses to handgrip in healthy men. Am J Hypertens 2011; 24:537-43. [PMID: 21331055 DOI: 10.1038/ajh.2011.14] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
BACKGROUND To determine whether angiotensin II (ANG II) contributes to the reflex skeletal muscle sympathoexcitation elicited by isometric and isotonic exercise, we tested the hypothesis that angiotensin AT(1) receptor blockade (ARB) would attenuate reflex sympathoneural responses to handgrip (HG) and to post-handgrip ischemia (PHGI). METHODS Seventeen healthy men were studied before and 1 week after random double-blind crossover allocation to oral losartan (100 mg daily) and placebo. Heart rate (HR), blood pressure (BP), and muscle sympathetic nerve activity (MSNA) were recorded at rest, and during 2 min bouts of isotonic HG at 50% maximum voluntary contraction (MVC) and isometric HG at 30% MVC, performed randomly, each followed by 2 min of PHGI. RESULTS At rest, losartan doubled plasma renin (P = 0.01) and ANG II (P = 0.03) concentrations, and lowered BP (P < 0.01) yet had no effect on MSNA burst frequency or incidence. HR trended higher (P = 0.060). Losartan's hypotensive effect persisted throughout each exercise bout (P < 0.045). MSNA and HR responses to isotonic exercise and postexercise ischemia were not affected by losartan. Isometric exercise and postexercise ischemia increased MSNA on both sessions (all P < 0.01). Losartan augmented the HR response (P ≤ 0.03), and after losartan MSNA burst frequency (P < 0.01) and incidence (P < 0.04) were significantly higher at all time points, but the magnitude of the MSNA response to isometric exercise and postexercise ischemia was unchanged. CONCLUSION In healthy men, short-term ARB does not attenuate reflex sympathoneural responses to HG or PHGI.
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Abstract
In the concentration range that is normally achieved in humans, e.g., after the drinking of coffee or in patients treated with theophylline, the cardiovascular effects of methylxanthines are primarily due to antagonism of adenosine A(1) and A(2) receptors. Inhibition of phosphodiesterases or mobilization of intracellular calcium requires much higher concentrations. In conscious humans, acute exposure to caffeine results in an increase in blood pressure by an increased total peripheral resistance, and a slight decrease in heart rate. This overall hemodynamic response is composed of direct effects of caffeine on vascular tone, on myocardial contractility and conduction, and on the sympathetic nervous system. Caffeine is the most widely consumed methylxanthine, mainly derived from coffee intake. Regular coffee consumption can affect various traditional cardiovascular risk factors, including a slight increase in blood pressure, an increase in plasma cholesterol and homocysteine levels, and a reduced incidence of type 2 diabetes mellitus. Although most prospective studies have not reported an association between coffee consumption and coronary heart disease, these findings do not exclude that the acute hemodynamic and neurohumoral effects of coffee consumption could have an adverse effect in selected patient groups who are more vulnerable for these effects, based on their genetic profile or medication use.
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Affiliation(s)
- Niels P Riksen
- Department of Pharmacology, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands.
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22
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Cazé RF, Franco GAM, Porpino SKP, Souza AAD, Padilhas OP, Silva AS. Influência da cafeína na resposta pressórica ao exercício aeróbio em sujeitos hipertensos. REV BRAS MED ESPORTE 2010. [DOI: 10.1590/s1517-86922010000500001] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
A redução da pressão arterial (PA) promovida pelo exercício físico é evidente segundo a literatura atual. Mecanismos neuro-humorais explicam essa resposta hipotensora, em que a diminuição da atividade simpática apresenta-se como um dos principais mecanismos. Porém, a ingestão de alimentos ricos em cafeína (CA) pode suprimir esta atenuação simpática. O objetivo desse estudo foi elucidar o impacto da ingestão de CA na resposta pressórica ao exercício em pessoas hipertensas. Sete hipertensos (52,3 ± 3,3 anos), sendo cinco mulheres, realizaram duas sessões de caminhada com 40 minutos de duração, em dois dias de treinamento, tendo previamente ingerido CA (4mg/kg de peso corporal) ou placebo (PL). A PA e a frequência cardíaca foram verificadas anteriormente a ingestão, após 15, 30, 45, 60 minutos da ingestão em estado de repouso e com 10, 20 e 30 minutos após o exercício. Os dados foram tratados por meio de estatística descritiva, e pelo teste não paramétrico de Wilcoxon (p < 0,05). A média da PA aumentou de 124,9/80,9mmHg antes da ingestão de CA para 129,4/84,3mmHg 60 minutos após, ainda no repouso (p < 0,05). Trinta minutos após o exercício observou-se resposta hipotensora no procedimento PL (queda da PA de 122,6/79,4mmHg para 115,7/78,6mmHg), enquanto que no procedimento com CA, a PA mostrou-se significativamente mais alta em relação aos valores de repouso (aumento de 124,9/80,9mmHg para 136,9/90,9mmHg, p < 0,05). Conclui-se que a ingestão de CA não só suprime a resposta hipotensora do exercício, como provoca uma hipertensão pós-exercício.
