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Moreno-Domínguez A, Colinas O, Smani T, Ureña J, López-Barneo J. Acute oxygen sensing by vascular smooth muscle cells. Front Physiol 2023; 14:1142354. [PMID: 36935756 PMCID: PMC10020353 DOI: 10.3389/fphys.2023.1142354] [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: 01/11/2023] [Accepted: 02/21/2023] [Indexed: 03/06/2023] Open
Abstract
An adequate supply of oxygen (O2) is essential for most life forms on earth, making the delivery of appropriate levels of O2 to tissues a fundamental physiological challenge. When O2 levels in the alveoli and/or blood are low, compensatory adaptive reflexes are produced that increase the uptake of O2 and its distribution to tissues within a few seconds. This paper analyzes the most important acute vasomotor responses to lack of O2 (hypoxia): hypoxic pulmonary vasoconstriction (HPV) and hypoxic vasodilation (HVD). HPV affects distal pulmonary (resistance) arteries, with its homeostatic role being to divert blood to well ventilated alveoli to thereby optimize the ventilation/perfusion ratio. HVD is produced in most systemic arteries, in particular in the skeletal muscle, coronary, and cerebral circulations, to increase blood supply to poorly oxygenated tissues. Although vasomotor responses to hypoxia are modulated by endothelial factors and autonomic innervation, it is well established that arterial smooth muscle cells contain an acute O2 sensing system capable of detecting changes in O2 tension and to signal membrane ion channels, which in turn regulate cytosolic Ca2+ levels and myocyte contraction. Here, we summarize current knowledge on the nature of O2 sensing and signaling systems underlying acute vasomotor responses to hypoxia. We also discuss similarities and differences existing in O2 sensors and effectors in the various arterial territories.
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Affiliation(s)
- Alejandro Moreno-Domínguez
- Instituto de Biomedicina de Sevilla (IBiS), Hospital Universitario Virgen del Rocío/CSIC/Universidad de Sevilla, Seville, Spain
- Departamento de Fisiología Médica y Biofísica, Facultad de Medicina, Universidad de Sevilla, Seville, Spain
- Centro de Investigación Biomédica en Red Sobre Enfermedades Neurodegenerativas (CIBERNED), Madrid, Spain
| | - Olaia Colinas
- Instituto de Biomedicina de Sevilla (IBiS), Hospital Universitario Virgen del Rocío/CSIC/Universidad de Sevilla, Seville, Spain
- Departamento de Fisiología Médica y Biofísica, Facultad de Medicina, Universidad de Sevilla, Seville, Spain
- Centro de Investigación Biomédica en Red Sobre Enfermedades Neurodegenerativas (CIBERNED), Madrid, Spain
| | - Tarik Smani
- Instituto de Biomedicina de Sevilla (IBiS), Hospital Universitario Virgen del Rocío/CSIC/Universidad de Sevilla, Seville, Spain
- Departamento de Fisiología Médica y Biofísica, Facultad de Medicina, Universidad de Sevilla, Seville, Spain
| | - Juan Ureña
- Instituto de Biomedicina de Sevilla (IBiS), Hospital Universitario Virgen del Rocío/CSIC/Universidad de Sevilla, Seville, Spain
- Departamento de Fisiología Médica y Biofísica, Facultad de Medicina, Universidad de Sevilla, Seville, Spain
| | - José López-Barneo
- Instituto de Biomedicina de Sevilla (IBiS), Hospital Universitario Virgen del Rocío/CSIC/Universidad de Sevilla, Seville, Spain
- Departamento de Fisiología Médica y Biofísica, Facultad de Medicina, Universidad de Sevilla, Seville, Spain
- Centro de Investigación Biomédica en Red Sobre Enfermedades Neurodegenerativas (CIBERNED), Madrid, Spain
- *Correspondence: José López-Barneo,
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Fernández-Morales JC, Morad M. Oxygen Sensor of the Heart. Can J Physiol Pharmacol 2022; 100:848-857. [PMID: 35679617 DOI: 10.1139/cjpp-2022-0072] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
How oxygen is sensed by the heart and what mechanisms mediate its sensing remain poorly understood. Since recent reports show that low PO2 levels are detected by the cardiomyocytes in a few seconds, the rapid and short applications of low levels of oxygen (acute hypoxia), that avoid multiple effects of chronic hypoxia may be used to probe the oxygen sensing pathway of the heart. Here we explore the oxygen sensing pathway, focusing primarily on cellular surface membrane proteins that are first exposed to low PO2. Such studies suggest that acute hypoxia primarily targets the cardiac calcium channels, where either the channel itself or moieties closely associated with it, for instance, heme-oxygenase-2 (HO-2) interacting through kinase phosphorylation, signals the α-subunit of the channel as to the altered levels of PO2. Amino acids 1572-1651, the CaMKII phosphorylation sites (S1487 and S1545), CaM-binding site (I1624, Q1625) and Ser1928 of the carboxyl tail of the α-subunit appear to be critical residues that sense oxygen. Future studies in HO-2 knockout mice or CRISPR/Cas9 gene-edited hiPSC-CMs that reduce CaM-binding affinity are likely to provide deeper insights in the O2-sensinsing mechanisms.
