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Strutynskyi R, Strutynska N, Mys L, Goshovska Y, Korkach Y, Fedichkina R, Okhai I, Strutynskyi V, Sagach V. Glutathione Upregulates the Expression of K ATP Channels and Vasorelaxation Responses and Inhibits mPTP Opening and Oxidative Stress in the Heart Mitochondria of Old Rats. BIOMED RESEARCH INTERNATIONAL 2023; 2023:3562847. [PMID: 37265475 PMCID: PMC10232108 DOI: 10.1155/2023/3562847] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/01/2022] [Revised: 04/25/2023] [Accepted: 05/13/2023] [Indexed: 06/03/2023]
Abstract
Background In the present work, we investigated the effect of exogenous glutathione in old rats on the expression of ATP-sensitive potassium (KATP) channels, the mitochondrial permeability transition pore (mPTP) opening in the heart, and the vasorelaxation responses of isolated aortic rings to activation of KATP channels. Methods Experiments were performed on adult (6 months) and old (24 months) male Wistar rats, which were divided into three groups: adult, old, and glutathione-treated old rats. Glutathione was injected intraperitoneally at a dose of 52 mg/kg 1 hour before the studies. The mRNA expression of KATP channels was determined using reverse transcription and real-time polymerase chain reaction analysis. The effect of glutathione administration on mPTP opening, relaxation responses of isolated aortic rings, and oxidative stress markers was studied. Results It was shown that the expression levels of Kir6.1, Kir6.2, and SUR1 subunits of KATP channels and levels of reduced glutathione were significantly increased in glutathione-treated old rats (by 8.3, 2.8, 13.1, and 1.5-fold, respectively), whereas the levels of oxidative stress markers (hydrogen peroxide, diene conjugates, malondialdehyde, and rate of superoxide generation) in heart mitochondria and mPTP opening were significantly reduced. Relaxation of aortic rings was significantly increased in response to the actions of KATP channel openers flocalin and pinacidil in glutathione-treated animals, which was prevented by glibenclamide. Conclusions Thus, the administration of exogenous glutathione to old rats resulted in a significant increase in the expression levels of the Kir6.1, Kir6.2, and SUR1 subunits of KATP channels and a decrease in oxidative stress. This was accompanied by inhibition of mPTP opening and enhancement of vasorelaxation responses to activation of KATP channels.
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Affiliation(s)
- Ruslan Strutynskyi
- Department of General and Molecular Pathophysiology, Bogomoletz Institute of Physiology, National Academy of Sciences of Ukraine, 4, Bogomoletz Str., Kyiv 01024, Ukraine
| | - Nataliіa Strutynska
- Department of Blood Circulation, Bogomoletz Institute of Physiology, National Academy of Sciences of Ukraine, 4, Bogomoletz Str., Kyiv 01024, Ukraine
| | - Lidiia Mys
- Department of Blood Circulation, Bogomoletz Institute of Physiology, National Academy of Sciences of Ukraine, 4, Bogomoletz Str., Kyiv 01024, Ukraine
| | - Yulia Goshovska
- Department of Blood Circulation, Bogomoletz Institute of Physiology, National Academy of Sciences of Ukraine, 4, Bogomoletz Str., Kyiv 01024, Ukraine
| | - Yuliia Korkach
- Department of Blood Circulation, Bogomoletz Institute of Physiology, National Academy of Sciences of Ukraine, 4, Bogomoletz Str., Kyiv 01024, Ukraine
| | - Raisa Fedichkina
- Department of Blood Circulation, Bogomoletz Institute of Physiology, National Academy of Sciences of Ukraine, 4, Bogomoletz Str., Kyiv 01024, Ukraine
| | - Iryna Okhai
- Department of Blood Circulation, Bogomoletz Institute of Physiology, National Academy of Sciences of Ukraine, 4, Bogomoletz Str., Kyiv 01024, Ukraine
| | - Vladyslav Strutynskyi
- Department of Immunophysiology, Bogomoletz Institute of Physiology, National Academy of Sciences of Ukraine, 4, Bogomoletz Str., Kyiv 01024, Ukraine
| | - Vadym Sagach
- Department of Blood Circulation, Bogomoletz Institute of Physiology, National Academy of Sciences of Ukraine, 4, Bogomoletz Str., Kyiv 01024, Ukraine
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Strutynskyi RB, Strutynska NA, Piven OO, Mys LA, Goshovska YV, Fedichkina RA, Okhai IY, Strutynskyi VR, Dosenko VE, Dobrzyn P, Sagach VF. Upregulation of ATP-Sensitive Potassium Channels as the Potential Mechanism of Cardioprotection and Vasorelaxation Under the Action of Pyridoxal-5-Phosphate in Old Rats. J Cardiovasc Pharmacol Ther 2023; 28:10742484231213175. [PMID: 37946524 DOI: 10.1177/10742484231213175] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/12/2023]
Abstract
Background: The aging process is accompanied by the weakening of the protective systems of the organism, in particular by the decrease in the expression of ATP-sensitive potassium (KATP) channels and in the synthesis of H2S. The aim of our work was to investigate the role of KATP channels in the cardioprotection induced by pyridoxal-5-phosphate (PLP) in aging. Methods: Experiments were performed on adult and old (aged 24 months) male Wistar rats, which were divided into 3 groups: adults, old, and old PLP-treated rats. PLP was administered orally once a day for 14 days at a dose of 0.7 mg/kg. The levels of mRNA expression of subunits KATP channels were determined by reverse transcription and real-time polymerase chain reaction analysis. Protein expression levels were determined by the Western blot. Cardiac tissue morphology was determined using transverse 6 μm deparaffinized sections stained with picrosirius red staining. Vasorelaxation responses of isolated aortic rings and the function of Langendorff-perfused isolated hearts during ischemia-reperfusion, H2S levels, and markers of oxidative stress were also studied. Results: Administration of PLP to old rats reduces cardiac fibrosis and improves cardiac function during ischemia-reperfusion and vasorelaxation responses to KATP channels opening. At the same time, there was a significant increase in mRNA and protein expression of SUR2 and Kir6.1 subunits of KATP channels, H2S production, and reduced markers of oxidative stress. The specific KATP channel inhibitor-glibenclamide prevented the enhancement of vasodilator responses and anti-ischemic protection in PLP-treated animals. Conclusions: We suggest that this potential therapeutic effect of PLP in old animals may be a result of increased expression of KATP channels and H2S production.
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Affiliation(s)
- Ruslan B Strutynskyi
- Department of General and Molecular Pathophysiology, Bogomoletz Institute of Physiology, National Academy of Sciences of Ukraine, Kyiv, Ukraine
| | - Nataliіa A Strutynska
- Department of Blood Circulation, Bogomoletz Institute of Physiology, National Academy of Sciences of Ukraine, Kyiv, Ukraine
| | - Oksana O Piven
- The Laboratory of Molecular Medical Biochemistry of Nencki, Institute of Experimental Biology, Polish Academy of Sciences, Warsaw, Poland
- Department of Human Genetics, Institute of Molecular Biology and Genetics, National Academy of Sciences of Ukraine, Kyiv, Ukraine
| | - Lidiia A Mys
- Department of Blood Circulation, Bogomoletz Institute of Physiology, National Academy of Sciences of Ukraine, Kyiv, Ukraine
| | - Yulia V Goshovska
- Department of Blood Circulation, Bogomoletz Institute of Physiology, National Academy of Sciences of Ukraine, Kyiv, Ukraine
| | - Raisa A Fedichkina
- Department of Blood Circulation, Bogomoletz Institute of Physiology, National Academy of Sciences of Ukraine, Kyiv, Ukraine
| | - Iryna Y Okhai
- Department of Blood Circulation, Bogomoletz Institute of Physiology, National Academy of Sciences of Ukraine, Kyiv, Ukraine
| | - Vladyslav R Strutynskyi
- Department of Immunophysiology, Bogomoletz Institute of Physiology, National Academy of Sciences of Ukraine, Kyiv, Ukraine
| | - Victor E Dosenko
- Department of General and Molecular Pathophysiology, Bogomoletz Institute of Physiology, National Academy of Sciences of Ukraine, Kyiv, Ukraine
| | - Pawel Dobrzyn
- The Laboratory of Molecular Medical Biochemistry of Nencki, Institute of Experimental Biology, Polish Academy of Sciences, Warsaw, Poland
| | - Vadim F Sagach
- Department of Blood Circulation, Bogomoletz Institute of Physiology, National Academy of Sciences of Ukraine, Kyiv, Ukraine
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Yang HQ, Echeverry FA, ElSheikh A, Gando I, Anez Arredondo S, Samper N, Cardozo T, Delmar M, Shyng SL, Coetzee WA. Subcellular trafficking and endocytic recycling of K ATP channels. Am J Physiol Cell Physiol 2022; 322:C1230-C1247. [PMID: 35508187 PMCID: PMC9169827 DOI: 10.1152/ajpcell.00099.2022] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2022] [Revised: 04/27/2022] [Accepted: 04/30/2022] [Indexed: 11/22/2022]
Abstract
Sarcolemmal/plasmalemmal ATP-sensitive K+ (KATP) channels have key roles in many cell types and tissues. Hundreds of studies have described how the KATP channel activity and ATP sensitivity can be regulated by changes in the cellular metabolic state, by receptor signaling pathways and by pharmacological interventions. These alterations in channel activity directly translate to alterations in cell or tissue function, that can range from modulating secretory responses, such as insulin release from pancreatic β-cells or neurotransmitters from neurons, to modulating contractile behavior of smooth muscle or cardiac cells to elicit alterations in blood flow or cardiac contractility. It is increasingly becoming apparent, however, that KATP channels are regulated beyond changes in their activity. Recent studies have highlighted that KATP channel surface expression is a tightly regulated process with similar implications in health and disease. The surface expression of KATP channels is finely balanced by several trafficking steps including synthesis, assembly, anterograde trafficking, membrane anchoring, endocytosis, endocytic recycling, and degradation. This review aims to summarize the physiological and pathophysiological implications of KATP channel trafficking and mechanisms that regulate KATP channel trafficking. A better understanding of this topic has potential to identify new approaches to develop therapeutically useful drugs to treat KATP channel-related diseases.
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Affiliation(s)
- Hua-Qian Yang
- Cyrus Tang Hematology Center, Soochow University, Suzhou, People's Republic of China
| | | | - Assmaa ElSheikh
- Department of Biochemistry and Molecular Biology, Oregon Health & Science University, Portland, Oregon
- Department of Medical Biochemistry, Tanta University, Tanta, Egypt
| | - Ivan Gando
- Department of Pathology, NYU School of Medicine, New York, New York
| | | | - Natalie Samper
- Department of Pathology, NYU School of Medicine, New York, New York
| | - Timothy Cardozo
- Department of Biochemistry and Molecular Pharmacology, NYU School of Medicine, New York, New York
| | - Mario Delmar
- Department of Biochemistry and Molecular Pharmacology, NYU School of Medicine, New York, New York
- Department of Medicine, NYU School of Medicine, New York, New York
| | - Show-Ling Shyng
- Department of Biochemistry and Molecular Biology, Oregon Health & Science University, Portland, Oregon
| | - William A Coetzee
- Department of Pathology, NYU School of Medicine, New York, New York
- Department of Neuroscience & Physiology, NYU School of Medicine, New York, New York
- Department of Biochemistry and Molecular Pharmacology, NYU School of Medicine, New York, New York
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Naryzhnaya NV, Maslov LN, Derkachev IA, Fu F. The Significance of NO-Synthase, Reactive Oxygen Species, Kinases and KATP-Channels in the Development of the Infarct-Limiting Effect of Adaptation to Hypoxia. J EVOL BIOCHEM PHYS+ 2022. [DOI: 10.1134/s0022093022020211] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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Mahdi H, Jovanović A. SUR2A as a base for cardioprotective therapeutic strategies. Mol Biol Rep 2022; 49:6717-6723. [PMID: 35301655 DOI: 10.1007/s11033-022-07281-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2021] [Revised: 02/13/2022] [Accepted: 02/16/2022] [Indexed: 10/18/2022]
Abstract
BACKGROUND ATP-sensitive K+ (KATP) channels link the metabolic state of the cell with membrane excitability and SUR2A serves as a regulatory subunit of sarcolemmal KATP channels. The aim of the present study was to review SUR2A-mediated cardioprotection. METHODS AND RESULTS A related literature search in PubMed, Scopus, Web of Science, Google Scholar, and Science direct was performed. Levels of SUR2A regulate number of fully assembled KATP channels in the sarcolemma. Increased numbers of sarcolemmal KATP channels protect cardiomyocytes against different types of stress by improving the timing of KATP channels opening, but, also, by catalyzing ATP production in subsarcolemmal space. Fully-assembled sarcolemmal KATP channels protein complex contain ATP-producing enzymes in addition to channel subunits, SUR2A and Kir6.2. An increase in the number of fully-assembled channels results in increased levels of ATP-producing enzymes and subsarcolemmal ATP, which is beneficial in ischemia. Expression of SUR2A is regulated by diverse mechanisms, including AMPK, PI3K/Akt, and ERK1/2 as well as intracellular levels of NAD+/NADH and ATP. There are many compounds and treatments that can be used to regulate SUR2A and some of them seem to be clinically viable options. The most suitable medication to use to increase SUR2A and confer cardioprotection in the clinical setting seems to be nicotinamide. It is one of the safest compounds used in clinical practice and all pre-clinical studies demonstrated that it is an efficient cardioprotective agent. CONCLUSIONS Taken all together, SUR2A-based cardioprotection is a likely efficient and safe cardioprotective strategy that can be quickly introduced into clinical practice.
