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Mechanisms of Fluoride Toxicity: From Enzymes to Underlying Integrative Networks. APPLIED SCIENCES-BASEL 2020. [DOI: 10.3390/app10207100] [Citation(s) in RCA: 30] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Fluoride has been employed in laboratory investigations since the early 20th century. These studies opened the understanding of fluoride interventions to fundamental biological processes. Millions of people living in endemic fluorosis areas suffer from various pathological disturbances. The practice of community water fluoridation used prophylactically against dental caries increased concern of adverse fluoride effects. We assessed the publications on fluoride toxicity until June 2020. We present evidence that fluoride is an enzymatic poison, inducing oxidative stress, hormonal disruptions, and neurotoxicity. Fluoride in synergy with aluminum acts as a false signal in G protein cascades of hormonal and neuronal regulations in much lower concentrations than fluoride acting alone. Our review shows the impact of fluoride on human health. We suggest focusing the research on fluoride toxicity to the underlying integrative networks. Ignorance of the pluripotent toxic effects of fluoride might contribute to unexpected epidemics in the future.
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Venous thrombosis at altitude presents with distinct biochemical profiles: a comparative study from the Himalayas to the plains. Blood Adv 2020; 3:3713-3723. [PMID: 31765479 DOI: 10.1182/bloodadvances.2018024554] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2018] [Accepted: 10/22/2019] [Indexed: 11/20/2022] Open
Abstract
High-altitude (HA) hypoxia exposure is believed to induce venous thromboembolism (VTE) in otherwise healthy individuals, although this needs to be fully established. The present study aims to ascertain the role of HA exposure in aggravating any predisposition toward VTE and to explore whether the etiology of HA-induced VTE is different from that of VTE closer to sea level. We compared manifestation-matched male VTE patients from HA (HAPs) and VTE patients from the plains closer to sea level (SLPs) for 54 parameters, including coagulation-related, fibrinolytic, and thrombophilic variables, as well as markers for stress and inflammatory response and platelet and endothelial activation. Our results established an association between HA hypoxia and VTE in alterations of primarily hemostatic variables. Approximately 96% of HAPs presented with ≥10 altered parameters out of 54 studied compared with 7% of SLPs. Elevated platelet count, von Willebrand factor, and clotting factors and altered coagulation exhibited significant associations with VTE events and altitude exposure (all P < .05). Additionally, most VTEs at HA were associated with younger age groups, unlike those on the plains. A receiver operator characteristic curve analysis revealed differences between HAPs and SLPs for CD40 ligand (area under the curve [AUC], 0.90; 95% confidence interval [CI], 0.84-0.96]), P-selectin (0.79; 0.70-0.88), platelet factor-4 (0.90; 0.84-0.96), intracellular adhesion molecule-1 (0.86; 0.79-0.93), vascular cell adhesion molecule-1 (0.97; 0.95-0.99), vascular endothelial growth factor (0.87; 0.8-0.94), FLT4 (0.94; 0.89-0.99), and Toll-like receptor-2 (0.98; 0.96-1.0) (all P < .05). In conclusion, this study suggests that HA exposure perturbs the molecules associated with vascular integrity and contributes to the early onset of VTE.
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Papoušek F, Sedmera D, Neckář J, Ošťádal B, Kolář F. Left ventricular function and remodelling in rats exposed stepwise up to extreme chronic intermittent hypoxia. Respir Physiol Neurobiol 2020; 282:103526. [PMID: 32805421 DOI: 10.1016/j.resp.2020.103526] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2020] [Revised: 07/20/2020] [Accepted: 08/10/2020] [Indexed: 11/30/2022]
Abstract
The main aim was to find out whether long-lasting stepwise exposure to extreme hypoxia affects left ventricular (LV) geometry and systolic function. Adult male rats were exposed to intermittent hypobaric hypoxia (8 h/day) with increasing altitude in steps of 1000 m every 3 weeks up to 8000 m. While the LV cavity diastolic diameter did not change over the whole range of hypoxia, the wall thickness increased significantly at the altitude of 8000 m. LV fractional shortening ranged between 48.1 % and 50.1 % and remained unaffected even at the most severe hypoxia. At the end of experiment, haematocrit reached 83 %, mean systemic arterial pressure 120 % and relative LV weight 154 % of normoxic values while RV systolic pressure and relative RV weight doubled. Myocyte hypertrophy and myocardial fibrosis were more pronounced in RV than in LV. In conclusion, LV systolic function was preserved after chronic stepwise exposure of rats to extreme intermittent hypoxia despite moderate concentric hypertrophy and myocardial remodelling.
