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de Souza IIA, da Silva Barenco T, Pavarino MEMF, Couto MT, de Resende GO, de Oliveira DF, Ponte CG, Nascimento JHM, Maciel L. A potent and selective activator of large-conductance Ca 2+-activated K + channels induces preservation of mitochondrial function after hypoxia and reoxygenation by handling of calcium and transmembrane potential. Acta Physiol (Oxf) 2024; 240:e14151. [PMID: 38676357 DOI: 10.1111/apha.14151] [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: 10/31/2023] [Revised: 02/15/2024] [Accepted: 04/12/2024] [Indexed: 04/28/2024]
Abstract
AIMS Ischaemic heart disease remains a significant cause of mortality globally. A pharmacological agent that protects cardiac mitochondria against oxygen deprivation injuries is welcome in therapy against acute myocardial infarction. Here, we evaluate the effect of large-conductance Ca2+-activated K+ channels (BKCa) activator, Compound Z, in isolated mitochondria under hypoxia and reoxygenation. METHODS Mitochondria from mice hearts were obtained by differential centrifugation. The isolated mitochondria were incubated with a BKCa channel activator, Compound Z, and subjected to normoxia or hypoxia/reoxygenation. Mitochondrial function was evaluated by measurement of O2 consumption in the complexes I, II, and IV in the respiratory states 1, 2, 3, and by maximal uncoupled O2 uptake, ATP production, ROS production, transmembrane potential, and calcium retention capacity. RESULTS Incubation of isolated mitochondria with Compound Z under normoxia conditions reduced the mitochondrial functions and induced the production of a significant amount of ROS. However, under hypoxia/reoxygenation, the Compound Z prevented a profound reduction in mitochondrial functions, including reducing ROS production over the hypoxia/reoxygenation group. Furthermore, hypoxia/reoxygenation induced a large mitochondria depolarization, which Compound Z incubation prevented, but, even so, Compound Z created a small depolarization. The mitochondrial calcium uptake was prevented by the BKCa activator, extruding the mitochondrial calcium present before Compound Z incubation. CONCLUSION The Compound Z acts as a mitochondrial BKCa channel activator and can protect mitochondria function against hypoxia/reoxygenation injury, by handling mitochondrial calcium and transmembrane potential.
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Affiliation(s)
- Itanna Isis Araujo de Souza
- Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brasil
- Programa de Pós-Graduação Em Cardiologia, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brasil
| | - Thais da Silva Barenco
- Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brasil
- Programa de Pós-Graduação Em Cardiologia, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brasil
| | | | - Marcos Tadeu Couto
- Instituto Federal de Educação, Ciência e Tecnologia do Rio de Janeiro, Rio de Janeiro, Brasil
| | | | | | | | - José Hamilton Matheus Nascimento
- Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brasil
- Programa de Pós-Graduação Em Cardiologia, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brasil
| | - Leonardo Maciel
- Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brasil
- Universidade Federal do Rio de Janeiro, Duque de Caxias, Brasil
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2
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Stamerra CA, Di Giosia P, Giorgini P, Ferri C, Sukhorukov VN, Sahebkar A. Mitochondrial Dysfunction and Cardiovascular Disease: Pathophysiology and Emerging Therapies. OXIDATIVE MEDICINE AND CELLULAR LONGEVITY 2022; 2022:9530007. [PMID: 35958017 PMCID: PMC9363184 DOI: 10.1155/2022/9530007] [Citation(s) in RCA: 21] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/31/2022] [Accepted: 07/15/2022] [Indexed: 11/24/2022]
Abstract
Mitochondria ensure the supply of cellular energy through the production of ATP via oxidative phosphorylation. The alteration of this process, called mitochondrial dysfunction, leads to a reduction in ATP and an increase in the production of reactive oxygen species (ROS). Mitochondrial dysfunction can be caused by mitochondrial/nuclear DNA mutations, or it can be secondary to pathological conditions such as cardiovascular disease, aging, and environmental stress. The use of therapies aimed at the prevention/correction of mitochondrial dysfunction, in the context of the specific treatment of cardiovascular diseases, is a topic of growing interest. In this context, the data are conflicting since preclinical studies are numerous, but there are no large randomized studies.
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Affiliation(s)
- Cosimo Andrea Stamerra
- University of L'Aquila, Department of Life, Health and Environmental Sciences, Building Delta 6, San Salvatore Hospital, Via Vetoio, Coppito 67100 L'Aquila, Italy
- Department of Internal Medicine, Mazzoni Hospital, Ascoli Piceno, Italy
| | - Paolo Di Giosia
- University of L'Aquila, Department of Life, Health and Environmental Sciences, Building Delta 6, San Salvatore Hospital, Via Vetoio, Coppito 67100 L'Aquila, Italy
- Department of Internal Medicine, Mazzoni Hospital, Ascoli Piceno, Italy
| | - Paolo Giorgini
- University of L'Aquila, Department of Life, Health and Environmental Sciences, Building Delta 6, San Salvatore Hospital, Via Vetoio, Coppito 67100 L'Aquila, Italy
| | - Claudio Ferri
- University of L'Aquila, Department of Life, Health and Environmental Sciences, Building Delta 6, San Salvatore Hospital, Via Vetoio, Coppito 67100 L'Aquila, Italy
| | - Vasily N. Sukhorukov
- Institute for Atherosclerosis Research, Osennyaya Street 4-1-207, Moscow 121609, Russia
| | - Amirhossein Sahebkar
- Biotechnology Research Center, Pharmaceutical Technology Institute, Mashhad University of Medical Sciences, Mashhad, Iran
- Applied Biomedical Research Center, Mashhad University of Medical Sciences, Mashhad, Iran
- Department of Biotechnology, School of Pharmacy, Mashhad University of Medical Sciences, Mashhad, Iran
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3
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Sanghvi S, Szteyn K, Ponnalagu D, Sridharan D, Lam A, Hansra I, Chaudhury A, Majumdar U, Kohut AR, Gururaja Rao S, Khan M, Garg V, Singh H. Inhibition of BK Ca channels protects neonatal hearts against myocardial ischemia and reperfusion injury. Cell Death Dis 2022; 8:175. [PMID: 35393410 PMCID: PMC8989942 DOI: 10.1038/s41420-022-00980-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2021] [Revised: 03/15/2022] [Accepted: 03/23/2022] [Indexed: 11/30/2022]
Abstract
BKCa channels are large-conductance calcium and voltage-activated potassium channels that are heterogeneously expressed in a wide array of cells. Activation of BKCa channels present in mitochondria of adult ventricular cardiomyocytes is implicated in cardioprotection against ischemia-reperfusion (IR) injury. However, the BKCa channel’s activity has never been detected in the plasma membrane of adult ventricular cardiomyocytes. In this study, we report the presence of the BKCa channel in the plasma membrane and mitochondria of neonatal murine and rodent cardiomyocytes, which protects the heart on inhibition but not activation. Furthermore, K+ currents measured in neonatal cardiomyocyte (NCM) was sensitive to iberiotoxin (IbTx), suggesting the presence of BKCa channels in the plasma membrane. Neonatal hearts subjected to IR when post-conditioned with NS1619 during reoxygenation increased the myocardial infarction whereas IbTx reduced the infarct size. In agreement, isolated NCM also presented increased apoptosis on treatment with NS1619 during hypoxia and reoxygenation, whereas IbTx reduced TUNEL-positive cells. In NCMs, activation of BKCa channels increased the intracellular reactive oxygen species post HR injury. Electrophysiological characterization of NCMs indicated that NS1619 increased the beat period, field, and action potential duration, and decreased the conduction velocity and spike amplitude. In contrast, IbTx had no impact on the electrophysiological properties of NCMs. Taken together, our data established that inhibition of plasma membrane BKCa channels in the NCM protects neonatal heart/cardiomyocytes from IR injury. Furthermore, the functional disparity observed towards the cardioprotective activity of BKCa channels in adults compared to neonatal heart could be attributed to their differential localization.
