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Abstract
Driven by autonomous molecular clocks that are synchronized by a master pacemaker in the suprachiasmatic nucleus, cardiac physiology fluctuates in diurnal rhythms that can be partly or entirely circadian. Cardiac contractility, metabolism, and electrophysiology, all have diurnal rhythms, as does the neurohumoral control of cardiac and kidney function. In this review, we discuss the evidence that circadian biology regulates cardiac function, how molecular clocks may relate to the pathogenesis of heart failure, and how chronotherapeutics might be applied in heart failure. Disrupting molecular clocks can lead to heart failure in animal models, and the myocardial response to injury seems to be conditioned by the time of day. Human studies are consistent with these findings, and they implicate the clock and circadian rhythms in the pathogenesis of heart failure. Certain circadian rhythms are maintained in patients with heart failure, a factor that can guide optimal timing of therapy. Pharmacologic and nonpharmacologic manipulation of circadian rhythms and molecular clocks show promise in the prevention and treatment of heart failure.
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Affiliation(s)
- Nadim El Jamal
- Institute for Translational Medicine and Therapeutics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, United States
- Department of Systems Pharmacology and Translational Therapeutics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, United States
- Department of Medicine, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA, USA
| | - Ronan Lordan
- Institute for Translational Medicine and Therapeutics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, United States
- Department of Systems Pharmacology and Translational Therapeutics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, United States
- Department of Medicine, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA, USA
| | - Sarah L. Teegarden
- Institute for Translational Medicine and Therapeutics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, United States
- Department of Systems Pharmacology and Translational Therapeutics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, United States
- Department of Medicine, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA, USA
| | - Tilo Grosser
- Institute for Translational Medicine and Therapeutics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, United States
- Department of Translational Pharmacology, Bielefeld University, Bielefeld, Germany
| | - Garret FitzGerald
- Institute for Translational Medicine and Therapeutics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, United States
- Department of Systems Pharmacology and Translational Therapeutics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, United States
- Department of Medicine, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA, USA
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2
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Joshi K, Das M, Sarma A, Arora MK, SInghal M, Kumar B. Insight on Cardiac Chronobiology and Latest Developments of Chronotherapeutic Antihypertensive Interventions for Better Clinical Outcomes. Curr Hypertens Rev 2023; 19:106-122. [PMID: 36624649 DOI: 10.2174/1573402119666230109142156] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2022] [Revised: 11/10/2022] [Accepted: 11/15/2022] [Indexed: 01/11/2023]
Abstract
Cardiac circadian rhythms are an important regulator of body functions, including cardiac activities and blood pressure. Disturbance of circadian rhythm is known to trigger and aggravate various cardiovascular diseases. Thus, modulating the circadian rhythm can be used as a therapeutic approach to cardiovascular diseases. Through this work, we intend to discuss the current understanding of cardiac circadian rhythms, in terms of quantifiable parameters like BP and HR. We also elaborate on the molecular regulators and the molecular cascades along with their specific genetic aspects involved in modulating circadian rhythms, with specific reference to cardiovascular health and cardiovascular diseases. Along with this, we also presented the latest pharmacogenomic and metabolomics markers involved in chronobiological control of the cardiovascular system along with their possible utility in cardiovascular disease diagnosis and therapeutics. Finally, we reviewed the current expert opinions on chronotherapeutic approaches for utilizing the conventional as well as the new pharmacological molecules for antihypertensive chronotherapy.
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Affiliation(s)
- Kumud Joshi
- Department of Pharmacy, Lloyd Institute of Management and Technology, Greater Noida, India
| | - Madhubanti Das
- Department of Zoology, Gauhati University, Guwahati, Assam, India
| | - Anupam Sarma
- Advanced Drug Delivery Laboratory, GIPS, Girijananda Chowdhury University, Guwahati, Assam, India
| | - Mandeep K Arora
- School of Pharmacy and population health informatics, DIT University, Dehradun, India
| | - Manmohan SInghal
- School of Pharmacy and population health informatics, DIT University, Dehradun, India
| | - Bhavna Kumar
- School of Pharmacy and population health informatics, DIT University, Dehradun, India
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3
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Kenig A, Kolben Y, Asleh R, Amir O, Ilan Y. Improving Diuretic Response in Heart Failure by Implementing a Patient-Tailored Variability and Chronotherapy-Guided Algorithm. Front Cardiovasc Med 2021; 8:695547. [PMID: 34458334 PMCID: PMC8385752 DOI: 10.3389/fcvm.2021.695547] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2021] [Accepted: 07/21/2021] [Indexed: 01/12/2023] Open
Abstract
Heart failure is a major public health problem, which is associated with significant mortality, morbidity, and healthcare expenditures. A substantial amount of the morbidity is attributed to volume overload, for which loop diuretics are a mandatory treatment. However, the variability in response to diuretics and development of diuretic resistance adversely affect the clinical outcomes. Morevoer, there exists a marked intra- and inter-patient variability in response to diuretics that affects the clinical course and related adverse outcomes. In the present article, we review the mechanisms underlying the development of diuretic resistance. The role of the autonomic nervous system and chronobiology in the pathogenesis of congestive heart failure and response to therapy are also discussed. Establishing a novel model for overcoming diuretic resistance is presented based on a patient-tailored variability and chronotherapy-guided machine learning algorithm that comprises clinical, laboratory, and sensor-derived inputs, including inputs from pulmonary artery measurements. Inter- and intra-patient signatures of variabilities, alterations of biological clock, and autonomic nervous system responses are embedded into the algorithm; thus, it may enable a tailored dose regimen in a continuous manner that accommodates the highly dynamic complex system.