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Affiliation(s)
- Habib Mahdi
- Department of Basic and Clinical Sciences, University of Nicosia Medical School, 21 Ilia Papakyriakou Engomi, P.O. Box 24005, 2414, CY-1700, Nicosia, Cyprus
| | - Aleksandar Jovanović
- Department of Basic and Clinical Sciences, University of Nicosia Medical School, 21 Ilia Papakyriakou Engomi, P.O. Box 24005, 2414, CY-1700, Nicosia, Cyprus. .,Center for Neuroscience and Integrative Brain Research (CENIBRE), University of Nicosia Medical School, Nicosia, Cyprus.
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Mys L, Goshovska Y, Strutynska N, Fedichkina R, Korkach Y, Strutynskyi R, Sagach V. Pyridoxal-5-phosphate induced cardioprotection in aging associated with up-expression of cystathionine-γ-lyase, 3-mercaptopyruvate sulfurtransferase, and ATP-sensitive potassium channels. Eur J Clin Invest 2022; 52:e13683. [PMID: 34587304 DOI: 10.1111/eci.13683] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/28/2021] [Revised: 09/16/2021] [Accepted: 09/21/2021] [Indexed: 11/27/2022]
Abstract
BACKGROUND In the present work, we investigated the cardioprotective potential of pyridoxal-5-phosphate (PLP) in old rats as a cofactor of enzymes that synthesize hydrogen sulphide (H2 S). MATERIALS AND METHODS PLP was administered per os in a dose of 0.7 mg per kg daily for 2 weeks. Rats were divided into three groups (adult, old and old +PLP) of 20 animals. The cardiac mRNA levels of genes encoding H2 S-synthesizing enzymes cystathionine-γ-lyase (CSE) and 3-mercaptopyruvate sulfurtransferase (3-MST), uncoupling proteins (UCP3), subunits of ATP-sensitive potassium (KATP ) channels were determined using real-time polymerase chain reaction analysis. We also studied the effect of PLP-administration on the content of H2 S, oxidative stress, the activities of inducible and constitutive NO-synthase (iNOS, cNOS), arginase and nitrate reductase in the heart homogenates as well as cardiac resistance to ischemia-reperfusion in Langendorff-isolated heart model. RESULTS It was shown that PLP restored mRNA levels of CSE, 3-MST and UCP3 genes, and H2 S content and also significantly increased the expression of SUR2 and Kir6.1 (2.2 and 3.3 times, respectively) in the heart of old rats. PLP significantly reduced the formation of superoxide, malondialdehyde, diene conjugates as well as the activity of iNOS and arginase. PLP significantly increased constitutive synthesis of NO and prevented reperfusion disturbances of the heart function after ischemia. CONCLUSIONS Thus, PLP-administration in old rats was associated with up-expression of CSE, 3-MST, UCP3 and SUR2 and Kir6.1 subunits of KATP channels, and also increased cNOS activity and reduced oxidative stress and prevented reperfusion dysfunction of the heart in ischemia-reperfusion.
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Affiliation(s)
- Lidiia Mys
- Department of Blood Circulation, Bogomoletz Institute of Physiology, National Academy of Sciences of Ukraine, Kyiv, Ukraine
| | - Yulia Goshovska
- Department of Blood Circulation, Bogomoletz Institute of Physiology, National Academy of Sciences of Ukraine, Kyiv, Ukraine
| | - Nataliia Strutynska
- Department of Blood Circulation, Bogomoletz Institute of Physiology, National Academy of Sciences of Ukraine, Kyiv, Ukraine
| | - Raisa Fedichkina
- Department of Blood Circulation, Bogomoletz Institute of Physiology, National Academy of Sciences of Ukraine, Kyiv, Ukraine
| | - Yuliia Korkach
- Department of Blood Circulation, Bogomoletz Institute of Physiology, National Academy of Sciences of Ukraine, Kyiv, Ukraine
| | - Ruslan Strutynskyi
- Department of General and Molecular Pathophysiology, Bogomoletz Institute of Physiology, National Academy of Sciences of Ukraine, Kyiv, Ukraine
| | - Vadim Sagach
- Department of Blood Circulation, Bogomoletz Institute of Physiology, National Academy of Sciences of Ukraine, Kyiv, Ukraine
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Naryzhnaya NV, Maslov LN, Derkachev IA, Ma H, Zhang Y, Prasad NR, Singh N, Fu F, Pei JM, Sarybaev A, Sydykov A. The effect of adaptation to hypoxia on cardiac tolerance to ischemia/reperfusion. J Biomed Res 2022:1-25. [PMID: 37183617 PMCID: PMC10387748 DOI: 10.7555/jbr.36.20220125] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
The acute myocardial infarction (AMI) and sudden cardiac death (SCD), both associated with acute cardiac ischemia, are one of the leading causes of adult death in economically developed countries. The development of new approaches for the treatment and prevention of AMI and SCD remains the highest priority for medicine. A study on the cardiovascular effects of chronic hypoxia (CH) may contribute to the development of these methods. Chronic hypoxia exerts both positive and adverse effects. The positive effects are the infarct-reducing, vasoprotective, and antiarrhythmic effects, which can lead to the improvement of cardiac contractility in reperfusion. The adverse effects are pulmonary hypertension and right ventricular hypertrophy. This review presents a comprehensive overview of how CH enhances cardiac tolerance to ischemia/reperfusion. It is an in-depth analysis of the published data on the underlying mechanisms, which can lead to future development of the cardioprotective effect of CH. A better understanding of the CH-activated protective signaling pathways may contribute to new therapeutic approaches in an increase of cardiac tolerance to ischemia/reperfusion.
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Strutynskyi RB, Goncharov SV, Tumanovska LV, Nagibin VS, Dosenko VE. Cardiac dysfunction in spontaneously hypertensive old rats is associated with a significant decrease of SUR2 expression. Mol Cell Biochem 2021; 476:4343-4349. [PMID: 34455535 DOI: 10.1007/s11010-021-04237-8] [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: 09/08/2020] [Accepted: 07/28/2021] [Indexed: 11/24/2022]
Abstract
ATP-sensitive potassium (KATP) channels are participants of mechanisms of pathological myocardial remodeling containment. The aim of our work was to find the association of changes in the expression of Kir6.1, Kir6.2, SUR1, and SUR2 subunits of KATP channels with changes in heart function and structure during aging under conditions of the constant increase of vascular pressure. The experiments were carried out on young and old spontaneously hypertensive rats (SHR) and Wistar rats. The expression levels of KATP channels subunits were determined using reverse transcription and quantitative PCR. It is shown that the mRNA expression level of Kir6.1 in young SHR rats is significantly lower (6.3-fold, p = 0.035) than that of young Wistar rats that may be one of the causes of arterial hypertension in SHR. At the same time, mRNA expression of both Kir6.1 and Kir6.2 in old SHR rats was significantly higher (6.8-fold, p = 0.003, and 5.9-fold, p = 0.006, respectively) than in young hypertensive animals. In both groups of old animals, SUR2 expression was significantly reduced compared to young animals, in Wistar rats at 3.87-fold (p = 0.028) and in SHR rats at 48.2-fold (p = 0.033). Changes in SUR1 expression were not significant. Thus, significant changes in the cardiovascular system, including impaired function and structure of the heart in old SHR rats, were associated with a significant decrease in SUR2 expression that may be one of the mechanisms of heart failure decompensation. Therefore, it can be assumed that increased expression of SUR2 may be one of the protective mechanisms against pathological myocardial remodeling.
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Affiliation(s)
- Ruslan B Strutynskyi
- Department of General and Molecular Pathophysiology, Bogomoletz Institute of Physiology, National Academy of Sciences of Ukraine, Address: 4, Bogomoletz str., Kyiv, 01024, Ukraine
| | - Serhii V Goncharov
- Department of General and Molecular Pathophysiology, Bogomoletz Institute of Physiology, National Academy of Sciences of Ukraine, Address: 4, Bogomoletz str., Kyiv, 01024, Ukraine
| | - Lesya V Tumanovska
- Department of General and Molecular Pathophysiology, Bogomoletz Institute of Physiology, National Academy of Sciences of Ukraine, Address: 4, Bogomoletz str., Kyiv, 01024, Ukraine
| | - Vasyl S Nagibin
- Department of General and Molecular Pathophysiology, Bogomoletz Institute of Physiology, National Academy of Sciences of Ukraine, Address: 4, Bogomoletz str., Kyiv, 01024, Ukraine.
| | - Victor E Dosenko
- Department of General and Molecular Pathophysiology, Bogomoletz Institute of Physiology, National Academy of Sciences of Ukraine, Address: 4, Bogomoletz str., Kyiv, 01024, Ukraine
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Mohammed Abdul KS, Rayadurgam J, Faiz N, Jovanović A, Tan W. Cardioprotection by isosteviol derivate JC105: A unique drug property to activate ERK1/2 only when cells are exposed to hypoxia-reoxygenation. J Cell Mol Med 2020; 24:10924-10934. [PMID: 32794652 PMCID: PMC7521240 DOI: 10.1111/jcmm.15721] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2020] [Revised: 07/13/2020] [Accepted: 07/19/2020] [Indexed: 01/19/2023] Open
Abstract
In the present study, we have investigated potential cardioprotective properties of Isosteviol analogue we recently synthesized and named JC105. Treatment of heart embryonic H9c2 cells with JC105 (10 μM) significantly increased survival of cells exposed to hypoxia‐reoxygenation. JC105 (10 μM) activated ERK1/2, DRP1 and increased levels of cardioprotective SUR2A in hypoxia‐reoxygenation, but did not have any effects on ERK1/2, DRP1 and/or SUR2A in normoxia. U0126 (10 μM) inhibited JC105‐mediated phosphorylation of ERK1/2 and DRP1 without affecting AKT or AMPK, which were also not regulated by JC105. Seahorse bioenergetic analysis demonstrated that JC105 (10 μM) did not affect mitochondria at rest, but it counteracted all mitochondrial effects of hypoxia‐reoxygenation. Cytoprotection afforded by JC105 was inhibited by U0126 (10 μM). Taken all together, these demonstrate that (a) JC105 protects H9c2 cells against hypoxia‐reoxygenation and that (b) this effect is mediated via ERK1/2. The unique property of JC105 is that selectively activates ERK1/2 in cells exposed to stress, but not in cells under non‐stress conditions.
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Affiliation(s)
| | - Jayachandra Rayadurgam
- Institute of Biomedical and Pharmaceutical Sciences, Guangdong University of Technology, Guangzhou, PR China.,Research Center for Drug Discovery, School of Pharmaceutical Sciences, Sun Yat-Sen University, Guangzhou, PR China
| | - Neha Faiz
- Institute of Biomedical and Pharmaceutical Sciences, Guangdong University of Technology, Guangzhou, PR China
| | - Aleksandar Jovanović
- Department of Basic and Clinical Sciences, University of Nicosia Medical School, Nicosia, Cyprus.,Centre for Neuroscience and Integrative Brain Research (CENIBRE), University of Nicosia Medical School, Nicosia, Cyprus
| | - Wen Tan
- Institute of Biomedical and Pharmaceutical Sciences, Guangdong University of Technology, Guangzhou, PR China.,Jeffrey Cheah School of Medicine and Health Sciences, Monash University Malaysia, Selangor Darul Ehsan, Malaysia
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Sztormowska-Achranowicz K, Jankowski Z, Kocić I. Protective effect of nicotinamide and L-arginine against monocrotaline-induced pulmonary hypertension in rats: gender dependence. Pharmacol Rep 2020; 72:1334-1346. [PMID: 32632916 PMCID: PMC7550290 DOI: 10.1007/s43440-020-00125-y] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2020] [Revised: 06/27/2020] [Accepted: 06/29/2020] [Indexed: 11/24/2022]
Abstract
Background The purpose of this paper was to examine the effects of nicotinamide (ND) and l-arginine (l-ARG) on pulmonary vascular and heart changes induced by pulmonary hypertension in rats in a gender-dependent way. Methods Experiments were performed on male (M) and female (F) rats. PAH was induced via monocrotaline injection (sc, 60/kg B.W.) on day one of the 23-day observational period. After that, the animals were sacrificed, hearts removed and weighed and the papillary muscles isolated to measure force of contraction (Fc). Morphological changes of pulmonary vessels were also examined. Results Mixed diet supplementation with l-ARG + ND prevented highly significant right ventricle enlargement induced by PAH in both, male and female rats. Weight ratios between the right ventricle (RV) on one side and the left ventricle with septum on the other (LV + S) decreased from 0.46 ± 0.016 g to 0.29 ± 0.006 g in males and from 0.63 ± 0.03 g to 0.24 ± 0.008 g in females, n = 6, p < 0.001. Additionally, PAH increased basal contractility in female groups, and each of the diet allocations (l-ARG, ND, and mixed) were found to restore contractility to control values. All diet protocols in male and female restored decreased responsiveness of the myocardium to norepinephrine in hearts obtained from rats with PAH and prevented vascular changes observed in pulmonary hypertension (thickness of blood vessels and cell infiltration). Conclusion Our study suggests that l-arginine, nicotinamide or both play a positive role in right ventricle function or the process reducing pulmonary vascular remodeling especially in a gender-independent way.
