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Filatova TS, Dzhumaniiazova I, Abramochkin DV. The metamorphosis of amphibian myocardium: moving to the heart of the matter. J Exp Biol 2024; 227:jeb247712. [PMID: 38916053 DOI: 10.1242/jeb.247712] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2024] [Accepted: 04/26/2024] [Indexed: 06/26/2024]
Abstract
Amphibians are a classical object for physiological studies, and they are of great value for developmental studies owing to their transition from an aquatic larval form to an adult form with a terrestrial lifestyle. Axolotls (Ambystoma mexicanum) are of special interest for such studies because of their neoteny and facultative pedomorphosis, as in these animals, metamorphosis can be induced and fully controlled in laboratory conditions. It has been suggested that their metamorphosis, associated with gross anatomical changes in the heart, also involves physiological and electrical remodeling of the myocardium. We used whole-cell patch clamp to investigate possible changes caused by metamorphosis in electrical activity and major ionic currents in cardiomyocytes isolated from paedomorphic and metamorphic axolotls. T4-induced metamorphosis caused shortening of atrial and ventricular action potentials (APs), with no changes in resting membrane potential or maximum velocity of AP upstroke, favoring higher heart rate possible in metamorphic animals. Potential-dependent potassium currents in axolotl myocardium were represented by delayed rectifier currents IKr and IKs, and upregulation of IKs caused by metamorphosis probably underlies AP shortening. Metamorphosis was associated with downregulation of inward rectifier current IK1, probably serving to increase the excitability of myocardium in metamorphic animals. Metamorphosis also led to a slight increase in fast sodium current INa with no changes in its steady-state kinetics and to a significant upregulation of ICa in both atrial and ventricular cells, indicating stronger Ca2+ influx for higher cardiac contractility in metamorphic salamanders. Taken together, these changes serve to increase cardiac reserve in metamorphic animals.
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Affiliation(s)
- Tatiana S Filatova
- Department of Human and Animal Physiology, Lomonosov Moscow State University, Leninskiye gory, 1, 12, Moscow 119234, Russia
| | - Irina Dzhumaniiazova
- Department of Human and Animal Physiology, Lomonosov Moscow State University, Leninskiye gory, 1, 12, Moscow 119234, Russia
| | - Denis V Abramochkin
- Department of Human and Animal Physiology, Lomonosov Moscow State University, Leninskiye gory, 1, 12, Moscow 119234, Russia
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Guagnoni IN, Armelin VA, da Silva Braga VH, Monteiro DA, Florindo LH. Cardiovascular responses and the role of the neurohumoral cardiac regulation during digestion in the herbivorous lizard Iguana iguana. J Exp Biol 2024; 227:jeb247105. [PMID: 38186316 DOI: 10.1242/jeb.247105] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2023] [Accepted: 12/27/2023] [Indexed: 01/09/2024]
Abstract
Carnivorous reptiles exhibit an intense metabolic increment during digestion, which is accompanied by several cardiovascular adjustments responsible for meeting the physiological demands of the gastrointestinal system. Postprandial tachycardia, a well-documented phenomenon in these animals, is mediated by the withdrawal of vagal tone associated with the chronotropic effects of non-adrenergic and non-cholinergic (NANC) factors. However, herbivorous reptiles exhibit a modest metabolic increment during digestion and there is no information about postprandial cardiovascular adjustments. Considering the significant impact of feeding characteristics on physiological responses, we investigated cardiovascular and metabolic responses, as well as the neurohumoral mechanisms of cardiac control, in the herbivorous lizard Iguana iguana during digestion. We measured oxygen consumption rate (O2), heart rate (fH), mean arterial blood pressure (MAP), myocardial activity, cardiac autonomic tone, fH/MAP variability and baroreflex efficiency in both fasting and digesting animals before and after parasympathetic blockade with atropine followed by double autonomic blockade with atropine and propranolol. Our results revealed that the peak of O2 in iguanas was reached 24 h after feeding, accompanied by an increase in myocardial activity and a subtle tachycardia mediated exclusively by a reduction in cardiac parasympathetic activity. This represents the first reported case of postprandial tachycardia in digesting reptiles without the involvement of NANC factors. Furthermore, this withdrawal of vagal stimulation during digestion may reduce the regulatory range for short-term fH adjustments, subsequently intensifying the blood pressure variability as a consequence of limiting baroreflex efficiency.
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Affiliation(s)
- Igor Noll Guagnoni
- Department of Biological Sciences, São Paulo State University (UNESP), Rua Cristóvão Colombo, 2265, São José do Rio Preto, SP 15054-000, Brazil
- National Institute of Science and Technology in Comparative Physiology (INCT - FAPESP/CNPq), São Paulo, SP 13506-900, Brazil
| | - Vinicius Araújo Armelin
- Department of Biological Sciences, São Paulo State University (UNESP), Rua Cristóvão Colombo, 2265, São José do Rio Preto, SP 15054-000, Brazil
- National Institute of Science and Technology in Comparative Physiology (INCT - FAPESP/CNPq), São Paulo, SP 13506-900, Brazil
- Department of Physiology, Institute of Biosciences (IB), University of São Paulo (USP), São Paulo, SP 05508-090, Brazil
| | - Victor Hugo da Silva Braga
- Department of Biological Sciences, São Paulo State University (UNESP), Rua Cristóvão Colombo, 2265, São José do Rio Preto, SP 15054-000, Brazil
- National Institute of Science and Technology in Comparative Physiology (INCT - FAPESP/CNPq), São Paulo, SP 13506-900, Brazil
| | - Diana Amaral Monteiro
- Department of Physiological Sciences, Federal University of São Carlos (UFSCar), Rodovia Washington Luiz, km 235, São Carlos, SP 13565-905, Brazil
| | - Luiz Henrique Florindo
- Department of Biological Sciences, São Paulo State University (UNESP), Rua Cristóvão Colombo, 2265, São José do Rio Preto, SP 15054-000, Brazil
- National Institute of Science and Technology in Comparative Physiology (INCT - FAPESP/CNPq), São Paulo, SP 13506-900, Brazil
- Department of Physiological Sciences, Federal University of São Carlos (UFSCar), Rodovia Washington Luiz, km 235, São Carlos, SP 13565-905, Brazil
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Olejnickova V, Hamor PU, Janacek J, Bartos M, Zabrodska E, Sankova B, Kvasilova A, Kolesova H, Sedmera D. Development of ventricular trabeculae affects electrical conduction in the early endothermic heart. Dev Dyn 2024; 253:78-90. [PMID: 36400745 DOI: 10.1002/dvdy.552] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2022] [Revised: 11/09/2022] [Accepted: 11/09/2022] [Indexed: 11/20/2022] Open
Abstract
BACKGROUND The ventricular trabeculae play a role, among others, in the impulse spreading in ectothermic hearts. Despite the morphological similarity with the early developing hearts of endotherms, this trabecular function in mammalian and avian embryos was poorly addressed. RESULTS We simulated impulse propagation inside the looping ventricle and revealed delayed apical activation in the heart with inhibited trabecular growth. This finding was corroborated by direct imaging of the endocardial surface showing early activation within the trabeculae implying preferential spreading of depolarization along with them. Targeting two crucial pathways of trabecular formation (Neuregulin/ErbB and Nkx2.5), we showed that trabecular development is also essential for proper conduction patterning. Persistence of the slow isotropic conduction likely contributed to the pumping failure in the trabeculae-deficient hearts. CONCLUSIONS Our results showed the essential role of trabeculae in intraventricular impulse spreading and conduction patterning in the early endothermic heart. Lack of trabeculae leads to the failure of conduction parameters differentiation resulting in primitive ventricular activation with consequent impact on the cardiac pumping function.