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Affiliation(s)
- Ariel Kenig
- Department of Medicine, Hebrew University-Hadassah Medical Center, Jerusalem, Israel
| | - Yotam Kolben
- Department of Medicine, Hebrew University-Hadassah Medical Center, Jerusalem, Israel
| | - Rabea Asleh
- Department of Cardiology, Hebrew University-Hadassah Medical Center, Jerusalem, Israel
| | - Offer Amir
- Department of Cardiology, Hebrew University-Hadassah Medical Center, Jerusalem, Israel
- The Azrieli Faculty of Medicine in the Galilee, Bar-Ilan University, Safed, Israel
| | - Yaron Ilan
- Department of Medicine, Hebrew University-Hadassah Medical Center, Jerusalem, Israel
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4
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Wang Y, Jiang W, Chen H, Zhou H, Liu Z, Liu Z, Liu Z, Zhou Y, Zhou X, Yu L, Jiang H. Sympathetic Nervous System Mediates Cardiac Remodeling After Myocardial Infarction in a Circadian Disruption Model. Front Cardiovasc Med 2021; 8:668387. [PMID: 33842566 PMCID: PMC8032890 DOI: 10.3389/fcvm.2021.668387] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2021] [Accepted: 03/04/2021] [Indexed: 12/20/2022] Open
Abstract
Background: Circadian rhythms have a considerable impact on the daily physiology of the heart, and their disruption causes pathology. Several studies have revealed that circadian disruption impaired cardiac remodeling after myocardial infarction (MI); however, the underlying brain-heart mechanisms remain unknown. We aim to discuss whether circadian disruption facilitates cardiac remodeling after MI by activating sympathetic nervous system. Methods: Rats were randomly divided into three groups: Sham group (Sham), MI group (MI), and MI+ circadian disruption group (MI+Dis); rats were treated with pseudorabies virus (PRV) injections for trans-synaptic retrograde tracing; rats were randomly divided into two groups: MI+ circadian disruption + Empty Vector+ clozapine N-oxide (CNO) (Empty Vector), and MI+ circadian disruption + hM4D(Gi)+ CNO [hM4D(Gi)]. Results: Circadian disruption significantly facilitated cardiac remodeling after MI with lower systolic function, larger left ventricular volume, and aggravated cardiac fibrosis. Cardiac sympathetic remodeling makers and serum norepinephrine levels were also significantly increased by circadian disruption. PRV virus-labeled neurons were identified in the superior cervical ganglion (SCG), paraventricular nucleus (PVN), and suprachiasmatic nucleus (SCN) regions. Ganglionic blockade via designer receptors exclusively activated by designer drugs (DREADD) technique suppressed the activity of sympathetic nervous system and significantly alleviated the disruption-related cardiac dysfunction. Conclusion: Circadian disruption adversely affected cardiac remodeling after MI possibly by activating sympathetic nervous system, and suppressing sympathetic activity can attenuate this disruption-related cardiac dysfunction.
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Affiliation(s)
- Yuhong Wang
- Department of Cardiology, Renmin Hospital of Wuhan University, Wuhan, China.,Cardiac Autonomic Nervous Research Center, Wuhan University, Wuhan, China.,Department of Cardiology Cardiovascular Research Institute, Wuhan University, Wuhan, China.,Hubei Key Laboratory of Cardiology, Wuhan, China
| | - Wanli Jiang
- Department of Thoracic Surgery, Renmin Hospital of Wuhan University, Wuhan, China
| | - Hu Chen
- Department of Cardiology, Renmin Hospital of Wuhan University, Wuhan, China.,Cardiac Autonomic Nervous Research Center, Wuhan University, Wuhan, China.,Department of Cardiology Cardiovascular Research Institute, Wuhan University, Wuhan, China.,Hubei Key Laboratory of Cardiology, Wuhan, China
| | - Huixin Zhou
- Department of Cardiology, Renmin Hospital of Wuhan University, Wuhan, China.,Cardiac Autonomic Nervous Research Center, Wuhan University, Wuhan, China.,Department of Cardiology Cardiovascular Research Institute, Wuhan University, Wuhan, China.,Hubei Key Laboratory of Cardiology, Wuhan, China
| | - Zhihao Liu
- Department of Cardiology, Renmin Hospital of Wuhan University, Wuhan, China.,Cardiac Autonomic Nervous Research Center, Wuhan University, Wuhan, China.,Department of Cardiology Cardiovascular Research Institute, Wuhan University, Wuhan, China.,Hubei Key Laboratory of Cardiology, Wuhan, China
| | - Zihan Liu
- Department of Cardiology, Renmin Hospital of Wuhan University, Wuhan, China.,Cardiac Autonomic Nervous Research Center, Wuhan University, Wuhan, China.,Department of Cardiology Cardiovascular Research Institute, Wuhan University, Wuhan, China.,Hubei Key Laboratory of Cardiology, Wuhan, China
| | - Zhihao Liu
- Department of Cardiology, Renmin Hospital of Wuhan University, Wuhan, China.,Cardiac Autonomic Nervous Research Center, Wuhan University, Wuhan, China.,Department of Cardiology Cardiovascular Research Institute, Wuhan University, Wuhan, China.,Hubei Key Laboratory of Cardiology, Wuhan, China
| | - Yuyang Zhou
- Department of Cardiology, Renmin Hospital of Wuhan University, Wuhan, China.,Cardiac Autonomic Nervous Research Center, Wuhan University, Wuhan, China.,Department of Cardiology Cardiovascular Research Institute, Wuhan University, Wuhan, China.,Hubei Key Laboratory of Cardiology, Wuhan, China
| | - Xiaoya Zhou
- Department of Cardiology, Renmin Hospital of Wuhan University, Wuhan, China.,Cardiac Autonomic Nervous Research Center, Wuhan University, Wuhan, China.,Department of Cardiology Cardiovascular Research Institute, Wuhan University, Wuhan, China.,Hubei Key Laboratory of Cardiology, Wuhan, China
| | - Lilei Yu
- Department of Cardiology, Renmin Hospital of Wuhan University, Wuhan, China.,Cardiac Autonomic Nervous Research Center, Wuhan University, Wuhan, China.,Department of Cardiology Cardiovascular Research Institute, Wuhan University, Wuhan, China.,Hubei Key Laboratory of Cardiology, Wuhan, China
| | - Hong Jiang
- Department of Cardiology, Renmin Hospital of Wuhan University, Wuhan, China.,Cardiac Autonomic Nervous Research Center, Wuhan University, Wuhan, China.,Department of Cardiology Cardiovascular Research Institute, Wuhan University, Wuhan, China.,Hubei Key Laboratory of Cardiology, Wuhan, China