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Affiliation(s)
| | - Zbigniew Jankowski
- Department of Forensic Medicine, Medical University of Gdansk, Gdańsk, Poland
| | - Ivan Kocić
- Department of Pharmacology, Medical University of Gdansk, Gdańsk, Poland.
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Wang J, Liu J, Xie L, Cai X, Ma X, Gong J. Bisoprolol, a β 1 antagonist, protects myocardial cells from ischemia-reperfusion injury via PI3K/AKT/GSK3β pathway. Fundam Clin Pharmacol 2020; 34:708-720. [PMID: 32363697 DOI: 10.1111/fcp.12562] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2020] [Revised: 04/23/2020] [Accepted: 04/29/2020] [Indexed: 12/30/2022]
Abstract
The aim of this work was to explore whether bisoprolol plays a protective role in cardiomyocytes against ischemia-reperfusion injury via PI3K/AKT/ GSK3β pathway. We pretreated male Sprague Dawley (SD) rats with bisoprolol by oral administration prior to 0.5 h ischemia/4 h reperfusion. Myocardial infarct size and serum levels of cTnI and CK-MB were measured. In vitro, H9c2 cells were treated with hypoxia and reoxygenation, followed by measurement of cell viability, apoptosis, ROS production, cytometry, activities of AKT, GSK3β, and p-38 in the presence and absence of GSK3β siRNA. We found that bisoprolol reduced infarct size from 44% in I/R group to 31% in treated group (P < 0.05). The levels of cTnI and CK-MB were decreased from 286 ± 7 pg/mL and 32.2 ± 2 ng/mL in I/R group to 196 ± 2 pg/mL and 19.6 ± 0.9 ng/mL in the treated group, respectively (P < 0.05). Bisoprolol also increased cell viability while decreased apoptosis and ROS production in the treatment of hypoxia/ reoxygenation. Furthermore, bisoprolol increased AKT and GSK3β phosphorylation, an effect that was immediately eliminated by LY294002. GSK3β-specific siRNA experiment further confirmed that bisoprolol protected the myocardium against hypoxia/reoxygenation-induced injury via suppressing GSK3β activity. In conclusion, bisoprolol protected myocardium against ischemia-reperfusion injury via the PI3K/AKT/ GSK3β pathway.
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Affiliation(s)
- Jing Wang
- Department of Cardiology, Jinling Hospital, Nanjing University School of Medicine, 305 East Zhongshan Rd., Nanjing, 210002, Jiangsu, China
| | - Jing Liu
- Department of Cardiology, Jinling Hospital, Nanjing University School of Medicine, 305 East Zhongshan Rd., Nanjing, 210002, Jiangsu, China
| | - Liang Xie
- Department of Cardiology, Jinling Hospital, Nanjing University School of Medicine, 305 East Zhongshan Rd., Nanjing, 210002, Jiangsu, China
| | - Xiaomin Cai
- Department of Cardiology, Jinling Hospital, Nanjing University School of Medicine, 305 East Zhongshan Rd., Nanjing, 210002, Jiangsu, China
| | - Xiaohua Ma
- Department of Cardiology, Jinling Hospital, Nanjing University School of Medicine, 305 East Zhongshan Rd., Nanjing, 210002, Jiangsu, China
| | - Jianbin Gong
- Department of Cardiology, Jinling Hospital, Nanjing University School of Medicine, 305 East Zhongshan Rd., Nanjing, 210002, Jiangsu, China
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12
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Jovanović A. SUR2A: How to exploit this protein to treat ischaemic heart disease? ARHIV ZA FARMACIJU 2020. [DOI: 10.5937/arhfarm2001001j] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
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13
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Pyrazinamide may possess cardioprotective properties. J Antibiot (Tokyo) 2019; 72:714-717. [PMID: 31243346 PMCID: PMC6760625 DOI: 10.1038/s41429-019-0202-z] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2019] [Revised: 05/14/2019] [Accepted: 06/09/2019] [Indexed: 11/21/2022]
Abstract
Pyrazinamide is an anti-tubercular agent, used as a part of a three-drug regime (any three of the following: rifampicin, isoniazid, pyrazinamide, streptomycin or ethambutol) for the initial phase of treatment. One of the effects pyrazinamide has on mammalian cells is to regulate NAD+/NADH levels. We have recently found that changes in NAD+/NADH are associated with regulation of expression levels of SUR2A, a cardioprotective protein serving as a regulatory subunit of cardiac ATP-sensitive K+ (KATP) channels. Here, we have tested whether pyrazinamide regulate expression of SUR2A/KATP channel subunits and resistance to metabolic stress in embryonic heart-derived H9c2 cells. We have found that 24-h-long treatment with pyrazinamide (3 mcg/ml) increased mRNA levels of SUR2A, SUR2B and Kir6.1 without affecting mRNA levels of other KATP channel subunits. This treatment with pyrazinamide (3 mcg/ml) protected H9c2 cells against stress induced by 10 mM 2,4-dinitrophenol (DNP). The survival rate of DNP-treated cells was 45.6 ± 2.3% (n = 5) if not treated with pyrazinamide and 90.8 ± 2.3% (n = 5; P < 0.001) if treated with pyrazinamide. We conclude that pyrazinamide increases resistance to metabolic stress in heart H9c2 cells probably by increasing SUR2A and SUR2B expression. Our results of this study indicate that pyrazinamide should be seriously considered as a drug of choice for patients with tuberculosis and ischaemic heart disease.
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14
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Zheng Y, Lu L, Yan Z, Jiang S, Yang S, Zhang Y, Xu K, He C, Tao X, Zhang Q. mPEG-icariin nanoparticles for treating myocardial ischaemia. ARTIFICIAL CELLS NANOMEDICINE AND BIOTECHNOLOGY 2019; 47:801-811. [PMID: 30836782 DOI: 10.1080/21691401.2018.1554579] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Icariin (ICA), a major active ingredient from Chinese medicine, has unique pharmacological effects on ischaemic heart disease. However, its hydrophobic property limits its administration and leads to poor efficacy. This work aimed to change its hydrophobic property and improve the treatment efficacy. We designed a new nano-drug to increase the ICA delivery. ICA was modified with hydrophilic polyethylene glycol monomethyl ether (mPEG) by a succinic anhydride linker to form a polyethylene glycol-icariin (mPEG-ICA) polymer. The structure of this polymer was identified by Fourier transform infrared spectroscopy and nuclear magnetic resonance spectroscopy. The content of ICA in the polymer was 32% as detected by ultraviolet spectrophotometry. mPEG-ICA nanoparticles, of 143.3 nm, were prepared by the dialysis method, and zeta potential was 0.439 mV by dynamic light scattering. The nanoparticles had a spherical shape on transmission electron microscopy. In media with pH 7.4 and 6.8, ICA release from mPEG-ICA nanoparticles after 72 h was about 0.78% and 64.05%, respectively, so the ICA release depended on the release media pH. On MTT and lactate dehydrogenase activity assay, mPEG-ICA nanoparticles could reduce cell damage induced by oxgen-glucose deprivation. Hoechst 33258 staining and TUNEL and AnnexinV-FITC/PI double staining showed that ICA nanoparticles could increase the activity of H9c2 cardiomyocytes under oxgen-glucose deprivation conditions by decreasing apoptosis. ICA modified by hydrophilic mPEG could improve its efficacy.
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Affiliation(s)
- Yongqiang Zheng
- a Department of Pharmacology, Laboratory of Chinese Herbal Pharmacology , Biomedical Research Institute, Hubei University of Medicine , Shiyan , Hubei , China
| | - Lingli Lu
- a Department of Pharmacology, Laboratory of Chinese Herbal Pharmacology , Biomedical Research Institute, Hubei University of Medicine , Shiyan , Hubei , China
| | - Zhengli Yan
- b Key Laboratory of Study and Discovery of Small Targeted Molecules of Hunan Province, School of Medicine, Hunan Normal University , Changsha , China
| | - Sufang Jiang
- b Key Laboratory of Study and Discovery of Small Targeted Molecules of Hunan Province, School of Medicine, Hunan Normal University , Changsha , China
| | - Shanyi Yang
- b Key Laboratory of Study and Discovery of Small Targeted Molecules of Hunan Province, School of Medicine, Hunan Normal University , Changsha , China
| | - Yingzi Zhang
- b Key Laboratory of Study and Discovery of Small Targeted Molecules of Hunan Province, School of Medicine, Hunan Normal University , Changsha , China
| | - Kangwei Xu
- b Key Laboratory of Study and Discovery of Small Targeted Molecules of Hunan Province, School of Medicine, Hunan Normal University , Changsha , China
| | - Chunlian He
- b Key Laboratory of Study and Discovery of Small Targeted Molecules of Hunan Province, School of Medicine, Hunan Normal University , Changsha , China
| | - Xiaojun Tao
- a Department of Pharmacology, Laboratory of Chinese Herbal Pharmacology , Biomedical Research Institute, Hubei University of Medicine , Shiyan , Hubei , China.,b Key Laboratory of Study and Discovery of Small Targeted Molecules of Hunan Province, School of Medicine, Hunan Normal University , Changsha , China
| | - Qiufang Zhang
- a Department of Pharmacology, Laboratory of Chinese Herbal Pharmacology , Biomedical Research Institute, Hubei University of Medicine , Shiyan , Hubei , China
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15
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Liu J, Li Y, Tang Y, Cheng J, Wang J, Li J, Ma X, Zhuang W, Gong J, Liu Z. Rhein protects the myocardiac cells against hypoxia/reoxygention-induced injury by suppressing GSK3β activity. PHYTOMEDICINE : INTERNATIONAL JOURNAL OF PHYTOTHERAPY AND PHYTOPHARMACOLOGY 2018; 51:1-6. [PMID: 30466606 DOI: 10.1016/j.phymed.2018.06.029] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/02/2016] [Revised: 05/22/2018] [Accepted: 06/19/2018] [Indexed: 06/09/2023]
Abstract
BACKGROUND Rhein, an anthraquinone compound isolated from rhubarb, has been shown to protect the pancreatic β cells from hyperglycemia induced apoptosis in our previous studies. PURPOSE In the present study, we examined whether rhein can protect myocardial cells against ischemia reperfusion (I/R)-induced apoptosis and investigated the underlying mechanism. METHODS We used an in vitro model of myocardial hypoxia/reoxygenation (H/R) injury. H9c2 cells were incubated with rhein for 1 h and then subjected to hypoxia for 6 h, followed by reoxygenation for 2 h. Cells viability, apoptosis and ROS were assayed for the treated cells. AKT, p-AKT, GSK3β, p- GSK3β, P38 and p-P38 proteins were analyzed using Western blotting. PI3K/AKT inhibitor, LY294002, and GSK3β siRNA were also used to determine the signaling pathways involved in the protection by rhein. RESULTS Rhein increased viability, decreased apoptosis and ROS production, of the cells that were exposed to H/R. Rhein also increased the phosphorylation of AKT and GSK3β, an effect that was eliminated by LY294002. GSK3β silencing by siRNA showed similar effect as LY294002. The p-P38 level was upregulated by H/R and downregulated in the presence of rhein; however, the p-P38 downregulation was completely abolished by GSK3β silencing. CONCLUSION Rhein protects myocardial H9c2 cells against hypoxia/reoxygenation induced injury via AKT/ GSK3β/p38 pathway.