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Raupach T, Bahr F, Herrmann P, Lüthje L, Hasenfuss G, Andreas S. Inspiratory resistive loading does not increase sympathetic tone in COPD. Respir Med 2010; 104:107-13. [DOI: 10.1016/j.rmed.2009.06.011] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/30/2009] [Revised: 06/11/2009] [Accepted: 06/15/2009] [Indexed: 10/20/2022]
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Dickie A, Tabasam G, Tashani O, Marchant P, Johnson MI. A preliminary investigation into the effect of coffee on hypolagesia associated with transcutaneous electrical nerve stimulation. Clin Physiol Funct Imaging 2009; 29:293-9. [DOI: 10.1111/j.1475-097x.2009.00869.x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Montes FR, Cabrera M, Delgadillo A, Salgar C, Echeverri D. The role of potassium channels in the vasodilatory effect of caffeine in human internal mammary arteries. Vascul Pharmacol 2009; 50:132-6. [DOI: 10.1016/j.vph.2008.11.002] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2008] [Revised: 11/11/2008] [Accepted: 11/14/2008] [Indexed: 11/27/2022]
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Riksen NP, Rongen GA, Smits P. Acute and long-term cardiovascular effects of coffee: Implications for coronary heart disease. Pharmacol Ther 2009; 121:185-91. [DOI: 10.1016/j.pharmthera.2008.10.006] [Citation(s) in RCA: 80] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2008] [Accepted: 10/21/2008] [Indexed: 10/21/2022]
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27
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Yang JN, Björklund O, Lindström-Törnqvist K, Lindgren E, Eriksson TM, Kahlström J, Chen JF, Schwarzschild MA, Tobler I, Fredholm BB. Mice heterozygous for both A1 and A(2A) adenosine receptor genes show similarities to mice given long-term caffeine. J Appl Physiol (1985) 2008; 106:631-9. [PMID: 19036889 DOI: 10.1152/japplphysiol.90971.2008] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Caffeine is believed to exert its stimulant effects by blocking A(2A) and A(1) adenosine receptors (A(2A)R and A(1)R). Although a genetic knockout of A(2A)R eliminates effects of caffeine, the phenotype of the knockout animal does not resemble that of caffeine treatment. In this study we explored the possibility that a mere reduction of the number of A(1)Rs and A(2A)Rs, achieved by deleting one of the two copies of the A(1)R and A(2A)R genes, would mimic some aspects of long-term caffeine ingestion. The A(1)R and A(2A)R double heterozygous (A(1)R-A(2A)R dHz) mice indeed had approximately one-half the number of A(1)R and A(2A)R, and there were little compensatory changes in A(2B) or A(3) adenosine receptor (A(2B)R or A(3)R) expression. The ability of a stable adenosine analog to activate receptors was shifted to the right by caffeine and in A(1)R-A(2A)R dHz tissue. Caffeine (0.3 g/l in drinking water for 7-10 days) and A(1)R-A(2A)R dHz genotype increased locomotor activity (LA) and decreased heart rate without significantly influencing body temperature. The acute stimulatory effect of a single injection of caffeine was reduced in A(1)R-A(2A)R dHz mice and in mice treated long term with oral caffeine. Thus at least some aspects of long-term caffeine use can be mimicked by genetic manipulation of the A(1)R and A(2A)R.
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Affiliation(s)
- Jiang-Ning Yang
- Department of Physiology and Pharmacology, Karolinska Institutet, Stockholm, Sweden.