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Affiliation(s)
- Veronika Olejnickova
- Institute of Anatomy, First Faculty of Medicine, Charles University, Prague, Czech Republic
- Laboratory of Developmental Cardiology, Institute of Physiology, Czech Academy of Sciences, Prague, Czech Republic
| | - Peter Uriel Hamor
- Institute of Anatomy, First Faculty of Medicine, Charles University, Prague, Czech Republic
| | - Jiri Janacek
- Laboratory of Biomathematics, Institute of Physiology, Czech Academy of Sciences, Prague, Czech Republic
| | - Martin Bartos
- Institute of Anatomy, First Faculty of Medicine, Charles University, Prague, Czech Republic
- Department of Stomatology, General University Hospital in Prague, First Faculty of Medicine, Charles University, Prague, Czech Republic
| | - Eva Zabrodska
- Institute of Anatomy, First Faculty of Medicine, Charles University, Prague, Czech Republic
| | - Barbora Sankova
- Institute of Anatomy, First Faculty of Medicine, Charles University, Prague, Czech Republic
| | - Alena Kvasilova
- Institute of Anatomy, First Faculty of Medicine, Charles University, Prague, Czech Republic
| | - Hana Kolesova
- Institute of Anatomy, First Faculty of Medicine, Charles University, Prague, Czech Republic
- Laboratory of Developmental Cardiology, Institute of Physiology, Czech Academy of Sciences, Prague, Czech Republic
| | - David Sedmera
- Institute of Anatomy, First Faculty of Medicine, Charles University, Prague, Czech Republic
- Laboratory of Developmental Cardiology, Institute of Physiology, Czech Academy of Sciences, Prague, Czech Republic
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Gondim ML, Rocha HNM, Mira PAC, Nobrega ACL, Prodel E. Effects of alpha-adrenergic receptor blockade on coronary circulation in postmenopausal women. Eur J Appl Physiol 2023; 123:2779-2790. [PMID: 37368136 DOI: 10.1007/s00421-023-05267-4] [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: 01/31/2023] [Accepted: 06/19/2023] [Indexed: 06/28/2023]
Abstract
We sought to investigate the effect of the α1-adrenergic receptor blockade during handgrip exercise (Grip), isolated metaboreflex activation (Metabo), and cold pressor test (CPT) on coronary circulation in young (YW) and postmenopausal women (PMW). Ten YW and 9 PMW underwent two protocols: (1) 3 min of baseline followed by 3 min of CPT and (2) 3 min of rest, 3 min of Grip followed by 3 min of Metabo. Protocols were carried out under control conditions and α1-adrenergic receptor blockade (oral prazosin 0.03 mg·kg-1). Coronary blood velocity (CBV) and vascular conductance (CCI) were lower in PMW. Grip increased CBV only in YW (YW: Δ18.0 ± 21.1% vs. PMW: Δ4.2 ± 10.1%; p < 0.05), and the blockade did not change the CBV response to Grip in YW and PMW. During the Metabo, CBV returned to resting levels in YW and was unchanged from rest in PMW, before (YW:Δ1.7 ± 8.7% vs. PMW: Δ- 1.5 ± 8.6) and under the blockade (YW: Δ4.5 ± 14.8% vs. PMW: Δ9.1 ± 29.5%). CPT did not change CBV in both groups (YW: Δ3.9 ± 8.0 vs. PMW: Δ- 4.1 ± 6.2%), following the α1-blockade, CPT increased CBV only in YW (YW: Δ11.2 ± 12.8% vs. PMW: Δ2.2 ± 7.1%; p < 0.05 for group and condition). CCI decreased during Grip, Metabo, and CPT in YW and PMW, while the blockade prevented that decrease only in YW. The α1-adrenergic receptor plays a role in the control of coronary circulation in young women, evoking stronger vasoconstriction during CPT than Grip and Metabo in YW. PMW have impaired vasomotor control in the coronary circulation, which seems not to be caused by the α1-adrenergic receptor.
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Affiliation(s)
- Maitê L Gondim
- Laboratory of Exercise Science, Department of Physiology and Pharmacology, Fluminense Federal University, Niterói, Brazil
| | - Helena N M Rocha
- Laboratory of Exercise Science, Department of Physiology and Pharmacology, Fluminense Federal University, Niterói, Brazil
- Laboratory of Integrative Cardiometabology, Department of Physiology and Pharmacology, Fluminense Federal University, Niterói, Brazil
| | - Pedro A C Mira
- Laboratory of Exercise Science, Department of Physiology and Pharmacology, Fluminense Federal University, Niterói, Brazil
| | - Antonio C L Nobrega
- Laboratory of Exercise Science, Department of Physiology and Pharmacology, Fluminense Federal University, Niterói, Brazil
| | - Eliza Prodel
- Laboratory of Exercise Science, Department of Physiology and Pharmacology, Fluminense Federal University, Niterói, Brazil.
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Smith B, Crossley JL, Conner J, Elsey RM, Wang T, Crossley DA. Exposure to hypoxia during embryonic development affects blood flow patterns and heart rate in juvenile American alligators during digestion. Comp Biochem Physiol A Mol Integr Physiol 2023; 282:111440. [PMID: 37169243 DOI: 10.1016/j.cbpa.2023.111440] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2022] [Revised: 05/08/2023] [Accepted: 05/08/2023] [Indexed: 05/13/2023]
Abstract
The developmental environment can alter an organism's phenotype through epigenetic mechanisms. We incubated eggs from American alligators in 10% O2 (hypoxia) to investigate the functional plasticity of blood flow patterns in response to feeding later in life. Digestion is associated with marked elevations of metabolism, and we therefore used the feeding-induced stimulation of tissue O2 demand to determine whether there are lasting effects of developmental hypoxia on the cardiovascular response to digestion later in life. In all animals studied, digestion elicited tachycardia and an elevation of blood flow in the right aorta, left aorta, and the pulmonary artery, whereas flows in the carotid and subclavian artery did not change. We found that heart rate and systemic blood flow remained elevated for a longer time period in juvenile alligators that had been incubated in hypoxia; we also found that the pulmonary blood flow was elevated at 24, 36, and 48 h. Collectively, our findings demonstrate that exposure to hypoxia during incubation has lasting effects on the hemodynamics of juvenile alligators 4 years after hatching.
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Affiliation(s)
- Brandt Smith
- University of North Texas, Department of Biological Sciences, 1155 Union Circle, Denton, TX 76203, USA
| | - Janna L Crossley
- University of North Texas, Department of Biological Sciences, 1155 Union Circle, Denton, TX 76203, USA; Department of Surgery, Center for Organogenesis and Trauma, University of Texas Southwestern, TX 75390, USA
| | - Justin Conner
- University of North Texas, Department of Biological Sciences, 1155 Union Circle, Denton, TX 76203, USA
| | - Ruth M Elsey
- Louisiana Department of Wildlife and Fisheries, Rockefeller Wildlife Refuge, Grand Chenier, LA 70643, USA
| | - Tobias Wang
- Department of Biology- Zoophysiology, Aarhus University, Aarhus C, Denmark
| | - Dane A Crossley
- University of North Texas, Department of Biological Sciences, 1155 Union Circle, Denton, TX 76203, USA.