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Affiliation(s)
| | - Martin Morad
- USC, MUSC, and Clemson University, Cardiac Signaling Center, Charleston, South Carolina, United States;
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Yuan X, Zhu X, Chen Y, Liu W, Qian W, Xu Y, Zhu Y. Cardiac energetics alteration in a chronic hypoxia rat model: A non-invasive in vivo31P magnetic resonance spectroscopy study. JOURNAL OF X-RAY SCIENCE AND TECHNOLOGY 2022; 30:165-175. [PMID: 34744047 DOI: 10.3233/xst-210985] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
BACKGROUND Energetics alteration plays a crucial role in the myocardial injury process in chronic hypoxia diseases (CHD). 31P magnetic resonance spectroscopy (MRS) can investigate alterations in cardiac energetics in vivo. OBJECTIVE To characterize the potential value of 31P MRS in evaluating cardiac energetics alteration of chronic hypoxic rats (CHRs). METHODS Twenty-four CHRs were induced by SU5416 combined with hypoxia and divided into four groups according to the modeling time of one, two, three and five weeks, respectively. Control group also contains six rats. 31P MRS was performed weekly and the ratio of concentrations of phosphocreatine (PCr) to adenosine triphosphate (ATP) (PCr/ATP) was obtained. In addition, the cardiac structure index and systolic function parameters, including the right ventricular ejection fraction (RVEF), right ventricular end-diastolic volume index (RVEDVi), right ventricular end-systolic volume index (RVESVi), and the left ventricular function parameters, were measured. RESULTS Decreased resting cardiac PCr/ATP ratio in CHRs was observed at the first week, compared to the control group (2.90±0.35 vs. 3.31±0.45, p = 0.045), while the RVEF, RVEDVi, and RVESVi decreased at the second week (p < 0.05). The PCr/ATP ratio displayed a significant correlation with RVEF (r = 0.605, p = 0.001), RVEDVi, and RVESVi (r = -0.661, r = -0.703; p < 0.001). CONCLUSIONS 31P MRS can easily detect the cardiac energetics alteration in a CHR model before the onset of ventricular dysfunction. The decreased PCr/ATP ratio likely reveales myocardial injury and cardiac dysfunction.
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Affiliation(s)
- Xiaohan Yuan
- Department of Ultrasuond, The Affiliated Huaian No. 1 People's Hospital of Nanjing Medical University, Huaian, Jiangsu, China
- Department of Radiology, The First Affiliated Hospital of Nanjing Medical University, Nanjing, Jiangsu, China
| | - Xiaomei Zhu
- Department of Radiology, The First Affiliated Hospital of Nanjing Medical University, Nanjing, Jiangsu, China
| | - Yang Chen
- Department of Radiology, The First Affiliated Hospital of Nanjing Medical University, Nanjing, Jiangsu, China
| | - Wangyan Liu
- Department of Radiology, The First Affiliated Hospital of Nanjing Medical University, Nanjing, Jiangsu, China
| | - Wen Qian
- Department of Radiology, The First Affiliated Hospital of Nanjing Medical University, Nanjing, Jiangsu, China
| | - Yi Xu
- Department of Radiology, The First Affiliated Hospital of Nanjing Medical University, Nanjing, Jiangsu, China
| | - Yinsu Zhu
- Department of Radiology, The First Affiliated Hospital of Nanjing Medical University, Nanjing, Jiangsu, China
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Yoo HY, Kim SJ. Oxygen-dependent regulation of ion channels: acute responses, post-translational modification, and response to chronic hypoxia. Pflugers Arch 2021; 473:1589-1602. [PMID: 34142209 DOI: 10.1007/s00424-021-02590-7] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2020] [Revised: 05/15/2021] [Accepted: 05/30/2021] [Indexed: 12/19/2022]
Abstract
Oxygen is a vital element for the survival of cells in multicellular aerobic organisms such as mammals. Lack of O2 availability caused by environmental or pathological conditions leads to hypoxia. Active oxygen distribution systems (pulmonary and circulatory) and their neural control mechanisms ensure that cells and tissues remain oxygenated. However, O2-carrying blood cells as well as immune and various parenchymal cells experience wide variations in partial pressure of oxygen (PO2) in vivo. Hence, the reactive modulation of the functions of the oxygen distribution systems and their ability to sense PO2 are critical. Elucidating the physiological responses of cells to variations in PO2 and determining the PO2-sensing mechanisms at the biomolecular level have attracted considerable research interest in the field of physiology. Herein, we review the current knowledge regarding ion channel-dependent oxygen sensing and associated signalling pathways in mammals. First, we present the recent findings on O2-sensing ion channels in representative chemoreceptor cells as well as in other types of cells such as immune cells. Furthermore, we highlight the transcriptional regulation of ion channels under chronic hypoxia and its physiological implications and summarize the findings of studies on the post-translational modification of ion channels under hypoxic or ischemic conditions.