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Middlekauff HR, Chiu J, Hamilton MA, Fonarow GC, Maclellan WR, Hage A, Moriguchi J, Patel J. Cyclooxygenase products sensitize muscle mechanoreceptors in humans with heart failure. Am J Physiol Heart Circ Physiol 2008; 294:H1956-62. [PMID: 18296564 DOI: 10.1152/ajpheart.01304.2007] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Prior work in animals and humans suggests that muscle mechanoreceptor control of sympathetic activation [muscle sympathetic nerve activity (MSNA)] during exercise in heart failure (HF) patients is heightened compared with that of healthy humans and that muscle mechanoreceptors are sensitized by metabolic by-products. We sought to determine whether cyclooxygenase products and/or endogenous adenosine, two metabolites of ischemic exercise, sensitize muscle mechanoreceptors during rhythmic handgrip (RHG) exercise in HF patients. Indomethacin, which inhibits the production of prostaglandins, and saline control were infused in 12 HF patients. In a different protocol, aminophylline, which inhibits adenosine receptors, and saline control were infused in 12 different HF patients. MSNA was recorded (microneurography). During exercise following saline, MSNA increased in the first minute of exercise, consistent with baseline heightened mechanoreceptor sensitivity. MSNA continued to increase during 3 min of RHG, indicative that muscle mechanoreceptors are sensitized by ischemia metabolites. Indomethacin, but not aminophylline, markedly attenuated the increase in MSNA during the entire 3 min of low-level rhythmic exercise, consistent with the sensitization of muscle mechanoreceptors by cyclooxygenase products. Interestingly, even the early increase in MSNA was abolished by indomethacin infusion, indicative of the very early generation of cyclooxygenase products after the onset of exercise in HF patients. In conclusion, muscle mechanoreceptors mediate the increase in MSNA during low-level RHG exercise in HF. Cyclooxygenase products, but not endogenous adenosine, play a central role in muscle mechanoreceptor sensitization. Finally, muscle mechanoreceptors in patients with HF have heightened basal sensitivity to mechanical stimuli, which also appears to be mediated by the early generation of cyclooxygenase products, resulting in exaggerated early increases in MSNA.
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Affiliation(s)
- Holly R Middlekauff
- Dept. of Medicine, David Geffen School of Medicine, University of California, Los Angeles, CA 90095, USA.
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Notarius CF, Floras JS. Point:counterpoint: Increased mechanoreceptor/metaboreceptor stimulation explains the exaggerated exercise pressor reflex seen in heart failure. J Appl Physiol (1985) 2007; 102:824. [PMID: 17284659 DOI: 10.1152/japplphysiol.01330.2006] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
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Notarius CF, Morris B, Floras JS. Caffeine Prolongs Exercise Duration in Heart Failure. J Card Fail 2006; 12:220-6. [PMID: 16624688 DOI: 10.1016/j.cardfail.2005.12.005] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2005] [Revised: 12/12/2005] [Accepted: 12/22/2005] [Indexed: 11/19/2022]
Abstract
BACKGROUND Caffeine increases submaximal exercise performance in healthy young subjects; its effects on exercise tolerance in heart failure (HF) have not been characterized. METHODS AND RESULTS To determine whether caffeine increases exercise tolerance in HF, caffeine (4 mg/kg intravenously, equivalent to 2 cups of coffee) or vehicle were infused into 10 treated HF patients (left ventricular ejection fraction 25 +/- 2 %), and 10 age-matched normal subjects (N) on 2 separate days in a double-blind, randomized, crossover design. We measured heart rate, blood pressure, and ventilation at rest and during graded cycling (15 W/minute) to peak effort. Peak oxygen consumption was unaffected in either group. Mean exercise time was unchanged in N (1,013 +/- 87 versus 988 +/- 107 seconds; P = .86) but was significantly increased by caffeine in HF (from 511 +/- 28 to 560 +/- 37 seconds; P = .004) despite an increase in peak minute ventilation (P < .05). Resting and peak blood pressures were higher after caffeine (P < .05) in HF, not N. CONCLUSION Caffeine allows HF patients to exercise longer at peak effort.