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Affiliation(s)
- František Papoušek
- Laboratory of Developmental Cardiology, Institute of Physiology of the Czech Academy of Sciences, Prague, Czech Republic
| | - David Sedmera
- Laboratory of Developmental Cardiology, Institute of Physiology of the Czech Academy of Sciences, Prague, Czech Republic; Institute of Anatomy, First Faculty of Medicine, Charles University, Prague, Czech Republic
| | - Jan Neckář
- Laboratory of Developmental Cardiology, Institute of Physiology of the Czech Academy of Sciences, Prague, Czech Republic
| | - Bohuslav Ošťádal
- Laboratory of Developmental Cardiology, Institute of Physiology of the Czech Academy of Sciences, Prague, Czech Republic
| | - František Kolář
- Laboratory of Developmental Cardiology, Institute of Physiology of the Czech Academy of Sciences, Prague, Czech Republic.
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4
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Tibenska V, Benesova A, Vebr P, Liptakova A, Hejnová L, Elsnicová B, Drahota Z, Hornikova D, Galatík F, Kolar D, Vybiral S, Alánová P, Novotný J, Kolar F, Novakova O, Zurmanova JM. Gradual cold acclimation induces cardioprotection without affecting β-adrenergic receptor-mediated adenylyl cyclase signaling. J Appl Physiol (1985) 2020; 128:1023-1032. [DOI: 10.1152/japplphysiol.00511.2019] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Novel strategies are needed that can stimulate endogenous signaling pathways to protect the heart from myocardial infarction. The present study tested the hypothesis that appropriate regimen of cold acclimation (CA) may provide a promising approach for improving myocardial resistance to ischemia/reperfusion (I/R) injury without negative side effects. We evaluated myocardial I/R injury, mitochondrial swelling, and β-adrenergic receptor (β-AR)-adenylyl cyclase-mediated signaling. Male Wistar rats were exposed to CA (8°C, 8 h/day for a week, followed by 4 wk at 8°C for 24 h/day), while the recovery group (CAR) was kept at 24°C for an additional 2 wk. The myocardial infarction induced by coronary occlusion for 20 min followed by 3-h reperfusion was reduced from 56% in controls to 30% and 23% after CA and CAR, respectively. In line, the rate of mitochondrial swelling at 200 μM Ca2+ was decreased in both groups. Acute administration of metoprolol decreased infarction in control group and did not affect the CA-elicited cardiprotection. Accordingly, neither β1-AR-Gsα-adenylyl cyclase signaling, stimulated with specific ligands, nor p-PKA/PKA ratios were affected after CA or CAR. Importantly, Western blot and immunofluorescence analyses revealed β2- and β3-AR protein enrichment in membranes in both experimental groups. We conclude that gradual cold acclimation results in a persisting increase of myocardial resistance to I/R injury without hypertension and hypertrophy. The cardioprotective phenotype is associated with unaltered adenylyl cyclase signaling and increased mitochondrial resistance to Ca2+-overload. The potential role of upregulated β2/β3-AR pathways remains to be elucidated. NEW & NOTEWORTHY We present a new model of mild gradual cold acclimation increasing tolerance to myocardial ischemia/reperfusion injury without hypertension and hypertrophy. Cardioprotective phenotype is accompanied by unaltered adenylyl cyclase signaling and increased mitochondrial resistance to Ca2+-overload. The potential role of upregulated β2/β3-adrenoreceptor activation is considered. These findings may stimulate the development of novel preventive and therapeutic strategies against myocardial ischemia/reperfusion injury.
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Affiliation(s)
- V. Tibenska
- Department of Physiology, Faculty of Science, Charles University, Prague, Czech Republic
| | - A. Benesova
- Department of Physiology, Faculty of Science, Charles University, Prague, Czech Republic
| | - P. Vebr
- Department of Physiology, Faculty of Science, Charles University, Prague, Czech Republic
| | - A. Liptakova
- Department of Physiology, Faculty of Science, Charles University, Prague, Czech Republic
| | - L. Hejnová
- Department of Physiology, Faculty of Science, Charles University, Prague, Czech Republic
| | - B. Elsnicová
- Department of Physiology, Faculty of Science, Charles University, Prague, Czech Republic
| | - Z. Drahota
- Institute of Physiology of the Czech Academy of Sciences, Prague, Czech Republic
| | - D. Hornikova
- Department of Physiology, Faculty of Science, Charles University, Prague, Czech Republic
| | - F. Galatík
- Department of Physiology, Faculty of Science, Charles University, Prague, Czech Republic
| | - D. Kolar
- Department of Physiology, Faculty of Science, Charles University, Prague, Czech Republic
| | - S. Vybiral
- Department of Physiology, Faculty of Science, Charles University, Prague, Czech Republic
| | - P. Alánová
- Institute of Physiology of the Czech Academy of Sciences, Prague, Czech Republic
| | - J. Novotný
- Department of Physiology, Faculty of Science, Charles University, Prague, Czech Republic
| | - F. Kolar
- Institute of Physiology of the Czech Academy of Sciences, Prague, Czech Republic
| | - O. Novakova
- Department of Physiology, Faculty of Science, Charles University, Prague, Czech Republic
- Institute of Physiology of the Czech Academy of Sciences, Prague, Czech Republic
| | - J. M. Zurmanova
- Department of Physiology, Faculty of Science, Charles University, Prague, Czech Republic
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5