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5
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Koba S, Hisatome I, Watanabe T. Augmented fear bradycardia in rats with heart failure. J Physiol Sci 2019; 69:875-883. [PMID: 31363992 PMCID: PMC10717697 DOI: 10.1007/s12576-019-00698-1] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2018] [Accepted: 07/23/2019] [Indexed: 02/07/2023]
Abstract
In congestive heart failure (CHF), while resting parasympathetic activity becomes reduced, parasympathetically-mediated responses to stressors have not been described. This study aimed to (1) elucidate the effect of CHF on fear bradycardia, a parasympathetically-mediated response, and (2) examine if brain oxidative stress of CHF mediates fear bradycardia. White noise sound (WNS) exposure to conscious rats induced freezing behavior and elicited bradycardia. WNS exposure-elicited bradycardia was greater in rats with CHF than in controls. Superoxide dismutase mimetics administered in the lateral/ventrolateral midbrain periaqueductal gray (l/vlPAG), a region that contributes to the generation of fear bradycardia, had no effect on the bradycardia response in control and CHF rats. Dihydroethidium staining in situ showed that superoxide generation in the l/vlPAG of CHF rats was increased as compared to controls. These results demonstrate that CHF leads to the augmentation of fear bradycardia. Moreover, oxidative stress in the l/vlPAG of CHF unlikely mediates the augmented fear bradycardia.
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Affiliation(s)
- Satoshi Koba
- Division of Integrative Physiology, Faculty of Medicine, Tottori University, Nishi-cho 86, Yonago, Tottori, 683-8503, Japan.
| | - Ichiro Hisatome
- Division of Regenerative Medicine and Therapeutics, Graduate School of Medical Science, Tottori University, Nishi-cho 86, Yonago, Tottori, 683-8503, Japan
| | - Tatsuo Watanabe
- Division of Integrative Physiology, Faculty of Medicine, Tottori University, Nishi-cho 86, Yonago, Tottori, 683-8503, Japan
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6
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Rodrigo GC, Herbert KE. Regulation of vascular function and blood pressure by circadian variation in redox signalling. Free Radic Biol Med 2018; 119:115-120. [PMID: 29106991 DOI: 10.1016/j.freeradbiomed.2017.10.381] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/21/2017] [Revised: 10/24/2017] [Accepted: 10/25/2017] [Indexed: 12/21/2022]
Abstract
There is accumulating evidence that makes the link between the circadian variation in blood pressure and circadian variations in vascular contraction. The importance of vascular endothelium-derived redox-active and redox-derived species in the signalling pathways involved in controlling vascular smooth muscle contraction are well known, and when linked to the circadian variations in the processes involved in generating these species, suggests a cellular mechanism for the circadian variations in blood pressure that links directly to the peripheral circadian clock. Relaxation of vascular smooth muscle cells involves endothelial-derived relaxing factor (EDRF) which is nitric oxide (NO) produced by endothelial NO synthase (eNOS), and endothelial-derived hyperpolarising factor (EDHF) which includes hydrogen peroxide (H2O2) produced by NADPH oxidase (Nox). Both of these enzymes appear to be under the direct control of the circadian clock mechanism in the endothelial cells, and disruption to the clock results in endothelial and vascular dysfunction. In this review, we focus on EDRF and EDHF and summarise the recent findings on the influence of the peripheral circadian clock mechanism on processes involved in generating the redox species involved and how this influences vascular contractility, which may account for some of the circadian variations in blood pressure and peripheral resistance. Moreover, the direct link between the peripheral circadian clock and redox-signalling pathways in the vasculature, has a bearing on vascular endothelial dysfunction in disease and aging, which are both known to lead to dysfunction of the circadian clock.
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Affiliation(s)
- Glenn C Rodrigo
- Department of Cardiovascular Sciences, University of Leicester, Glenfield General Hospital, Leicester, United Kingdom.
| | - Karl E Herbert
- Department of Cardiovascular Sciences, University of Leicester, Glenfield General Hospital, Leicester, United Kingdom
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7
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Moura ALD, Hyslop S, Grassi-Kassisse DM, Spadari RC. Functional β2-adrenoceptors in rat left atria: effect of foot-shock stress. Can J Physiol Pharmacol 2017; 95:999-1008. [DOI: 10.1139/cjpp-2016-0622] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Altered sensitivity to the chronotropic effect of catecholamines and a reduction in the β1/β2-adrenoceptor ratio have previously been reported in right atria of stressed rats, human failing heart, and aging. In this report, we investigated whether left atrial inotropism was affected by foot-shock stress. Male rats were submitted to 3 foot-shock sessions and the left atrial inotropic response, adenylyl cyclase activity, and β-adrenoceptor expression were investigated. Left atria of stressed rats were supersensitive to isoprenaline when compared with control rats and this effect was abolished by ICI118,551, a selective β2-receptor antagonist. Schild plot slopes for the antagonism between CGP20712A (a selective β1-receptor antagonist) and isoprenaline differed from unity in atria of stressed but not control rats. Atrial sensitivity to norepinephrine, as well as basal and forskolin- or isoprenaline-stimulated adenylyl cyclase activities were not altered by stress. The effect of isoprenaline on adenylyl cyclase stimulation was partially blocked by ICI118,551 in atrial membranes of stressed rats. These findings indicate that foot-shock stress equally affects inotropism and chronotropism and that β2-adrenoceptor upregulation contributes to the enhanced inotropic response to isoprenaline.