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Affiliation(s)
- Catherine F Notarius
- Division of Cardiology and Faculty of Medicine, University Health Network and Mount Sinai Hospital, University of Toronto, Toronto, Ontario, Canada
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Riksen NP, van Ginneken EEM, van den Broek PHH, Smits P, Rongen GA. In vivo evidence against a role for adenosine in the exercise pressor reflex in humans. J Appl Physiol (1985) 2005; 99:522-7. [PMID: 15817726 DOI: 10.1152/japplphysiol.00108.2005] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The pressor response to exercise is of great importance in both physiology and pathophysiology. Whether endogenous adenosine is a trigger for this reflex remains controversial. Muscle interstitial adenosine concentration can be determined by microdialysis. However, there are indications that local muscle cell damage by the microdialysis probe confounds these measurements in exercising muscle. Therefore, we used the nucleoside uptake inhibitor dipyridamole as pharmacological tool to bypass this confounding. We used microdialysis probes to measure endogenous adenosine in forearm skeletal muscle of healthy volunteers during two cycles of 15 min of intermittent isometric handgripping. During the second contraction, dipyridamole (12 microg.min(-1).dl forearm(-1)) was administered into the brachial artery. Dipyridamole potentiated the exercise-induced increase in dialysate adenosine from 0.30 +/- 0.08 to 0.48 +/- 0.10 micromol/l (n = 9, P < 0.05), but it did not potentiate the exercise-induced increase in blood pressure. A time-control study without dipyridamole revealed no difference in exercise-induced increase in adenosine between both contractions (n = 8). To exclude the possibility that the dipyridamole-induced increase in dialysate adenosine originates from extravasation of increased circulating adenosine, we simultaneously measured adenosine with microdialysis probes in forearm muscle and antecubital vein. In a separate group of nine volunteers, simultaneous intrabrachial infusion of 100 microg.min(-1).dl(-1) dipyridamole and 5 microg.min(-1).dl(-1) adenosine increased dialysate adenosine from the intravenous but not the interstitial probe, indicating preserved endothelial barrier function for adenosine. We conclude that dipyridamole significantly inhibits uptake of interstitial adenosine without affecting the pressor response to exercise, suggesting that interstitial adenosine is not involved in the pressor response to rhythmic isometric exercise.
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Affiliation(s)
- Niels P Riksen
- Dept. of Pharmacology-Toxicology 233, Radboud University Nijmegen Medical Centre, P.O. Box 9101, 6500 HB Nijmegen, The Netherlands.
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Middlekauff HR, Chiu J, Hamilton MA, Fonarow GC, Maclellan WR, Hage A, Moriguchi J, Patel J. Muscle mechanoreceptor sensitivity in heart failure. Am J Physiol Heart Circ Physiol 2004; 287:H1937-43. [PMID: 15475527 DOI: 10.1152/ajpheart.00330.2004] [Citation(s) in RCA: 86] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Prior work in animals suggests that muscle mechanoreceptor control of sympathetic activation (MSNA) during exercise in heart failure (HF) is heightened and that muscle mechanoreceptors are sensitized by metabolic by-products. We sought to determine whether 1) muscle mechanoreceptor control of MSNA is enhanced in HF patients and 2) lactic acid sensitizes muscle mechanoreceptors during rhythmic handgrip (RHG) exercise in healthy humans and patients with HF. Dichloroacetate (DCA), which reduces the production of lactic acid, or saline control was infused in 12 patients with HF and 13 controls during RHG. MSNA was recorded (microneurography). After saline was administered and during exercise thereafter, MSNA increased earlier in HF compared with controls, consistent with baseline-heightened mechanoreceptor sensitivity. In both HF and controls, MSNA increased during the 3-min exercise protocol, consistent with further sensitization of muscle mechanoreceptors by metabolic by-product(s). During posthandgrip circulatory arrest, MSNA returned rapidly to baseline levels, excluding the muscle metaboreceptors as mediators of the sympathetic excitation during RHG. To isolate muscle mechanoreceptors from central command, we utilized passive exercise in 8 HF and 11 controls, and MSNA was recorded. MSNA increased significantly during passive exercise in HF but not in controls. In conclusion, muscle mechanoreceptors mediate the increase in MSNA during low-level RHG exercise in healthy humans, and this muscle mechanoreceptor control is augmented further in HF. Neither lactate generation nor the fall in pH during RHG plays a central role in muscle mechanoreceptor sensitization. Finally, muscle mechanoreceptors in patients with HF have heightened basal sensitivity to mechanical stimuli resulting in exaggerated early increases in MSNA.