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Affiliation(s)
- Hae Young Yoo
- Department of Nursing, Chung-Ang University, Seoul, 06974, Republic of Korea
| | - Sung Joon Kim
- Department of Physiology, Seoul National University College of Medicine, 103 Daehak-ro, Jongno-gu, Seoul, 03080, Republic of Korea. .,Ischemic/Hypoxic Disease Institute, Seoul National University College of Medicine, Seoul, 03080, Republic of Korea.
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Zhang XH, Šarić T, Mehrjardi NZ, Hamad S, Morad M. Acid-Sensitive Ion Channels Are Expressed in Human Induced Pluripotent Stem Cell-Derived Cardiomyocytes. Stem Cells Dev 2019; 28:920-932. [PMID: 31119982 DOI: 10.1089/scd.2018.0234] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
Human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) are potential sources for cardiac regeneration and drug development. hiPSC-CMs express all the cardiac ion channels and the unique cardiac Ca2+-signaling phenotype. In this study, we tested for expression of acid sensing ion channels (ASICs) in spontaneously beating cardiomyocytes derived from three different hiPSC lines (IMR-90, iPSC-K3, and Ukki011-A). Rapid application of solutions buffered at pH 6.7, 6.0, or 5.0 triggered rapidly activating and slowly inactivating voltage-independent inward current that reversed at voltages positive to ENa, was suppressed by 5 μM amiloride and withdrawal of [Na+]o, like neuronal ASIC currents. ASIC currents were expressed at much lower percentages and densities in undifferentiated hiPSC and in dermal fibroblasts. ASIC1 mRNA and protein were measured in first 60 days but decreased in 100 days postdifferentiation hiPSC cultures. Hyperacidification (pH 5 and 6) also triggered large Ca2+ transients in intact hiPSC-CMs that were neither ruthenium red nor amiloride-sensitive, but were absent in whole cell-clamped hiPSC-CMs. Neither ASIC1 current nor its protein was detected in rat adult cardiomyocytes, but hyperacidification did activate smaller and slowly activating currents with drug sensitivity similar to TRPV channels. Considering ASIC expression in developing but not adult myocardium, a role in heart development is likely.
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Affiliation(s)
- Xiao-Hua Zhang
- 1Cardiac Signaling Center of University of South Carolina, Medical University of South Carolina, Clemson University, Charleston, South Carolina
| | - Tomo Šarić
- 2Medical Faculty, Center for Physiology and Pathophysiology, Institute for Neurophysiology, University of Cologne, Cologne, Germany
| | - Narges Zare Mehrjardi
- 2Medical Faculty, Center for Physiology and Pathophysiology, Institute for Neurophysiology, University of Cologne, Cologne, Germany
| | - Sarkawt Hamad
- 2Medical Faculty, Center for Physiology and Pathophysiology, Institute for Neurophysiology, University of Cologne, Cologne, Germany
| | - Martin Morad
- 1Cardiac Signaling Center of University of South Carolina, Medical University of South Carolina, Clemson University, Charleston, South Carolina
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Fernández-Morales JC, Hua W, Yao Y, Morad M. Regulation of Ca 2+ signaling by acute hypoxia and acidosis in cardiomyocytes derived from human induced pluripotent stem cells. Cell Calcium 2018; 78:1-14. [PMID: 30579812 DOI: 10.1016/j.ceca.2018.12.006] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2018] [Revised: 12/11/2018] [Accepted: 12/11/2018] [Indexed: 12/20/2022]
Abstract
AIMS The effects of acute (100 s) hypoxia and/or acidosis on Ca2+ signaling parameters of human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CM) are explored here for the first time. METHODS AND RESULTS 1) hiPSC-CMs express two cell populations: rapidly-inactivating ICa myocytes (τi<40 ms, in 4-5 day cultures) and slowly-inactivating ICa (τi ≥ 40 ms, in 6-8 day cultures). 2) Hypoxia suppressed ICa by 10-20% in rapidly- and 40-55% in slowly-inactivating ICa cells. 3) Isoproterenol enhanced ICa in hiPSC-CMs, but either enhanced or did not alter the hypoxic suppression. 4) Hypoxia had no differential suppressive effects in the two cell-types when Ba2+ was the charge carrier through the calcium channels, implicating Ca2+-dependent inactivation in O2 sensing. 5) Acidosis suppressed ICa by ∼35% and ∼25% in rapidly and slowly inactivating ICa cells, respectively. 6) Hypoxia and acidosis suppressive effects on Ca-transients depended on whether global or RyR2-microdomain were measured: with acidosis suppression was ∼25% in global and ∼37% in RyR2 Ca2+-microdomains in either cell type, whereas with hypoxia suppression was ∼20% and ∼25% respectively in global and RyR2-microdomaine in rapidly and ∼35% and ∼45% respectively in global and RyR2-microdomaine in slowly-inactivating cells. CONCLUSIONS Variability in ICa inactivation kinetics rather than cellular ancestry seems to underlie the action potential morphology differences generally attributed to mixed atrial and ventricular cell populations in hiPSC-CMs cultures. The differential hypoxic regulation of Ca2+-signaling in the two-cell types arises from differential Ca2+-dependent inactivation of the Ca2+-channel caused by proximity of Ca2+-release stores to the Ca2+ channels.