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Tavares D, da Silva Matos SLB, Duran LM, Castro SA, Taylor EW, Filogonio R, Fernandes MN, Leite CA. Baroreflex responses of decerebrate rattlesnakes (Crotalus durissus) are comparable to awake animals. Comp Biochem Physiol A Mol Integr Physiol 2022; 273:111286. [DOI: 10.1016/j.cbpa.2022.111286] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2022] [Revised: 07/29/2022] [Accepted: 08/02/2022] [Indexed: 11/30/2022]
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Joyce W, Pan YK, Garvey K, Saxena V, Perry S. Regulation of heart rate following genetic deletion of the ß1 adrenergic receptor in larval zebrafish. Acta Physiol (Oxf) 2022; 235:e13849. [PMID: 35665450 PMCID: PMC9539580 DOI: 10.1111/apha.13849] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2022] [Revised: 05/17/2022] [Accepted: 06/01/2022] [Indexed: 12/01/2022]
Abstract
Aim Although zebrafish are gaining popularity as biomedical models of cardiovascular disease, our understanding of their cardiac control mechanisms is fragmentary. Our goal was to clarify the controversial role of the ß1‐adrenergic receptor (AR) in the regulation of heart rate in zebrafish. Methods CRISPR‐Cas9 was used to delete the adrb1 gene in zebrafish allowing us to generate a stable adrb1−/− line. Larval heart rates were measured during pharmacological protocols and with exposure to hypercapnia. Expression of the five zebrafish adrb genes were measured in larval zebrafish hearts using qPCR. Results Compared with genetically matched wild‐types (adrb1+/+), adrb1−/− larvae exhibited ~20 beats min−1 lower heart rate, measured from 2 to 21 days post‐fertilization (dpf). Nevertheless, adrb1−/− larvae exhibited preserved positive chronotropic responses to pharmacological treatment with AR agonists (adrenaline, noradrenaline, isoproterenol), which were blocked by propranolol (general ß‐AR antagonist). Regardless of genotype, larvae exhibited similar increases in heart rate in response to hypercapnia (1% CO2) at 5 dpf, but tachycardia was blunted in adrb1−/− larvae at 6 dpf. adrb1 gene expression was abolished in the hearts of adrb1−/− larvae, confirming successful knockout. While gene expression of adrb2a and adrb3a was unchanged, adrb2b and adrb3b mRNA levels increased in adrb1−/− larval hearts. Conclusion Despite adrb1 contributing to the setting of resting heart rate in larvae, it is not strictly essential for zebrafish, as we generated a viable and breeding adrb1−/− line. The chronotropic effects of adrenergic stimulation persist in adrb1−/− zebrafish, likely due to the upregulation of other ß‐AR subtypes.
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Affiliation(s)
- William Joyce
- Department of Biology University of Ottawa Ottawa Ontario Canada
- Department of Biology – Zoophysiology Aarhus Universitet Aarhus C Denmark
| | - Yihang K. Pan
- Department of Biology University of Ottawa Ottawa Ontario Canada
| | - Kayla Garvey
- Department of Biology University of Ottawa Ottawa Ontario Canada
| | - Vishal Saxena
- Department of Biology University of Ottawa Ottawa Ontario Canada
| | - Steve F. Perry
- Department of Biology University of Ottawa Ottawa Ontario Canada
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Joyce W, Wang T. Regulation of heart rate in vertebrates during hypoxia: A comparative overview. Acta Physiol (Oxf) 2022; 234:e13779. [PMID: 34995393 DOI: 10.1111/apha.13779] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2021] [Revised: 11/12/2021] [Accepted: 01/01/2022] [Indexed: 12/18/2022]
Abstract
Acute exposure to low oxygen (hypoxia) places conflicting demands on the heart. Whilst an increase in heart rate (tachycardia) may compensate systemic oxygen delivery as arterial oxygenation falls, the heart itself is an energetically expensive organ that may benefit from slowing (bradycardia) to reduce work when oxygen is limited. Both strategies are apparent in vertebrates, with tetrapods (mammals, birds, reptiles, and amphibians) classically exhibiting hypoxic tachycardia and fishes displaying characteristic hypoxic bradycardia. With a richer understanding of the ontogeny and evolution of the responses, however, we see similarities in the underlying mechanisms between vertebrate groups. For example, in adult mammals, primary bradycardia results from the hypoxic stimulation of carotid body chemoreceptors that are overwhelmed by mechano-sensory feedback from the lung associated with hyperpnoea. Fish-like bradycardia prevails in the mammalian foetus (which, at this stage, is incapable of pulmonary ventilation), and in fish and foetus alike, the bradycardia ensues despite an elevation of circulating catecholamines. In both cases, the reduced heart rate may primarily serve to protect the heart. Thus, the comparative perspective offers fundamental insight into how and why different vertebrates regulate heart rate in different ways during periods of hypoxia.
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Affiliation(s)
- William Joyce
- Department of Biology—Zoophysiology Aarhus University Aarhus C Denmark
| | - Tobias Wang
- Department of Biology—Zoophysiology Aarhus University Aarhus C Denmark
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9
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Smith B, Crossley DA, Wang T, Joyce W. No evidence for pericardial restraint in the snapping turtle (Chelydra serpentina) following pharmacologically-induced bradycardia at rest or during exercise. Am J Physiol Regul Integr Comp Physiol 2022; 322:R389-R399. [PMID: 35200048 PMCID: PMC9018006 DOI: 10.1152/ajpregu.00004.2022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Most animals elevate cardiac output during exercise through a rise in heart rate (fH), whilst stroke volume (VS) remains relatively unchanged. Cardiac pacing reveals that elevating fH alone does not alter cardiac output, which is instead largely regulated by the peripheral vasculature. In terms of myocardial oxygen demand, an increase in fH is more costly than that which would incur if VS instead were to increase. We hypothesized that fH must increase because any substantial rise in VS would be constrained by the pericardium. To investigate this hypothesis, we explored the effects of pharmacologically-induced bradycardia, with ivabradine treatment, on VS at rest and during exercise in the common snapping turtle (Chelydra serpentina) with intact or opened pericardium. We first showed that, in isolated myocardial preparations, ivabradine exerted a pronounced positive inotropic effect on atrial tissue, but only minor effects on ventricle. Ivabradine reduced fH in vivo, such that exercise tachycardia was attenuated. Pulmonary and systemic VS rose in response to ivabradine. The rise in pulmonary VS largely compensated for the bradycardia at rest, leaving total pulmonary flow unchanged by ivabradine, although ivabradine reduced pulmonary blood flow during swimming (exercise x ivabradine interaction, P<0.05). Although systemic VS increased, systemic blood flow was reduced by ivabradine both at rest and during exercise, in spite of ivabradine's potential to increase cardiac contractility. Opening the pericardium had no effect on fH, VS or blood flows before or after ivabradine, indicating that the pericardium does not constrain VS in turtles, even during pharmacologically-induced bradycardia.
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Affiliation(s)
- Brandt Smith
- Department of Biological Sciences, University of North Texas, Denton, TX, United States
| | - Dane A Crossley
- Department of Biological Sciences, University of North Texas, Denton, TX, United States
| | - Tobias Wang
- Department of Biology- Zoophysiology, Aarhus University, Aarhus C, Denmark
| | - William Joyce
- Department of Biology- Zoophysiology, Aarhus University, Aarhus C, Denmark
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Travers G, Kippelen P, Trangmar SJ, González-Alonso J. Physiological Function during Exercise and Environmental Stress in Humans-An Integrative View of Body Systems and Homeostasis. Cells 2022; 11:383. [PMID: 35159193 PMCID: PMC8833916 DOI: 10.3390/cells11030383] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2021] [Revised: 01/18/2022] [Accepted: 01/19/2022] [Indexed: 11/26/2022] Open
Abstract
Claude Bernard's milieu intérieur (internal environment) and the associated concept of homeostasis are fundamental to the understanding of the physiological responses to exercise and environmental stress. Maintenance of cellular homeostasis is thought to happen during exercise through the precise matching of cellular energetic demand and supply, and the production and clearance of metabolic by-products. The mind-boggling number of molecular and cellular pathways and the host of tissues and organ systems involved in the processes sustaining locomotion, however, necessitate an integrative examination of the body's physiological systems. This integrative approach can be used to identify whether function and cellular homeostasis are maintained or compromised during exercise. In this review, we discuss the responses of the human brain, the lungs, the heart, and the skeletal muscles to the varying physiological demands of exercise and environmental stress. Multiple alterations in physiological function and differential homeostatic adjustments occur when people undertake strenuous exercise with and without thermal stress. These adjustments can include: hyperthermia; hyperventilation; cardiovascular strain with restrictions in brain, muscle, skin and visceral organs blood flow; greater reliance on muscle glycogen and cellular metabolism; alterations in neural activity; and, in some conditions, compromised muscle metabolism and aerobic capacity. Oxygen supply to the human brain is also blunted during intense exercise, but global cerebral metabolism and central neural drive are preserved or enhanced. In contrast to the strain seen during severe exercise and environmental stress, a steady state is maintained when humans exercise at intensities and in environmental conditions that require a small fraction of the functional capacity. The impact of exercise and environmental stress upon whole-body functions and homeostasis therefore depends on the functional needs and differs across organ systems.