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Affiliation(s)
- Jing Liu
- Department of Cardiology, Jinling Hospital, Nanjing University School of Medicine, Nanjing, Jiangsu, China
| | - Yanming Li
- Department of Cardiology, Jinling Hospital, Nanjing University School of Medicine, Nanjing, Jiangsu, China
| | - Yi Tang
- Department of Cardiology, Jinling Hospital, Nanjing University School of Medicine, Nanjing, Jiangsu, China
| | - Jinghua Cheng
- Department of Cardiology, Jinling Hospital, Nanjing University School of Medicine, Nanjing, Jiangsu, China
| | - Jing Wang
- Department of Cardiology, Jinling Hospital, Nanjing University School of Medicine, Nanjing, Jiangsu, China
| | - Jianhua Li
- Department of Cardiology, Jinling Hospital, Nanjing University School of Medicine, Nanjing, Jiangsu, China
| | - Xiaohua Ma
- Department of Cardiology, Jinling Hospital, Nanjing University School of Medicine, Nanjing, Jiangsu, China
| | - Wei Zhuang
- Department of Cardiology, Jinling Hospital, Nanjing University School of Medicine, Nanjing, Jiangsu, China
| | - Jianbin Gong
- Department of Cardiology, Jinling Hospital, Nanjing University School of Medicine, Nanjing, Jiangsu, China.
| | - Zhihong Liu
- National Clinical Research Center for Kidney Diseases, Jinling Hospital, Nanjing University School of Medicine, Nanjing, Jiangsu, China.
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16
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Du Q, Jovanović S, Sukhodub A, Ngoi YS, Lal A, Zheleva M, Jovanović A. Insulin down-regulates cardioprotective SUR2A in the heart-derived H9c2 cells: A possible explanation for some adverse effects of insulin therapy. Biochem Biophys Rep 2018; 16:12-18. [PMID: 30211323 PMCID: PMC6132176 DOI: 10.1016/j.bbrep.2018.08.005] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2018] [Revised: 07/28/2018] [Accepted: 08/27/2018] [Indexed: 12/12/2022] Open
Abstract
Some recent studies associated insulin therapy with negative cardiovascular events and shorter lifespan. SUR2A, a KATP channel subunit, regulate cardioprotection and cardiac ageing. Here, we have tested whether glucose and insulin regulate expression of SUR2A/KATP channel subunits and resistance to metabolic stress in heart H9c2 cells. Absence of glucose in culture media decreased SUR2A mRNA, while mRNAs of Kir6.2, Kir6.1, SUR1 and IES SUR2B were increased. 2-deoxyglucose (50 mM) decreased mRNAs of SUR2A, SUR2B and SUR1, did not affect IES SUR2A and IES SUR2B mRNAs and increased Kir6.2 mRNA. No glucose and 2-deoxyglucose (50 mM) decreased resistance to an inhibitor of oxidative phosphorylation, DNP (10 mM). 50 mM glucose did not alter KATP channel subunits nor cellular resistance to DNP (10 mM). Insulin (20 ng/ml) in both physiological and high glucose (50 mM) down-regulated SUR2A while upregulating Kir6.1 and Kir6.2 (in high glucose only). Insulin (20 ng/ml) in physiological and high glucose decreased cell survival in DNP (10 mM). As opposed to Kir6.2, infection with SUR2A resulted in titre-dependent cytoprotection. We conclude that insulin decreases resistance to metabolic stress in H9c2 cells by decreasing SUR2A expression. Lower cardiac SUR2A levels underlie increased myocardial susceptibility to metabolic stress and shorter lifespan.
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Affiliation(s)
- Qingyou Du
- Division of Molecular and Clinical Medicine, Medical School, University of Dundee, United Kingdom
| | - Sofija Jovanović
- Division of Molecular and Clinical Medicine, Medical School, University of Dundee, United Kingdom
| | - Andriy Sukhodub
- Division of Molecular and Clinical Medicine, Medical School, University of Dundee, United Kingdom
| | - Yong Shi Ngoi
- Division of Molecular and Clinical Medicine, Medical School, University of Dundee, United Kingdom
| | - Aashray Lal
- Division of Molecular and Clinical Medicine, Medical School, University of Dundee, United Kingdom
| | - Marina Zheleva
- Division of Molecular and Clinical Medicine, Medical School, University of Dundee, United Kingdom
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17
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Lu J, Pan SS, Wang QT, Yuan Y. Alterations of Cardiac K ATP Channels and Autophagy Contribute in the Late Cardioprotective Phase of Exercise Preconditioning. Int Heart J 2018; 59:1106-1115. [PMID: 30101842 DOI: 10.1536/ihj.17-003] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/09/2022]
Abstract
The cardiac effects of exercise preconditioning (EP) are well established; however, the mechanisms involving cardiac ATP-sensitive potassium channel (KATP channel) subunits and autophagy are yet to be fully established. The present work aims to investigate the alterations of cardiac KATP channel subunits Kir6.2, SUR2A, and autophagy-related LC3 during the late cardioprotective phase of EP against exhaustive exercise-induced myocardial injury. Rats run on treadmill for four running time intervals, each with 10 minutes running and rest. Exhaustive exercise was performed 24 h after EP. Cardiac biomarkers, cTnI and NT-proBNP, along with the histological stain, were served as indicators of myocardial injury. Cardiac KATP channel subunits Kir6.2 and SUR2A were analyzed in this study, and autophagy was evaluated by LC3. The results revealed that EP reduced the exhaustive exercise-induced high level of serum cTnI and myocardial ischemia/hypoxia; however, it did not reveal any changes in the serum NT-proBNP level or cardiac BNP. Cardiac SUR2A mRNA significantly upregulated during the exhaustive exercise. The high levels of Kir6.2, SUR2A, LC3IIpuncta and LC3II turnover observed after exhaustive exercise were significantly mitigated by EP in the late phase. These results suggest that EP alleviates myocardial injury induced by exhaustive exercise through the downregulation of cardiac KATP channels and autophagy.
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Affiliation(s)
- Jiao Lu
- School of Kinesiology, Shanghai University of Sport
| | | | | | - Yang Yuan
- School of Kinesiology, Shanghai University of Sport
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18
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Jovanović A. Cardioprotective signalling: Past, present and future. Eur J Pharmacol 2018; 833:314-319. [PMID: 29935170 DOI: 10.1016/j.ejphar.2018.06.029] [Citation(s) in RCA: 38] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2018] [Revised: 06/08/2018] [Accepted: 06/19/2018] [Indexed: 11/29/2022]
Abstract
A few decades ago, cardiac muscle was discovered to possess signalling pathways that, when activated, protect the myocardium against the damage induced by ischaemia-reperfusion. The ability of cardiac muscle to protect itself against injury has been termed 'cardioprotection'. Many compounds and procedures can trigger cardioprotection including conditionings (exposure to brief episodes of ischaemia-reperfusion to protect against sustained ischaemia-reperfusion), hypoxia, adenosine, acetylcholine, adrenomedullin, angiotensin, bradykinin, catecholamines, endothelin, estrogens, phenylephrine, opioids, testosterone, and many more. These triggers activate many intracellular signalling factors including protein kinases, different enzymes, transcription factors and defined signalling pathways to target structures in mitochondria, sarcoplasmic reticulum, nucleus and sarcolemma to mediate cardioprotection. Although a lot of information about cardioprotection has been acquired, there are still two major outstanding issues to be addressed in the future 1) better understanding of spatio-temporal relationships between signalling elements, and; 2) devising therapeutic strategies against myocardial diseases based on cardioprotective signalling. Further research is required to paint integral picture of cardioprotective signalling and more clinical studies are required to properly test clinical efficacy and safety of potential cardioprotective strategies. Therapies against cardiac diseases based on cardioprotective strategies would be a perfect adjunct to current therapeutic strategies based on restitution of coronary blood flow and regulation of myocardial metabolic demands.
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Affiliation(s)
- Aleksandar Jovanović
- University of Nicosia Medical School, 21 Ilia Papakyriakou, 2414 Engomi, P.O. Box 24005, CY-1700 Nicosia, Cyprus.
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Exposure of human neurons to silver nanoparticles induces similar pattern of ABC transporters gene expression as differentiation: Study on proliferating and post-mitotic LUHMES cells. Mech Ageing Dev 2018; 171:7-14. [DOI: 10.1016/j.mad.2018.02.004] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2017] [Revised: 01/26/2018] [Accepted: 02/22/2018] [Indexed: 11/17/2022]
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20
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Gangwar A, Paul S, Ahmad Y, Bhargava K. Competing trends of ROS and RNS-mediated protein modifications during hypoxia as an alternate mechanism of NO benefits. Biochimie 2018; 148:127-138. [PMID: 29571702 DOI: 10.1016/j.biochi.2018.03.009] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2018] [Accepted: 03/16/2018] [Indexed: 01/01/2023]
Abstract
Hypoxia, especially altitude associated hypoxia is known to cause severe physiological alterations and life-threatening conditions. Impaired redox balance along with oxidative stress, protein carbonylation and instigation of apoptotic events are common sub-cellular events that follow the hypoxic insult. The role of nitric oxide (NO) is very dynamic and versatile in preventing the ill effects of hypoxia vis-a-vis reacting with oxidative species and causing protein nitrosylation. Although several mechanisms of NO-mediated cytoprotection are known during hypoxic insult, limited pieces of evidence are available to support the relationship between two downstream events of oxidative stress, protein carbonylation (caused by carbonyl; CO radical) and protein nitrosylation/nitration (caused by NO/peroxynitrite; ONOO radical). In this study, we investigated an entirely new aspect of NO protection in hypoxia involving crosstalk between carbonylation and nitrosylation. Using standard NO inhibitor l-NAME and simulated hypoxic conditions in hypoxia-sensitive cell line H9c2, we evaluated the levels of radicals, cell death, mitochondrial membrane potential, levels of protein nitrosylation, protein nitration and carbonylation and glutathione content. The results were then carefully analyzed in light of NO bioavailability. Our study shows that reducing NO during hypoxia caused cell death via the increased degree of carbonylation in proteins. This provides a new aspect of NO benefits which furthers opens new possibilities to explore potential mechanisms and effects of cross-talk between nitrosylation, protein nitration and carbonylation, especially through some common antioxidant mediators such as glutathione and thioredoxin.
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Affiliation(s)
- Anamika Gangwar
- Peptide and Proteomics Division, Defence Institute of Physiology and Allied Sciences, Defence Research and Development Organization, Lucknow Road, Timarpur, Delhi, 110054, India
| | - Subhojit Paul
- Peptide and Proteomics Division, Defence Institute of Physiology and Allied Sciences, Defence Research and Development Organization, Lucknow Road, Timarpur, Delhi, 110054, India
| | - Yasmin Ahmad
- Peptide and Proteomics Division, Defence Institute of Physiology and Allied Sciences, Defence Research and Development Organization, Lucknow Road, Timarpur, Delhi, 110054, India
| | - Kalpana Bhargava
- Peptide and Proteomics Division, Defence Institute of Physiology and Allied Sciences, Defence Research and Development Organization, Lucknow Road, Timarpur, Delhi, 110054, India.
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21
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Feng Y, Liu J, Wang M, Liu M, Shi L, Yuan W, Ye J, Hu D, Wan J. The E23K variant of the Kir6.2 subunit of the ATP-sensitive potassium channel increases susceptibility to ventricular arrhythmia in response to ischemia in rats. Int J Cardiol 2017; 232:192-198. [DOI: 10.1016/j.ijcard.2017.01.022] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/10/2016] [Revised: 12/27/2016] [Accepted: 01/03/2017] [Indexed: 12/22/2022]
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22
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The Citrus Flavanone Naringenin Protects Myocardial Cells against Age-Associated Damage. OXIDATIVE MEDICINE AND CELLULAR LONGEVITY 2017; 2017:9536148. [PMID: 28386313 PMCID: PMC5366223 DOI: 10.1155/2017/9536148] [Citation(s) in RCA: 47] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/16/2016] [Revised: 02/06/2017] [Accepted: 02/28/2017] [Indexed: 12/21/2022]
Abstract
In recent years, the health-promoting effects of the citrus flavanone naringenin have been examined. The results have provided evidence for the modulation of some key mechanisms involved in cellular damage by this compound. In particular, naringenin has been revealed to have protective properties such as an antioxidant effect in cardiometabolic disorders. Very recently, beneficial effects of naringenin have been demonstrated in old rats. Because aging has been demonstrated to be directly related to the occurrence of cardiac disorders, in the present study, the ability of naringenin to prevent cardiac cell senescence was investigated. For this purpose, a cellular model of senescent myocardial cells was set up and evaluated using colorimetric, fluorimetric, and immunometric techniques. Relevant cellular senescence markers, such as X-gal staining, cell cycle regulator levels, and the percentage of cell cycle-arrested cells, were found to be reduced in the presence of naringenin. In addition, cardiac markers of aging-induced damage, including radical oxidative species levels, mitochondrial metabolic activity, mitochondrial calcium buffer capacity, and estrogenic signaling functions, were also modulated by the compound. These results suggested that naringenin has antiaging effects on myocardial cells.