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Affiliation(s)
- Shridhar Sanghvi
- Department of Physiology and Cell Biology, The Ohio State University Wexner Medical Center, Columbus, OH, USA.,Department of Molecular Cellular and Developmental Biology, The Ohio State University, Columbus, OH, USA
| | - Kalina Szteyn
- Department of Physiology and Cell Biology, The Ohio State University Wexner Medical Center, Columbus, OH, USA
| | - Devasena Ponnalagu
- Department of Physiology and Cell Biology, The Ohio State University Wexner Medical Center, Columbus, OH, USA
| | - Divya Sridharan
- Department of Emergency Medicine, Wexner Medical Center, The Ohio State University, Columbus, OH, USA
| | - Alexander Lam
- Department of Internal Medicine, Drexel University College of Medicine, Philadelphia, PA, USA
| | - Inderjot Hansra
- Department of Physiology and Cell Biology, The Ohio State University Wexner Medical Center, Columbus, OH, USA
| | - Ankur Chaudhury
- Department of Internal Medicine, Drexel University College of Medicine, Philadelphia, PA, USA
| | - Uddalak Majumdar
- Center for Cardiovascular Research and The Heart Center, Nationwide Children's Hospital, Columbus, OH, USA
| | - Andrew R Kohut
- Department of Internal Medicine, Drexel University College of Medicine, Philadelphia, PA, USA.,Division of Cardiology, Department of Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Shubha Gururaja Rao
- Department of Pharmaceutical and Biomedical Sciences, The Raabe College of Pharmacy, Ohio Northern University, Ada, OH, USA
| | - Mahmood Khan
- Department of Physiology and Cell Biology, The Ohio State University Wexner Medical Center, Columbus, OH, USA.,Department of Emergency Medicine, Wexner Medical Center, The Ohio State University, Columbus, OH, USA
| | - Vidu Garg
- Center for Cardiovascular Research and The Heart Center, Nationwide Children's Hospital, Columbus, OH, USA.,Department of Pediatrics, The Ohio State University, Columbus, OH, USA
| | - Harpreet Singh
- Department of Physiology and Cell Biology, The Ohio State University Wexner Medical Center, Columbus, OH, USA. .,Department of Molecular Cellular and Developmental Biology, The Ohio State University, Columbus, OH, USA.
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4
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González-Sanabria N, Echeverría F, Segura I, Alvarado-Sánchez R, Latorre R. BK in Double-Membrane Organelles: A Biophysical, Pharmacological, and Functional Survey. Front Physiol 2021; 12:761474. [PMID: 34764886 PMCID: PMC8577798 DOI: 10.3389/fphys.2021.761474] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2021] [Accepted: 09/29/2021] [Indexed: 12/04/2022] Open
Abstract
In the 1970s, calcium-activated potassium currents were recorded for the first time. In 10years, this Ca2+-activated potassium channel was identified in rat skeletal muscle, chromaffin cells and characterized in skeletal muscle membranes reconstituted in lipid bilayers. This calcium- and voltage-activated potassium channel, dubbed BK for “Big K” due to its large ionic conductance between 130 and 300 pS in symmetric K+. The BK channel is a tetramer where the pore-forming α subunit contains seven transmembrane segments. It has a modular architecture containing a pore domain with a highly potassium-selective filter, a voltage-sensor domain and two intracellular Ca2+ binding sites in the C-terminus. BK is found in the plasma membrane of different cell types, the inner mitochondrial membrane (mitoBK) and the nuclear envelope’s outer membrane (nBK). Like BK channels in the plasma membrane (pmBK), the open probability of mitoBK and nBK channels are regulated by Ca2+ and voltage and modulated by auxiliary subunits. BK channels share common pharmacology to toxins such as iberiotoxin, charybdotoxin, paxilline, and agonists of the benzimidazole family. However, the precise role of mitoBK and nBK remains largely unknown. To date, mitoBK has been reported to play a role in protecting the heart from ischemic injury. At the same time, pharmacology suggests that nBK has a role in regulating nuclear Ca2+, membrane potential and expression of eNOS. Here, we will discuss at the biophysical level the properties and differences of mitoBK and nBK compared to those of pmBK and their pharmacology and function.
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Affiliation(s)
- Naileth González-Sanabria
- Facultad de Ciencias, Centro Interdisciplinario de Neurociencia de Valparaíso, Universidad de Valparaíso, Valparaíso, Chile
| | - Felipe Echeverría
- Facultad de Ciencias, Centro Interdisciplinario de Neurociencia de Valparaíso, Universidad de Valparaíso, Valparaíso, Chile
| | - Ignacio Segura
- Facultad de Ciencias, Centro Interdisciplinario de Neurociencia de Valparaíso, Universidad de Valparaíso, Valparaíso, Chile
| | - Rosangelina Alvarado-Sánchez
- Facultad de Ciencias, Centro Interdisciplinario de Neurociencia de Valparaíso, Universidad de Valparaíso, Valparaíso, Chile
| | - Ramon Latorre
- Facultad de Ciencias, Centro Interdisciplinario de Neurociencia de Valparaíso, Universidad de Valparaíso, Valparaíso, Chile
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5
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Sanghvi S, Szteyn K, Ponnalagu D, Sridharan D, Lam A, Hansra I, Chaudhury A, Majumdar U, Kohut AR, Rao SG, Khan M, Garg V, Singh H. Inhibition of BK Ca channels protects neonatal hearts against myocardial ischemia and reperfusion injury.. [DOI: 10.1101/2021.11.02.466585] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/19/2023]
Abstract
AbstractBKCa channels are large-conductance calcium and voltage-activated potassium channels that are heterogeneously expressed in a wide array of cells. Activation of BKCa channels present in mitochondria of adult ventricular cardiomyocytes is implicated in cardioprotection against ischemia-reperfusion (IR) injury. However, the BKCa channel’s activity has never been detected in the plasma membrane of adult ventricular cardiomyocytes. In this study, we report the presence of the BKCa channel in the plasma membrane and mitochondria of neonatal murine and rodent cardiomyocytes which protects the heart on inhibition but not activation. Furthermore, K+ currents measured in neonatal cardiomyocyte (NCM) was sensitive to iberiotoxin (IbTx), suggesting the presence of BKCa channels in the plasma membrane. Neonatal hearts subjected to IR when post-conditioned with NS1619 during reoxygenation increased the myocardial infarction whereas IbTx reduced the infarct size. In agreement, isolated NCM also presented increased apoptosis on treatment with NS1619 during hypoxia and reoxygenation, whereas IbTx reduced TUNEL positive cells. In NCMs, activation of BKCa channels increased the intracellular reactive oxygen species post HR injury. Electrophysiological characterization of NCMs indicated that NS1619 increased the beat period, field, and action potential duration, and decreased the conduction velocity and spike amplitude. In contrast, IbTx had no impact on the electrophysiological properties of NCMs. Taken together, our data established that inhibition of plasma membrane BKCa channels in the NCM protects neonatal heart/cardiomyocytes from IR injury. Furthermore, the functional disparity observed towards the cardioprotective activity of BKCa channels in adults compared to neonatal heart could be attributed to their differential localization.
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6
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Szteyn K, Singh H. BK Ca Channels as Targets for Cardioprotection. Antioxidants (Basel) 2020; 9:antiox9080760. [PMID: 32824463 PMCID: PMC7463653 DOI: 10.3390/antiox9080760] [Citation(s) in RCA: 35] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2020] [Revised: 08/09/2020] [Accepted: 08/13/2020] [Indexed: 12/16/2022] Open
Abstract
The large-conductance calcium- and voltage-activated K+ channel (BKCa) are encoded by the Kcnma1 gene. They are ubiquitously expressed in neuronal, smooth muscle, astrocytes, and neuroendocrine cells where they are known to play an important role in physiological and pathological processes. They are usually localized to the plasma membrane of the majority of the cells with an exception of adult cardiomyocytes, where BKCa is known to localize to mitochondria. BKCa channels couple calcium and voltage responses in the cell, which places them as unique targets for a rapid physiological response. The expression and activity of BKCa have been linked to several cardiovascular, muscular, and neurological defects, making them a key therapeutic target. Specifically in the heart muscle, pharmacological and genetic activation of BKCa channels protect the heart from ischemia-reperfusion injury and also facilitate cardioprotection rendered by ischemic preconditioning. The mechanism involved in cardioprotection is assigned to the modulation of mitochondrial functions, such as regulation of mitochondrial calcium, reactive oxygen species, and membrane potential. Here, we review the progress made on BKCa channels and cardioprotection and explore their potential roles as therapeutic targets for preventing acute myocardial infarction.