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Affiliation(s)
- Gavin Travers
- The European Astronaut Centre, The European Space Agency, Linder Höhe, 51147 Cologne, Germany;
| | - Pascale Kippelen
- Centre for Human Performance, Exercise and Rehabilitation, Brunel University London, Uxbridge UB8 3PH, UK;
- Division of Sport, Health and Exercise Sciences, Department of Life Sciences, Brunel University London, Uxbridge UB8 3PH, UK
| | - Steven J. Trangmar
- School of Life and Health Sciences, University of Roehampton, London SW15 4JD, UK;
| | - José González-Alonso
- Centre for Human Performance, Exercise and Rehabilitation, Brunel University London, Uxbridge UB8 3PH, UK;
- Division of Sport, Health and Exercise Sciences, Department of Life Sciences, Brunel University London, Uxbridge UB8 3PH, UK
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Wang T, Abe AS, Cruz-Neto AP, Andrade DV, Taylor EW. Maintained barostatic regulation of heart rate in digesting snakes (Boa constrictor). J Exp Biol 2021; 224:271931. [PMID: 34427663 DOI: 10.1242/jeb.242202] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2020] [Accepted: 08/18/2021] [Indexed: 02/03/2023]
Abstract
When snakes digest large meals, heart rate is accelerated by withdrawal of vagal tone and an increased non-adrenergic-non-cholinergic tone that seems to stem from circulating blood-borne factors exerting positive chronotropic effects. To investigate whether this tonic elevation of heart rate impairs the ability for autonomic regulation of heart during digestion, we characterised heart rate responses to pharmacological manipulation of blood pressure in the snake Boa constrictor through serial injections of sodium nitroprusside and phenylephrine. Both fasting and digesting snakes responded with a robust tachycardia to hypotension induced by sodium nitroprusside, with digesting snakes attaining higher maximal heart rates than fasting snakes. Both fasting and digesting snakes exhibited small reductions of the cardiac chronotropic response to hypertension, induced by injection of phenylephrine. All heart rate changes were abolished by autonomic blockade with the combination of atropine and propranolol. The digesting snakes retained the capacity for compensatory heart rate responses to hypotension, despite their higher resting values, and the upward shift of the barostatic response curve enables snakes to maintain the cardiac limb of barostatic regulation for blood pressure regulation.
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Affiliation(s)
- Tobias Wang
- Zoophysiology, Department of Biology, Aarhus University, 8000 Aarhus C, Denmark.,Department of Biodiversity, State University of São Paulo, PO BOX 199 13506-900, Rio Claro, Sao Paulo, Brazil
| | - Augusto S Abe
- Department of Biodiversity, State University of São Paulo, PO BOX 199 13506-900, Rio Claro, Sao Paulo, Brazil
| | - Ariovaldo P Cruz-Neto
- Department of Biodiversity, State University of São Paulo, PO BOX 199 13506-900, Rio Claro, Sao Paulo, Brazil
| | - Denis V Andrade
- Department of Biodiversity, State University of São Paulo, PO BOX 199 13506-900, Rio Claro, Sao Paulo, Brazil
| | - Edwin W Taylor
- Department of Biodiversity, State University of São Paulo, PO BOX 199 13506-900, Rio Claro, Sao Paulo, Brazil.,School of Biosciences, The University of Birmingham, Edgbaston B15 2TT, England
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Filice M, Cerra MC, Imbrogno S. The goldfish Carassius auratus: an emerging animal model for comparative cardiac research. J Comp Physiol B 2021; 192:27-48. [PMID: 34455483 PMCID: PMC8816371 DOI: 10.1007/s00360-021-01402-9] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2021] [Revised: 08/09/2021] [Accepted: 08/18/2021] [Indexed: 12/12/2022]
Abstract
The use of unconventional model organisms is significantly increasing in different fields of research, widely contributing to advance life sciences understanding. Among fishes, the cyprinid Carassius auratus (goldfish) is largely used for studies on comparative and evolutionary endocrinology, neurobiology, adaptive and conservation physiology, as well as for translational research aimed to explore mechanisms that may be useful in an applicative biomedical context. More recently, the research possibilities offered by the goldfish are further expanded to cardiac studies. A growing literature is available to illustrate the complex networks involved in the modulation of the goldfish cardiac performance, also in relation to the influence of environmental signals. However, an overview on the existing current knowledge is not yet available. By discussing the mechanisms that in C. auratus finely regulate the cardiac function under basal conditions and under environmental challenges, this review highlights the remarkable flexibility of the goldfish heart in relation not only to the basic morpho-functional design and complex neuro-humoral traits, but also to its extraordinary biochemical-metabolic plasticity and its adaptive potential. The purpose of this review is also to emphasize the power of the heart of C. auratus as an experimental tool useful to investigate mechanisms that could be difficult to explore using more conventional animal models and complex cardiac designs.
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Affiliation(s)
- Mariacristina Filice
- Department of Biology, Ecology and Earth Sciences, University of Calabria, 87036, Arcavacata di Rende, CS, Italy.
| | - Maria Carmela Cerra
- Department of Biology, Ecology and Earth Sciences, University of Calabria, 87036, Arcavacata di Rende, CS, Italy
| | - Sandra Imbrogno
- Department of Biology, Ecology and Earth Sciences, University of Calabria, 87036, Arcavacata di Rende, CS, Italy
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13
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Baroreflex responses to activity at different temperatures in the South American rattlesnake, Crotalus durissus. J Comp Physiol B 2021; 191:917-925. [PMID: 34363512 DOI: 10.1007/s00360-021-01396-4] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2021] [Revised: 07/15/2021] [Accepted: 07/30/2021] [Indexed: 10/20/2022]
Abstract
In humans, physical exercise imposes narrower limits for the heart rate (fH) response of the baroreflex, and vascular modulation becomes largely responsible for arterial pressure regulation. In undisturbed reptiles, the baroreflex-related fH alterations at the operating point (Gop) decreases at elevated body temperatures (Tb) and the vascular regulation changes accordingly. We investigated how the baroreflex of rattlesnakes, Crotalus durissus, is regulated during an activity at different Tb, expecting that activity would reduce the capacity of the cardiac baroreflex neural pathway to buffer arterial pressure fluctuations while being compensated by the vascular neural pathway regulation. Snakes were catheterized for blood pressure assessment at three different Tb: 15, 20 and 30 °C. Data were collected before and after activity at each Tb. Baroreflex gain (Gop) was assessed with the sequence method; the vascular limb, with the time constant of pressure decay (τ), using the two-element Windkessel equation. Both Gop and τ reduced when Tb increased. Activity also reduced Gop and τ in all Tb. The relationship between τ and pulse interval (τ/PI) was unaffected by the temperature at resting snakes, albeit it reduced after activity at 20 °C and 30 °C. The unchanged τ/PI and normalized Gop at different Tb indicated those variables are actively adjusted to work at different fH and pressure conditions at rest. Our data suggest that during activity, the baroreflex-related fH response is attenuated and hypertension is buffered by a disproportional increase in the rate which pressure decays during diastole. This compensation seems especially important at higher Tb where Gop is already low.