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Affiliation(s)
- Holly R Middlekauff
- Div. of Cardiology, 47-123 CHS, UCLA Dept. of Medicine, 10833 Le Conte Ave., Los Angeles, CA 90095, USA.
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Andreas S, Reiter H, Lüthje L, Delekat A, Grunewald RW, Hasenfuss G, Somers VK. Differential effects of theophylline on sympathetic excitation, hemodynamics, and breathing in congestive heart failure. Circulation 2004; 110:2157-62. [PMID: 15466632 DOI: 10.1161/01.cir.0000144356.39262.16] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
BACKGROUND Patients with heart failure have high levels of central sympathetic outflow and also have a high prevalence of sleep-related breathing disorders, predominantly central sleep apnea. The options for treating central sleep apnea in heart failure are limited and include theophylline. Whether theophylline alters sympathetic activity in heart failure patients is not known. METHODS AND RESULTS Using a single-blinded, randomized, placebo-controlled study design, we investigated the sympathetic, hemodynamic, neurohumoral, and ventilatory effects of theophylline in patients with congestive heart failure compared with healthy control subjects closely matched for age, sex, and body mass index. Theophylline increased muscle sympathetic nerve activity and lowered transcutaneous CO2 in the control subjects but only lowered transcutaneous CO2 in the heart failure patients. Theophylline nearly doubled plasma renin concentration in both the healthy subjects (P<0.01) and the heart failure patients (P<0.02). CONCLUSIONS Our study shows that in heart failure patients, there are differential effects of theophylline: in contrast to healthy subjects, theophylline does not increase sympathetic activity in heart failure, whereas increases in plasma renin and ventilation are still evident. These novel findings may have important implications for understanding the potential harmful and beneficial effects of theophylline and related substances in heart failure patients.
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Affiliation(s)
- Stefan Andreas
- Department of Cardiology and Pneumology, Georg-August-Universität, Göttingen, Germany.
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O'Connor PJ, Motl RW, Broglio SP, Ely MR. Dose-dependent effect of caffeine on reducing leg muscle pain during cycling exercise is unrelated to systolic blood pressure. Pain 2004; 109:291-298. [PMID: 15157690 DOI: 10.1016/j.pain.2004.01.017] [Citation(s) in RCA: 70] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2003] [Revised: 12/17/2003] [Accepted: 01/16/2004] [Indexed: 11/28/2022]
Abstract
This double-blind, within-subjects experiment examined the effects of ingesting two doses of caffeine on perceptions of leg muscle pain and blood pressure during moderate intensity cycling exercise. Low caffeine consuming college-aged males (N=12) ingested one of two doses of caffeine (5 or 10 mg.kg(-1) body weight) or placebo and 1 h later completed 30 min of moderate intensity cycling exercise (60% VO2peak). The order of drug administration was counter-balanced. Resting blood pressure and heart rate were recorded immediately before and 1 h after drug administration. Perceptions of leg muscle pain as well as work rate, blood pressure, heart rate, and oxygen uptake (VO2) were recorded during exercise. Caffeine increased resting systolic pressure in a dose-dependent fashion but these blood pressure effects were not maintained during exercise. Caffeine had a significant linear effect on leg muscle pain ratings [F(2,22)=14.06; P < 0.0001; eta2=0.56 ]. The mean (+/-SD) pain intensity scores during exercise after ingesting 10 mg.kg(-1) body weight caffeine, 5 mg.kg(-1) body weight caffeine, and placebo were 2.1+/-1.4, 2.6+/-1.5, and 3.5+/-1.7, respectively. The results support the conclusion that caffeine ingestion has a dose-response effect on reducing leg muscle pain during exercise and that these effects do not depend on caffeine-induced increases in systolic blood pressure during exercise.