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7
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Hausenloy DJ, Schulz R, Girao H, Kwak BR, De Stefani D, Rizzuto R, Bernardi P, Di Lisa F. Mitochondrial ion channels as targets for cardioprotection. J Cell Mol Med 2020; 24:7102-7114. [PMID: 32490600 PMCID: PMC7339171 DOI: 10.1111/jcmm.15341] [Citation(s) in RCA: 32] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2020] [Revised: 03/31/2020] [Accepted: 04/12/2020] [Indexed: 12/14/2022] Open
Abstract
Acute myocardial infarction (AMI) and the heart failure (HF) that often result remain the leading causes of death and disability worldwide. As such, new therapeutic targets need to be discovered to protect the myocardium against acute ischaemia/reperfusion (I/R) injury in order to reduce myocardial infarct (MI) size, preserve left ventricular function and prevent the onset of HF. Mitochondrial dysfunction during acute I/R injury is a critical determinant of cell death following AMI, and therefore, ion channels in the inner mitochondrial membrane, which are known to influence cell death and survival, provide potential therapeutic targets for cardioprotection. In this article, we review the role of mitochondrial ion channels, which are known to modulate susceptibility to acute myocardial I/R injury, and we explore their potential roles as therapeutic targets for reducing MI size and preventing HF following AMI.
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Affiliation(s)
- Derek J. Hausenloy
- Cardiovascular & Metabolic Disorders ProgramDuke‐National University of Singapore Medical SchoolSingaporeSingapore
- National Heart Research Institute SingaporeNational Heart CentreSingaporeSingapore
- Yong Loo Lin School of MedicineNational University SingaporeSingaporeSingapore
- The Hatter Cardiovascular InstituteUniversity College LondonLondonUK
- Cardiovascular Research CenterCollege of Medical and Health SciencesAsia UniversityTaichung CityTaiwan
| | - Rainer Schulz
- Institute of PhysiologyJustus‐Liebig University GiessenGiessenGermany
| | - Henrique Girao
- Coimbra Institute for Clinical and Biomedical Research (iCBR), Faculty of MedicineUniversity of CoimbraCoimbraPortugal
- Center for Innovative Biomedicine and Biotechnology (CIBB)University of CoimbraCoimbraPortugal
- Clinical Academic Centre of CoimbraCACCCoimbraPortugal
| | - Brenda R. Kwak
- Department of Pathology and ImmunologyUniversity of GenevaGenevaSwitzerland
| | - Diego De Stefani
- Department of Biomedical SciencesUniversity of PadovaPadovaItaly
| | - Rosario Rizzuto
- Department of Biomedical SciencesUniversity of PadovaPadovaItaly
| | - Paolo Bernardi
- Department of Biomedical SciencesUniversity of PadovaPadovaItaly
- CNR Neuroscience InstitutePadovaItaly
| | - Fabio Di Lisa
- Department of Biomedical SciencesUniversity of PadovaPadovaItaly
- CNR Neuroscience InstitutePadovaItaly
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Goswami SK, Ponnalagu D, Hussain AT, Shah K, Karekar P, Gururaja Rao S, Meredith AL, Khan M, Singh H. Expression and Activation of BK Ca Channels in Mice Protects Against Ischemia-Reperfusion Injury of Isolated Hearts by Modulating Mitochondrial Function. Front Cardiovasc Med 2019; 5:194. [PMID: 30746365 PMCID: PMC6360169 DOI: 10.3389/fcvm.2018.00194] [Citation(s) in RCA: 37] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2018] [Accepted: 12/18/2018] [Indexed: 12/14/2022] Open
Abstract
Aims: Activation and expression of large conductance calcium and voltage-activated potassium channel (BKCa) by pharmacological agents have been implicated in cardioprotection from ischemia-reperfusion (IR) injury possibly by regulating mitochondrial function. Given the non-specific effects of pharmacological agents, it is not clear whether activation of BKCa is critical to cardioprotection. In this study, we aimed to decipher the mechanistic role of BKCa in cardioprotection from IR injury by genetically activating BKCa channels. Methods and Results: Hearts from adult (3 months old) wild-type mice (C57/BL6) and mice expressing genetically activated BKCa (Tg-BKCa R207Q, referred as Tg-BKCa) along with wild-type BKCa were subjected to 20 min of ischemia and 30 min of reperfusion with or without ischemic preconditioning (IPC, 2 times for 2.5 min interval each). Left ventricular developed pressure (LVDP) was recorded using Millar's Mikrotip® catheter connected to ADInstrument data acquisition system. Myocardial infarction was quantified by 2,3,5-triphenyl tetrazolium chloride (TTC) staining. Our results demonstrated that Tg-BKCa mice are protected from IR injury, and BKCa also contributes to IPC-mediated cardioprotection. Cardiac function parameters were also measured by echocardiography and no differences were observed in left ventricular ejection fraction, fractional shortening and aortic velocities. Amplex Red® was used to assess reactive oxygen species (ROS) production in isolated mitochondria by spectrofluorometry. We found that genetic activation of BKCa reduces ROS after IR stress. Adult cardiomyocytes and mitochondria from Tg-BKCa mice were isolated and labeled with Anti-BKCa antibodies. Images acquired via confocal microscopy revealed localization of cardiac BKCa in the mitochondria. Conclusions: Activation of BKCa is essential for recovery of cardiac function after IR injury and is likely a factor in IPC mediated cardioprotection. Genetic activation of BKCa reduces ROS produced by complex I and complex II/III in Tg-BKCa mice after IR, and IPC further decreases it. These results implicate BKCa-mediated cardioprotection, in part, by reducing mitochondrial ROS production. Localization of Tg-BKCa in adult cardiomyocytes of transgenic mice was similar to BKCa in wild-type mice.