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14
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Joyce W, Perry SF. Hif-1α is not required for the development of cardiac adrenergic control in zebrafish (Danio rerio). JOURNAL OF EXPERIMENTAL ZOOLOGY PART 2021; 335:623-631. [PMID: 34288573 DOI: 10.1002/jez.2507] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/26/2021] [Revised: 06/23/2021] [Accepted: 07/01/2021] [Indexed: 12/23/2022]
Abstract
Adrenergic regulation, acting via the sympathetic nervous system, provides a major mechanism to control cardiac function. It has recently been shown that hypoxia inducible factor-1α (Hif-1α) is necessary for normal development of sympathetic innervation and control of cardiac function in the mouse. To investigate whether this may represent a fundamental trait shared across vertebrates, we assessed adrenergic regulation of the heart in wild-type and Hif-1α knockout (hif-1α -/- ) zebrafish (Danio rerio). Wild-type and hif-1α -/- zebrafish larvae (aged 4 and 7 days postfertilisation) exhibited similar routine heart rates within a given age group, and β-adrenergic receptor blockade with propranolol universally reduced heart rate to comparable levels, indicating similar adrenergic tone in both genotypes. In adult fish, in vivo heart rate measured during anaesthesia was identical between genotypes. Treatment of spontaneously beating hearts in vitro with adrenaline revealed a similar positive chronotropic effect and similar maximum heart rates in both genotypes. Tyrosine hydroxylase immunohistochemistry with confocal microscopy demonstrated that the bulbus arteriosus (outflow tract of the teleost heart) of adult fish was particularly well innervated by sympathetic nerves, and nerve density (as a percentage of bulbus arteriosus area) was similar between wild-types and hif-1α -/- mutants. In summary, we did not find any evidence that adrenergic cardiac control was perturbed in larval or adult zebrafish lacking Hif-1α. We conclude that Hif-1α is not essential for the normal development of cardiovascular control or adult sympathetic cardiac innervation in zebrafish, although it is possible that it plays a redundant or auxiliary role.
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Affiliation(s)
- William Joyce
- Department of Biology, University of Ottawa, Ottawa, Ontario, Canada.,Department of Biology-Zoophysiology, Aarhus University, Aarhus C, Denmark
| | - Steve F Perry
- Department of Biology, University of Ottawa, Ottawa, Ontario, Canada
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15
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O'Brien KM, Joyce W, Crockett EL, Axelsson M, Egginton S, Farrell AP. Resilience of cardiac performance in Antarctic notothenioid fishes in a warming climate. J Exp Biol 2021; 224:268390. [PMID: 34042975 DOI: 10.1242/jeb.220129] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Warming in the region of the Western Antarctic Peninsula is occurring at an unprecedented rate, which may threaten the survival of Antarctic notothenioid fishes. Herein, we review studies characterizing thermal tolerance and cardiac performance in notothenioids - a group that includes both red-blooded species and the white-blooded, haemoglobinless icefishes - as well as the relevant biochemistry associated with cardiac failure during an acute temperature ramp. Because icefishes do not feed in captivity, making long-term acclimation studies unfeasible, we focus only on the responses of red-blooded notothenioids to warm acclimation. With acute warming, hearts of the white-blooded icefish Chaenocephalus aceratus display persistent arrhythmia at a lower temperature (8°C) compared with those of the red-blooded Notothenia coriiceps (14°C). When compared with the icefish, the enhanced cardiac performance of N. coriiceps during warming is associated with greater aerobic capacity, higher ATP levels, less oxidative damage and enhanced membrane integrity. Cardiac performance can be improved in N. coriiceps with warm acclimation to 5°C for 6-9 weeks, accompanied by an increase in the temperature at which cardiac failure occurs. Also, both cardiac mitochondrial and microsomal membranes are remodelled in response to warm acclimation in N. coriiceps, displaying homeoviscous adaptation. Overall, cardiac performance in N. coriiceps is malleable and resilient to warming, yet thermal tolerance and plasticity vary among different species of notothenioid fishes; disruptions to the Antarctic ecosystem driven by climate warming and other anthropogenic activities endanger the survival of notothenioids, warranting greater protection afforded by an expansion of marine protected areas.
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Affiliation(s)
- Kristin M O'Brien
- Institute of Arctic Biology , University of Alaska Fairbanks, Fairbanks, AK 99775-7000, USA
| | - William Joyce
- Department of Biology - Zoophysiology, Aarhus University, 8000 Aarhus C, Denmark
| | | | - Michael Axelsson
- Department of Biological and Environmental Sciences, University of Gothenburg, 40530 Gothenburg, Sweden
| | - Stuart Egginton
- School of Biomedical Sciences , University of Leeds, Leeds LS2 9JT, UK
| | - Anthony P Farrell
- Department of Zoology, and Faculty of Land and Food Systems, University of British Columbia, Vancouver, BC, Canada, V6T 1Z4
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16
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Wang T, Rindom E. The physiological response to digestion in snakes: A feast for the integrative physiologist. Comp Biochem Physiol A Mol Integr Physiol 2021; 254:110891. [DOI: 10.1016/j.cbpa.2020.110891] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2020] [Revised: 12/28/2020] [Accepted: 12/28/2020] [Indexed: 02/06/2023]
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17
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Lopes AG, Monteiro DA, Kalinin AL. Effects of change in temperature on the cardiac contractility of broad-snouted caiman (Caiman latirostris) during digestion. JOURNAL OF EXPERIMENTAL ZOOLOGY PART 2021; 335:417-425. [PMID: 33773091 DOI: 10.1002/jez.2457] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/06/2021] [Revised: 03/12/2021] [Accepted: 03/13/2021] [Indexed: 11/07/2022]
Abstract
In many reptiles, digestion has been associated with the selection of higher body temperatures, the so-called post-prandial thermophilic response. This study aimed to investigate the excitation-contraction (E-C) coupling in postprandial broad-snouted caimans (Caiman latirostris) in response to acute warming within a preferred body temperature range of crocodiles. Isometric preparations subjected to a temperature transition from 25°C to 30°C were used to investigate myocardial contractility of postprandial caimans, that is, 48 h after the animals ingested a rodent meal corresponding to 15% of body mass. The caiman heart exhibits a negative force-frequency relationship that is independent of the temperature. At 25°C, cardiac muscle was able to maintain a constant force up to 36 bpm, above which it decreased significantly, reaching minimum values at the highest frequency of 84 bpm. Moreover, E-C coupling is predominantly dependent on transsarcolemmal Ca2+ transport denoted by the lack of significant ryanodine effects on force generation. On the contrary, ventricular strips at 30°C were able to sustain the cardiac contractility at higher pacing frequencies (from 12 to 144 bpm) due to an important role of Na+ /Ca2+ exchanger in Ca2+ cycling, as indicated by the decay of the post-rest contraction, and a significant contribution of the sarcoplasmic reticulum above 72 bpm. Our results demonstrated that the myocardium of postprandial caimans exhibits a significant degree of thermal plasticity of E-C coupling during acute warming. Therefore, myocardial contractility can be maximized when postprandial broad-snouted caimans select higher body temperatures (preferred temperature zone) following feeding.