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Affiliation(s)
| | - Wei Hua
- Cardiac Signaling Center of MUSC, USC and Clemson, Charleston, SC, USA
| | - Yuyu Yao
- Cardiac Signaling Center of MUSC, USC and Clemson, Charleston, SC, USA
| | - Martin Morad
- Cardiac Signaling Center of MUSC, USC and Clemson, Charleston, SC, USA; Department of Pharmacology,Georgetown University Medical Center, Washington, DC, USA.
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Hopster K, Wittenberg-Voges L, Geburek F, Hopster-Iversen C, Kästner SBR. Effects of controlled hypoxemia or hypovolemia on global and intestinal oxygenation and perfusion in isoflurane anesthetized horses receiving an alpha-2-agonist infusion. BMC Vet Res 2017; 13:361. [PMID: 29183321 PMCID: PMC5706348 DOI: 10.1186/s12917-017-1265-3] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2016] [Accepted: 11/09/2017] [Indexed: 12/26/2022] Open
Abstract
BACKGROUND Aim of this prospective experimental study was to assess effects of systemic hypoxemia and hypovolemia on global and gastrointestinal oxygenation and perfusion in anesthetized horses. Therefore, we anesthetized twelve systemically healthy warmblood horses using either xylazine or dexmedetomidine for premedication and midazolam and ketamine for induction. Anesthesia was maintained using isoflurane in oxygen with either xylazine or dexmedetomidine and horses were ventilated to normocapnia. During part A arterial oxygen saturation (SaO2) was reduced by reducing inspiratory oxygen fraction in steps of 5%. In part B hypovolemia was induced by controlled arterial exsanguination via roller pump (rate: 38 ml/kg/h). Mean arterial blood pressure (MAP), heart rate, pulmonary artery pressure, arterial and central venous blood gases and cardiac output were measured, cardiac index (CI) was calculated. Intestinal microperfusion and oxygenation were measured using laser Doppler flowmetry and white-light spectrophotometry. Surface probes were placed via median laparotomy on the stomach, jejunum and colon. RESULTS Part A: Reduction in arterial oxygenation resulted in a sigmoid decrease in central venous oxygen partial pressure. At SaO2 < 80% no further decrease in central venous oxygen partial pressure occurred. Intestinal oxygenation remained unchanged until SaO2 of 80% and then decreased. Heart rate and pulmonary artery pressure increased significantly during hypoxemia. Part B: Progressive reduction in circulating blood volume resulted in a linear decrease in MAP and CI. Intestinal perfusion was preserved until blood loss resulted in MAP and CI lower 51 ± 5 mmHg and 40 ± 3 mL/kg/min, respectively, and then decreased rapidly. CONCLUSIONS Under isoflurane, intestinal tissue oxygenation remained at baseline when arterial oxygenation exceeded 80% and intestinal perfusion remained at baseline when MAP exceeded 51 mmHg and CI exceeded 40 mL/kg/min in this group of horses. TRIAL REGISTRY NUMBER 33.14-42,502-04-14/1547.
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Affiliation(s)
- Klaus Hopster
- Equine Clinic, University of Veterinary Medicine Hanover, Foundation, Bünteweg 9, D-30559, Hanover, Germany.