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Sikarwar AS, Hinton M, Santhosh KT, Dhanaraj P, Talabis M, Chelikani P, Dakshinamurti S. Hypoxia inhibits adenylyl cyclase catalytic activity in a porcine model of persistent pulmonary hypertension of the newborn. Am J Physiol Lung Cell Mol Physiol 2018; 315:L933-L944. [PMID: 30234376 DOI: 10.1152/ajplung.00130.2018] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Persistent pulmonary hypertension of the newborn (PPHN) features hypoxemia, pulmonary vasoconstriction, and impaired cardiac inotropy. We previously reported low basal and stimulated cAMP in hypoxic pulmonary artery smooth muscle cells (PASMCs). We now examine pulmonary arterial adenylyl cyclase (AC) activity and regulation in hypoxic PPHN. PPHN was induced in newborn swine by normobaric hypoxia (fraction of inspired oxygen 0.10) for 72 h and compared with age-matched normoxic controls. We studied relaxation of pulmonary arterial (PA) rings to AC activator forskolin and cGMP activator sodium nitroprusside (SNP) by isometric myography, ATP content, phosphodiesterase activity, AC content, isoform expression, and catalytic activity in presence or absence of Gαs-coupled receptor agonists, forskolin, or transnitrosylating agents in human and neonatal porcine PASMCs and HEK293T stably expressing AC isoform 6, after 72 h hypoxia (10% O2) or normoxia (21% O2). Relaxation to forskolin and SNP were equally impaired in PPHN PA. AC-specific activity decreased in hypoxia. PASMC from PPHN swine had reduced AC activity despite exposure to normoxia in culture; transient hypoxia in vitro further decreased AC activity. Prostacyclin receptor ligand affinity decreased, but its association with Gαs increased in hypoxia. Total AC content was unchanged by hypoxia, but AC6 increased in hypoxic cells and PPHN pulmonary arteries. Impairment of AC6 activity in hypoxia was associated with nitrosylation. PPHN PA relaxation is impaired because of loss of AC activity. Hypoxic AC is inhibited because of S-nitrosylation; inhibition persists after removal from hypoxia. Downregulation of AC-mediated relaxation in hypoxic PA has implications for utility of Gαs-coupled receptor agonists in PPHN treatment.
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Affiliation(s)
- A S Sikarwar
- Biology of Breathing Group, Children's Hospital Research Institute of Manitoba , Winnipeg , Canada.,Department of Physiology, University of Manitoba , Winnipeg , Canada.,Department of Oral Biology, University of Manitoba , Winnipeg , Canada
| | - M Hinton
- Biology of Breathing Group, Children's Hospital Research Institute of Manitoba , Winnipeg , Canada
| | - K T Santhosh
- Biology of Breathing Group, Children's Hospital Research Institute of Manitoba , Winnipeg , Canada
| | - P Dhanaraj
- Biology of Breathing Group, Children's Hospital Research Institute of Manitoba , Winnipeg , Canada.,Department of Oral Biology, University of Manitoba , Winnipeg , Canada
| | - M Talabis
- Biology of Breathing Group, Children's Hospital Research Institute of Manitoba , Winnipeg , Canada
| | - P Chelikani
- Biology of Breathing Group, Children's Hospital Research Institute of Manitoba , Winnipeg , Canada.,Department of Oral Biology, University of Manitoba , Winnipeg , Canada
| | - S Dakshinamurti
- Biology of Breathing Group, Children's Hospital Research Institute of Manitoba , Winnipeg , Canada.,Department of Physiology, University of Manitoba , Winnipeg , Canada.,Department of Pediatrics, University of Manitoba , Winnipeg , Canada
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Hahnova K, Brabcova I, Neckar J, Weissova R, Svatonova A, Novakova O, Zurmanova J, Kalous M, Silhavy J, Pravenec M, Kolar F, Novotny J. β-Adrenergic signaling, monoamine oxidase A and antioxidant defence in the myocardium of SHR and SHR-mtBN conplastic rat strains: the effect of chronic hypoxia. J Physiol Sci 2018; 68:441-454. [PMID: 28567570 PMCID: PMC10717553 DOI: 10.1007/s12576-017-0546-8] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2017] [Accepted: 05/23/2017] [Indexed: 01/24/2023]
Abstract
The β-adrenergic signaling pathways and antioxidant defence mechanisms play important roles in maintaining proper heart function. Here, we examined the effect of chronic normobaric hypoxia (CNH, 10% O2, 3 weeks) on myocardial β-adrenergic signaling and selected components of the antioxidant system in spontaneously hypertensive rats (SHR) and in a conplastic SHR-mtBN strain characterized by the selective replacement of the mitochondrial genome of SHR with that of the more ischemia-resistant Brown Norway strain. Our investigations revealed some intriguing differences between the two strains at the level of β-adrenergic receptors (β-ARs), activity of adenylyl cyclase (AC) and monoamine oxidase A (MAO-A), as well as distinct changes after CNH exposure. The β2-AR/β1-AR ratio was significantly higher in SHR-mtBN than in SHR, apparently due to increased expression of β2-ARs. Adaptation to hypoxia elevated β2-ARs in SHR and decreased the total number of β-ARs in SHR-mtBN. In parallel, the ability of isoprenaline to stimulate AC activity was found to be higher in SHR-mtBN than that in SHR. Interestingly, the activity of MAO-A was notably lower in SHR-mtBN than in SHR, and it was markedly elevated in both strains after exposure to hypoxia. In addition to that, CNH markedly enhanced the expression of catalase and aldehyde dehydrogenase-2 in both strains, and decreased the expression of Cu/Zn superoxide dismutase in SHR. Adaptation to CNH intensified oxidative stress to a similar extent in both strains and elevated the IL-10/TNF-α ratio in SHR-mtBN only. These data indicate that alterations in the mitochondrial genome can result in peculiar changes in myocardial β-adrenergic signaling, MAO-A activity and antioxidant defence and may, thus, affect the adaptive responses to hypoxia.