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Affiliation(s)
- Patrick J O'Connor
- Department of Exercise Science, University of Georgia, 115-L Ramsey Center, Athens, GA 30602-6554, USA
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Floras JS. Sympathetic activation in human heart failure: diverse mechanisms, therapeutic opportunities. ACTA PHYSIOLOGICA SCANDINAVICA 2003; 177:391-8. [PMID: 12609011 DOI: 10.1046/j.1365-201x.2003.01087.x] [Citation(s) in RCA: 78] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Plasma noradrenaline (NA) concentrations relate both to the severity of heart failure, and to its impact on survival, but have shortcomings that limit their usefulness as measures of sympathetic discharge. Neural recordings and the isotopic dilution method for determining organ-specific rates of NA spillover into plasma have enhanced our understanding of mechanisms responsible for sympathetic activation. Because the arterial baroreceptor reflex control of heart rate is impaired in heart failure, a parallel reduction in the reflex inhibition of sympathetic outflow has been assumed. However, human heart failure is characterized by rapidly responsive arterial baroreflex regulation of muscle sympathetic nerve activity (MSNA), attenuated cardiopulmonary reflex modulation of MSNA, and activation of a cardiac-specific sympatho-excitatory reflex related to increased cardiopulmonary filling pressures. Together, these baroreceptor mediated mechanisms account only, in part, for the time course and magnitude of adrenergic activation in heart failure. Non-baroreflex sympatho-excitatory mechanisms include: a metaboreflex arising from exercising skeletal muscle, mediated, in part, by adenosine, co-existing sleep apnoea, and pre-junctional facilitation of NA release. Thus, sympathetic activation in the setting of impaired systolic function reflects the net balance and interaction between augmented excitatory and diminished inhibitory influences. Variation, between patients, in the dynamics, magnitude and progression of sympathetic activation mandates an individualized approach to investigation and therapy. Excessive sympathetic outflow to the heart and periphery can be addressed by several complimentary strategies: attenuating these sympatho-excitatory stimuli, modulating the neural regulation of NA release, and blocking the actions of catecholamines at post-junctional receptors.
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Affiliation(s)
- J S Floras
- Division of Cardiology, University Health Network and Mount Sinai Hospital, University of Toronto, Canada
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Scott AC, Wensel R, Davos CH, Georgiadou P, Kemp M, Hooper J, Coats AJS, Piepoli MF. Skeletal muscle reflex in heart failure patients: role of hydrogen. Circulation 2003; 107:300-6. [PMID: 12538432 DOI: 10.1161/01.cir.0000042704.37387.29] [Citation(s) in RCA: 57] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
BACKGROUND An important role of the increased stimulation of skeletal muscle ergoreceptors (intramuscular afferents sensitive to products of muscle work) in the genesis of symptoms of exertion intolerance in chronic heart failure (CHF) has been proposed. With the use of selective infusions and dietary manipulation methods, we sought to identify the role of H+, K+, lactate, and peripheral hemodynamics on ergoreflex overactivation. METHODS AND RESULTS Ten stable CHF patients (aged 67.9+/-2.5 years, peak oxygen uptake 16.3+/-1.2 mL x kg(-1) x min(-1)) and 10 age-matched and sex-matched healthy subjects were studied. The ergoreflex contribution to ventilation was assessed by post-handgrip regional circulatory occlusion (PH-RCO) and computed as the difference in ventilation between PH-RCO and a control run without PH-RCO. This test was performed on 6 separate occasions. On each occasion a different chemical was infused (insulin, sodium nitroprusside, sodium bicarbonate, dopamine, or saline) or a 36-hour glucose-free diet was undertaken before the test. During all stages of the protocol, the local muscular blood effluent concentrations of H+, K+, glucose, and lactate were assessed. An ergoreflex effect on the ventilatory response was seen in patients (versus control subjects) during the saline infusions (6.7+/-2.3 L/min versus -0.1+/-0.5 L/min, P<0.01). The only intervention to significantly lower the ergoreflex was sodium bicarbonate (0.4+/-0.3 L/min versus -0.2+/-0.4 L/min in control subjects, P=NS; versus saline P<0.05), which also reduced H(+) concentration during exercise (47.4+/-1.3 versus 50.0+/-1.4 nmol/L on saline, P<0.05). CONCLUSION A reduction of the H+ concentration by infusion of sodium bicarbonate abolishes the increased ergoreceptor activity in CHF, suggesting a role of H+ in ergoreflex activation, either directly or indirectly.
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Affiliation(s)
- Adam C Scott
- National Heart and Lung Institute, and Royal Brompton Hospital, Imperial College School of Science, Technology and Medicine, London, United Kingdom
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