- Department of Clinical Studies-NBC, School of Veterinary Medicine, University of Pennsylvania, 382 West Street Road, Kennett Square, PA, 19348, USA.
| | - Liza Wittenberg-Voges
- Equine Clinic, University of Veterinary Medicine Hanover, Foundation, Bünteweg 9, D-30559, Hanover, Germany
| | - Florian Geburek
- Equine Clinic, University of Veterinary Medicine Hanover, Foundation, Bünteweg 9, D-30559, Hanover, Germany
| | - Charlotte Hopster-Iversen
- Equine Clinic, University of Veterinary Medicine Hanover, Foundation, Bünteweg 9, D-30559, Hanover, Germany
| | - Sabine B R Kästner
- Equine Clinic, University of Veterinary Medicine Hanover, Foundation, Bünteweg 9, D-30559, Hanover, Germany
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Fernández-Morales JC, Morad M. Regulation of Ca 2+ signaling by acute hypoxia and acidosis in rat neonatal cardiomyocytes. J Mol Cell Cardiol 2017; 114:58-71. [PMID: 29032102 DOI: 10.1016/j.yjmcc.2017.10.004] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/18/2017] [Revised: 09/20/2017] [Accepted: 10/08/2017] [Indexed: 11/25/2022]
Abstract
Ischemic heart disease is an arrhythmogenic condition, accompanied by hypoxia, acidosis, and impaired Ca2+ signaling. Here we report on effects of acute hypoxia and acidification in rat neonatal cardiomyocytes cultures. RESULTS Two populations of neonatal cardiomyocyte were identified based on inactivation kinetics of L-type ICa: rapidly-inactivating ICa (τ~20ms) myocytes (prevalent in 3-4-day cultures), and slow-inactivating ICa (τ≥40ms) myocytes (dominant in 7-day cultures). Acute hypoxia (pO2<5mmHg for 50-100s) suppressed ICa reversibly in both cell-types to different extent and with different kinetics. This disparity disappeared when Ba2+ was the channel charge carrier, or when the intracellular Ca2+ buffering capacity was increased by dialysis of high concentrations of EGTA and BAPTA, suggesting critical role for calcium-dependent inactivation. Suppressive effect of acute acidosis on ICa (~40%, pH6.7), on the other hand, was not cell-type dependent. Isoproterenol enhanced ICa in both cell-types, but protected only against suppressive effects of acidosis and not hypoxia. Hypoxia and acidosis suppressed global Ca2+ transients by ~20%, but suppression was larger, ~35%, at the RyR2 microdomains, using GCaMP6-FKBP targeted probe. Hypoxia and acidosis also suppressed mitochondrial Ca2+ uptake by 40% and 10%, respectively, using mitochondrial targeted Ca2+ biosensor (mito-GCaMP6). CONCLUSION Our studies suggest that acute hypoxia suppresses ICa in rapidly inactivating cell population by a mechanism involving Ca2+-dependent inactivation, while compromised mitochondrial Ca2+ uptake seems also to contribute to ICa suppression in slowly inactivating cell population. Proximity of cellular Ca2+ pools to sarcolemmal Ca2+ channels may contribute to the variability of inactivation kinetics of ICa in the two cell populations, while acidosis suppression of ICa appears mediated by proton-induced block of the calcium channel.
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Affiliation(s)
| | - Martin Morad
- Cardiac Signaling Center of MUSC, USC and Clemson, Charleston, SC, USA; Department of Pharmacology, Georgetown University Medical Center, Washington, DC, USA.
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Kanaporis G, Treinys R, Fischmeister R, Jurevičius J. Metabolic inhibition reduces cardiac L-type Ca2+ channel current due to acidification caused by ATP hydrolysis. PLoS One 2017; 12:e0184246. [PMID: 28859158 PMCID: PMC5578678 DOI: 10.1371/journal.pone.0184246] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2017] [Accepted: 08/21/2017] [Indexed: 01/14/2023] Open
Abstract
Metabolic stress evoked by myocardial ischemia leads to impairment of cardiac excitation and contractility. We studied the mechanisms by which metabolic inhibition affects the activity of L-type Ca2+ channels (LTCCs) in frog ventricular myocytes. Metabolic inhibition induced by the protonophore FCCP (as well as by 2,4- dinitrophenol, sodium azide or antimycin A) resulted in a dose-dependent reduction of LTCC current (ICa,L) which was more pronounced during β-adrenergic stimulation with isoprenaline. ICa,L was still reduced by metabolic inhibition even in the presence of 3 mM intracellular ATP, or when the cell was dialysed with cAMP or ATP-γ-S to induce irreversible thiophosphorylation of LTCCs, indicating that reduction in ICa,L is not due to ATP depletion and/or reduced phosphorylation of the channels. However, the effect of metabolic inhibition on ICa,L was strongly attenuated when the mitochondrial F1F0-ATP-synthase was blocked by oligomycin or when the cells were dialysed with the non-hydrolysable ATP analogue AMP-PCP. Moreover, increasing the intracellular pH buffering capacity or intracellular dialysis of the myocytes with an alkaline solution strongly attenuated the inhibitory effect of FCCP on ICa,L. Thus, our data demonstrate that metabolic inhibition leads to excessive ATP hydrolysis by the mitochondrial F1F0-ATP-synthase operating in the reverse mode and this results in intracellular acidosis causing the suppression of ICa,L. Limiting ATP break-down by F1F0-ATP-synthase and the consecutive development of intracellular acidosis might thus represent a potential therapeutic approach for maintaining a normal cardiac function during ischemia.