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Affiliation(s)
- Sumanta Kumar Goswami
- Department of Pharmacology and Physiology, Drexel University College of Medicine, Philadelphia, PA, United States.,Department of Physiology and Cell Biology, Wexner Medical Center, Ohio State University, Columbus, OH, United States
| | - Devasena Ponnalagu
- Department of Pharmacology and Physiology, Drexel University College of Medicine, Philadelphia, PA, United States.,Department of Physiology and Cell Biology, Wexner Medical Center, Ohio State University, Columbus, OH, United States
| | - Ahmed T Hussain
- Department of Pharmacology and Physiology, Drexel University College of Medicine, Philadelphia, PA, United States
| | - Kajol Shah
- Department of Pharmacology and Physiology, Drexel University College of Medicine, Philadelphia, PA, United States
| | - Priyanka Karekar
- Department of Pharmacology and Physiology, Drexel University College of Medicine, Philadelphia, PA, United States.,Department of Physiology and Cell Biology, Wexner Medical Center, Ohio State University, Columbus, OH, United States
| | - Shubha Gururaja Rao
- Department of Pharmacology and Physiology, Drexel University College of Medicine, Philadelphia, PA, United States.,Department of Physiology and Cell Biology, Wexner Medical Center, Ohio State University, Columbus, OH, United States
| | - Andrea L Meredith
- Department of Physiology, University of Maryland, Baltimore, MD, United States
| | - Mahmood Khan
- Department of Physiology and Cell Biology, Wexner Medical Center, Ohio State University, Columbus, OH, United States.,Department of Emergency Medicine, Wexner Medical Center, Ohio State University, Columbus, OH, United States
| | - Harpreet Singh
- Department of Pharmacology and Physiology, Drexel University College of Medicine, Philadelphia, PA, United States.,Department of Physiology and Cell Biology, Wexner Medical Center, Ohio State University, Columbus, OH, United States
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Dai H, Wang M, Patel PN, Kalogeris T, Liu Y, Durante W, Korthuis RJ. Preconditioning with the BK Ca channel activator NS-1619 prevents ischemia-reperfusion-induced inflammation and mucosal barrier dysfunction: roles for ROS and heme oxygenase-1. Am J Physiol Heart Circ Physiol 2017; 313:H988-H999. [PMID: 28822969 DOI: 10.1152/ajpheart.00620.2016] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/13/2016] [Revised: 07/25/2017] [Accepted: 08/07/2017] [Indexed: 12/12/2022]
Abstract
Activation of large-conductance Ca2+-activated K+ (BKCa) channels evokes cell survival programs that mitigate intestinal ischemia and reperfusion (I/R) inflammation and injury 24 h later. The goal of the present study was to determine the roles of reactive oxygen species (ROS) and heme oxygenase (HO)-1 in delayed acquisition of tolerance to I/R induced by pretreatment with the BKCa channel opener NS-1619. Superior mesentery arteries were occluded for 45 min followed by reperfusion for 70 min in wild-type (WT) or HO-1-null (HO-1-/-) mice that were pretreated with NS-1619 or saline vehicle 24 h earlier. Intravital microscopy was used to quantify the numbers of rolling and adherent leukocytes. Mucosal permeability, tumor necrosis factor-α (TNF-α) levels, and HO-1 activity and expression in jejunum were also determined. I/R induced leukocyte rolling and adhesion, increased intestinal TNF-α levels, and enhanced mucosal permeability in WT mice, effects that were largely abolished by pretreatment with NS-1619. The anti-inflammatory and mucosal permeability-sparing effects of NS-1619 were prevented by coincident treatment with the HO-1 inhibitor tin protoporphyrin-IX or a cell-permeant SOD mimetic, Mn(III)tetrakis (4-benzoic acid) porphyrin (MnTBAP), in WT mice. NS-1619 also increased jejunal HO-1 activity in WT animals, an effect that was attenuated by treatment with the BKCa channel antagonist paxilline or MnTBAP. I/R also increased postischemic leukocyte rolling and adhesion and intestinal TNF-α levels in HO-1-/- mice to levels comparable to those noted in WT animals. However, NS-1619 was ineffective in preventing these effects in HO-1-deficient mice. In summary, our data indicate that NS-1619 induces the development of an anti-inflammatory phenotype and mitigates postischemic mucosal barrier disruption in the small intestine by a mechanism that may involve ROS-dependent HO-1 activity.NEW & NOTEWORTHY Antecedent treatment with the large-conductance Ca2+-activated K+ channel opener NS-1619 24 h before ischemia-reperfusion limits postischemic tissue injury by an oxidant-dependent mechanism. The present study shows that NS-1619-induced oxidant production prevents ischemia-reperfusion-induced inflammation and mucosal barrier disruption in the small intestine by provoking increases in heme oxygenase-1 activity.
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Affiliation(s)
- Hongyan Dai
- Department of Medical Pharmacology and Physiology and Dalton Cardiovascular Research Center, University of Missouri School of Medicine, Columbia, Missouri
| | - Meifang Wang
- Department of Medical Pharmacology and Physiology and Dalton Cardiovascular Research Center, University of Missouri School of Medicine, Columbia, Missouri
| | - Parag N Patel
- Department of Medical Pharmacology and Physiology and Dalton Cardiovascular Research Center, University of Missouri School of Medicine, Columbia, Missouri
| | - Theodore Kalogeris
- Department of Medical Pharmacology and Physiology and Dalton Cardiovascular Research Center, University of Missouri School of Medicine, Columbia, Missouri
| | - Yajun Liu
- Department of Medical Pharmacology and Physiology and Dalton Cardiovascular Research Center, University of Missouri School of Medicine, Columbia, Missouri
| | - William Durante
- Department of Medical Pharmacology and Physiology and Dalton Cardiovascular Research Center, University of Missouri School of Medicine, Columbia, Missouri
| | - Ronald J Korthuis
- Department of Medical Pharmacology and Physiology and Dalton Cardiovascular Research Center, University of Missouri School of Medicine, Columbia, Missouri
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10
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The Slo(w) path to identifying the mitochondrial channels responsible for ischemic protection. Biochem J 2017; 474:2067-2094. [PMID: 28600454 DOI: 10.1042/bcj20160623] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2017] [Revised: 02/10/2017] [Accepted: 02/13/2017] [Indexed: 12/19/2022]
Abstract
Mitochondria play an important role in tissue ischemia and reperfusion (IR) injury, with energetic failure and the opening of the mitochondrial permeability transition pore being the major causes of IR-induced cell death. Thus, mitochondria are an appropriate focus for strategies to protect against IR injury. Two widely studied paradigms of IR protection, particularly in the field of cardiac IR, are ischemic preconditioning (IPC) and volatile anesthetic preconditioning (APC). While the molecular mechanisms recruited by these protective paradigms are not fully elucidated, a commonality is the involvement of mitochondrial K+ channel opening. In the case of IPC, research has focused on a mitochondrial ATP-sensitive K+ channel (mitoKATP), but, despite recent progress, the molecular identity of this channel remains a subject of contention. In the case of APC, early research suggested the existence of a mitochondrial large-conductance K+ (BK, big conductance of potassium) channel encoded by the Kcnma1 gene, although more recent work has shown that the channel that underlies APC is in fact encoded by Kcnt2 In this review, we discuss both the pharmacologic and genetic evidence for the existence and identity of mitochondrial K+ channels, and the role of these channels both in IR protection and in regulating normal mitochondrial function.
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Investigating the involvement of TRPV 1 ion channels in remote hind limb preconditioning-induced cardioprotection in rats. Naunyn Schmiedebergs Arch Pharmacol 2016; 390:117-126. [PMID: 27752734 DOI: 10.1007/s00210-016-1311-x] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2016] [Accepted: 10/09/2016] [Indexed: 01/03/2023]
Abstract
Remote ischemic preconditioning (RIPC) treatment strategy is a breakthrough in the field of cardiovascular pharmacology as it has the potential to attenuate myocardial ischemia-reperfusion injury. However, the underlying intracellular pathways have not been widely explored. The present study intends to explore the possible role of TRPV1 channels in mediating remote hind limb preconditioning-induced cardioprotection. Remote hind limb preconditioning stimulus (4 cycles in succession) was delivered by tying the blood pressure cuff at the inguinal level of the rat. The Langendorff system was used to perfuse the isolated heart and afterward was subjected to 30 min of global ischemia and 120 min of reperfusion. Sustained ischemia and, thereafter, reperfusion led to cardiac injury that was assessed in terms of infarct size, lactate dehydrogenase (LDH) release, creatine kinase (CK) release, left ventricular end diastolic pressure (LVEDP), left ventricular developed pressure (LVDP), +dp/dtmax, -dp/dtmin, heart rate, rate pressure product, and coronary flow rate. The pharmacological modulators employed included capsaicin as TRPV1 agonist and capsazepine as TRPV1 antagonist. Remote hind limb preconditioning stimulus and capsaicin preconditioning (5 and 10 mg/kg) led to significant reduction in infarct size, LVEDP, LDH release, CK release, and significant improvement in LVDP, +dp/dtmax, -dp/dtmin, heart rate, rate pressure product, and coronary flow rate. However, remote hind limb preconditioning-induced cardioprotective effects were considerably abolished in the presence of capsazepine (2.5 and 5 mg/kg). This indicates that remote hind limb preconditioning stimulus possibly activates TRPV1 channels to produce cardioprotective effects.