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Affiliation(s)
- Klara Hahnova
- Department of Physiology, Faculty of Science, Charles University, Prague, Czech Republic
| | - Iveta Brabcova
- Department of Physiology, Faculty of Science, Charles University, Prague, Czech Republic
| | - Jan Neckar
- Institute of Physiology, Czech Academy of Sciences, Prague, Czech Republic
| | - Romana Weissova
- Institute of Physiology, Czech Academy of Sciences, Prague, Czech Republic
| | - Anna Svatonova
- Institute of Physiology, Czech Academy of Sciences, Prague, Czech Republic
| | - Olga Novakova
- Department of Physiology, Faculty of Science, Charles University, Prague, Czech Republic
| | - Jitka Zurmanova
- Department of Physiology, Faculty of Science, Charles University, Prague, Czech Republic
| | - Martin Kalous
- Department of Cell Biology, Faculty of Science, Charles University, Prague, Czech Republic
| | - Jan Silhavy
- Institute of Physiology, Czech Academy of Sciences, Prague, Czech Republic
| | - Michal Pravenec
- Institute of Physiology, Czech Academy of Sciences, Prague, Czech Republic
| | - Frantisek Kolar
- Institute of Physiology, Czech Academy of Sciences, Prague, Czech Republic
| | - Jiri Novotny
- Department of Physiology, Faculty of Science, Charles University, Prague, Czech Republic.
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7
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Prolonged Morphine Treatment Alters Expression and Plasma Membrane Distribution of β-Adrenergic Receptors and Some Other Components of Their Signaling System in Rat Cerebral Cortex. J Mol Neurosci 2017; 63:364-376. [PMID: 29081032 DOI: 10.1007/s12031-017-0987-9] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2017] [Accepted: 10/05/2017] [Indexed: 01/15/2023]
Abstract
β-Adrenergic signaling plays an important role in regulating diverse brain functions and alterations in this signaling have been observed in different neuropathological conditions. In this study, we investigated the effect of a 10-day treatment with high doses of morphine (10 mg/kg per day) on major components and functional state of the β-adrenergic receptor (β-AR) signaling system in the rat cerebral cortex. β-ARs were characterized by radioligand binding assays and amounts of various G protein subunits, adenylyl cyclase (AC) isoforms, G protein-coupled receptor kinases (GRKs), and β-arrestin were examined by Western blot analysis. AC activity was determined as a measure of functionality of the signaling system. We also assessed the partitioning of selected signaling proteins between the lipid raft and non-raft fractions prepared from cerebrocortical plasma membranes. Morphine treatment resulted in a significant upregulation of β-ARs, GRK3, and some AC isoforms (AC-I, -II, and -III). There was no change in quantity of G proteins and some other signaling molecules (AC-IV, AC-V/VI, GRK2, GRK5, GRK6, and β-arrestin) compared with controls. Interestingly, morphine exposure caused a partial redistribution of β-ARs, Gsα, Goα, and GRK2 between lipid rafts and bulk plasma membranes. Spatial localization of other signaling molecules within the plasma membrane was not changed. Basal as well as fluoride- and forskolin-stimulated AC activities were not significantly different in membrane preparations from control and morphine-treated animals. However, AC activity stimulated by the beta-AR agonist isoprenaline was markedly increased. This is the first study to demonstrate lipid raft association of key components of the cortical β-AR system and its sensitivity to morphine.