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23
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Mohammed Abdul KS, Jovanović S, Jovanović A. Exposure to 15% oxygen in vivo up-regulates cardioprotective SUR2A without affecting ERK1/2 and AKT: a crucial role for AMPK. J Cell Mol Med 2017; 21:1342-1350. [PMID: 28121062 PMCID: PMC5487919 DOI: 10.1111/jcmm.13064] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2016] [Accepted: 11/15/2016] [Indexed: 11/28/2022] Open
Abstract
SUR2A is an 'atypical' ABC protein that forms sarcolemmal ATP-sensitive K+ (KATP ) channels by binding to inward rectifier Kir6.2. Manipulation with SUR2A levels has been suggested to be a promising therapeutic strategy against ischaemic heart diseases and other diseases where increased heart resistance to stress is beneficial. Some years ago, it has been reported that high-altitude residents have lower mortality rates for ischaemic heart disease. The purpose of this study was to determine whether SUR2A is regulated by mild-to-severe hypoxic conditions (15% oxygen; oxygen tension equivalent to 3000 m above sea level) and elucidate the underlying mechanism. Mice were exposed to either to 21% (control) or 15% concentration of oxygen for 24 hrs. Twenty-four hours long exposure to 15% oxygen decreased partial pressure of O2 (PO2 ), but did not affect blood CO2 (PCO2 ), haematocrit nor levels of ATP, lactate and NAD+/NADH in the heart. Cardiac SUR2A levels were significantly increased while Kir6.2 levels were not affected. Hypoxia did not induce phosphorylation of extracellular signal-regulated kinases (ERK1/2) or protein kinase B (Akt), but triggered phosphorylation of AMP activated protein kinase (AMPK). AICAR, an activator of AMPK, increased the level of SUR2A in H9c2 cells. We conclude that oxygen increases SUR2A level by activating AMPK. This is the first account of AMPK-mediated regulation of SUR2A.
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Affiliation(s)
- Khaja Shameem Mohammed Abdul
- Division of Molecular & Clinical Medicine, Ninewells Hospital & Medical School, University of Dundee, Dundee, UK
| | - Sofija Jovanović
- Division of Molecular & Clinical Medicine, Ninewells Hospital & Medical School, University of Dundee, Dundee, UK
| | - Aleksandar Jovanović
- Division of Molecular & Clinical Medicine, Ninewells Hospital & Medical School, University of Dundee, Dundee, UK
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24
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ARM-microcontroller based portable nitrite electrochemical analyzer using cytochrome c reductase biofunctionalized onto screen printed carbon electrode. Biosens Bioelectron 2016; 90:410-417. [PMID: 27836596 DOI: 10.1016/j.bios.2016.10.039] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2016] [Revised: 10/06/2016] [Accepted: 10/18/2016] [Indexed: 01/08/2023]
Abstract
Nitrite (NO2-) supplementation limits hypoxia-induced oxidative stress and activates the alternate NO pathway which may partially account for the nitrite-mediated cardioprotection. So, sensitive and selective biosensors with point-of-care devices need to be explored to detect the physiological nitrite level due to its important role in human pathophysiology. In this work, cytochrome c reductase (CcR) biofunctionalized self assembled monolayer (SAM) functionalized on gold nanoparticles (GNPs) in polypyrrole (PPy) nanocomposite onto the screen printed carbon electrode (SPCE) was investigated as a biosensor for the detection of nitrite based on its electrochemical and catalytic properties. CcR was covalently coupled with SAM layers on GNPs by using EDC and NHS. Direct electrochemical response of CcR biofunctionalized electrodes showed a couple of well-defined and nearly reversible cyclic voltammetric peaks at -0.34 and -0.45 vs. Ag/AgCl. Under optimal conditions, the biosensor could be used for the determination of NO2- with a linear range from 0.1-1600µm and a detection limit of 60nM with a sensitivity of 0.172µAµM-1cm-2. Further, we have designed and developed a novel and cost effective portable electrochemical analyzer for the measurement of NO2- in hypoxia induced H9c2 cardiac cells using ARM microcontroller. The results obtained here using the developed portable electrochemical nitrite analyzer were also compared with the standard cyclic voltammetry instrument and found in agreement with each other.
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25
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Keung W, Ren L, Sen Li, Wong AOT, Chopra A, Kong CW, Tomaselli GF, Chen CS, Li RA. Non-cell autonomous cues for enhanced functionality of human embryonic stem cell-derived cardiomyocytes via maturation of sarcolemmal and mitochondrial K ATP channels. Sci Rep 2016; 6:34154. [PMID: 27677332 PMCID: PMC5039730 DOI: 10.1038/srep34154] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2016] [Accepted: 09/08/2016] [Indexed: 01/22/2023] Open
Abstract
Human embryonic stem cells (hESCs) is a potential unlimited ex vivo source of ventricular (V) cardiomyocytes (CMs), but hESC-VCMs and their engineered tissues display immature traits. In adult VCMs, sarcolemmal (sarc) and mitochondrial (mito) ATP-sensitive potassium (KATP) channels play crucial roles in excitability and cardioprotection. In this study, we aim to investigate the biological roles and use of sarcKATP and mitoKATP in hESC-VCM. We showed that SarcIK, ATP in single hESC-VCMs was dormant under baseline conditions, but became markedly activated by cyanide (CN) or the known opener P1075 with a current density that was ~8-fold smaller than adult; These effects were reversible upon washout or the addition of GLI or HMR1098. Interestingly, sarcIK, ATP displayed a ~3-fold increase after treatment with hypoxia (5% O2). MitoIK, ATP was absent in hESC-VCMs. However, the thyroid hormone T3 up-regulated mitoIK, ATP, conferring diazoxide protective effect on T3-treated hESC-VCMs. When assessed using a multi-cellular engineered 3D ventricular cardiac micro-tissue (hvCMT) system, T3 substantially enhanced the developed tension by 3-folds. Diazoxide also attenuated the decrease in contractility induced by simulated ischemia (1% O2). We conclude that hypoxia and T3 enhance the functionality of hESC-VCMs and their engineered tissues by selectively acting on sarc and mitoIK, ATP.
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Affiliation(s)
- Wendy Keung
- Stem Cell &Regenerative Medicine Consortium, LKS Faculty of Medicine, The University of Hong Kong, Hong Kong.,Department of Physiology, The University of Hong Kong, Hong Kong
| | - Lihuan Ren
- Stem Cell &Regenerative Medicine Consortium, LKS Faculty of Medicine, The University of Hong Kong, Hong Kong.,Department of Physiology, The University of Hong Kong, Hong Kong
| | - Sen Li
- Stem Cell &Regenerative Medicine Consortium, LKS Faculty of Medicine, The University of Hong Kong, Hong Kong.,Department of Physiology, The University of Hong Kong, Hong Kong
| | - Andy On-Tik Wong
- Stem Cell &Regenerative Medicine Consortium, LKS Faculty of Medicine, The University of Hong Kong, Hong Kong.,Department of Physiology, The University of Hong Kong, Hong Kong
| | - Anant Chopra
- Department of Bioengineering, Boston University, Boston, MA, USA.,Harvard Wyss Institute for Biologically Inspired Engineering, Boston, MA, USA
| | - Chi-Wing Kong
- Stem Cell &Regenerative Medicine Consortium, LKS Faculty of Medicine, The University of Hong Kong, Hong Kong.,Department of Physiology, The University of Hong Kong, Hong Kong
| | - Gordon F Tomaselli
- Division of Cardiology, Department of Medicine, Johns Hopkins University, Baltimore, M.D., United States of America
| | - Christopher S Chen
- Department of Bioengineering, Boston University, Boston, MA, USA.,Harvard Wyss Institute for Biologically Inspired Engineering, Boston, MA, USA
| | - Ronald A Li
- Stem Cell &Regenerative Medicine Consortium, LKS Faculty of Medicine, The University of Hong Kong, Hong Kong.,Dr. Li Dak-Sum Research Centre, The University of Hong Kong - Karolinska Institutet Collaborations in Regenerative Medicine, The University of Hong Kong, Hong Kong.,Ming Wai Lau Centre for Reparative Medicine, Karolinska Institutet, Sweden
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Mo Y, Tang L, Ma Y, Wu S. Pramipexole pretreatment attenuates myocardial ischemia/reperfusion injury through upregulation of autophagy. Biochem Biophys Res Commun 2016; 473:1119-1124. [DOI: 10.1016/j.bbrc.2016.04.026] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2016] [Accepted: 04/07/2016] [Indexed: 01/09/2023]
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Chang YM, Chang HH, Kuo WW, Lin HJ, Yeh YL, Padma Viswanadha V, Tsai CC, Chen RJ, Chang HN, Huang CY. Anti-Apoptotic and Pro-Survival Effect of Alpinate Oxyphyllae Fructus (AOF) in a d-Galactose-Induced Aging Heart. Int J Mol Sci 2016; 17:466. [PMID: 27043531 PMCID: PMC4848922 DOI: 10.3390/ijms17040466] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2016] [Revised: 03/21/2016] [Accepted: 03/21/2016] [Indexed: 12/16/2022] Open
Abstract
Aging, a natural biological/physiological phenomenon, is accelerated by reactive oxygen species (ROS) accumulation and identified by a progressive decrease in physiological function. Several studies have shown a positive relationship between aging and chronic heart failure (HF). Cardiac apoptosis was found in age-related diseases. We used a traditional Chinese medicine, Alpinate Oxyphyllae Fructus (AOF), to evaluate its effect on cardiac anti-apoptosis and pro-survival. Male eight-week-old Sprague–Dawley (SD) rats were segregated into five groups: normal control group (NC), d-Galactose-Induced aging group (Aging), and AOF of 50 (AL (AOF low)), 100 (AM (AOF medium)), 150 (AH (AOF high)) mg/kg/day. After eight weeks, hearts were measured by an Hematoxylin–Eosin (H&E) stain, Terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL)-assays and Western blotting. The experimental results show that the cardiomyocyte apoptotic pathway protein expression increased in the d-Galactose-Induced aging groups, with dose-dependent inhibition in the AOF treatment group (AL, AM, and AH). Moreover, the expression of the pro-survival p-Akt (protein kinase B (Akt)), Bcl-2 (B-cell lymphoma 2), anti-apoptotic protein (Bcl-xL) protein decreased significantly in the d-Galactose-induced aging group, with increased performance in the AOF treatment group with levels of p-IGFIR and p-PI3K (Phosphatidylinositol-3′ kinase (PI3K)) to increase by dosage and compensatory performance. On the other hand, the protein of the Sirtuin 1 (SIRT1) pathway expression decreased in the aging groups and showed improvement in the AOF treatment group. Our results suggest that AOF strongly works against ROS-induced aging heart problems.
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Affiliation(s)
- Yung-Ming Chang
- The School of Chinese Medicine for Post-Baccalaureate, I-Shou University, Kaohsiung 84001, Taiwan.
- Chinese Medicine Department, E-DA Hospital, Kaohsiung 82445, Taiwan.
- 1PT Biotechnology Co., Ltd., Taichung 433, Taiwan.
| | - Hen-Hong Chang
- Research Center for Chinese Medicine & Acupuncture, China Medical University, Taichung 40402, Taiwan.
- Departments of Chinese Medicine, China Medical University Hospital, Taichung 40447, Taiwan.
- School of Post-Baccalaureate Chinese Medicine, College of Chinese Medicine, China Medical University, Taichung 40402, Taiwan.
| | - Wei-Wen Kuo
- Department of Biological Science and Technology, China Medical University, Taichung 40447, Taiwan.
| | - Hung-Jen Lin
- Departments of Chinese Medicine, China Medical University Hospital, Taichung 40447, Taiwan.
- School of Post-Baccalaureate Chinese Medicine, College of Chinese Medicine, China Medical University, Taichung 40402, Taiwan.
| | - Yu-Lan Yeh
- Department of pathology, Changhua Christian Hospital, Changhua 50506, Taiwan.
- Department of Medical Technology, Jen-Teh Junior College of Medicine, Nursing and Management, Miaoli 35665, Taiwan.
| | | | - Chin-Chuan Tsai
- The School of Chinese Medicine for Post-Baccalaureate, I-Shou University, Kaohsiung 84001, Taiwan.
- Chinese Medicine Department, E-DA Hospital, Kaohsiung 82445, Taiwan.
| | - Ray-Jade Chen
- Department of Surgery, School of Medicine, College of Medicine, Taipei Medical University, Taipei 11042, Taiwan.
| | - Hsin-Nung Chang
- Graduate Institute of Basic Medical Science, China Medical University, Taichung 40402, Taiwan.
| | - Chih-Yang Huang
- Graduate Institute of Basic Medical Science, China Medical University, Taichung 40402, Taiwan.
- School of Chinese Medicine, China Medical University, Taichung 40447, Taiwan.
- Department of Health and Nutrition Biotechnology, Asia University, Taichung 41354, Taiwan.