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Affiliation(s)
- André G Lopes
- Department of Physiological Sciences, Federal University of São Carlos, São Carlos, São Paulo, Brazil.,Joint Graduate Program in Physiological Sciences, Federal University of São Carlos-UFSCar/São Paulo State University, UNESP Campus Araraquara, Araraquara, São Paulo, Brazil
| | - Diana A Monteiro
- Department of Physiological Sciences, Federal University of São Carlos, São Carlos, São Paulo, Brazil
| | - Ana L Kalinin
- Department of Physiological Sciences, Federal University of São Carlos, São Carlos, São Paulo, Brazil
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18
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Joyce W, Wang T. How cardiac output is regulated: August Krogh's proto-Guytonian understanding of the importance of venous return. Comp Biochem Physiol A Mol Integr Physiol 2021; 253:110861. [DOI: 10.1016/j.cbpa.2020.110861] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2020] [Revised: 11/25/2020] [Accepted: 11/25/2020] [Indexed: 12/20/2022]
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19
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Nørgaard S, Joyce W, Jensen MF, Enok S, Skovgaard N, Wang T. Histamine exerts both direct H 2-mediated and indirect catecholaminergic effects on heart rate in pythons. J Comp Physiol B 2021; 191:347-355. [PMID: 33474644 DOI: 10.1007/s00360-020-01338-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2019] [Revised: 12/22/2020] [Accepted: 12/30/2020] [Indexed: 11/25/2022]
Abstract
The vertebrate heart is regulated by excitatory adrenergic and inhibitory cholinergic innervations, as well as non-adrenergic non-cholinergic (NANC) factors that may be circulating in the blood or released from the autonomic nerves. As an example of NANC signaling, an increased histaminergic tone, acting through stimulation of H2 receptors, contributes markedly to the rise in heart rate during digestion in pythons. In addition to the direct effects of histamine, it is also known that histamine can reinforce the cholinergic and adrenergic signaling. Thus, to further our understanding of the histaminergic regulation of the cardiovascular response in pythons, we designed a series of in vivo experiments complemented by in vitro experiments on sinoatrial and vascular ring preparations. We demonstrate the tachycardic mechanism of histamine works partly through a direct binding of cardiac H2 receptors and in part through a myocardial histamine-induced catecholamine release, which strengthens the sympathetic adrenergic signaling pathway.
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Affiliation(s)
- Simon Nørgaard
- Department of Biology, Aarhus University, C.F. Møllers Allé 3, building 1131, 8000, Aarhus C, Denmark
| | - William Joyce
- Department of Biology, Aarhus University, C.F. Møllers Allé 3, building 1131, 8000, Aarhus C, Denmark
| | - Maja Fuhlendorff Jensen
- Department of Biology, Aarhus University, C.F. Møllers Allé 3, building 1131, 8000, Aarhus C, Denmark
| | - Sanne Enok
- Department of Biology, Aarhus University, C.F. Møllers Allé 3, building 1131, 8000, Aarhus C, Denmark
| | - Nini Skovgaard
- Department of Biology, Aarhus University, C.F. Møllers Allé 3, building 1131, 8000, Aarhus C, Denmark
| | - Tobias Wang
- Department of Biology, Aarhus University, C.F. Møllers Allé 3, building 1131, 8000, Aarhus C, Denmark.
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20
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Britto-Júnior J, Fernandes Jacintho F, Campos R, Pinheiro DHA, Figueiredo Murari GM, de Souza VB, Schenka AA, Mónica FZ, Moreno RA, Antunes E, De Nucci G. The basal release of endothelium-derived catecholamines regulates the contractions of Chelonoidis carbonaria aorta caused by electrical-field stimulation. Biol Open 2021; 10:bio.057042. [PMID: 33277238 PMCID: PMC7847266 DOI: 10.1242/bio.057042] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
The contractions of Chelonoidis carbonaria aortic rings induced by electrical field stimulation (EFS) are not inhibited by blockade of the voltage-gated sodium channels by tetrodotoxin but almost abolished by the α1/α2-adrenoceptor antagonist phentolamine. The objective of this study was to identify the mediator(s) responsible for the EFS-induced contractions of Chelonoidis carbonaria aortic rings. Each ring was suspended between two wire hooks and mounted in isolated 10 ml organ chambers filled with oxygenated and heated Krebs-Henseleit's solution. Dopamine, noradrenaline and adrenaline concentrations were analysed by liquid chromatography coupled to tandem mass spectrometry. The contractions caused by dopamine and EFS were done in absence and presence of the nitric oxide (NO) synthesis inhibitor L-NAME, the NO-sensitive guanylyl cyclase inhibitor ODQ, the D1-like receptor antagonist SCH-23390, the D2-like receptor antagonists risperidone, quetiapine, haloperidol, and the tyrosine hydroxylase inhibitors salsolinol and 3-iodo-L-tyrosine. Basal concentrations of dopamine, noradrenaline and adrenaline were detected in Krebs-Henseleit solution containing the aortic rings. The catecholamine concentrations were significantly reduced in endothelium-denuded aortic rings. L-NAME and ODQ significantly potentiated the dopamine-induced contractions. The D2-like receptor antagonists inhibited the EFS-induced contractions of the aortic rings treated with L-NAME, whereas SCH 23390 had no effect. Similar results were observed in the contractions induced by dopamine in L-NAME treated aortic rings. These results indicate that catecholamines released by endothelium regulate the EFS-induced contractions. This may constitute a suitable mechanism by which reptilia modulate specific organ blood flow distribution. This paper has an associated First Person interview with the first author of the article. Summary:Chelonoidis carbonaria aortic rings release endothelium-derived catecholamines that modulate vascular smooth muscle reactivity.
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Affiliation(s)
- José Britto-Júnior
- Faculty of Medical Sciences, Department of Pharmacology, University of Campinas (UNICAMP), Campinas 13083-894, Brazil
| | - Felipe Fernandes Jacintho
- Faculty of Medical Sciences, Department of Pharmacology, University of Campinas (UNICAMP), Campinas 13083-894, Brazil
| | - Rafael Campos
- Department of Physiology, Superior Institute of Biomedical Sciences, Ceará State University (UECE), Fortaleza 60714-903, Brazil
| | - David Halen Araújo Pinheiro
- Faculty of Medical Sciences, Department of Pharmacology, University of Campinas (UNICAMP), Campinas 13083-894, Brazil
| | - Guilherme M Figueiredo Murari
- Faculty of Medical Sciences, Department of Pharmacology, University of Campinas (UNICAMP), Campinas 13083-894, Brazil
| | - Valéria B de Souza
- Faculty of Medical Sciences, Department of Pharmacology, University of Campinas (UNICAMP), Campinas 13083-894, Brazil
| | - André A Schenka
- Faculty of Medical Sciences, Department of Pharmacology, University of Campinas (UNICAMP), Campinas 13083-894, Brazil
| | - Fabíola Z Mónica
- Faculty of Medical Sciences, Department of Pharmacology, University of Campinas (UNICAMP), Campinas 13083-894, Brazil
| | - Ronilson Agnaldo Moreno
- Faculty of Medical Sciences, Department of Pharmacology, University of Campinas (UNICAMP), Campinas 13083-894, Brazil
| | - Edson Antunes
- Faculty of Medical Sciences, Department of Pharmacology, University of Campinas (UNICAMP), Campinas 13083-894, Brazil
| | - Gilberto De Nucci
- Faculty of Medical Sciences, Department of Pharmacology, University of Campinas (UNICAMP), Campinas 13083-894, Brazil.,Department of Pharmacology, Institute of Biomedical Sciences, University of São Paulo, São Paulo 05508-060, Brazil
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21
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Joyce W, Axelsson M. Regulation of splenic contraction persists as a vestigial trait in white-blooded Antarctic fishes. JOURNAL OF FISH BIOLOGY 2021; 98:287-291. [PMID: 33090461 DOI: 10.1111/jfb.14579] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/07/2020] [Revised: 09/30/2020] [Accepted: 10/05/2020] [Indexed: 06/11/2023]
Abstract
In fishes, the spleen can function as an important reservoir for red blood cells (RBCs), which, following splenic contraction, may be released into the circulation to increase haematocrit during energy-demanding activities. This trait is particularly pronounced in red-blooded Antarctic fishes in which the spleen can sequester a large proportion of RBCs during rest, thereby reducing blood viscosity, which may serve as an adaptation to life in cold environments. In one species, Pagothenia borchgrevinki, it has previously been shown that splenic contraction primarily depends on cholinergic stimulation. The aim of the present study was to investigate the regulation of splenic contraction in five other Antarctic fish species, three red-blooded notothenioids (Dissostichus mawsoni Norman, 1937, Gobionotothen gibberifrons Lönnberg, 1905, Notothenia coriiceps Richardson 1844) and two white-blooded "icefish" (Chaenocephalus aceratus Lönnberg, 1906 and Champsocephalus gunnari Lönnberg, 1905), which lack haemoglobin and RBCs, but nevertheless possess a large spleen. In all species, splenic strips constricted in response to both cholinergic (carbachol) and adrenergic (adrenaline) agonists. Surprisingly, in the two species of icefish, the spleen responded with similar sensitivity to red-blooded species, despite contraction being of little obvious benefit for releasing RBCs into the circulation. Although the icefish lineage lost functional haemoglobin before diversifying over the past 7.8-4.8 millions of years, they retain the capacity to contract the spleen, likely as a vestige inherited from their red-blooded ancestors.