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8
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Micova P, Hahnova K, Hlavackova M, Elsnicova B, Chytilova A, Holzerova K, Zurmanova J, Neckar J, Kolar F, Novakova O, Novotny J. Chronic intermittent hypoxia affects the cytosolic phospholipase A2α/cyclooxygenase 2 pathway via β2-adrenoceptor-mediated ERK/p38 stimulation. Mol Cell Biochem 2016; 423:151-163. [DOI: 10.1007/s11010-016-2833-8] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2016] [Accepted: 09/23/2016] [Indexed: 11/30/2022]
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9
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Richalet JP. Physiological and Clinical Implications of Adrenergic Pathways at High Altitude. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2016; 903:343-56. [DOI: 10.1007/978-1-4899-7678-9_23] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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10
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Weiss M, Arendt P, Hassna R. Effect of disease states on α1 -adrenoceptor binding and signal transduction parameters in isolated perfused heart: quantification by pharmacokinetic-pharmacodynamic modelling. J Pharm Pharmacol 2013; 66:668-76. [PMID: 24237130 DOI: 10.1111/jphp.12184] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2013] [Accepted: 10/15/2013] [Indexed: 01/11/2023]
Abstract
OBJECTIVES To employ a pharmacokinetic-pharmacodynamic modelling approach for analysing the effect of experimental endotoxemia and mild hypoxia on α1 -adrenoceptor (α1 AR) binding and signal transduction. METHODS In Langendorff-perfused rat hearts, phenylephrine was continuously infused, and [(3) H]-prazosin was injected as single dose (infused over 1 min). Simultaneous analysis of the time courses of prazosin outflow concentration and inotropic response (left ventricular developed pressure) using an agonist-antagonist interaction model and nonlinear regression allowed to estimate receptor affinity, as well as the parameters of the operational model of agonism. KEY FINDINGS Both endotoxemia and hypoxia, significantly reduced the maximum response achievable in the system to 67% and 49% of the control group mean, respectively. In addition, endotoxemia decreased the efficiency of stimulus-response coupling and increased the steepness of the stimulus-response curve. In both disease models, no change in receptor affinity and density were found. CONCLUSIONS The results revealed the causes of reduced α1 AR-mediated inotropic responsiveness in endotoxemia and hypoxia. In contrast with traditional dose-response studies, it was possible to quantify separately the underlying changes in α1 AR binding and signal transduction.
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Affiliation(s)
- Michael Weiss
- Section of Pharmacokinetics, Department of Pharmacology, Martin Luther University Halle-Wittenberg, Halle (Saale), Germany
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11
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Lindgren I, Altimiras J. Prenatal hypoxia programs changes in β-adrenergic signaling and postnatal cardiac contractile dysfunction. Am J Physiol Regul Integr Comp Physiol 2013; 305:R1093-101. [PMID: 24089370 DOI: 10.1152/ajpregu.00320.2013] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Prenatal hypoxia leads to an increased risk of adult cardiovascular disease. We have previously demonstrated a programming effect of prenatal hypoxia on the cardiac β-adrenergic (βAR) response. The aim of this study was to determine 1) whether the decrease in βAR sensitivity in prenatally hypoxic 5-wk old chicken hearts is linked to changes in β1AR/β2ARs, Gαi expression and cAMP accumulation and 2) whether prenatal hypoxia has an effect on heart function in vivo. We incubated eggs in normoxia (N, 21% O2) or hypoxia from day 0 (H, 14% O2) and raised the posthatchlings to 5 wk of age. Cardiac β1AR/β2ARs were assessed through competitive binding of [(3)H]CGP-12177 with specific β1AR or β2AR blockers. Gαs and Gαi proteins were assessed by Western blot and cAMP accumulation by ELISA. Echocardiograms were recorded in anesthetized birds to evaluate diastolic/systolic diameter and heart rate and tissue sections were stained for collagen. We found an increase in relative heart mass, β1ARs, and Gαs in prenatally hypoxic hearts. cAMP levels after isoproterenol stimulation and collagen content was not changed in H compared with N, but in vivo echocardiograms showed systolic contractile dysfunction. The changes in βAR and G protein subtypes may be indicative of an early compensatory stage in the progression of cardiac dysfunction, further supported by the cardiac hypertrophy and systolic contractile dysfunction. We suggest that it is not the changes in the proximal part of the βAR system that causes the decreased cardiac contractility, but Ca(2+) handling mechanisms further downstream in the βAR signaling cascade.