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Jia W, Jian Z, Li J, Luo L, Zhao L, Zhou Y, Tang F, Xiao Y. Upregulated ATF6 contributes to chronic intermittent hypoxia-afforded protection against myocardial ischemia/reperfusion injury. Int J Mol Med 2016; 37:1199-208. [PMID: 27035093 PMCID: PMC4829135 DOI: 10.3892/ijmm.2016.2535] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2015] [Accepted: 03/07/2016] [Indexed: 12/04/2022] Open
Abstract
In the present study, we investigated the role of activating transcription factor 6 (ATF6) in the mechanism by which chronic intermittent hypoxia (CIH) increases tolerance to myocardial ischemia/reperfusion (I/R). Experiments were conducted using a rat model of I/R injury in vivo and isolated Langendorff-perfused rat hearts ex vivo. The role of Akt in this process was also investigated in vitro using rat myoblast H9c2 cells. Cell viability was measured using a cell counting kit-8 assay. Lactate dehydrogenase (LDH) and creatine kinase cardiac isoenzyme activity were also measured as markers of cellular damage. ATF6, Akt and phosphorylated (p)-Akt expression was analyzed by western blot analysis. RNA interference (RNAi) was used to suppress ATF6 expression. We noted that ATF6 expression in the ventricular myocardium was significantly increased in rats exposed to CIH. Furthermore, we noted that CIH preserved cardiac function after I/R in vivo and improved post-ischemic recovery of myocardial performance in isolated rat hearts. ATF6 and p-Akt expression was upregulated in cultured H9c2 cells exposed to chronic mild hypoxia compared with those cultured under normoxic conditions. Chronic mild hypoxia attenuated subsequent simulated I/R injury in H9c2 cells (48 h), as evidenced by increased cell viability and decreased LDH activity. By contrast, decreased cell viability and increased LDH activity were observed in siRNA-ATF6-transfected H9c2 cells, with a concomitant reduction in p-Akt levels. These results indicated that ATF6 upregulation is involved in the mechanism by which CIH attenuates myocardial I/R injury, possibly through upregulation of p-Akt, which is a key regulator of cardiomyocyte survival.
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Affiliation(s)
- Weikun Jia
- Department of Cardiovascular Surgery, Xinqiao Hospital, Third Military Medical University, Chongqing 400037, P.R. China
| | - Zhao Jian
- Department of Cardiovascular Surgery, Xinqiao Hospital, Third Military Medical University, Chongqing 400037, P.R. China
| | - Jingwei Li
- Department of Cardiovascular Surgery, Xinqiao Hospital, Third Military Medical University, Chongqing 400037, P.R. China
| | - Lin Luo
- Department of Cardiovascular Surgery, Xinqiao Hospital, Third Military Medical University, Chongqing 400037, P.R. China
| | - Liang Zhao
- Department of Cardiovascular Surgery, Xinqiao Hospital, Third Military Medical University, Chongqing 400037, P.R. China
| | - Yang Zhou
- Department of Cardiovascular Surgery, Xinqiao Hospital, Third Military Medical University, Chongqing 400037, P.R. China
| | - Fuqin Tang
- Department of Cardiovascular Surgery, Xinqiao Hospital, Third Military Medical University, Chongqing 400037, P.R. China
| | - Yingbin Xiao
- Department of Cardiovascular Surgery, Xinqiao Hospital, Third Military Medical University, Chongqing 400037, P.R. China
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Abstract
KATP channels are integral to the functions of many cells and tissues. The use of electrophysiological methods has allowed for a detailed characterization of KATP channels in terms of their biophysical properties, nucleotide sensitivities, and modification by pharmacological compounds. However, even though they were first described almost 25 years ago (Noma 1983, Trube and Hescheler 1984), the physiological and pathophysiological roles of these channels, and their regulation by complex biological systems, are only now emerging for many tissues. Even in tissues where their roles have been best defined, there are still many unanswered questions. This review aims to summarize the properties, molecular composition, and pharmacology of KATP channels in various cardiovascular components (atria, specialized conduction system, ventricles, smooth muscle, endothelium, and mitochondria). We will summarize the lessons learned from available genetic mouse models and address the known roles of KATP channels in cardiovascular pathologies and how genetic variation in KATP channel genes contribute to human disease.
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Affiliation(s)
- Monique N Foster
- Departments of Pediatrics, Physiology & Neuroscience, and Biochemistry and Molecular Pharmacology, NYU School of Medicine, New York, New York
| | - William A Coetzee
- Departments of Pediatrics, Physiology & Neuroscience, and Biochemistry and Molecular Pharmacology, NYU School of Medicine, New York, New York
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Chen WK, Kuo WW, Hsieh DJY, Chang HN, Pai PY, Lin KH, Pan LF, Ho TJ, Viswanadha VP, Huang CY. CREB Negatively Regulates IGF2R Gene Expression and Downstream Pathways to Inhibit Hypoxia-Induced H9c2 Cardiomyoblast Cell Death. Int J Mol Sci 2015; 16:27921-30. [PMID: 26610485 PMCID: PMC4661925 DOI: 10.3390/ijms161126067] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2015] [Accepted: 10/23/2015] [Indexed: 01/18/2023] Open
Abstract
During hypoxia, gene expression is altered by various transcription factors. Insulin-like growth factor-II (IGF2) is known to be induced by hypoxia, which binds to IGF2 receptor IGF2R that acts like a G protein-coupled receptor, might cause pathological hypertrophy or activation of the mitochondria-mediated apoptosis pathway. Cyclic adenosine monophosphate (cAMP) responsive element-binding protein (CREB) is central to second messenger-regulated transcription and plays a critical role in the cardiomyocyte survival pathway. In this study, we found that IGF2R level was enhanced in H9c2 cardiomyoblasts exposed to hypoxia in a time-dependent manner but was down-regulated by CREB expression. The over-expression of CREB in H9c2 cardiomyoblasts suppressed the induction of hypoxia-induced IGF2R expression levels and reduced cell apoptosis. Gel shift assay results further indicated that CREB binds to the promoter sequence of IGF2R. With a luciferase assay method, we further observed that CREB represses IGF2R promoter activity. These results suggest that CREB plays an important role in the inhibition of IGF2R expression by binding to the IGF2R promoter and further suppresses H9c2 cardiomyoblast cell apoptosis induced by IGF2R signaling under hypoxic conditions.
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Affiliation(s)
- Wei-Kung Chen
- Department of Emergency Medicine, China Medical University Hospital, Taichung 40402, Taiwan.
| | - Wei-Wen Kuo
- Department of Biological Science and Technology, China Medical University, Taichung 40402, Taiwan.
| | - Dennis Jine-Yuan Hsieh
- School of Medical Laboratory and Biotechnology, Chung Shan Medical University, Taichung 40201, Taiwan.
| | - Hsin-Nung Chang
- Graduate Institute of Clinical Medical Science, China Medical University, Taichung 40402, Taiwan.
| | - Pei-Ying Pai
- Division of Cardiology, China Medical University Hospital, Taichung 40402, Taiwan.
| | - Kuan-Ho Lin
- Department of Emergency Medicine, China Medical University Hospital, Taichung 40402, Taiwan.
- Graduate Institute of Clinical Medical Science, China Medical University, Taichung 40402, Taiwan.
- College of Medicine, China Medical University, Taichung 40402, Taiwan.
| | - Lung-Fa Pan
- Cardiology Department, Taichung Armed Forces General Hospital. Taichung 41152, Taiwan.
- Department of Medical Imaging and Radiological Sciences, Central Taiwan University of Science and Technology, Taichung 40601, Taiwan.
| | - Tsung-Jung Ho
- School of Chinese Medicine, College of Chinese Medicine, China Medical University, Taichung 40402, Taiwan.
- Chinese Medicine Department, China Medical University Beigang Hospital, Yunlin 651, Taiwan.
| | | | - Chih-Yang Huang
- Chinese Medicine Department, China Medical University Beigang Hospital, Yunlin 651, Taiwan.
- Graduate Institute of Basic Medical Science, China Medical University, Taichung 40402, Taiwan.
- Department of Health and Nutrition Biotechnology, Asia University, Taichung 41354, Taiwan.
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31
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Jovanović S, Ballantyne T, Du Q, Blagojević M, Jovanović A. Phenylephrine preconditioning in embryonic heart H9c2 cells is mediated by up-regulation of SUR2B/Kir6.2: A first evidence for functional role of SUR2B in sarcolemmal KATP channels and cardioprotection. Int J Biochem Cell Biol 2015; 70:23-8. [PMID: 26556311 PMCID: PMC4711337 DOI: 10.1016/j.biocel.2015.10.029] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2015] [Revised: 10/22/2015] [Accepted: 10/30/2015] [Indexed: 02/07/2023]
Abstract
ATP-sensitive K+ (KATP) channels were originally described in cardiomyocytes, where physiological levels of intracellular ATP keep them in a closed state. Structurally, these channels are composed of pore-forming inward rectifier, Kir6.1 or Kir6.2, and a regulatory, ATP-binding subunit, SUR1, SUR2A or SUR2B. SUR1 and Kir6.2 form pancreatic type of KATP channels, SUR2A and Kir6.2 form cardiac type of KATP channels, SUR2B and Kir6.1 form vascular smooth muscle type of KATP channels. The presence of SUR2B has been described in cardiomyocytes, but its functional significance and role has remained unknown. Pretreatment with phenylephrine (100 nM) for 24 h increased mRNA levels of SUR2B and Kir6.2, without affecting those levels of SUR1, SUR2A and Kir6.1 in embryonic heart H9c2 cells. Such increase was associated with increased K+ current through KATP channels and Kir6.2/SUR2B protein complexes as revealed by whole cell patch clamp electrophysiology and immunoprecipitation/Western blotting respectively. Pretreatment with phenylephrine (100 nM) generated a cellular phenotype that acquired resistance to chemical hypoxia induced by 2,4-dinitrophenol (DNP; 10 mM), which was accompanied by increased in K+ current in response to DNP (10 mM). Cytoprotection afforded by phenylephrine (100 nM) was abolished by infection of H9c2 cells with adenovirus containing Kir6.2AFA, a mutant form of Kir6.2 with largely reduced K+ conductance. Taking all together, the present findings demonstrate that the activation of α1-adrenoceptors up-regulates SUR2B/Kir6.2 to confer cardioprotection. This is the first account of possible physiological role of SUR2B in cardiomyocytes.
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Affiliation(s)
- Sofija Jovanović
- Medical Research Institute, Division of Cardiovascular & Diabetic Medicine, Ninewells Hospital & Medical School, University of Dundee, UK
| | - Thomas Ballantyne
- Medical Research Institute, Division of Cardiovascular & Diabetic Medicine, Ninewells Hospital & Medical School, University of Dundee, UK
| | - Qingyou Du
- Medical Research Institute, Division of Cardiovascular & Diabetic Medicine, Ninewells Hospital & Medical School, University of Dundee, UK
| | - Miloš Blagojević
- Department of Anatomy, Faculty of Veterinary Medicine, University of Belgrade, Belgrade, Serbia
| | - Aleksandar Jovanović
- Medical Research Institute, Division of Cardiovascular & Diabetic Medicine, Ninewells Hospital & Medical School, University of Dundee, UK.
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Mohammed Abdul KS, Jovanović S, Du Q, Sukhodub A, Jovanović A. Mild hypoxia in vivo regulates cardioprotective SUR2A: A role for Akt and LDH. Biochim Biophys Acta Mol Basis Dis 2015; 1852:709-19. [PMID: 25576887 PMCID: PMC4547089 DOI: 10.1016/j.bbadis.2015.01.001] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2014] [Revised: 12/19/2014] [Accepted: 01/01/2015] [Indexed: 12/13/2022]
Abstract
High-altitude residents have lower mortality rates for ischaemic heart disease and this is ascribed to cardiac gene remodelling by chronic hypoxia. SUR2A is a cardioprotective ABC protein serving as a subunit of sarcolemmal ATP-sensitive K+ channels. The purpose of this study was to determine whether SUR2A is regulated by mild hypoxia in vivo and to elucidate the underlying mechanism. Mice were exposed to either 21% (control) or 18% (mild hypoxia) oxygen for 24 h. Exposure to 18% oxygen did not affect partial pressure of O2 (PO2) and CO2 (PCO2) in the blood, haematocrit or level of ATP in the heart. However, hypoxia increased myocardial lactate dehydrogenase (LDH) and lactate as well as NAD+ without affecting total NAD. SUR2A levels were significantly increased as well as myocardial resistance to ischaemia–reperfusion. Exposure to 18% oxygen did not phosphorylate extracellular signal regulated kinases (ERK1/2) or AMP activated protein kinase (AMPK), but it phosphorylated protein kinase B (Akt). An inhibitor of phosphoinositide 3-kinases (PI3K), LY294002 (0.2 mg/mouse), abolished all observed effects of hypoxia. LDH inhibitors, galloflavin (50 μM) and sodium oxamate (80 mM) significantly decreased levels of SUR2A in heart embryonic H9c2 cells, while inactive mutant LDH form, gly193-M-LDH increased cellular sensitivity towards stress induced by 2,4-dinitrophenol (10 mM). Treatment of H9c2 cells with sodium lactate (30 mM) increased intracellular lactate, but did not affect LDH activity or SUR2A levels. We conclude that PI3K/Akt signalling pathway and LDH play a crucial role in increase of cardiac SUR2A induced by in vivo exposure to 18% oxygen. Mild hypoxia increases levels of cardioprotective SUR2A in the heart. Phosphorylation of Akt mediates mild hypoxia-induced increase in SUR2A. Phosphorylation of ERK1/2 and AMPK is not involved in observed increase in SUR2A. PI3K/Akt target LDH to regulate SUR2A levels in the myocardium. LDH mediates regulation of SUR2A in a lactate-independent manner.