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Affiliation(s)
- André Luiz de Moura
- Department of Biosciences, Federal University of São Paulo (UNIFESP), Santos, SP, Brazil
| | - Stephen Hyslop
- Department of Pharmacology, Faculty of Medical Sciences, State University of Campinas (UNICAMP), Campinas, SP, Brazil
| | - Dora M. Grassi-Kassisse
- Department of Physiology and Biophysics, Institute of Biology, State University of Campinas (UNICAMP), Campinas, SP, Brazil
| | - Regina C. Spadari
- Department of Biosciences, Federal University of São Paulo (UNIFESP), Santos, SP, Brazil
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8
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Durand MT, Becari C, Tezini GCSV, Fazan R, Oliveira M, Guatimosim S, Prado VF, Prado MAM, Salgado HC. Autonomic cardiocirculatory control in mice with reduced expression of the vesicular acetylcholine transporter. Am J Physiol Heart Circ Physiol 2015; 309:H655-62. [PMID: 26092977 DOI: 10.1152/ajpheart.00114.2015] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/18/2015] [Accepted: 06/15/2015] [Indexed: 01/13/2023]
Abstract
In cardiovascular diseases, sympathetic tone has been comprehensively studied, whereas parasympathetic tone has received minor attention. The vesicular ACh transporter (VAChT) knockdown homozygous (VAChT KD(HOM)) mouse is a useful model for examining the cardiocirculatory sympathovagal balance. Therefore, we investigated whether cholinergic dysfunction caused by reduced VAChT expression could adversely impact hemodynamic parameter [arterial pressure (AP) and heart rate (HR)] daily oscillation, baroreflex sensitivity, hemodynamic variability, sympathovagal balance, and cardiovascular reactivity to restraint stress. Wild-type and VAChT KD(HOM) mice were anesthetized for telemetry transmitter implantation, and APs and HRs were recorded 10 days after surgical recovery. Changes in HR elicited by methylatropine and propranolol provided the indexes of sympathovagal tone. Cardiovascular reactivity in response to a restraint test was examined 24 h after continuous recordings of AP and HR. VAChT KD(HOM) mice exhibited reduced parasympathetic and elevated sympathetic tone. Daily oscillations of AP and HR as well as AP variability were similar between groups. Nevertheless, HR variability, patterns with two dissimilar variations from symbolic analysis, and baroreflex sensitivity were reduced in VAChT KD(HOM) mice. The change in mean AP due to restraint stress was greater in VAChT KD(HOM) mice, whereas the tachycardic response was not. These findings demonstrate that the cholinergic dysfunction present in the VAChT KD(HOM) mouse did not adversely impact basal hemodynamic parameters but promoted autonomic imbalance, an attenuation of baroreflex sensitivity, and a greater pressure response to restraint stress. These results provide a framework for understanding how autonomic imbalance impacts cardiovascular function.
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Affiliation(s)
- Marina T Durand
- Department of Physiology, Ribeirão Preto Medical School, University of São Paulo, Ribeirão Preto, São Paulo, Brazil
| | - Christiane Becari
- Department of Physiology, Ribeirão Preto Medical School, University of São Paulo, Ribeirão Preto, São Paulo, Brazil
| | - Geisa C S V Tezini
- Department of Physiology, Ribeirão Preto Medical School, University of São Paulo, Ribeirão Preto, São Paulo, Brazil
| | - Rubens Fazan
- Department of Physiology, Ribeirão Preto Medical School, University of São Paulo, Ribeirão Preto, São Paulo, Brazil
| | - Mauro Oliveira
- Department of Physiology, Ribeirão Preto Medical School, University of São Paulo, Ribeirão Preto, São Paulo, Brazil
| | - Silvia Guatimosim
- Department of Physiology and Biophysics, Institute of Biological Sciences, Federal University of Minas Gerais, Belo Horizonte, Minas Gerais, Brazil; and
| | - Vania F Prado
- Robarts Research Institute, Department of Anatomy and Cell Biology and Department of Physiology and Pharmacology, The University of Western Ontario, London, Ontario, Canada
| | - Marco A M Prado
- Robarts Research Institute, Department of Anatomy and Cell Biology and Department of Physiology and Pharmacology, The University of Western Ontario, London, Ontario, Canada
| | - Helio C Salgado
- Department of Physiology, Ribeirão Preto Medical School, University of São Paulo, Ribeirão Preto, São Paulo, Brazil;
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9
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Verkerk AO, van Borren MMGJ, van Ginneken ACG, Wilders R. Ca(2+) cycling properties are conserved despite bradycardic effects of heart failure in sinoatrial node cells. Front Physiol 2015; 6:18. [PMID: 25698973 PMCID: PMC4313601 DOI: 10.3389/fphys.2015.00018] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2014] [Accepted: 01/12/2015] [Indexed: 01/01/2023] Open
Abstract
BACKGROUND In animal models of heart failure (HF), heart rate decreases due to an increase in intrinsic cycle length (CL) of the sinoatrial node (SAN). Pacemaker activity of SAN cells is complex and modulated by the membrane clock, i.e., the ensemble of voltage gated ion channels and electrogenic pumps and exchangers, and the Ca(2+) clock, i.e., the ensemble of intracellular Ca(2+) ([Ca(2+)]i) dependent processes. HF in SAN cells results in remodeling of the membrane clock, but few studies have examined its effects on [Ca(2+)]i homeostasis. METHODS SAN cells were isolated from control rabbits and rabbits with volume and pressure overload-induced HF. [Ca(2+)]i concentrations, and action potentials (APs) and Na(+)-Ca(2+) exchange current (INCX) were measured using indo-1 and patch-clamp methodology, respectively. RESULTS The frequency of spontaneous [Ca(2+)]i transients was significantly lower in HF SAN cells (3.0 ± 0.1 (n = 40) vs. 3.4 ± 0.1 Hz (n = 45); mean ± SEM), indicating that intrinsic CL was prolonged. HF slowed the [Ca(2+)]i transient decay, which could be explained by the slower frequency and reduced sarcoplasmic reticulum (SR) dependent rate of Ca(2+) uptake. Other [Ca(2+)]i transient parameters, SR Ca(2+) content, INCX density, and INCX-[Ca(2+)]i relationship were all unaffected by HF. Combined AP and [Ca(2+)]i recordings demonstrated that the slower [Ca(2+)]i transient decay in HF SAN cells may result in increased INCX during the diastolic depolarization, but that this effect is likely counteracted by the HF-induced increase in intracellular Na(+). β-adrenergic and muscarinic stimulation were not changed in HF SAN cells, except that late diastolic [Ca(2+)]i rise, a prominent feature of the Ca(2+) clock, is lower during β-adrenergic stimulation. CONCLUSIONS HF SAN cells have a slower [Ca(2+)]i transient decay with limited effects on pacemaker activity. Reduced late diastolic [Ca(2+)]i rise during β-adrenergic stimulation may contribute to an impaired increase in intrinsic frequency in HF SAN cells.