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Affiliation(s)
- I Lindgren
- AVIAN Behavioural Genomics and Physiology, IFM Biology, Linköping University, Linköping, Sweden
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12
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13
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Guan Y, Gao L, Ma HJ, Li Q, Zhang H, Yuan F, Zhou ZN, Zhang Y. Chronic intermittent hypobaric hypoxia decreases β-adrenoceptor activity in right ventricular papillary muscle. Am J Physiol Heart Circ Physiol 2010; 298:H1267-72. [DOI: 10.1152/ajpheart.00410.2009] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Chronic intermittent hypobaric hypoxia (CIHH) has an effective cardiac protection against ischemia-reperfusion injury. However, the underlying mechanisms are not fully known. It has been shown that blockade of β-adrenergic receptor exerts anti-arrhythmic action and improves cardiac remodeling in ischemic myocardium. Thus we determined the influence of CIHH on β-adrenergic receptor activity in right ventricular papillary muscle of rats. We found that the action potential duration in right ventricular papillary muscle was significantly longer in CIHH rats than in control rats. Activation of β-adrenergic receptor with dl-isoproterenol dose-dependently increased action potential duration and the contractility in right ventricular papillary muscle. In CIHH rats, the prolonged effect of dl-isoproterenol on action potential duration and the positive inotropic effect were significantly decreased compared with that in control rats. Furthermore, radioligand-binding experiments revealed that the density and affinity of β-adrenergic receptor in right ventricular myocardium was significantly lower in CIHH rats. In addition, Western blot analysis revealed that the membrane-bound G protein Gsα expression level in cardiac myocardium was significantly lower in CIHH rats than that in control rats. Collectively, these data suggest that CIHH suppresses β-adrenergic receptor action in right ventricular papillary muscle through decreasing receptor density and affinity, as well as membrane-bound Gsα. This mechanism may be involved in the cardiac protective effect of CIHH.
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Affiliation(s)
- Yue Guan
- Department of Physiology, Hebei Medical University, Shijiazhuang, China; and
| | - Lu Gao
- Department of Physiology, Hebei Medical University, Shijiazhuang, China; and
| | - Hui-Jie Ma
- Department of Physiology, Hebei Medical University, Shijiazhuang, China; and
| | - Qian Li
- Department of Physiology, Hebei Medical University, Shijiazhuang, China; and
| | - Hao Zhang
- Department of Physiology, Hebei Medical University, Shijiazhuang, China; and
| | - Fang Yuan
- Department of Physiology, Hebei Medical University, Shijiazhuang, China; and
| | - Zhao-Nian Zhou
- Laboratory of Hypoxic Cardiovascular Physiology, Shanghai Institute for Biological Sciences, Chinese Academy of Sciences, Shanghai, China
| | - Yi Zhang
- Department of Physiology, Hebei Medical University, Shijiazhuang, China; and
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14
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Calbet JAL, Robach P, Lundby C. The exercising heart at altitude. Cell Mol Life Sci 2009; 66:3601-13. [PMID: 19809792 PMCID: PMC11115914 DOI: 10.1007/s00018-009-0148-6] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2009] [Accepted: 08/20/2009] [Indexed: 10/20/2022]
Abstract
Maximal cardiac output is reduced in severe acute hypoxia but also in chronic hypoxia by mechanisms that remain poorly understood. In theory, the reduction of maximal cardiac output could result from: (1) a regulatory response from the central nervous system, (2) reduction of maximal pumping capacity of the heart due to insufficient coronary oxygen delivery prior to the achievement of the normoxic maximal cardiac output, or (3) reduced central command. In this review, we focus on the effects that acute and chronic hypoxia have on the pumping capacity of the heart, particularly on myocardial contractility and the molecular responses elicited by acute and chronic hypoxia in the cardiac myocytes. Special emphasis is put on the cardioprotective effects of chronic hypoxia.
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Affiliation(s)
- José A L Calbet
- Department of Physical Education, University of Las Palmas de Gran Canaria, Campus Universitario de Tafira, 35017, Las Palmas de Gran Canaria, Canary Islands, Spain.
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15
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Lindgren I, Altimiras J. Chronic prenatal hypoxia sensitizes beta-adrenoceptors in the embryonic heart but causes postnatal desensitization. Am J Physiol Regul Integr Comp Physiol 2009; 297:R258-64. [PMID: 19458283 DOI: 10.1152/ajpregu.00167.2009] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Prenatal hypoxia in mammals causes fetal growth restriction and catecholaminergic overstimulation that, in turn, alter signaling pathways associated with adrenergic receptors. Beta-adrenoceptors (beta-ARs) are essential for fetal cardiac development and regulation of cardiac contractility. We studied the effects of chronic prenatal hypoxia on cardiac beta-AR signaling and the incidence of alterations in the juvenile beta-AR system due to the embryonic treatment. We measured functional beta-AR density (B(max)) through binding with [(3)H]CGP-12177 and the effect of agonists on beta-AR-dependent contractility (pEC(50)) through concentration-response curves to epinephrine. Eggs from broiler chickens were incubated in normoxia (N, 21% O(2)) or chronic hypoxia (H, 14% O(2)). Cardiac tissue from embryos and juveniles was used (15 and 19 day of embryonic development and 14 and 35 days posthatching, E19, E15, P14, and P35, respectively). Relative cardiac enlargement was found in the hypoxic groups at E15, E19, and P14, but not P35. B(max) significantly decreased in E19H. B(max) more than doubled posthatching but decreased from P14 to P35. The sensitivity to epinephrine was lower in E19N compared with E15N, but hypoxia increased the sensitivity to agonist in both E15H and E19H. Despite maintained receptor density, the P35H juvenile displayed a decreased sensitivity to beta-AR agonist, something that was not seen in P14H. The postnatal decrease in beta-AR sensitivity as an effect of chronic prenatal hypoxia, without a concomitant change in beta-AR density, leads us to conclude that the embryonic hypoxic challenge alters the future progression of beta-AR signaling and may have important implications for cardiovascular function in the adult.