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Affiliation(s)
- Khaja Shameem Mohammed Abdul
- Medical Research Institute, Division of Cardiovascular & Diabetic Medicine, Ninewells Hospital & Medical School, University of Dundee, Dundee DD1 9SY, UK
| | - Sofija Jovanović
- Medical Research Institute, Division of Cardiovascular & Diabetic Medicine, Ninewells Hospital & Medical School, University of Dundee, Dundee DD1 9SY, UK
| | - Qingyou Du
- Medical Research Institute, Division of Cardiovascular & Diabetic Medicine, Ninewells Hospital & Medical School, University of Dundee, Dundee DD1 9SY, UK
| | - Andriy Sukhodub
- Medical Research Institute, Division of Cardiovascular & Diabetic Medicine, Ninewells Hospital & Medical School, University of Dundee, Dundee DD1 9SY, UK
| | - Aleksandar Jovanović
- Medical Research Institute, Division of Cardiovascular & Diabetic Medicine, Ninewells Hospital & Medical School, University of Dundee, Dundee DD1 9SY, UK.
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33
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Mohammed Abdul KS, Jovanović S, Sukhodub A, Du Q, Jovanović A. Upregulation of cardioprotective SUR2A by sub-hypoxic drop in oxygen. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2014; 1843:2424-31. [PMID: 25064694 PMCID: PMC4331663 DOI: 10.1016/j.bbamcr.2014.07.007] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 04/12/2014] [Revised: 06/20/2014] [Accepted: 07/15/2014] [Indexed: 11/10/2022]
Abstract
The effects of hypoxia on gene expression have been vigorously studied, but possible effects of small changes in oxygen tension have never been addressed. SUR2A is an atypical ABC protein serving as a regulatory subunit of sarcolemmal ATP-sensitive K+ (KATP) channels. Up-regulation of SUR2A is associated with cardioprotection and improved physical endurance. Here, we have found that a 24 h-long exposure to slightly decreased ambient fractional concentration of oxygen (20% oxygen), which is an equivalent to oxygen tension at 350 m above sea level, significantly increased levels of SUR2A in the heart despite that this drop of oxygen did not affect levels of O2, CO2 and hematocrit in the blood or myocardial levels of ATP, lactate and NAD/NADH/NAD+. Hearts from mice exposed to 20% oxygen were significantly more resistant to ischaemia-reperfusion when compared to control ones. Decrease in fractional oxygen concentration of just 0.9% was associated with phosphorylation of ERK1/2, but not Akt, which was essential for up-regulation of SUR2A. These findings indicate that a small drop in oxygen tension up-regulates SUR2A in the heart by activating ERK signaling pathway. This is the first report to suggest that a minimal change in oxygen tension could have a profound signaling effect. Mice were exposed for 24 h to 20% oxygen (oxygen tension at sea level is 20.9%). Exposure to 20% oxygen did not produce measurable in vivo signs of hypoxia. However, 20% of oxygen up-regulated cardioprotective SUR2A. Phosphorylation of ERK1/2, but not Akt, mediated observed increase in SUR2A. Thus, a small drop in oxygen up-regulates cardiac SUR2A by activating ERK1/2.
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Affiliation(s)
- Khaja Shameem Mohammed Abdul
- Medical Research Institute, Division of Cardiovascular & Diabetic Medicine, Ninewells Hospital & Medical School, University of Dundee, Dundee, DD1 9SY Scotland, UK
| | - Sofija Jovanović
- Medical Research Institute, Division of Cardiovascular & Diabetic Medicine, Ninewells Hospital & Medical School, University of Dundee, Dundee, DD1 9SY Scotland, UK
| | - Andriy Sukhodub
- Medical Research Institute, Division of Cardiovascular & Diabetic Medicine, Ninewells Hospital & Medical School, University of Dundee, Dundee, DD1 9SY Scotland, UK
| | - Qingyou Du
- Medical Research Institute, Division of Cardiovascular & Diabetic Medicine, Ninewells Hospital & Medical School, University of Dundee, Dundee, DD1 9SY Scotland, UK
| | - Aleksandar Jovanović
- Medical Research Institute, Division of Cardiovascular & Diabetic Medicine, Ninewells Hospital & Medical School, University of Dundee, Dundee, DD1 9SY Scotland, UK.
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Murray AJ, Montgomery HE. How wasting is saving: weight loss at altitude might result from an evolutionary adaptation. Bioessays 2014; 36:721-9. [PMID: 24917038 PMCID: PMC4143966 DOI: 10.1002/bies.201400042] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
At extreme altitude (>5,000 – 5,500 m), sustained hypoxia threatens human function and survival, and is associated with marked involuntary weight loss (cachexia). This seems to be a coordinated response: appetite and protein synthesis are suppressed, and muscle catabolism promoted. We hypothesise that, rather than simply being pathophysiological dysregulation, this cachexia is protective. Ketone bodies, synthesised during relative starvation, protect tissues such as the brain from reduced oxygen availability by mechanisms including the reduced generation of reactive oxygen species, improved mitochondrial efficiency and activation of the ATP-sensitive potassium (KATP) channel. Amino acids released from skeletal muscle also protect cells from hypoxia, and may interact synergistically with ketones to offer added protection. We thus propose that weight loss in hypoxia is an adaptive response: the amino acids and ketone bodies made available act not only as metabolic substrates, but as metabolic modulators, protecting cells from the hypoxic challenge.
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Affiliation(s)
- Andrew J Murray
- Department of Physiology, Development & Neuroscience, University of Cambridge, Cambridge, UK
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Yang Y, Duan W, Li Y, Jin Z, Yan J, Yu S, Yi D. Novel role of silent information regulator 1 in myocardial ischemia. Circulation 2014; 128:2232-40. [PMID: 24218438 DOI: 10.1161/circulationaha.113.002480] [Citation(s) in RCA: 70] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Affiliation(s)
- Yang Yang
- Department of Cardiovascular Surgery, Xijing Hospital, The Fourth Military Medical University, Xi'an, China (Y.Y., W.D., Z.J., S.Y., D.Y.); Team 10, School of Stomatology, The Fourth Military Medical University, Xi'an, China (Y.L.); and Department of Prosthodontics, School of Stomatology, The Fourth Military Medical University, Xi'an, China (J.Y.)
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36
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Outcome of prolonged ventricular fibrillation and CPR in a rat model of chronic ischemic left ventricular dysfunction. BIOMED RESEARCH INTERNATIONAL 2013; 2013:564501. [PMID: 24455704 PMCID: PMC3877585 DOI: 10.1155/2013/564501] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/24/2013] [Accepted: 11/28/2013] [Indexed: 11/18/2022]
Abstract
Patients with chronic left ventricular (LV) dysfunction are assumed to have a lower chance of successful CPR and lower likelihood of ultimate survival. However, these assumptions have rarely been documented. Therefore, we investigated the outcome of prolonged ventricular fibrillation (VF) and CPR in a rat model of chronic LV dysfunction. Sprague-Dawley rats were randomized to (1) chronic LV dysfunction: animals underwent left coronary artery ligation; and (2) sham control. Echocardiography was used to measure cardiac performance before surgery and 4 weeks after surgery. Four weeks after surgical intervention, 8 min of VF was induced and defibrillation was delivered after 8 min of CPR. LV dilation and low ejection fraction were observed 4 weeks after coronary ligation. With optimal chest compressions, coronary perfusion pressure values during CPR were well maintained and indistinguishable between groups. There were no differences in resuscitability and numbers of shock required for successful resuscitation between groups. Despite the significantly decreased cardiac index in LV dysfunction animals before induction of VF, no differences in cardiac index were observed between groups following resuscitation, which was associated with the insignificant difference in postresuscitation survival. In conclusion, the outcomes of CPR were not compromised by the preexisting chronic LV dysfunction.
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Ballantyne T, Du Q, Jovanović S, Neemo A, Holmes R, Sinha S, Jovanović A. Testosterone protects female embryonic heart H9c2 cells against severe metabolic stress by activating estrogen receptors and up-regulating IES SUR2B. Int J Biochem Cell Biol 2013; 45:283-91. [PMID: 23085378 PMCID: PMC3573229 DOI: 10.1016/j.biocel.2012.10.005] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2012] [Revised: 10/11/2012] [Accepted: 10/12/2012] [Indexed: 11/02/2022]
Abstract
A recent clinical study demonstrated that a testosterone supplementation improves functional capacity in elderly female patients suffering from heart failure. These findings prompted us to consider possible mechanisms of testosterone-induced cardioprotection in females. To address this question we have used a pure female population of rat heart embryonic H9c2 cells. Pre-treatment of cells with testosterone for 24h significantly increased survival of H9c2 cells exposed to 2,4-dinitrophenol (DNP), an inhibitor of oxidative phosphorylation. These cells expressed low level of androgen receptors and the effect of testosterone was not modified by hydroxyflutamide, an antagonist of androgen receptor. In contrast, cyclohexamide, an inhibitor of protein biosynthesis, and tamoxifene, a partial agonist of estrogen receptors, abolished cardioprotection afforded by testosterone. In addition, finasteride, an inhibitor of 5α-reductase, and anastrazole, an inhibitor of α-aromatase, also blocked testosterone-induced cytoprotection. Real time RT-PCR revealed that testosterone did not regulate the expression of nine subunits and accessory proteins of sarcolemmal ATP-sensitive K(+) (K(ATP)) channels. On the other hand, testosterone, as well as 17β-estradiol, up-regulated a putative mitochondrial K(ATP) channel subunit, mitochondrial sulfonylurea receptor 2B intraexonics splice variant (IES SUR2B), without affecting expression of IES SUR2A. Tamoxifene inhibited testosterone-induced up-regulation of IES SUR2B without affecting IES SUR2A. In conclusion, this study has shown that testosterone protect female embryonic heart H9c2 cells against severe metabolic stress by its conversion into metabolites that activate estrogen receptors and up-regulate IES SUR2B.
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Affiliation(s)
| | | | | | | | | | | | - Aleksandar Jovanović
- Medical Research Institute, Division of Cardiovascular & Diabetes Medicine, Ninewells Hospital & Medical School, University of Dundee, Dundee DD1 9SY, Scotland, UK
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Toib A, Zhang HX, Broekelmann TJ, Hyrc KL, Guo Q, Chen F, Remedi MS, Nichols CG. Cardiac specific ATP-sensitive K+ channel (KATP) overexpression results in embryonic lethality. J Mol Cell Cardiol 2012; 53:437-45. [PMID: 22796573 PMCID: PMC3423334 DOI: 10.1016/j.yjmcc.2012.07.001] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/26/2012] [Revised: 06/23/2012] [Accepted: 07/02/2012] [Indexed: 11/26/2022]
Abstract
Transgenic mice overexpressing SUR1 and gain of function Kir6.2[∆N30, K185Q] K(ATP) channel subunits, under cardiac α-myosin heavy chain (αMHC) promoter control, demonstrate arrhythmia susceptibility and premature death. Pregnant mice, crossed to carry double transgenic progeny, which harbor high levels of both overexpressed subunits, exhibit the most extreme phenotype and do not deliver any double transgenic pups. To explore the fetal lethality and embryonic phenotype that result from K(ATP) overexpression, wild type (WT) and K(ATP) overexpressing embryonic cardiomyocytes were isolated, cultured and voltage-clamped using whole cell and excised patch clamp techniques. Whole mount embryonic imaging, Hematoxylin and Eosin (H&E) and α smooth muscle actin (αSMA) immunostaining were used to assess anatomy, histology and cardiac development in K(ATP) overexpressing and WT embryos. Double transgenic embryos developed in utero heart failure and 100% embryonic lethality by 11.5 days post conception (dpc). K(ATP) currents were detectable in both WT and K(ATP)-overexpressing embryonic cardiomyocytes, starting at early stages of cardiac development (9.5 dpc). In contrast to adult cardiomyocytes, WT and K(ATP)-overexpressing embryonic cardiomyocytes exhibit basal and spontaneous K(ATP) current, implying that these channels may be open and active under physiological conditions. At 9.5 dpc, live double transgenic embryos demonstrated normal looping pattern, although all cardiac structures were collapsed, probably representing failed, non-contractile chambers. In conclusion, K(ATP) channels are present and active in embryonic myocytes, and overexpression causes in utero heart failure and results in embryonic lethality. These results suggest that the K(ATP) channel may have an important physiological role during early cardiac development.
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Affiliation(s)
- Amir Toib
- Department of Pediatrics, St. Louis, MO, 63110, USA.