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Affiliation(s)
- William Joyce
- Department of Biology - Zoophysiology, Aarhus University, Aarhus, Denmark
- Department of Biology, University of Ottawa, Ottawa, Ontario, Canada
| | - Michael Axelsson
- Department of Biological and Environmental Sciences, University of Gothenburg, Gothenburg, Sweden
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22
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Joyce W, Scholman KT, Jensen B, Wang T, Boukens BJ. α 1-adrenergic stimulation increases ventricular action potential duration in the intact mouse heart. Facets (Ott) 2021. [DOI: 10.1139/facets-2020-0081] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The role of α1-adrenergic receptors (α-ARs) in the regulation of myocardial function is less well-understood than that of β-ARs. Previous reports in the mouse heart have described that α1-adrenergic stimulation shortens action potential duration in isolated cells or tissues, in contrast to prolongation of the action potential reported in most other mammalian hearts. It has since become appreciated, however, that the mouse heart exhibits marked variation in inotropic response to α1-adrenergic stimulation between ventricles and even individual cardiomyocytes. We investigated the effects of α1-adrenergic stimulation on action potential duration at 80% of repolarization in the right and left ventricles of Langendorff-perfused mouse hearts using optical mapping. In hearts under β-adrenergic blockade (propranolol), phenylephrine or noradrenaline perfusion both increased action potential duration in both ventricles. The increased action potential duration was partially reversed by subsequent perfusion with the α-adrenergic antagonist phentolamine (1 μmol L−1). These data show that α1-receptor stimulation may lead to a prolonging of action potential in the mouse heart and thereby refine our understanding of how action potential duration adjusts during sympathetic stimulation.
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Affiliation(s)
- William Joyce
- Department of Biology—Zoophysiology, Aarhus University, DK-8000 Aarhus C, Denmark
- Department of Biology, University of Ottawa, 30 Marie Curie, Ottawa, ON K1N 6N5, Canada
| | - Koen T. Scholman
- Department of Medical Biology, Amsterdam Cardiovascular Sciences, Amsterdam University Medical Centers, 11005 AZ Amsterdam, the Netherlands
| | - Bjarke Jensen
- Department of Medical Biology, Amsterdam Cardiovascular Sciences, Amsterdam University Medical Centers, 11005 AZ Amsterdam, the Netherlands
| | - Tobias Wang
- Department of Biology—Zoophysiology, Aarhus University, DK-8000 Aarhus C, Denmark
| | - Bastiaan J. Boukens
- Department of Medical Biology, Amsterdam Cardiovascular Sciences, Amsterdam University Medical Centers, 11005 AZ Amsterdam, the Netherlands
- Department of Experimental Cardiology, Amsterdam Cardiovascular Sciences, Amsterdam University Medical Centers, 1100 DD Amsterdam, the Netherlands
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23
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Travers G, González-Alonso J, Riding N, Nichols D, Shaw A, Périard JD. Exercise heat acclimation has minimal effects on left ventricular volumes, function and systemic hemodynamics in euhydrated and dehydrated trained humans. Am J Physiol Heart Circ Physiol 2020; 319:H965-H979. [DOI: 10.1152/ajpheart.00466.2020] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
This study demonstrates that 10 days of exercise heat acclimation has minimal effects on left ventricular volumes, intrinsic cardiac function, and systemic hemodynamics during prolonged, repeated semirecumbent exercise in moderate heat, where heart rate and blood volume are similar to preacclimation levels. However, progressive dehydration is consistently associated with similar degrees of hyperthermia and tachycardia and reductions in blood volume, diastolic filling of the left ventricle, stroke volume, and cardiac output, regardless of acclimation state.
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Affiliation(s)
- Gavin Travers
- Athlete Health and Performance Research Centre, Aspetar Orthopaedic and Sports Medicine Hospital, Doha, Qatar
- Centre for Human Performance, Exercise and Rehabilitation, College of Health, Medicine and Life Sciences, Brunel University London, Uxbridge, United Kingdom
- Division of Sport, Health and Exercise Sciences, Department of Life Sciences, College of Health, Medicine and Life Sciences, Brunel University London, Uxbridge, United Kingdom
| | - José González-Alonso
- Centre for Human Performance, Exercise and Rehabilitation, College of Health, Medicine and Life Sciences, Brunel University London, Uxbridge, United Kingdom
- Division of Sport, Health and Exercise Sciences, Department of Life Sciences, College of Health, Medicine and Life Sciences, Brunel University London, Uxbridge, United Kingdom
| | - Nathan Riding
- Athlete Health and Performance Research Centre, Aspetar Orthopaedic and Sports Medicine Hospital, Doha, Qatar
| | - David Nichols
- Sport Development Centre, Loughborough University, Loughborough, United Kingdom
| | - Anthony Shaw
- Athlete Health and Performance Research Centre, Aspetar Orthopaedic and Sports Medicine Hospital, Doha, Qatar
| | - Julien D. Périard
- Athlete Health and Performance Research Centre, Aspetar Orthopaedic and Sports Medicine Hospital, Doha, Qatar
- University of Canberra Research Institute for Sport and Exercise, University of Canberra, Bruce, Australia
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24
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van Loon LM, van der Hoeven H, Veltink PH, Lemson J. The inspiration hold maneuver is a reliable method to assess mean systemic filling pressure but its clinical value remains unclear. ANNALS OF TRANSLATIONAL MEDICINE 2020; 8:1390. [PMID: 33313135 PMCID: PMC7723632 DOI: 10.21037/atm-20-3540] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Background The upstream pressure for venous return (VR) is considered to be a combined conceptual blood pressure of the systemic vessels: the mean systemic filling pressure (MSFP). The relevance of estimating the MSFP during dynamic changes of the circulation at the bedside is controversial. Herein, we studied the effect of high ventilatory pressures on the relationship between VR and central venous pressure (CVP). Methods In 9 healthy pigs under anaesthesia and mechanically ventilated, MSFP was estimated from extrapolated VR versus CVP relationships during inspiratory hold maneuvers (IHMs) with different levels of ventilatory pressure (Pvent). MSFP was measure 3 times per animal during euvolemia and hypovolemia. Hypovolemia was induced by bleeding with 10 mL/kg. The estimated MSFP values were compared to the blood pressure recording after induced ventricle fibrillation (i.e., mean circulatory filling pressure). Results Our results revealed a strong linear correlation between VR and CVP [R2 of 0.92 (range, 0.67–0.99)], during IHMs with different levels of Pvent. Volume status significantly alters the resulting MSFP, 20±1 and 16±2 mmHg for euvolemia and hypovolemia respectively. This estimation of the MSFP was strongly correlated—but not interchangeable—to the blood pressure recording after induced ventricle fibrillation (R2=0.8 and P=0.045). Conclusions In conclusion, we showed a strong linear correlation between VR and CVP—when applying IHMs with high levels of Pvent—however the clinical applicability of this method to guide volume therapy in its current form is improbable.