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Randhawa PK, Jaggi AS. Gadolinium and ruthenium red attenuate remote hind limb preconditioning-induced cardioprotection: possible role of TRP and especially TRPV channels. Naunyn Schmiedebergs Arch Pharmacol 2016; 389:887-96. [PMID: 27118661 DOI: 10.1007/s00210-016-1251-5] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2015] [Accepted: 04/20/2016] [Indexed: 01/16/2023]
Abstract
Remote ischemic preconditioning is a well reported therapeutic strategy that induces cardioprotective effects but the underlying intracellular mechanisms have not been widely explored. The current study was designed to investigate the involvement of TRP and especially TRPV channels in remote hind limb preconditioning-induced cardioprotection. Remote hind limb preconditioning stimulus (4 alternate cycles of inflation and deflation of 5 min each) was delivered using a blood pressure cuff tied on the hind limb of the anesthetized rat. Using Langendorff's system, the heart was perfused and subjected to 30-min ischemia and 120-min reperfusion. The myocardial injury was assessed by measuring infarct size, lactate dehydrogenase (LDH), creatine kinase (CK), LVDP, +dp/dtmax, -dp/dtmin, heart rate, and coronary flow rate. Gadolinium, TRP blocker, and ruthenium red, TRPV channel blocker, were employed as pharmacological tools. Remote hind limb preconditioning significantly reduced the infarct size, LDH release, CK release and improved coronary flow rate, hemodynamic parameters including LVDP, +dp/dtmax, -dp/dtmin, and heart rate. However, gadolinium (7.5 and 15 mg kg(-1)) and ruthenium red (4 and 8 mg kg(-1)) significantly attenuated the cardioprotective effects suggesting the involvement of TRP especially TRPV channels in mediating remote hind limb preconditioning-induced cardioprotection. Remote hind limb preconditioning stimulus possibly activates TRPV channels on the heart or sensory nerve fibers innervating the heart to induce cardioprotective effects. Alternatively, remote hind limb preconditioning stimulus may also activate the mechanosensitive TRP and especially TRPV channels on the sensory nerve fibers innervating the skeletal muscles to trigger cardioprotective neurogenic signaling cascade. The cardioprotective effects of remote hind limb preconditioning may be mediated via activation of mechanosensitive TRP and especially TRPV channels.
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Affiliation(s)
- Puneet Kaur Randhawa
- Department of Pharmaceutical Sciences and Drug Research, Punjabi University, Patiala, 147002, India
| | - Amteshwar Singh Jaggi
- Department of Pharmaceutical Sciences and Drug Research, Punjabi University, Patiala, 147002, India.
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Kinoshita M, M. Tsutsumi Y, Fukuta K, Kasai A, Tanaka K. Isoflurane-induced postconditioning via mitochondrial calcium-activated potassium channels. THE JOURNAL OF MEDICAL INVESTIGATION 2016; 63:80-4. [DOI: 10.2152/jmi.63.80] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
Affiliation(s)
| | - Yasuo M. Tsutsumi
- Department of Anesthesiology, Institute of Biomedical Sciences, Tokushima University Graduate School
| | - Kohei Fukuta
- Department of Anesthesiology, Tokushima University Hospital
| | - Asuka Kasai
- Department of Anesthesiology, Tokushima University Hospital
| | - Katsuya Tanaka
- Department of Anesthesiology, Institute of Biomedical Sciences, Tokushima University Graduate School
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Impact of Mitochondrial Ca2+-Sensitive Potassium (mBKCa) Channels in Sildenafil-Induced Cardioprotection in Rats. PLoS One 2015; 10:e0144737. [PMID: 26671662 PMCID: PMC4684397 DOI: 10.1371/journal.pone.0144737] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2015] [Accepted: 11/23/2015] [Indexed: 12/13/2022] Open
Abstract
BACKGROUND Mitochondrial large-conductance Ca2+-sensitive potassium (mBKCa) channels are involved in myocardial ischemic preconditioning. Their role in sildenafil-induced cardioprotection is unknown. We investigated whether sildenafil-induced acute cardioprotection is mediated by activation of mBKCa channels in the rat heart in vitro. METHODS Male Wistar rats (n = 8 per group) were randomized and anesthetized with pentobarbital (90 mg/kg). Hearts were isolated, mounted on a Langendorff system and perfused with Krebs-Henseleit buffer at a constant pressure of 80 mmHg. Hearts underwent 30 min of global ischemia followed by 60 min of reperfusion. At the end of the experiments infarct size was determined by TTC staining. In the control group rats were not further treated. Sildenafil (3 μM) was administered over 10 min before the beginning of ischemia. The mBKCa channel inhibitor paxilline (1 μM) was administered with and without sildenafil before the onset of ischemia. The pathway underlying sildenafil-induced cardioprotection was further investigated with the protein kinase G blocker KT5823 (1 μM). Myocardial cGMP concentration was measured by ELISA. Data (mean±SD) were analysed with a one and two-way analysis of variance as appropriate. RESULTS In control animals infarct size was 52±8%. Sildenafil increased cGMP concentration and reduced infarct size to 35±6% (P<0.05 vs. control). Paxilline and KT5823 completely blocked sildenafil-induced cardioprotection (paxilline+sildenafil: 50±8%, KT5823+sildenafil: 45±8%; both P<0.05 vs. sildenafil). Functional heart parameters and coronary flow were not different between the study groups. CONCLUSION This study shows that in male rats protein kinase G-dependent opening of mBKCa channels plays a pivotal role in sildenafil-induced cardioprotection.
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Hermann A, Sitdikova GF, Weiger TM. Oxidative Stress and Maxi Calcium-Activated Potassium (BK) Channels. Biomolecules 2015; 5:1870-911. [PMID: 26287261 PMCID: PMC4598779 DOI: 10.3390/biom5031870] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2015] [Revised: 07/17/2015] [Accepted: 07/20/2015] [Indexed: 01/13/2023] Open
Abstract
All cells contain ion channels in their outer (plasma) and inner (organelle) membranes. Ion channels, similar to other proteins, are targets of oxidative impact, which modulates ion fluxes across membranes. Subsequently, these ion currents affect electrical excitability, such as action potential discharge (in neurons, muscle, and receptor cells), alteration of the membrane resting potential, synaptic transmission, hormone secretion, muscle contraction or coordination of the cell cycle. In this chapter we summarize effects of oxidative stress and redox mechanisms on some ion channels, in particular on maxi calcium-activated potassium (BK) channels which play an outstanding role in a plethora of physiological and pathophysiological functions in almost all cells and tissues. We first elaborate on some general features of ion channel structure and function and then summarize effects of oxidative alterations of ion channels and their functional consequences.
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Affiliation(s)
- Anton Hermann
- Department of Cell Biology, Division of Cellular and Molecular Neurobiology, University of Salzburg, Salzburg 5020, Austria.
| | - Guzel F Sitdikova
- Department of Physiology of Man and Animals, Kazan Federal University, Kazan 420008, Russia.
| | - Thomas M Weiger
- Department of Cell Biology, Division of Cellular and Molecular Neurobiology, University of Salzburg, Salzburg 5020, Austria.
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Bentzen BH, Olesen SP, Rønn LCB, Grunnet M. BK channel activators and their therapeutic perspectives. Front Physiol 2014; 5:389. [PMID: 25346695 PMCID: PMC4191079 DOI: 10.3389/fphys.2014.00389] [Citation(s) in RCA: 113] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2014] [Accepted: 09/19/2014] [Indexed: 01/05/2023] Open
Abstract
The large conductance calcium- and voltage-activated K+ channel (KCa1.1, BK, MaxiK) is ubiquitously expressed in the body, and holds the ability to integrate changes in intracellular calcium and membrane potential. This makes the BK channel an important negative feedback system linking increases in intracellular calcium to outward hyperpolarizing potassium currents. Consequently, the channel has many important physiological roles including regulation of smooth muscle tone, neurotransmitter release and neuronal excitability. Additionally, cardioprotective roles have been revealed in recent years. After a short introduction to the structure, function and regulation of BK channels, we review the small organic molecules activating BK channels and how these tool compounds have helped delineate the roles of BK channels in health and disease.