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Affiliation(s)
- Arie O Verkerk
- Department of Anatomy, Embryology and Physiology, Academic Medical Center, University of Amsterdam Amsterdam, Netherlands
| | - Marcel M G J van Borren
- Department of Anatomy, Embryology and Physiology, Academic Medical Center, University of Amsterdam Amsterdam, Netherlands ; Laboratory of Clinical Chemistry and Haematology, Rijnstate Hospital Arnhem, Netherlands
| | - Antoni C G van Ginneken
- Department of Anatomy, Embryology and Physiology, Academic Medical Center, University of Amsterdam Amsterdam, Netherlands
| | - Ronald Wilders
- Department of Anatomy, Embryology and Physiology, Academic Medical Center, University of Amsterdam Amsterdam, Netherlands
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10
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Lee HW, Han TH, Yi KJ, Choi MC, Lee SY, Ryu PD. Time course of diurnal rhythm disturbances in autonomic function of rats with myocardial infarction. Auton Neurosci 2013; 179:28-36. [DOI: 10.1016/j.autneu.2013.06.007] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2012] [Revised: 06/17/2013] [Accepted: 06/19/2013] [Indexed: 10/26/2022]
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11
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Schrepper A, Schwarzer M, Schöpe M, Amorim PA, Doenst T. Biphasic response of skeletal muscle mitochondria to chronic cardiac pressure overload - role of respiratory chain complex activity. J Mol Cell Cardiol 2011; 52:125-35. [PMID: 22100228 DOI: 10.1016/j.yjmcc.2011.10.022] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/04/2011] [Revised: 10/07/2011] [Accepted: 10/28/2011] [Indexed: 10/15/2022]
Abstract
Pressure overload induced heart failure affects cardiac mitochondrial function and leads to decreased respiratory capacity during contractile dysfunction. A similar cardiac mitochondrial dysfunction has been demonstrated by studies which induce heart failure through myocardial infarction or pacing. These heart failure models differ in their loading conditions to the heart and show nevertheless the same cardiac mitochondrial changes. Based on these observations we speculated that a workload independent mechanism may be responsible for the impairment in mitochondrial function after pressure overload, which may then also affect the skeletal muscle. We aimed to characterize changes in mitochondrial function of skeletal muscle during the transition from pressure overload (PO) induced cardiac hypertrophy to chronic heart failure. PO by transverse aortic constriction caused compensated hypertrophy at 2 weeks, HF with normal ejection fraction (EF) at 6 and 10 weeks, and hypertrophy with reduced EF at 20 weeks. Cardiac output was normal at all investigated time points. PO did not cause skeletal muscle atrophy. Mitochondrial respiratory capacity in soleus and gastrocnemius muscles showed an early increase (up to 6 weeks) and a later decline (significant at 20 weeks). Respiratory chain complex activities responded to PO in a biphasic manner. At 2 weeks, activity of complexes I and II was increased. These changes pseudo-normalized within the 6-10 week interval. At 20 weeks, all complexes showed reduced activities which coincided with clinical heart failure symptoms. However, both protein expression and supercomplex assembly (Blue-Native gel) remained normal. There were also no relevant changes in mRNA expression of genes involved in mitochondrial biogenesis. This temporal analysis reveals that mitochondrial function of skeletal muscle is changed early in the development of pressure overload induced heart failure without being directly influenced by an increased loading condition. The observed early increase and the later decline in respiratory capacity can be explained by concomitant activity changes of complex I and complex II and is not due to differences in gene expression or supercomplex assembly.
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Affiliation(s)
- Andrea Schrepper
- Department of Cardiothoracic Surgery, Jena University Hospital - Friedrich Schiller University Jena, Germany
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12
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Sachan N, Dey A, Rotter D, Grinsfelder DB, Battiprolu PK, Sikder D, Copeland V, Oh M, Bush E, Shelton JM, Bibb JA, Hill JA, Rothermel BA. Sustained hemodynamic stress disrupts normal circadian rhythms in calcineurin-dependent signaling and protein phosphorylation in the heart. Circ Res 2011; 108:437-45. [PMID: 21233454 DOI: 10.1161/circresaha.110.235309] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
RATIONALE Despite overwhelming evidence of the importance of circadian rhythms in cardiovascular health and disease, little is known regarding the circadian regulation of intracellular signaling pathways controlling cardiac function and remodeling. OBJECTIVE To assess circadian changes in processes dependent on the protein phosphatase calcineurin, relative to changes in phosphorylation of cardiac proteins, in normal, hypertrophic, and failing hearts. METHODS AND RESULTS We found evidence of large circadian oscillations in calcineurin-dependent activities in the left ventricle of healthy C57BL/6 mice. Calcineurin-dependent transcript levels and nuclear occupancy of the NFAT (nuclear factor of activated T cells) regularly fluctuated as much as 20-fold over the course of a day, peaking in the morning when mice enter a period of rest. Phosphorylation of the protein phosphatase 1 inhibitor 1 (I-1), a direct calcineurin substrate, and phospholamban, an indirect target, oscillated directly out of phase with calcineurin-dependent signaling. Using a surgical model of cardiac pressure overload, we found that although calcineurin-dependent activities were markedly elevated, the circadian pattern of activation was maintained, whereas, oscillations in phospholamban and I-1 phosphorylation were lost. Changes in the expression of fetal gene markers of heart failure did not mirror the rhythm in calcineurin/NFAT activation, suggesting that these may not be direct transcriptional target genes. Cardiac function in mice subjected to pressure overload was significantly lower in the morning than in the evening when assessed by echocardiography. CONCLUSIONS Normal, opposing circadian oscillations in calcineurin-dependent activities and phosphorylation of proteins that regulate contractility are disrupted in heart failure.