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Affiliation(s)
- Lex M van Loon
- Cardiovascular and Respiratory Physiology Group, Faculty of Science and Technology, Technical Medical Centre, University of Twente, Enschede, The Netherlands.,Department of Intensive Care Medicine, Radboud university medical center, Nijmegen, The Netherlands
| | - Hans van der Hoeven
- Department of Intensive Care Medicine, Radboud university medical center, Nijmegen, The Netherlands.,Radboud Center for Infectious Diseases, Nijmegen, The Netherlands
| | - Peter H Veltink
- Biomedical Signals and Systems, Faculty of Electrical Engineering, Mathematics and Computer Science, Technical Medical Centre, University of Twente, Enschede, The Netherlands
| | - Joris Lemson
- Department of Intensive Care Medicine, Radboud university medical center, Nijmegen, The Netherlands
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25
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Filogonio R, Sartori MR, Morgensen S, Tavares D, Campos R, Abe AS, Taylor EW, Rodrigues GJ, De Nucci G, Simonsen U, Leite CAC, Wang T. Cholinergic regulation along the pulmonary arterial tree of the South American rattlesnake: vascular reactivity, muscarinic receptors, and vagal innervation. Am J Physiol Regul Integr Comp Physiol 2020; 319:R156-R170. [DOI: 10.1152/ajpregu.00310.2019] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
Vascular tone in the reptilian pulmonary vasculature is primarily under cholinergic, muscarinic control exerted via the vagus nerve. This control has been ascribed to a sphincter located at the arterial outflow, but we speculated whether the vascular control in the pulmonary artery is more widespread, such that responses to acetylcholine and electrical stimulation, as well as the expression of muscarinic receptors, are prevalent along its length. Working on the South American rattlesnake ( Crotalus durissus), we studied four different portions of the pulmonary artery (truncus, proximal, distal, and branches). Acetylcholine elicited robust vasoconstriction in the proximal, distal, and branch portions, but the truncus vasodilated. Electrical field stimulation (EFS) caused contractions in all segments, an effect partially blocked by atropine. We identified all five subtypes of muscarinic receptors (M1–M5). The expression of the M1 receptor was largest in the distal end and branches of the pulmonary artery, whereas expression of the muscarinic M3 receptor was markedly larger in the truncus of the pulmonary artery. Application of the neural tracer 1,1′-dioctadecyl-3,3,3′,3′-tetramethylindo-carbocyanine perchlorate (DiI) revealed widespread innervation along the whole pulmonary artery, and retrograde transport of the same tracer indicated two separate locations in the brainstem providing vagal innervation of the pulmonary artery, the medial dorsal motor nucleus of the vagus and a ventro-lateral location, possibly constituting a nucleus ambiguus. These results revealed parasympathetic innervation of a large portion of the pulmonary artery, which is responsible for regulation of vascular conductance in C. durissus, and implied its integration with cardiorespiratory control.
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Affiliation(s)
- Renato Filogonio
- Zoophysiology, Department of Bioscience, Aarhus University, Aarhus, Denmark
- Department of Physiological Sciences, Federal University of São Carlos, São Carlos, Brazil
| | - Marina R. Sartori
- Department of Zoology, State University of São Paulo, Rio Claro, São Paulo, Brazil
| | - Susie Morgensen
- Department of Biomedicine, Pulmonary, and Cardiovascular Pharmacology, Aarhus University, Aarhus, Denmark
| | - Driele Tavares
- Department of Physiological Sciences, Federal University of São Carlos, São Carlos, Brazil
| | - Rafael Campos
- Superior Institute of Biomedical Sciences, Ceará State University, Fortaleza, Brazil
| | - Augusto S. Abe
- Department of Zoology, State University of São Paulo, Rio Claro, São Paulo, Brazil
| | - Edwin W. Taylor
- Department of Physiological Sciences, Federal University of São Carlos, São Carlos, Brazil
- School of Biosciences, University of Birmingham, Birmingham, United Kingdom
| | - Gerson J. Rodrigues
- Department of Physiological Sciences, Federal University of São Carlos, São Carlos, Brazil
| | - Gilberto De Nucci
- Faculty of Medical Sciences, Department of Pharmacology, University of Campinas, Campinas, Brazil
| | - Ulf Simonsen
- Department of Biomedicine, Pulmonary, and Cardiovascular Pharmacology, Aarhus University, Aarhus, Denmark
| | - Cléo A. C. Leite
- Department of Physiological Sciences, Federal University of São Carlos, São Carlos, Brazil
| | - Tobias Wang
- Zoophysiology, Department of Bioscience, Aarhus University, Aarhus, Denmark
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Affiliation(s)
- William Joyce
- Zoophysiology, Department of Bioscience, Aarhus University, 8000 Aarhus C, Denmark .,Department of Biology, University of Ottawa, 30 Marie Curie, Ottawa, ON K1N 6N5, Canada
| | - Tobias Wang
- Zoophysiology, Department of Bioscience, Aarhus University, 8000 Aarhus C, Denmark
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Watanabe K, Stöhr EJ, Akiyama K, Watanabe S, González‐Alonso J. Dehydration reduces stroke volume and cardiac output during exercise because of impaired cardiac filling and venous return, not left ventricular function. Physiol Rep 2020; 8:e14433. [PMID: 32538549 PMCID: PMC7294577 DOI: 10.14814/phy2.14433] [Citation(s) in RCA: 33] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2020] [Accepted: 04/12/2020] [Indexed: 12/17/2022] Open
Abstract
Dehydration accrued during intense prolonged whole-body exercise in the heat compromises peripheral blood flow and cardiac output ( Q ˙ ). A markedly reduced stroke volume (SV) is a key feature of the dehydration-induced cardiovascular strain, but whether the lower output of the heart is mediated by peripheral or cardiac factors remains unknown. Therefore, we repeatedly quantified left ventricular (LV) volumes, LV mechanics (LV twist, a marker of systolic muscle function, and LV untwisting rate, an independent marker of LV muscle relaxation), left intra-ventricular pressure gradients, blood volume and peripheral blood flow during 2 hr of cycling in the heat with and without dehydration (DEH: 4.0 ± 0.2% body mass loss and EUH: euhydration control, respectively) in eight participants (three females and five males). While brachial and carotid blood flow, blood volume, SV, LV end-diastolic volume (LVEDV), cardiac filling time, systemic vascular conductance and Q ˙ were reduced in DEH compared to EUH after 2 hr, LV twist and untwisting rate tended to be higher (p = .09 and .06, respectively) and intra-ventricular pressure gradients were not different between the two conditions (p = .22). Furthermore, LVEDV in DEH correlated strongly with blood volume (r = .995, p < .01), head and forearms beat volume (r = .98, p < .05), and diastolic LV filling time (r = .98, p < .05). These findings suggest that the decline in SV underpinning the blunted Q ˙ with exercise-induced dehydration is caused by compromised LV filling and venous return, but not intrinsic systolic or diastolic LV function.
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Affiliation(s)
- Kazuhito Watanabe
- Centre for Human Performance, Exercise and RehabilitationBrunel University LondonUxbridgeUK
- Faculty of Education and Human StudiesAkita UniversityAkitaJapan
| | - Eric J. Stöhr
- Cardiff School of Sport and Health SciencesCardiff Metropolitan UniversityCardiffUK
- Department of MedicineDivision of CardiologyColumbia University Irving Medical CenterNew York CityNYUSA
| | - Koichi Akiyama
- Department of AnesthesiologyYodogawa Christian HospitalOsakaJapan
| | - Sumie Watanabe
- Centre for Human Performance, Exercise and RehabilitationBrunel University LondonUxbridgeUK
| | - José González‐Alonso
- Centre for Human Performance, Exercise and RehabilitationBrunel University LondonUxbridgeUK
- Division of Sport, Health and Exercise SciencesDepartment of Life SciencesBrunel University LondonUxbridgeUK
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28
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Affiliation(s)
- William Joyce
- Zoophysiology, Department of Bioscience, Aarhus University, 8000 Aarhus C, Denmark .,Department of Biology, University of Ottawa, 30 Marie Curie, Ottawa, ON K1N 6N5, Canada
| | - Tobias Wang
- Zoophysiology, Department of Bioscience, Aarhus University, 8000 Aarhus C, Denmark
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Affiliation(s)
- Rafael Dalmau
- Department of Anesthesiology, Hospital Español de Rosario, S2001SBL Rosario, Argentina
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