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Affiliation(s)
- Bo H Bentzen
- Department of Biomedical Sciences, Faculty of Health Sciences, Danish Arrhythmia Research Centre, University of Copenhagen Copenhagen, Denmark ; Acesion Pharma Copenhagen, Denmark
| | - Søren-Peter Olesen
- Department of Biomedical Sciences, Faculty of Health Sciences, Danish Arrhythmia Research Centre, University of Copenhagen Copenhagen, Denmark
| | | | - Morten Grunnet
- Acesion Pharma Copenhagen, Denmark ; H. Lundbeck A/S Copenhagen, Denmark
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Tano JY, Gollasch M. Calcium-activated potassium channels in ischemia reperfusion: a brief update. Front Physiol 2014; 5:381. [PMID: 25339909 PMCID: PMC4186282 DOI: 10.3389/fphys.2014.00381] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2014] [Accepted: 09/13/2014] [Indexed: 12/24/2022] Open
Abstract
Ischemia and reperfusion (IR) injury constitutes one of the major causes of cardiovascular morbidity and mortality. The discovery of new therapies to block/mediate the effects of IR is therefore an important goal in the biomedical sciences. Dysfunction associated with IR involves modification of calcium-activated potassium channels (KCa) through different mechanisms, which are still under study. Respectively, the KCa family, major contributors to plasma membrane calcium influx in cells and essential players in the regulation of the vascular tone are interesting candidates. This family is divided into two groups including the large conductance (BKCa) and the small/intermediate conductance (SKCa/IKCa) K(+) channels. In the heart and brain, these channels have been described to offer protection against IR injury. BKCa and SKCa channels deserve special attention since new data demonstrate that these channels are also expressed in mitochondria. More studies are however needed to fully determine their potential use as therapeutic targets.
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Affiliation(s)
- Jean-Yves Tano
- Experimental and Clinical Research Center, Charité University Medicine - Max Delbrück Center (MDC) for Molecular Medicine Berlin, Germany ; Nephrology/Intensive Care Section, Charité University Medicine Berlin, Germany
| | - Maik Gollasch
- Experimental and Clinical Research Center, Charité University Medicine - Max Delbrück Center (MDC) for Molecular Medicine Berlin, Germany ; Nephrology/Intensive Care Section, Charité University Medicine Berlin, Germany
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Kalogeris T, Bao Y, Korthuis RJ. Mitochondrial reactive oxygen species: a double edged sword in ischemia/reperfusion vs preconditioning. Redox Biol 2014; 2:702-14. [PMID: 24944913 PMCID: PMC4060303 DOI: 10.1016/j.redox.2014.05.006] [Citation(s) in RCA: 510] [Impact Index Per Article: 51.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2014] [Revised: 05/23/2014] [Accepted: 05/27/2014] [Indexed: 02/06/2023] Open
Abstract
Reductions in the blood supply produce considerable injury if the duration of ischemia is prolonged. Paradoxically, restoration of perfusion to ischemic organs can exacerbate tissue damage and extend the size of an evolving infarct. Being highly metabolic organs, the heart and brain are particularly vulnerable to the deleterious effects of ischemia/reperfusion (I/R). While the pathogenetic mechanisms contributing to I/R-induced tissue injury and infarction are multifactorial, the relative importance of each contributing factor remains unclear. However, an emerging body of evidence indicates that the generation of reactive oxygen species (ROS) by mitochondria plays a critical role in damaging cellular components and initiating cell death. In this review, we summarize our current understanding of the mechanisms whereby mitochondrial ROS generation occurs in I/R and contributes to myocardial infarction and stroke. In addition, mitochondrial ROS have been shown to participate in preconditioning by several pharmacologic agents that target potassium channels (e.g., ATP-sensitive potassium (mKATP) channels or large conductance, calcium-activated potassium (mBKCa) channels) to activate cell survival programs that render tissues and organs more resistant to the deleterious effects of I/R. Finally, we review novel therapeutic approaches that selectively target mROS production to reduce postischemic tissue injury, which may prove efficacious in limiting myocardial dysfunction and infarction and abrogating neurocognitive deficits and neuronal cell death in stroke.
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Affiliation(s)
- Theodore Kalogeris
- Department of Medical Pharmacology and Physiology, School of Medicine, Dalton Cardiovascular Research Center, University of Missouri, 1 Hospital Drive, Columbia, MO 65212-0001, United States of America
| | - Yimin Bao
- Department of Medical Pharmacology and Physiology, School of Medicine, Dalton Cardiovascular Research Center, University of Missouri, 1 Hospital Drive, Columbia, MO 65212-0001, United States of America
| | - Ronald J Korthuis
- Department of Medical Pharmacology and Physiology, School of Medicine, Dalton Cardiovascular Research Center, University of Missouri, 1 Hospital Drive, Columbia, MO 65212-0001, United States of America
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Wang Q, Kalogeris TJ, Wang M, Jones AW, Korthuis RJ. Antecedent ethanol attenuates cerebral ischemia/reperfusion-induced leukocyte-endothelial adhesive interactions and delayed neuronal death: role of large conductance, Ca2+-activated K+ channels. Microcirculation 2010; 17:427-38. [PMID: 20690981 DOI: 10.1111/j.1549-8719.2010.00041.x] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
EtOH-PC reduces postischemic neuronal injury in response to cerebral (I/R). We examined the mechanism underlying this protective effect by determining (i) whether it was associated with a decrease in I/R-induced leukocyte-endothelial adhesive interactions in postcapillary venules, and (ii) whether the protective effects were mediated by activation of large conductance, calcium-activated potassium (BK(Ca)) channels. Mice were administered ethanol by gavage or treated with the BK(Ca) channel opener, NS1619, 24 hours prior to I/R with or without prior treatment with the BK(Ca) channel blocker, PX. Both CCA were occluded for 20 minutes followed by two and three hours of reperfusion, and rolling (LR) and adherent (LA) leukocytes were quantified in pial venules using intravital microscopy. The extent of DND, apoptosis and glial activation in hippocampus were assessed four days after I/R. Compared with sham, I/R elicited increases in LR and LA in pial venules and DND and apoptosis as well as glial activation in the hippocampus. These effects were attenuated by EtOH-PC or antecedent NS1619 administration, and this protection was reversed by prior treatment with PX. Our results support a role for BK(Ca) channel activation in the neuroprotective effects of EtOH-PC in cerebral I/R.
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Affiliation(s)
- Qun Wang
- Department of Medical Pharmacology and Physiology, University of Missouri School of Medicine, Columbia, Missouri 65212, USA
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20
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Zuidema MY, Yang Y, Wang M, Kalogeris T, Liu Y, Meininger CJ, Hill MA, Davis MJ, Korthuis RJ. Antecedent hydrogen sulfide elicits an anti-inflammatory phenotype in postischemic murine small intestine: role of BK channels. Am J Physiol Heart Circ Physiol 2010; 299:H1554-67. [PMID: 20833953 DOI: 10.1152/ajpheart.01229.2009] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
The objectives of this study were to determine the role of calcium-activated, small (SK), intermediate (IK), and large (BK) conductance potassium channels in initiating the development of an anti-inflammatory phenotype elicited by preconditioning with an exogenous hydrogen sulfide (H(2)S) donor, sodium hydrosulfide (NaHS). Intravital microscopy was used to visualize rolling and firmly adherent leukocytes in vessels of the small intestine of mice preconditioned with NaHS (in the absence and presence of SK, IK, and BK channel inhibitors, apamin, TRAM-34, and paxilline, respectively) or SK/IK (NS-309) or BK channel activators (NS-1619) 24 h before ischemia-reperfusion (I/R). I/R induced marked increases in leukocyte rolling and adhesion, effects that were largely abolished by preconditioning with NaHS, NS-309, or NS-1619. The postischemic anti-inflammatory effects of NaHS-induced preconditioning were mitigated by BKB channel inhibitor treatment coincident with NaHS, but not by apamin or TRAM-34, 24 h before I/R. Confocal imaging and immunohistochemistry were used to demonstrate the presence of BKα subunit staining in both endothelial and vascular smooth muscle cells of isolated, pressurized mesenteric venules. Using patch-clamp techniques, we found that BK channels in cultured endothelial cells were activated after exposure to NaHS. Bath application of the same concentration of NaHS used in preconditioning protocols led to a rapid increase in a whole cell K(+) current; specifically, the component of K(+) current blocked by the selective BK channel antagonist iberiotoxin. The activation of BK current by NaHS could also be demonstrated in single channel recording mode where it was independent of a change in intracellular Ca(+) concentration. Our data are consistent with the concept that H(2)S induces the development of an anti-adhesive state in I/R in part mediated by a BK channel-dependent mechanism.