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Affiliation(s)
- Nita Sachan
- Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, TX 75390-8573, USA
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Circadian changes in autonomic function in conscious rats with heart failure: Effects of amiodarone on sympathetic surge. Auton Neurosci 2011; 159:20-5. [PMID: 20674512 DOI: 10.1016/j.autneu.2010.07.001] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2010] [Revised: 06/29/2010] [Accepted: 07/08/2010] [Indexed: 11/23/2022]
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14
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Collins HE, Rodrigo GC. Inotropic response of cardiac ventricular myocytes to beta-adrenergic stimulation with isoproterenol exhibits diurnal variation: involvement of nitric oxide. Circ Res 2010; 106:1244-52. [PMID: 20167926 DOI: 10.1161/circresaha.109.213942] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
RATIONALE Although >10% of cardiac gene expression displays diurnal variations, little is known of their impact on excitation-contraction coupling. OBJECTIVE To determine whether the time of day affects excitation-contraction coupling in rat ventricles. METHODS AND RESULTS Left ventricular myocytes were isolated from rat hearts at 2 opposing time points, corresponding to the animals resting or active periods. Basal contraction and [Ca(2+)](i) was significantly greater in myocytes isolated during the resting versus active periods (cell shortening 12.4+/-0.3 versus 11.0+/-0.2%; P<0.05 and systolic [Ca(2+)](i) 422+/-12 versus 341+/-9 nmol/L; P<0.01. This corresponded to a greater sarcoplasmic reticulum (SR) Ca(2+) load (672+/-20 versus 551+/-13 nmol/L P<0.001). The increase in systolic [Ca(2+)](i) in response to isoproterenol (>3 nmol/L) was also significantly greater in resting versus active period myocytes, reflecting a greater SR Ca(2+) load at this time. This diurnal variation in response of Ca(2+)-homeostasis to isoproterenol translated to a greater incidence of arrhythmic activity in resting period myocytes. Inhibition of neuronal NO synthase during stimulation with isoproterenol, further increased systolic [Ca(2+)](i) and the percentage of arrhythmic myocytes, but this effect was significantly greater in active period versus resting period myocytes. Quantitative RT-PCR analysis revealed a 2.65-fold increase in neuronal NO synthase mRNA levels in active over resting period myocytes (P<0.05). CONCLUSIONS The threshold for the development of arrhythmic activity in response to isoproterenol is higher during the active period of the rat. We suggest this reflects a reduction in SR Ca(2+) loading and a diurnal variation in neuronal NO synthase signaling.
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MESH Headings
- Adrenergic beta-Agonists/adverse effects
- Adrenergic beta-Agonists/pharmacology
- Animals
- Arrhythmias, Cardiac/chemically induced
- Arrhythmias, Cardiac/metabolism
- Calcium/metabolism
- Calcium Channels, L-Type/drug effects
- Calcium Channels, L-Type/metabolism
- Calcium Signaling/drug effects
- Cardiac Pacing, Artificial
- Circadian Rhythm
- Dose-Response Relationship, Drug
- Excitation Contraction Coupling/drug effects
- Gene Expression Regulation, Enzymologic/drug effects
- Heart Ventricles/drug effects
- Heart Ventricles/metabolism
- Homeostasis
- Isoproterenol/adverse effects
- Isoproterenol/pharmacology
- Male
- Myocardial Contraction/drug effects
- Myocytes, Cardiac/drug effects
- Myocytes, Cardiac/metabolism
- Nitric Oxide/metabolism
- Nitric Oxide Synthase/genetics
- Nitric Oxide Synthase/metabolism
- Nitric Oxide Synthase Type I
- RNA, Messenger/metabolism
- Rats
- Rats, Wistar
- Sarcoplasmic Reticulum/drug effects
- Sarcoplasmic Reticulum/metabolism
- Up-Regulation
- Ventricular Function, Left/drug effects
- Ventricular Pressure/drug effects
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Affiliation(s)
- Helen E Collins
- Department of Cardiovascular Sciences, University of Leicester, Glenfield General Hospital, Leicester LE3 9QP, United Kingdom
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15
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Wang Y, Hill JA. Electrophysiological remodeling in heart failure. J Mol Cell Cardiol 2010; 48:619-32. [PMID: 20096285 DOI: 10.1016/j.yjmcc.2010.01.009] [Citation(s) in RCA: 87] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/14/2008] [Revised: 01/11/2010] [Accepted: 01/12/2010] [Indexed: 11/25/2022]
Abstract
Heart failure affects nearly 6 million Americans, with a half-million new cases emerging each year. Whereas up to 50% of heart failure patients die of arrhythmia, the diverse mechanisms underlying heart failure-associated arrhythmia are poorly understood. As a consequence, effectiveness of antiarrhythmic pharmacotherapy remains elusive. Here, we review recent advances in our understanding of heart failure-associated molecular events impacting the electrical function of the myocardium. We approach this from an anatomical standpoint, summarizing recent insights gleaned from pre-clinical models and discussing their relevance to human heart failure.