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Affiliation(s)
- Isa Lindgren
- Department of Physics, Chemistry, and Biology (IFM), Division of Zoology, Linköping University, Linköping, Sweden
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Favret F, Richalet JP. Exercise and hypoxia: The role of the autonomic nervous system. Respir Physiol Neurobiol 2007; 158:280-6. [PMID: 17521971 DOI: 10.1016/j.resp.2007.04.001] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2007] [Revised: 03/14/2007] [Accepted: 04/05/2007] [Indexed: 10/23/2022]
Abstract
The reduction in maximal oxygen consumption in hypoxia can be due to physiological factors, the relative importance of which depends on the degree of hypoxia: the reduction in inspired PO2, the impairment of lung gas exchange contributing to an exercise-induced decrease in arterial O(2) saturation, the reduction in maximal cardiac output and the limitation in tissue diffusion. This paper focuses on two aspects of this oxygen cascade. First, the decrease in heart rate at maximal exercise in prolonged exposure to hypoxia is discussed and the role of changes in the autonomous nervous system is emphasised. The desensitization of the beta-adrenergic pathway and the upregulation of the muscarinic pathway, both using G-protein systems, contribute to limit the myocardial O(2) consumption in face of reduced O(2) availability during maximal exercise in hypoxia. The changes in O(2) diffusion to the tissues are discussed in relation to the expression of hypoxia inducible factor (HIF-1alpha) and vascular endothelial growth factor (VEGF) and their possible changes induced by training and/or hypoxic exposure.
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Affiliation(s)
- Fabrice Favret
- Université Paris 13, Laboratoire EA2363 Réponses Cellulaires et Fonctionnelles à l'hypoxie, 74 rue Marcel Cachin, Bobigny, France
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Ostadal B, Kolar F. Cardiac adaptation to chronic high-altitude hypoxia: beneficial and adverse effects. Respir Physiol Neurobiol 2007; 158:224-36. [PMID: 17442631 DOI: 10.1016/j.resp.2007.03.005] [Citation(s) in RCA: 85] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2007] [Revised: 03/06/2007] [Accepted: 03/06/2007] [Indexed: 01/28/2023]
Abstract
This review deals with the capability of the heart to adapt to chronic hypoxia in animals exposed to either natural or simulated high altitude. From the broad spectrum of related issues, we focused on the development and reversibility of both beneficial and adverse adaptive myocardial changes. Particular attention was paid to cardioprotective effects of adaptation to chronic high-altitude hypoxia and their molecular mechanisms. Moreover, interspecies and age differences in the cardiac sensitivity to hypoxia-induced effects in various experimental models were emphasized.
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Affiliation(s)
- B Ostadal
- Centre for Cardiovascular Research, Institute of Physiology, Academy of Sciences of the Czech Republic, Videnska 1083, 142 20 Prague 4, Czech Republic.
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Asanuma H, Minamino T, Ogai A, Kim J, Asakura M, Komamura K, Sanada S, Fujita M, Hirata A, Wakeno M, Tsukamoto O, Shinozaki Y, Myoishi M, Takashima S, Tomoike H, Kitakaze M. Blockade of histamine H2 receptors protects the heart against ischemia and reperfusion injury in dogs. J Mol Cell Cardiol 2006; 40:666-74. [PMID: 16603184 DOI: 10.1016/j.yjmcc.2006.02.001] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/15/2005] [Revised: 02/03/2006] [Accepted: 02/08/2006] [Indexed: 11/21/2022]
Abstract
We have previously reported that histamine H(2) blockers may be cardioprotective in patients with chronic heart failure. Since both endogenous histamine and histamine H(2) receptors are present in heart tissue, we tested the hypothesis that the blockade of histamine H(2) receptors mediates protection against reversible or irreversible ischemia and reperfusion injury. In open-chest dogs, the left anterior descending coronary artery was occluded for 90 minutes, followed by reperfusion for 6 hours. Administration of famotidine and cimetidine from 10 minutes before occlusion until after 1 hour of reperfusion reduced infarct size (17.0 +/- 4.1% and 17.8 +/- 2.9% vs. 36.9 +/- 5.9% of the solvent group, respectively) Famotidine administration only during the reperfusion period for 1 hour also attenuated infarct size (22.5 +/- 3.5%). There were no differences in either area at risk or collateral flow among the groups. In another set of experiments, we decreased coronary perfusion pressure in dogs so that the coronary blood flow decreased to 50% of the non-ischemic level. In such conditions, we observed the increases in histamine release compared with non-ischemic conditions (0.04 +/- 0.03 to 0.28 +/- 0.13 ng/ml, p < 0.05). Famotidine improved anaerobic myocardial metabolism gauged by both lactate extraction ratio and myocardial oxygen consumption. We conclude that the blockade of histamine H(2) receptors mediates improvements in the anaerobic myocardial metabolism, and thus protects against ischemia and reperfusion injury.