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Affiliation(s)
- Giedrius Kanaporis
- Institute of Cardiology, Lithuanian University of Health Sciences, Kaunas, Lithuania
| | - Rimantas Treinys
- Institute of Cardiology, Lithuanian University of Health Sciences, Kaunas, Lithuania
| | - Rodolphe Fischmeister
- INSERM UMR-S 1180, Univ Paris-Sud, Université Paris-Saclay, Châtenay-Malabry, France
| | - Jonas Jurevičius
- Institute of Cardiology, Lithuanian University of Health Sciences, Kaunas, Lithuania
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Cserne Szappanos H, Viola H, Hool LC. L-type calcium channel: Clarifying the "oxygen sensing hypothesis". Int J Biochem Cell Biol 2017; 86:32-36. [PMID: 28323207 DOI: 10.1016/j.biocel.2017.03.010] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2016] [Revised: 03/08/2017] [Accepted: 03/14/2017] [Indexed: 11/30/2022]
Abstract
The heart is able to respond acutely to changes in oxygen tension. Since ion channels can respond rapidly to stimuli, the "ion channel oxygen sensing hypothesis" has been proposed to explain acute adaptation of cells to changes in oxygen demand. However the exact mechanism for oxygen sensing continues to be debated. Mitochondria consume the lion's share of oxygen in the heart, fuelling the production of ATP that drives excitation and contraction. Mitochondria also produce reactive oxygen species that are capable of altering the redox state of proteins. The cardiac L-type calcium channel is responsible for maintaining excitation and contraction. Recently, the reactive cysteine on the cardiac L-type calcium channel was identified. These data clarified that the channel does not respond directly to changes in oxygen tension, but rather responds to cellular redox state. This leads to acute alterations in cell signalling responsible for the development of arrhythmias and pathology.
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Affiliation(s)
- Henrietta Cserne Szappanos
- School of Anatomy, Physiology and Human Biology, University of Western Australia, Crawley, WA, Australia
| | - Helena Viola
- School of Anatomy, Physiology and Human Biology, University of Western Australia, Crawley, WA, Australia
| | - Livia C Hool
- School of Anatomy, Physiology and Human Biology, University of Western Australia, Crawley, WA, Australia; Victor Chang Cardiac Research Institute, Sydney, NSW, Australia.
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11
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Muralidharan P, Cserne Szappanos H, Ingley E, Hool L. Evidence for redox sensing by a human cardiac calcium channel. Sci Rep 2016; 6:19067. [PMID: 26750869 PMCID: PMC4707475 DOI: 10.1038/srep19067] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2015] [Accepted: 11/26/2015] [Indexed: 02/07/2023] Open
Abstract
Ion channels are critical to life and respond rapidly to stimuli to evoke physiological responses. Calcium influx into heart muscle occurs through the ion conducting α1C subunit (Cav1.2) of the L-type Ca2+ channel. Glutathionylation of Cav1.2 results in increased calcium influx and is evident in ischemic human heart. However controversy exists as to whether direct modification of Cav1.2 is responsible for altered function. We directly assessed the function of purified human Cav1.2 in proteoliposomes. Truncation of the C terminus and mutation of cysteines in the N terminal region and cytoplasmic loop III-IV linker did not alter the effects of thiol modifying agents on open probability of the channel. However mutation of cysteines in cytoplasmic loop I-II linker altered open probability and protein folding assessed by thermal shift assay. We find that C543 confers sensitivity of Cav1.2 to oxidative stress and is sufficient to modify channel function and posttranslational folding. Our data provide direct evidence for the calcium channel as a redox sensor that facilitates rapid physiological responses.