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Affiliation(s)
- Yanggan Wang
- Department of Pediatrics, Emory University, Atlanta, GA, USA.
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16
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Witte K, Engelhardt S, Janssen BJA, Lohse M, Lemmer B. Circadian and Short-Term Regulation of Blood Pressure and Heart Rate in Transgenic Mice with Cardiac Overexpression of The β1-Adrenoceptor. Chronobiol Int 2009; 21:205-16. [PMID: 15332342 DOI: 10.1081/cbi-120037801] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Congestive heart failure is associated with a loss of circadian and short-term variability in blood pressure and heart rate. In order to assess the contribution of elevated cardiac sympathetic activity to the disturbed cardiovascular regulation, we monitored blood pressure and heart rate in mice with cardiac overexpression of the beta1-adrenoceptor prior to the development of overt heart failure. Telemetry transmitters for continuous monitoring of blood pressure and heart rate were implanted in 8 to 9-week-old wildtype and transgenic mice, derived from crosses of heterozygous transgenic (line beta1TG4) and wildtype mice. Cardiovascular circadian patterns were analyzed under baseline conditions and during treatment with propranolol (500mg/L in drinking water). Short-term variability was assessed by spectral analysis of beat-to-beat data sampled for 30min at four circadian times. Transgenic beta1TG4 mice showed an increase in 24h heart rate, while blood pressure was not different from wildtype controls. Circadian patterns in blood pressure and heart were preserved in beta1TG4 mice. Addition of propranolol to the animals' drinking water led to a reduction in heart rate and its 24 h variation in both strains of mice. Short-term variability in blood pressure was not different between wildtype and beta1TG4 mice, but heart rate variability in the transgenic animals showed a rightward shift of the high-frequency component in the nocturnal activity period, suggesting an increase in respiratory frequency. In conclusion, the present study shows that both the circadian and the short-term regulation of blood pressure and heart rate are largely preserved in young, nonfailing beta1-transgenic mice. This finding suggests that the loss of blood pressure and heart rate variability observed in human congestive heart failure cannot be attributed solely to sympathetic overactivity but reflects the loss of adrenergic responsiveness to changes in the activity of the autonomic nervous system.
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Affiliation(s)
- Klaus Witte
- Institute of Pharmacology and Toxicology, University of Heidelberg, Mannheim, Germany
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17
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Christ T, Galindo-Tovar A, Thoms M, Ravens U, Kaumann AJ. Inotropy and L-type Ca2+ current, activated by beta1- and beta2-adrenoceptors, are differently controlled by phosphodiesterases 3 and 4 in rat heart. Br J Pharmacol 2009; 156:62-83. [PMID: 19133992 DOI: 10.1111/j.1476-5381.2008.00015.x] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
Abstract
BACKGROUND AND PURPOSE beta(1)- and beta(2)-adrenoceptors coexist in rat heart but beta(2)-adrenoceptor-mediated inotropic effects are hardly detectable, possibly due to phosphodiesterase (PDE) activity. We investigated the influence of the PDE3 inhibitor cilostamide (300 nmol x L(-1)) and the PDE4 inhibitor rolipram (1 micromol x L(-1)) on the effects of (-)-catecholamines. EXPERIMENTAL APPROACH Cardiostimulation evoked by (-)-noradrenaline (ICI118551 present) and (-)-adrenaline (CGP20712A present) through beta(1)- and beta(2)-adrenoceptors, respectively, was compared on sinoatrial beating rate, left atrial and ventricular contractile force in isolated tissues from Wistar rats. L-type Ca(2+)-current (I(Ca-L)) was assessed with whole-cell patch clamp. KEY RESULTS Rolipram caused sinoatrial tachycardia. Cilostamide and rolipram did not enhance chronotropic potencies of (-)-noradrenaline and (-)-adrenaline. Rolipram but not cilostamide potentiated atrial and ventricular inotropic effects of (-)-noradrenaline. Cilostamide potentiated the ventricular effects of (-)-adrenaline but not of (-)-noradrenaline. Concurrent cilostamide + rolipram uncovered left atrial effects of (-)-adrenaline. Both rolipram and cilostamide augmented the (-)-noradrenaline (1 micromol x L(-1)) evoked increase in I(Ca-L). (-)-Adrenaline (10 micromol x L(-1)) increased I(Ca-L) only in the presence of cilostamide but not rolipram. CONCLUSIONS AND IMPLICATIONS PDE4 blunts the beta(1)-adrenoceptor-mediated inotropic effects. PDE4 reduces basal sinoatrial rate in a compartment distinct from compartments controlled by beta(1)- and beta(2)-adrenoceptors. PDE3 and PDE4 jointly prevent left atrial beta(2)-adrenoceptor-mediated inotropy. Both PDE3 and PDE4 reduce I(Ca-L) responses through beta(1)-adrenoceptors but the PDE3 component is unrelated to inotropy. PDE3 blunts both ventricular inotropic and I(Ca-L) responses through beta(2)-adrenoceptors.
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Affiliation(s)
- Torsten Christ
- Department of Pharmacology, Dresden University of Technology, Dresden, Germany
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18
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Charloux A, Chaouat A, Brandenberger G, Piquard F, Weitzenblum E, Geny B. Reduced pulsatility does not explain renal hyporesponsiveness to cardiac natriuretic peptides in pulmonary hypertension. Peptides 2006; 27:864-70. [PMID: 16242811 DOI: 10.1016/j.peptides.2005.09.005] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/11/2005] [Revised: 09/09/2005] [Accepted: 09/09/2005] [Indexed: 11/17/2022]
Abstract
A pulsatile secretory pattern is assumed to improve hormonal efficiency. We examined the short-term time courses of circulating atrial (ANP) and brain natriuretic peptides (BNP) in patients with pulmonary hypertension (PH) and reduced renal efficiency of ANP-BNP, reflected by low natriuresis/ANP or BNP ratios. Compared to controls, we observed a persistence of ANP and BNP pulsatility in PH patients with a similar periodicity of 20min. Pulse amplitude increased proportionally to the rise in mean plasma level observed in patients (around 27%). In PH patients, the decrease in ANP-BNP renal efficiency is not attributable to a loss of the rhythmic pulsatility of these hormones.