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Affiliation(s)
- Hiroshi Asanuma
- Cardiovascular Division, National Cardiovascular Center, Suita, Suita City, Osaka Prefacture, Tokai University School of Medicine, Isehara, Japan
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La Padula P, Costa LE. Effect of sustained hypobaric hypoxia during maturation and aging on rat myocardium. I. Mechanical activity. J Appl Physiol (1985) 2005; 98:2363-9. [PMID: 15705729 DOI: 10.1152/japplphysiol.00988.2004] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Long-lasting cardioprotection may be attained by chronic hypoxia. The basal parameters of contractile function and their response to hypoxia/reoxygenation were measured under isometric conditions, in papillary muscles isolated from left ventricle of rats that were submitted to 53.8 kPa in a hypobaric chamber from 7 wk of age and for their lifetime and of their siblings kept at 101.3 kPa. During acclimatization, hematocrit increased, body weight gain decreased, and heart weight increased with right ventricle hypertrophy. Papillary muscle cross-sectional area was similar in both control and hypoxic groups up to 45 wk of exposure. Developed tension (DT) was 34–64% higher in rats exposed to hypoxia for 10, 26, and 45 wk than in their age-matched controls, whereas resting tension was unchanged. Maximal rates of contraction and relaxation showed a similar pattern of changes as DT. Recovery of DT and maximal rates of contraction and relaxation after 60-min hypoxia and 30-min reoxygenation was also improved in adult hypoxic rats to values similar to those of young rats. Heart acclimatization was lost after 74 wk of exposure. Results are consistent with the development of cardioprotection during high-altitude acclimatization and provide an experimental model to study the mechanisms involved, which are addressed in the accompanying paper.
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Affiliation(s)
- Pablo La Padula
- Instituto de Investigaciones Cardiológicas, Marcelo T. de Alvear 2270, C1122AAJ Buenos Aires, Argentina
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Neckár J, Marková I, Novák F, Nováková O, Szárszoi O, Ost'ádal B, Kolár F. Increased expression and altered subcellular distribution of PKC-delta in chronically hypoxic rat myocardium: involvement in cardioprotection. Am J Physiol Heart Circ Physiol 2004; 288:H1566-72. [PMID: 15576445 DOI: 10.1152/ajpheart.00586.2004] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
We examined the role of protein kinase C (PKC) in the cardioprotective mechanism induced by long-term adaptation to chronic intermittent hypoxia. Adult male Wistar rats were exposed to hypobaric hypoxia of 7,000 m for 8 h/day, 5 days/wk; the total number of exposures was 24-32. A control group was kept under normoxic conditions. Western blot analysis of PKC isoforms-delta and -epsilon was performed in the cytosol and three particulate fractions of left ventricular myocardium. Infarct size was determined in open-chest animals subjected to 20-min coronary artery occlusion and 3-h reperfusion. The PKC inhibitors chelerythrine (1 or 5 mg/kg) or rottlerin (selective for PKC-delta isoform; 0.3 mg/kg) were administered intravenously as a single bolus 15 min before ischemia. Chronic hypoxia had no effect on the expression and distribution of PKC-epsilon. The relative amount of PKC-delta increased in the cytosol and nuclear-cytoskeletal, mitochondrial, and microsomal fractions of chronically hypoxic myocardium by 100%, 212%, 237%, and 146%, respectively, compared with corresponding normoxic values. Chronic hypoxia decreased the size of myocardial infarction (normalized to the area at risk) by about one-third on the average (P < 0.05). Both doses of chelerythrine tended to reduce infarction in controls, and only the high dose completely abolished the improvement of ischemic tolerance in hypoxic hearts (P < 0.05). Rottlerin attenuated the infarct size-limiting effect of chronic hypoxia (P < 0.05), and it had no effect in controls. These results suggest that chronic intermittent hypoxia-induced cardioprotection in rats is partially mediated by PKC-delta; the contribution of other isoforms remains to be determined.
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Affiliation(s)
- Jan Neckár
- Institute of Physiology, Academy of Sciences of the Czech Republic, Videnska 1083, 142 20 Prague 4, Czech Republic
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