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Affiliation(s)
- Mozow Y Zuidema
- Department of Medical Pharmacology and Physiology, Dalton Cardiovascular Research Center, University of Missouri School of Medicine, Columbia, Missouri 65212, USA
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Frässdorf J, Huhn R, Niersmann C, Weber NC, Schlack W, Preckel B, Hollmann MW. Morphine induces preconditioning via activation of mitochondrial K(Ca) channels. Can J Anaesth 2010; 57:767-73. [PMID: 20461490 PMCID: PMC2899019 DOI: 10.1007/s12630-010-9325-1] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2010] [Accepted: 04/19/2010] [Indexed: 12/13/2022] Open
Abstract
Purpose Mitochondrial calcium sensitive potassium (mKCa) channels are involved in cardioprotection induced by ischemic preconditioning. In the present study we investigated whether morphine-induced preconditioning also involves activation of mKCa channels. Methods Isolated rat hearts (six groups; each n = 8) underwent global ischemia for 30 min followed by a 60-min reperfusion. Control animals were not further treated. Morphine preconditioning (MPC) was initiated by two five-minute cycles of morphine 1 μM infusion with one five-minute washout and one final ten-minute washout period before ischemia. The mKCa blocker, paxilline 1 μM, was administered, with and without morphine administration (MPC + Pax and Pax). As a positive control, we added an ischemic preconditioning group (IPC) alone and combined with paxilline (IPC + Pax). At the end of reperfusion, infarct sizes were determined by triphenyltetrazoliumchloride staining. Results Infarct size was (mean ± SD) 45 ± 9% of the area at risk in the Control group. The infarct size was less in the morphine or ischemic preconditioning groups (MPC: 23 ± 8%, IPC: 20 ± 5%; each P < 0.05 vs Control). Infarct size reduction was abolished by paxilline (MPC + Pax: 37 ± 7%, P < 0.05 vs MPC and IPC + Pax: 36 ± 6%, P < 0.05 vs IPC), whereas paxilline alone had no effect (Pax: 46 ± 7%, not significantly different from Control). Conclusion Cardioprotection by morphine-induced preconditioning is mediated by activation of mKCa channels.
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Affiliation(s)
- Jan Frässdorf
- Department of Anesthesiology, Academic Medical Center, University of Amsterdam, The Netherlands
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Gáspár T, Domoki F, Lenti L, Katakam PVG, Snipes JA, Bari F, Busija DW. Immediate neuronal preconditioning by NS1619. Brain Res 2009; 1285:196-207. [PMID: 19523929 DOI: 10.1016/j.brainres.2009.06.008] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2009] [Revised: 06/03/2009] [Accepted: 06/05/2009] [Indexed: 01/21/2023]
Abstract
The objectives of our present experiments were to determine whether the BK(Ca) channel agonist NS1619 is able to induce immediate preconditioning in cultured rat cortical neurons and to elucidate the role of BK(Ca) channels in the initiation of immediate preconditioning. NS1619 depolarized mitochondria and increased reactive oxygen species (ROS) generation, but neither of these effects was inhibited by BK(Ca) channel antagonists. NS1619 also activated the extracellular signal-regulated kinase signaling pathways. One-hour treatment with NS1619 induced immediate protection against glutamate excitotoxicity (viability 24 h after glutamate exposure: control, 58.45+/-0.95%; NS1619 50 microM, 78.99+/-0.90%; NS1619 100 microM, 86.89+/-1.20%; NS1619 150 microM, 93.23+/-1.23%; mean+/-SEM; p<0.05 vs. control; n=16-32). Eliminating ROS during the preconditioning phase effectively blocked the development of cytoprotection. In contrast, the BK(Ca) channel blockers iberiotoxin and paxilline, the phosphoinositide 3-kinase inhibitor wortmannin, the protein kinase C blocker chelerythrine, and the mitogen activated protein kinase antagonist PD98059 were unable to antagonize the immediate neuroprotective effect. Finally, preconditioning with NS1619 reduced the calcium load and ROS surge upon glutamate exposure and increased superoxide dismutase activity. Our results indicate that NS1619 is an effective inducer of immediate neuronal preconditioning, but the neuroprotective effect is independent of the activation of BK(Ca) channels.
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Affiliation(s)
- Tamás Gáspár
- Department of Physiology and Pharmacology, Wake Forest University Health Sciences, Winston-Salem, NC 27157, USA.
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Feng J, Liu Y, Khabbaz KR, Sodha NR, Osipov RM, Hagberg R, Alper SL, Sellke FW. Large conductance calcium-activated potassium channels contribute to the reduced myogenic tone of peripheral microvasculature after cardiopulmonary bypass. J Surg Res 2009; 157:123-8. [PMID: 19765723 DOI: 10.1016/j.jss.2009.03.043] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2009] [Revised: 02/24/2009] [Accepted: 03/25/2009] [Indexed: 11/26/2022]
Abstract
BACKGROUND We investigated the role of calcium-activated potassium (K(Ca)) channel activation in myogenic tone in human peripheral microvasculature after heart surgery. METHODS Human skeletal muscle arterioles (90-180microm diameter) were dissected from tissue harvested pre- and post-cardiopulmonary bypass (CPB) during cardiac surgery. Myogenic reactivity in response to stepwise increases in intraluminal pressure was studied between pressure steps. Microvessel tone was determined pre-CPB, post-CPB, and after blockade of K(Ca) channels. Expression and localization of large conductance (BK) K(Ca) channels in the coronary microvasculature was assessed by immunoblot and immunofluorescence photomicroscopy. RESULTS Myogenic tone of skeletal muscle arterioles was significantly reduced post-CPB compared with pre-CPB. Decrease in myogenic tone after CPB was reflected by the increase in microvessel internal diameter. Myogenic tone of post-CPB microvessels was significantly increased after treatment with BK(Ca)-blocker iberiotoxin, but unchanged in the combined presence of the blockers of intermediate (IK(Ca)) and small conductance (SK(Ca)) K(Ca) channels, TRAM34/apamin. The increases in myogenic tone after iberiotoxin treatment were demonstrated as a decrease in microvessel internal diameter. No significant differences in BK(Ca) protein levels were noted comparing pre- and post-CPB conditions judged by immunoblot and by immunofluorescence staining of skeletal muscle microvessels. Prominent staining for BK(Ca)-alpha and BK(Ca)-beta(1) subunits localized to the microvascular smooth muscle. CONCLUSION CPB-associated decrease in peripheral myogenic reactivity is likely due to activation of BK(Ca), but not IK(Ca) or SK(Ca). CPB may increase BK(Ca) activity without increasing BK polypeptide level.
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Affiliation(s)
- Jun Feng
- Department of Surgery, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts, USA
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Gáspár T, Katakam P, Snipes JA, Kis B, Domoki F, Bari F, Busija DW. Delayed neuronal preconditioning by NS1619 is independent of calcium activated potassium channels. J Neurochem 2007; 105:1115-28. [PMID: 18182041 DOI: 10.1111/j.1471-4159.2007.05210.x] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
1,3-Dihydro-1-[2-hydroxy-5-(trifluoromethyl)phenyl]-5-(trifluoromethyl)-2H-benzimidazol-2-one (NS1619), a potent activator of the large conductance Ca2+ activated potassium (BK(Ca)) channel, has been demonstrated to induce preconditioning (PC) in the heart. The aim of our study was to test the delayed PC effect of NS1619 in rat cortical neuronal cultures against oxygen-glucose deprivation, H2O2, or glutamate excitotoxicity. We also investigated its actions on reactive oxygen species (ROS) generation, and on mitochondrial and plasma membrane potentials. Furthermore, we tested the activation of the phosphoinositide 3-kinase (PI3K) signaling pathway, and the effect of NS1619 on caspase-3/7. NS1619 dose-dependently protected the cells against the toxic insults, and the protection was completely blocked by a superoxide dismutase mimetic and a PI3K antagonist, but not by BK(Ca) channel inhibitors. Application of NS1619 increased ROS generation, depolarized isolated mitochondria, hyperpolarized the neuronal cell membrane, and activated the PI3K signaling cascade. However, only the effect on the cell membrane potential was antagonized by BK(Ca) channel blockers. NS1619 inhibited the activation of capase-3/7. In summary, NS1619 is a potent inducer of delayed neuronal PC. However, the neuroprotective effect seems to be independent of cell membrane and mitochondrial BK(Ca) channels. Rather it is the consequence of ROS generation, activation of the PI3K pathway, and inhibition of caspase activation.