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Affiliation(s)
- Anne Charloux
- Laboratoire des Régulations Physiologiques et des Rythmes Biologiques chez l'Homme, Institut de Physiologie, 4 rue Kirschleger, 67085 Strasbourg Cedex, France.
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19
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Mortola JP, Lanthier C. Scaling the amplitudes of the circadian pattern of resting oxygen consumption, body temperature and heart rate in mammals. Comp Biochem Physiol A Mol Integr Physiol 2004; 139:83-95. [PMID: 15471685 DOI: 10.1016/j.cbpb.2004.07.007] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2004] [Revised: 07/01/2004] [Accepted: 07/12/2004] [Indexed: 11/25/2022]
Abstract
We questioned whether the amplitudes of the circadian pattern of body temperature (T(b)), oxygen consumption (V (O(2))) and heart rate (HR) changed systematically among species of different body weight (W). Because bodies of large mass have a greater heat capacitance than those of smaller mass, if the relative amplitude (i.e., amplitude/mean value) of metabolic rate was constant, one would expect the T(b) oscillation to decrease with the increase in the species W. We compiled data of T(b), V (O(2)) and HR from a literature survey of over 200 studies that investigated the circadian pattern of these parameters. Monotremata, Marsupials and Chiroptera, were excluded because of their characteristically low metabolic rate and T(b). The peak-trough ratios of V (O(2)) (42 species) and HR (35 species) averaged, respectively, 1.57+/-0.08, and 1.35+/-0.07, and were independent of W. The daily high values of T(b) did not change, while the daily low T(b) values slightly increased, with the species W; hence, the high-low T(b) difference (57 species) decreased with W (3.3 degrees C.W(-0.13)). However, the decrease in T(b) amplitude with W was much less than expected from physical principles, and the high-low T(b) ratio remained significantly above unity even in the largest mammals. Thus, it appears that in mammals, despite the huge differences in physical characteristics, the amplitude of the circadian pattern is a fixed (for V (O(2)) and HR), or almost fixed (for T(b)), fraction of the 24-h mean value. Presumably, the amplitudes of the oscillations are controlled parameters of physiological significance.
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Affiliation(s)
- Jacopo P Mortola
- Department of Physiology, McGill University, 3655, Sir William Osler Promenade Montreal, Quebec, Canada, H3G 1Y6.
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20
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Abstract
BACKGROUND In animal models of heart failure (HF), heart rate decreases as the result of an increase in intrinsic cycle length of the sinoatrial node (SAN). In this study, we evaluate the HF-induced remodeling of membrane potentials and currents in SAN cells. METHODS AND RESULTS SAN cells were isolated from control rabbits and rabbits with volume and pressure overload-induced HF and patch-clamped to measure their electrophysiological properties. HF cells were not hypertrophied (capacitance, mean+/-SEM, 52+/-3 versus 50+/-4 pF in control). HF increased intrinsic cycle length by 15% and decreased diastolic depolarization rate by 30%, whereas other action potential parameters were unaltered. In HF, the hyperpolarization-activated "pacemaker" current (If) and slow component of the delayed rectifier current (IKs) were reduced by 40% and 20%, respectively, without changes in voltage dependence or kinetics. T-type and L-type calcium current, rapid and ultrarapid delayed rectifier current, transient outward currents, and sodium-calcium exchange current were unaltered. CONCLUSIONS In single SAN cells of rabbits with HF, intrinsic cycle length is increased as the result of a decreased diastolic depolarization rate rather than a change in action potential duration. HF reduced both If and IKs density. Since IKs plays a limited role in pacemaker activity, the HF-induced decrease in heart rate is attributable to remodeling of If.
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Affiliation(s)
- Arie O Verkerk
- Department of Physiology, Academic Medical Center, University of Amsterdam, The Netherlands.
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21
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Lunde PK, Dahlstedt AJ, Bruton JD, Lännergren J, Thorén P, Sejersted OM, Westerblad H. Contraction and intracellular Ca(2+) handling in isolated skeletal muscle of rats with congestive heart failure. Circ Res 2001; 88:1299-305. [PMID: 11420307 DOI: 10.1161/hh1201.092041] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
A decreased exercise tolerance is a common symptom in patients with congestive heart failure (CHF). This decrease has been suggested to be partly due to altered skeletal muscle function. Therefore, we have studied contractile function and cytoplasmic free Ca(2+) concentration ([Ca(2+)](i), measured with the fluorescent dye indo 1) in isolated muscles from rats in which CHF was induced by ligation of the left coronary artery. The results show no major changes of the contractile function and [Ca(2+)](i) handling in unfatigued intact fast-twitch fibers isolated from flexor digitorum brevis muscles of CHF rats, but these fibers were markedly more susceptible to damage during microdissection. Furthermore, CHF fibers displayed a marked increase of baseline [Ca(2+)](i) during fatigue. Isolated slow-twitch soleus muscles of CHF rats displayed slower twitch contraction and tetanic relaxation than did muscles from sham-operated rats; the slowing of relaxation became more pronounced during fatigue in CHF muscles. Immunoblot analyses of sarcoplasmic reticulum proteins and sarcolemma Na(+),K(+)-ATPase showed no difference in flexor digitorum brevis muscles of sham-operated versus CHF rats. In conclusion, functional impairments can be observed in limb muscle isolated from rats with CHF. These impairments seem to mainly involve structures surrounding the muscle cells and sarcoplasmic reticulum Ca(2+) pumps, the dysfunction of which becomes obvious during fatigue.
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Affiliation(s)
- P K Lunde
- Institute for Experimental Medical Research, University of Oslo, Ullevaal Hospital, Oslo, Norway
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