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Affiliation(s)
- Padmapriya Muralidharan
- School of Anatomy, Physiology and Human Biology, The University of Western Australia, Crawley, WA, Australia
| | - Henrietta Cserne Szappanos
- School of Anatomy, Physiology and Human Biology, The University of Western Australia, Crawley, WA, Australia
| | - Evan Ingley
- Harry Perkins Institute of Medical Research, QEII Medical Centre, Nedlands and Centre for Medical Research, The University of Western Australia, Crawley, WA, Australia
| | - Livia Hool
- School of Anatomy, Physiology and Human Biology, The University of Western Australia, Crawley, WA, Australia.,Victor Chang Cardiac Research Institute, Sydney, NSW, Australia
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12
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Karabowicz P, Schlicker E, Pędzińska-Betiuk A, Kloza M, Malinowska B. The adrenal medulla, not CB1 receptors, mediates the inhibitory effect of acute transverse aortic constriction on the neurogenic vasopressor response. Life Sci 2015; 138:86-93. [PMID: 25498898 DOI: 10.1016/j.lfs.2014.11.032] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2014] [Revised: 11/12/2014] [Accepted: 11/21/2014] [Indexed: 11/26/2022]
Affiliation(s)
- Piotr Karabowicz
- Department of Experimental Physiology and Pathophysiology, Medical University of Białystok, Mickiewicz str. 2A, 15-222 Białystok, Poland
| | - Eberhard Schlicker
- Department of Pharmacology and Toxicology, University of Bonn, Sigmund-Freud-Str. 25, 53127 Bonn, Germany
| | - Anna Pędzińska-Betiuk
- Department of Experimental Physiology and Pathophysiology, Medical University of Białystok, Mickiewicz str. 2A, 15-222 Białystok, Poland
| | - Monika Kloza
- Department of Experimental Physiology and Pathophysiology, Medical University of Białystok, Mickiewicz str. 2A, 15-222 Białystok, Poland
| | - Barbara Malinowska
- Department of Experimental Physiology and Pathophysiology, Medical University of Białystok, Mickiewicz str. 2A, 15-222 Białystok, Poland.
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13
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Trimetazidine protects cardiomyocytes against hypoxia-induced injury through ameliorates calcium homeostasis. Chem Biol Interact 2015; 236:47-56. [PMID: 25937560 DOI: 10.1016/j.cbi.2015.04.022] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2014] [Revised: 03/28/2015] [Accepted: 04/24/2015] [Indexed: 12/24/2022]
Abstract
Intracellular calcium (Ca(2+)i) overload induced by chronic hypoxia alters Ca(2+)i homeostasis, which plays an important role on mediating myocardial injury. We tested the hypothesis that treatment with trimetazidine (TMZ) would improve Ca(2+)i handling in hypoxic myocardial injury. Cardiomyocytes isolated from neonatal Sprague-Dawley rats were exposed to chronic hypoxia (1% O2, 5% CO2, 37 °C). Intracellular calcium concentration ([Ca(2+)]i) was measured with Fura-2/AM. Perfusion of cardiomyocytes with a high concentration of caffeine (10 mM) was carried out to verify the function of the cardiac Na(+)/Ca(2+) exchanger (NCX) and the activity of sarco(endo)-plasmic reticulum Ca(2+)-ATPase (SERCA2a). For TMZ-treated cardiomyocytes exposured in hypoxia, we observed a decrease in mRNA expression of proapoptotic Bax, caspase-3 activation and enhanced expression of anti-apoptotic Bcl-2. The cardiomyocyte hypertrophy were also alleviated in hypoxic cardiomyocyte treated with TMZ. Moreover, we found that TMZ treatment cardiomyocytes enhanced "metabolic shift" from lipid oxidation to glucose oxidation. Compared with hypoxic cardiomyocyte, the diastolic [Ca(2+)]i was decreased, the amplitude of Ca(2+)i oscillations and sarcoplasmic reticulum Ca(2+) load were recovered, the activities of ryanodine receptor 2 (RyR2), NCX and SERCA2a were increased in cardiomyocytes treated with TMZ. TMZ attenuated abnormal changes of RyR2 and SERCA2a genes in hypoxic cardiomyocytes. In addition, cholinergic signaling are involved in hypoxic stress and the cardioprotective effects of TMZ. These results suggest that TMZ ameliorates Ca(2+)i homeostasis through switch of lipid to glucose metabolism, thereby producing the cardioprotective effect and reduction in hypoxic cardiomyocytes damage.
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14
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Abstract
SIGNIFICANCE Oxygen plays a key role in cellular metabolism and function. Oxygen delivery to cells is crucial, and a lack of oxygen such as that which occurs during myocardial infarction can be lethal. Cells should, therefore, be able to respond to changes in oxygen tension. RECENT ADVANCES Since the first studies examining the acute cellular effect of hypoxia on activation of transmitter release from glomus or type I chemoreceptor cells, it is now known that virtually all cells are able to respond to changes in oxygen tension. CRITICAL ISSUES Despite advances made in characterizing hypoxic responses, the identity of the "oxygen sensor" remains debated. Recently, more evidence has evolved as to how cardiac myocytes sense acute changes in oxygen. This review will examine the available evidence in support of acute oxygen-sensing mechanisms providing a brief historical perspective and then more detailed insights into the heart and the role of cardiac ion channels in hypoxic responses. FUTURE DIRECTIONS A further understanding of these cellular processes should result in interventions that assist in preventing the deleterious effects of acute changes in oxygen tension such as alterations in contractile function and cardiac arrhythmia.