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Affiliation(s)
- Tamás Gáspár
- Department of Physiology and Pharmacology, Wake Forest University Health Sciences, Medical Center Boulevard, Winston-Salem, North Carolina, USA.
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Abstract
In work spanning more than a century, mitochondria have been recognized for their multifunctional roles in metabolism, energy transduction, ion transport, inheritance, signaling, and cell death. Foremost among these tasks is the continuous production of ATP through oxidative phosphorylation, which requires a large electrochemical driving force for protons across the mitochondrial inner membrane. This process requires a membrane with relatively low permeability to ions to minimize energy dissipation. However, a wealth of evidence now indicates that both selective and nonselective ion channels are present in the mitochondrial inner membrane, along with several known channels on the outer membrane. Some of these channels are active under physiological conditions, and others may be activated under pathophysiological conditions to act as the major determinants of cell life and death. This review summarizes research on mitochondrial ion channels and efforts to identify their molecular correlates. Except in a few cases, our understanding of the structure of mitochondrial ion channels is limited, indicating the need for focused discovery in this area.
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Affiliation(s)
- Brian O'Rourke
- Institute of Molecular Cardiobiology, Division of Cardiology, Department of Medicine, The Johns Hopkins University, Baltimore, Maryland 21205, USA.
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Ljubkovic M, Marinovic J, Fuchs A, Bosnjak ZJ, Bienengraeber M. Targeted expression of Kir6.2 in mitochondria confers protection against hypoxic stress. J Physiol 2006; 577:17-29. [PMID: 16959852 PMCID: PMC2000685 DOI: 10.1113/jphysiol.2006.118299] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
Selective K(+) transport in the inner mitochondrial membrane has been attributed to at least three different channel types: ATP-sensitive, Ca(2+)-regulated and voltage-dependent K(+) channels. Studies utilizing their selective modulators have suggested that an increased activity of these channels plays an important role in the cellular protection from metabolic stress. However, direct evidence for this effect is largely absent, and recent findings on the lack of specificity for several channel openers and blockers have questioned the actual contribution of the mitochondrial K(+) channels in the preservation of cellular viability. In order to directly investigate the role of enhanced mitochondrial K(+) uptake in cellular protection, we selectively expressed the inward rectifying K(+) channel Kir6.2 in the mitochondria of HEK293 and HL-1 cells. Targeted Kir6.2 expression was achieved by cloning the Kir6.2 gene in pCMV/mito/GFP vector and the proper trafficking to mitochondria was confirmed by colocalization studies and Western blot. An increased K(+) influx to mitochondria overexpressing Kir6.2, as evidenced by using the K(+)-sensitive PBFI AM fluorescent dye, substantially improved the cellular viability after hypoxic stress, which was assessed by lactate dehydrogenase (LDH) release. In parallel, monitoring of mitochondrial Ca(2+) during stress, via the specific indicator rhod-2, revealed a significant attenuation of Ca(2+) accumulation in mitochondria overexpressing K(+) channels. This effect was abolished in mitochondria expressing an inactive mutant of Kir6.2. Mitochondria expressing Kir6.2 K(+) channel also exhibited a significant degree of depolarization that became even more pronounced during the stress. In conclusion, this study provides the first non-pharmacological evidence that an increased K(+) influx to mitochondria protects against hypoxic stress by preventing detrimental effects of Ca(2+) overload.
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Affiliation(s)
- Marko Ljubkovic
- Department of Anesthesiology, Medical College of Wisconsin, 8701 Watertown Plank Road, Milwaukee, WI 53226, USA
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Cao CM, Chen M, Wong TM. The K(Ca) channel as a trigger for the cardioprotection induced by kappa-opioid receptor stimulation -- its relationship with protein kinase C. Br J Pharmacol 2006; 145:984-91. [PMID: 15912131 PMCID: PMC1576218 DOI: 10.1038/sj.bjp.0706268] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
We first determined whether the cardioprotection resulting from kappa opioid receptor (kappa-OR) stimulation was blocked by the K(Ca) channel inhibitor, paxilline (Pax), administered before or during ischaemic insults in vitro. In isolated rat hearts, 30 min of ischaemia and 120 min of reperfusion induced infarction and increased lactate dehydrogenase (LDH) release. In isolated ventricular myocytes subjected to 5 min of metabolic inhibition and anoxia followed by 10 min of reperfusion, the percentage of live cells and the amplitude of the electrically induced intracellular Ca(2+) ([Ca(2+)](i)) transient decreased, while diastolic [Ca(2+)](i) increased. Pretreatment with 10 microM U50,488H, a kappa-OR agonist, attenuated the undesirable effects of ischaemic insults in both preparations. The beneficial effects of kappa-OR stimulation, that were abolished by 5 microM nor-BNI, a kappa-OR antagonist, were also abolished by 1 microM Pax administered before ischaemic insults or 20 microM atractyloside, an opener of the mitochondrial permeability transition pore. Activation of protein kinase C (PKC) with 0.1 microM phorbol 12-myristate 13-acetate decreased the infarct size and LDH release in isolated rat hearts subjected to ischaemia/reperfusion, and these effects were abolished by blockade of PKC with its inhibitors, 10 microM GF109203X or 5 microM chelerythrine, and more importantly by 1 microM Pax. On the other hand, the cardioprotective effects of opening the K(Ca) channel with 10 microM NS1619 were not altered by either PKC inhibitor. In conclusion, the high-conductance K(Ca) channel triggers cardioprotection induced by kappa-OR stimulation that involves inhibition of MPTP opening. The K(Ca) channel is located downstream of PKC.
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MESH Headings
- 3,4-Dichloro-N-methyl-N-(2-(1-pyrrolidinyl)-cyclohexyl)-benzeneacetamide, (trans)-Isomer/pharmacology
- Animals
- Calcium/metabolism
- Cardiotonic Agents/pharmacology
- Cell Survival/drug effects
- Heart/drug effects
- In Vitro Techniques
- Indoles/pharmacology
- Ion Channels/antagonists & inhibitors
- Ion Channels/metabolism
- L-Lactate Dehydrogenase/metabolism
- Male
- Mitochondria, Heart/drug effects
- Mitochondria, Heart/metabolism
- Mitochondrial Membrane Transport Proteins
- Mitochondrial Permeability Transition Pore
- Myocardial Ischemia/enzymology
- Myocardial Ischemia/metabolism
- Myocardium/enzymology
- Myocardium/metabolism
- Myocytes, Cardiac/drug effects
- Myocytes, Cardiac/metabolism
- Potassium Channel Blockers/pharmacology
- Potassium Channels, Calcium-Activated/drug effects
- Potassium Channels, Calcium-Activated/metabolism
- Potassium Channels, Calcium-Activated/physiology
- Protein Kinase C/metabolism
- Rats
- Rats, Sprague-Dawley
- Receptors, Opioid, kappa/agonists
- Receptors, Opioid, kappa/metabolism
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Affiliation(s)
- Chun-Mei Cao
- Department of Physiology, The University of Hong Kong, Hong Kong SAR, China
| | - Mai Chen
- Department of Physiology, The University of Hong Kong, Hong Kong SAR, China
| | - Tak-Ming Wong
- Department of Physiology, The University of Hong Kong, Hong Kong SAR, China
- Author for correspondence:
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