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Affiliation(s)
- Livia C Hool
- School of Anatomy, Physiology, and Human Biology, The University of Western Australia , Crawley, Australia
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15
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Scaringi JA, Rosa AO, Morad M, Cleemann L. A new method to detect rapid oxygen changes around cells: how quickly do calcium channels sense oxygen in cardiomyocytes? J Appl Physiol (1985) 2013; 115:1855-61. [PMID: 24157525 DOI: 10.1152/japplphysiol.00770.2013] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Acute hypoxia is thought to trigger protective responses that, in tissues like heart and carotid body, include rapid (5-10 s) suppression of Ca(2+) and K(+) channels. To gain insight into the mechanism for the suppression of the cardiac l-type Ca(2+) channel, we measured O2-dependent fluorescence in the immediate vicinity of voltage-clamped cardiac cells subjected to rapid exchange of solutions with different O2 tensions. This was accomplished with an experimental chamber with a glass bottom that was used as a light guide for excitation of a thin ruthenium-based O2-sensitive ORMOSIL coating. Fluorescence imaging showed that steady-state Po2 was well controlled within the entire stream from an electromagnetically controlled solution "puffer" but that changes were slower at the periphery of the stream (τ1/2 ∼ 500 ms) than immediately around the voltage-clamped myocyte (τ1/2 ∼ 225 ms) where, in turn, firmly attached cells produced an additional local delay of 50-100 ms. Performing simultaneous voltage clamp and O2 measurements, we found that acute hypoxia gradually and reversibly suppressed the Ca(2+) channel (CaV1.2). Using Ba(2+) as charge carrier, the suppression was significant after 1.5 s, reached ∼10% after 2.5 s, and was nearly completely reversible in 5 s. The described fluorescence measurements provide the means to check and fine tune solution puffers and suggest that changes in Po2 can be accomplished within ∼200 ms. The rapid and reversible suppression of barium current under hypoxia is consistent with the notion that the cardiac Ca(2+) channel is directly modulated by O2.
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Affiliation(s)
- John A Scaringi
- Cardiac Signaling Center of University of South Carolina, Medical University of South Carolina, and Clemson University, Charleston, South Carolina
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16
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Smeding L, Kuiper JW, Plötz FB, Kneyber MC, Groeneveld AJ. Aggravation of myocardial dysfunction by injurious mechanical ventilation in LPS-induced pneumonia in rats. Respir Res 2013; 14:92. [PMID: 24047433 PMCID: PMC3848739 DOI: 10.1186/1465-9921-14-92] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2013] [Accepted: 09/09/2013] [Indexed: 02/07/2023] Open
Abstract
BACKGROUND Mechanical ventilation (MV) may cause ventilator-induced lung injury (VILI) and may thereby contribute to fatal multiple organ failure. We tested the hypothesis that injurious MV of lipopolysaccharide (LPS) pre-injured lungs induces myocardial inflammation and further dysfunction ex vivo, through calcium (Ca2+)-dependent mechanism. MATERIALS AND METHODS N = 35 male anesthetized and paralyzed male Wistar rats were randomized to intratracheal instillation of 2 mg/kg LPS or nothing and subsequent MV with lung-protective settings (low tidal volume (Vt) of 6 mL/kg and 5 cmH2O positive end-expiratory pressure (PEEP)) or injurious ventilation (high Vt of 19 mL/kg and 1 cmH2O PEEP) for 4 hours. Myocardial function ex vivo was evaluated in a Langendorff setup and Ca2+ exposure. Key mediators were determined in lung and heart at the mRNA level. RESULTS Instillation of LPS and high Vt MV impaired gas exchange and, particularly when combined, increased pulmonary wet/dry ratio; heat shock protein (HSP)70 mRNA expression also increased by the interaction between LPS and high Vt MV. For the heart, C-X-C motif ligand (CXCL)1 and Toll-like receptor (TLR)2 mRNA expression increased, and ventricular (LV) systolic pressure, LV developed pressure, LV +dP/dtmax and contractile responses to increasing Ca2+ exposure ex vivo decreased by LPS. High Vt ventilation aggravated the effects of LPS on myocardial inflammation and dysfunction but not on Ca2+ responses. CONCLUSIONS Injurious MV by high Vt aggravates the effects of intratracheal instillation of LPS on myocardial dysfunction, possibly through enhancing myocardial inflammation via pulmonary release of HSP70 stimulating cardiac TLR2, not involving Ca2+ handling and sensitivity.
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Affiliation(s)
- Lonneke Smeding
- Institute for Cardiovascular Research ICaR-VU, VU University Medical Center, Amsterdam, Netherlands.
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