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39
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Fatima N, Schooley JF, Claycomb WC, Flagg TP. Promoter DNA methylation regulates murine SUR1 (Abcc8) and SUR2 (Abcc9) expression in HL-1 cardiomyocytes. PLoS One 2012; 7:e41533. [PMID: 22844491 PMCID: PMC3402388 DOI: 10.1371/journal.pone.0041533] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2011] [Accepted: 06/27/2012] [Indexed: 01/28/2023] Open
Abstract
Two mammalian genes encode the SURx (SUR1, Abcc8 and SUR2, Abcc9) subunits that combine with Kir6.2 (Kcnj11) subunits to form the ATP-sensitive potassium (KATP) channel in cardiac myocytes. Different isoform combinations endow the channel with distinct physiological and pharmacological properties, and we have recently reported that the molecular composition of sarcolemmal KATP channels is chamber specific in the mouse heart. KATP channel composition is determined by what subunits are expressed in a cell or tissue. In the present study, we explore the role of CpG methylation in regulating SUR1 and SUR2 expression. In HL-1 cardiomyocytes, as in atrial myocytes, SUR1 expression is markedly greater than SUR2. Consistent with CpG methylation-dependent silencing of SUR2 expression, bisulfite sequencing of genomic DNA isolated from HL-1 cells demonstrates that 57.6% of the CpGs in the promoter region of the SUR2 gene are methylated, compared with 0.14% of the the CpG residues in the SUR1 sequence. Moreover, treatment with 10 µM 5-aza-2'-deoxycytidine (Aza-dC) significantly increased both the unmethylated fraction of the SUR2 CpG island and mRNA expression. However, we cannot rule out additional mechanisms of Aza-dC action, as Aza-dC also causes a decrease in SUR1 expression and lower doses of Aza-dC do not alter the unmethylated DNA fraction but do elicit a small increase in SUR2 expression. The conclusion that DNA methylation alone is not the only regulator of SUR subunit expression is also consistent with observations in native myocytes, where the CpG islands of both SUR genes are essentially unmethylated in both atrial and ventricular myocytes. Collectively, these data demonstrate the potential for CpG methylation to regulate SURx subunit expression and raises the possibility that regulated or aberrant CpG methylation might play a role in controlling channel structure and function under different physiological conditions or different species.
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Affiliation(s)
- Naheed Fatima
- Department of Anatomy, Physiology and Genetics, Uniformed Services University of the Health Sciences, F. Edward Hebert School of Medicine, Bethesda, Maryland, United States of America
| | - James F. Schooley
- Department of Anatomy, Physiology and Genetics, Uniformed Services University of the Health Sciences, F. Edward Hebert School of Medicine, Bethesda, Maryland, United States of America
| | - Willliam C. Claycomb
- Department of Biochemistry and Molecular Biology, LSU Health Sciences Center, New Orleans, Louisiana, United States of America
| | - Thomas P. Flagg
- Department of Anatomy, Physiology and Genetics, Uniformed Services University of the Health Sciences, F. Edward Hebert School of Medicine, Bethesda, Maryland, United States of America
- * E-mail:
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40
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Zhao Y, Yang Y. Frex and FrexH: Indicators of metabolic states in living cells. Bioeng Bugs 2012; 3:181-8. [PMID: 22572785 DOI: 10.4161/bbug.19769] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
Reduced nicotinamide adenine dinucleotide (NADH) and its oxidized form play central roles in energy and redox metabolisms. For many years, researchers have relied on the weak NADH endogenous fluorescence signal to determine the NADH level in living cells. We recently reported a series of genetically encoded fluorescent sensors highly specific for NADH. These sensors allow real-time, quantitative measurement of this significant molecule in different subcellular compartments. In this study, we provide a more detailed discussion of the benefits and limitations of these genetically encoded fluorescent sensors. These sensors are utilized in most laboratories without the need for sophisticated instruments because of their superior sensitivity and specificity. They are also viable alternatives to existing techniques for measuring the endogenous fluorescence of intracellular NAD(P)H.
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Affiliation(s)
- Yuzheng Zhao
- Synthetic Biology and Biotechnology Laboratory, State Key Laboratory of Bioreactor Engineering, School of Pharmacy, East China University of Science and Technology, Shanghai, China
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41
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Tsounapi P, Saito M, Dimitriadis F, Kitatani K, Kinoshita Y, Shomori K, Takenaka A, Satoh K. The role of KATP channels on ischemia-reperfusion injury in the rat testis. Life Sci 2012; 90:649-56. [DOI: 10.1016/j.lfs.2012.03.006] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2011] [Revised: 02/16/2012] [Accepted: 02/28/2012] [Indexed: 12/30/2022]
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Sukhodub A, Sudhir R, Du Q, Jovanović S, Reyes S, Jovanović A. Nicotinamide-rich diet improves physical endurance by up-regulating SUR2A in the heart. J Cell Mol Med 2011; 15:1703-12. [PMID: 20731746 PMCID: PMC4373361 DOI: 10.1111/j.1582-4934.2010.01156.x] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2010] [Accepted: 07/14/2010] [Indexed: 11/29/2022] Open
Abstract
SUR2A is an ATP-binding protein that serves as a regulatory subunit of cardioprotective ATP-sensitive K(+) (K(ATP) ) channels. Based on signalling pathway regulating SUR2A expression and SUR2A role in regulating numbers of fully assembled K(ATP) channels, we have suggested that nicotinamide-rich diet could improve physical endurance by stimulating SUR2A expression. We have found that mice on nicotinamide-rich diet significantly improved physical endurance, which was associated with significant increase in expression of SUR2A. Transgenic mice with solely overexpressed SUR2A on control diet had increased physical endurance in a similar manner as the wild-type mice on nicotinamide-rich diet. The experiments focused on action membrane potential and intracellular Ca(2+) concentration have demonstrated that increased SUR2A expression was associated with the activation of sarcolemmal K(ATP) channels and steady Ca(2+) levels in cardiomyocytes in response to β-adrenergic stimulation. In contrast, the same challenge in the wild-type was characterized by a lack of the channel activation and rise in intracellular Ca(2+) . Nicotinamide-rich diet was ineffective to increase physical endurance in mice lacking K(ATP) channels. This study has shown that nicotinamide-rich diet improves physical endurance by increasing expression of SUR2A and that this is a sole mechanism of the nicotinamide-rich diet effect. The obtained results suggest that oral nicotinamide is a regulator of SUR2A expression and has a potential as a drug that can improve physical endurance in conditions where this effect would be desirable.
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MESH Headings
- ATP-Binding Cassette Transporters/genetics
- ATP-Binding Cassette Transporters/metabolism
- Adrenergic beta-Agonists/pharmacology
- Animals
- Calcium/metabolism
- Cells, Cultured
- Diet
- Female
- Gene Expression/drug effects
- Heart Ventricles/cytology
- Heart Ventricles/drug effects
- Heart Ventricles/metabolism
- Isoproterenol/pharmacology
- Male
- Membrane Potentials/drug effects
- Mice
- Mice, Inbred C57BL
- Mice, Knockout
- Mice, Transgenic
- Motor Activity/drug effects
- Myocardium/cytology
- Myocardium/metabolism
- Myocytes, Cardiac/drug effects
- Myocytes, Cardiac/metabolism
- Myocytes, Cardiac/physiology
- Niacinamide/administration & dosage
- Niacinamide/pharmacology
- Physical Conditioning, Animal/physiology
- Potassium Channels, Inwardly Rectifying/genetics
- Potassium Channels, Inwardly Rectifying/metabolism
- Receptors, Drug/genetics
- Receptors, Drug/metabolism
- Reverse Transcriptase Polymerase Chain Reaction
- Sulfonylurea Receptors
- Up-Regulation/drug effects
- Vitamin B Complex/administration & dosage
- Vitamin B Complex/pharmacology
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Affiliation(s)
- Andriy Sukhodub
- Division of Medical Sciences, Centre for Cardiovascular and Lung Biology, Ninewells Hospital & Medical School, University of DundeeDundee, UK
| | - Rajni Sudhir
- Division of Medical Sciences, Centre for Cardiovascular and Lung Biology, Ninewells Hospital & Medical School, University of DundeeDundee, UK
| | - Qingyou Du
- Division of Medical Sciences, Centre for Cardiovascular and Lung Biology, Ninewells Hospital & Medical School, University of DundeeDundee, UK
| | - Sofija Jovanović
- Division of Medical Sciences, Centre for Cardiovascular and Lung Biology, Ninewells Hospital & Medical School, University of DundeeDundee, UK
| | | | - Aleksandar Jovanović
- Division of Medical Sciences, Centre for Cardiovascular and Lung Biology, Ninewells Hospital & Medical School, University of DundeeDundee, UK
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43
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Sudhir R, Sukhodub A, Du Q, Jovanović S, Jovanović A. Ageing-induced decline in physical endurance in mice is associated with decrease in cardiac SUR2A and increase in cardiac susceptibility to metabolic stress: therapeutic prospects for up-regulation of SUR2A. Biogerontology 2011; 12:147-55. [PMID: 20972622 DOI: 10.1007/s10522-010-9306-3] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2010] [Accepted: 10/08/2010] [Indexed: 10/18/2022]
Abstract
Ageing is characterized by decline in physical endurance which has been suggested to be partly due to diminished functional and adaptive reserve capacity of the heart. Ageing is associated with decrease in numbers of sarcolemmal ATP-sensitive K(+) (K(ATP)) channels, but whether this has anything to do with ageing-induced decline in physical endurance is yet to be determined. We have previously shown that the numbers of sarcolemmal K(ATP) channels are controlled by the level of expression of SUR2A, a K(ATP) channel regulatory subunit. Here, we have found that ageing decreases the level of SUR2A mRNA in the heart without affecting expression of pore-forming K(ATP) channel subunits, Kir6.1 and Kir6.2. This effect of ageing was associated with decrease in levels of fully-assembled sarcolemmal K(ATP) channels. At the same time, ageing was associated with decreased physical endurance. In order to determine whether increased expression of SUR2A would counteract ageing-induced decrease in physical endurance, we have taken advantage of mice which SUR2A levels are regulated by more efficient CMV promoter. These mice had increased resistance of cardiomyocytes to metabolic stress/hypoxia and increased physical endurance when compared to the wild type. In transgenic mice, ageing did not affect the level of SUR2A mRNA in the heart and the level of fully-assembled sarcolemmal K(ATP) channels. The effect of increased SUR2A to resistance of cardiomyocytes to hypoxia and physical endurance was retained in old mice. The magnitude of these effects was such that they were significantly increased even when compared to those in wild type young mice. We conclude that (1) the level of SUR2A expression in the heart is important factor in regulating physical endurance, (2) ageing-induced decrease in cardiac SUR2A is, at least in part, responsible for ageing-induced decline in physical fitness and (3) up-regulation of SUR2A could be a viable strategy to counteract ageing-induced decline in physical endurance.
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MESH Headings
- ATP-Binding Cassette Transporters/genetics
- ATP-Binding Cassette Transporters/metabolism
- Aging/physiology
- Animals
- Cell Hypoxia
- Cell Survival
- Cells, Cultured
- Female
- Male
- Mice
- Mice, Inbred BALB C
- Mice, Inbred C57BL
- Mice, Inbred CBA
- Myocardium/cytology
- Myocardium/metabolism
- Myocytes, Cardiac/cytology
- Myocytes, Cardiac/metabolism
- Physical Endurance/physiology
- Potassium Channels, Inwardly Rectifying/genetics
- Potassium Channels, Inwardly Rectifying/metabolism
- Receptors, Drug/genetics
- Receptors, Drug/metabolism
- Stress, Physiological/physiology
- Sulfonylurea Receptors
- Up-Regulation
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Affiliation(s)
- Rajni Sudhir
- Division of Medical Sciences/MACHS, Centre for Cardiovascular and Lung Biology, Ninewells Hospital & Medical School, University of Dundee, Scotland, UK
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Zingman LV, Zhu Z, Sierra A, Stepniak E, Burnett CML, Maksymov G, Anderson ME, Coetzee WA, Hodgson-Zingman DM. Exercise-induced expression of cardiac ATP-sensitive potassium channels promotes action potential shortening and energy conservation. J Mol Cell Cardiol 2011; 51:72-81. [PMID: 21439969 DOI: 10.1016/j.yjmcc.2011.03.010] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/10/2011] [Revised: 02/19/2011] [Accepted: 03/14/2011] [Indexed: 12/25/2022]
Abstract
Physical activity is one of the most important determinants of cardiac function. The ability of the heart to increase delivery of oxygen and metabolic fuels relies on an array of adaptive responses necessary to match bodily demand while avoiding exhaustion of cardiac resources. The ATP-sensitive potassium (K(ATP)) channel has the unique ability to adjust cardiac membrane excitability in accordance with ATP and ADP levels, and up-regulation of its expression that occurs in response to exercise could represent a critical element of this adaption. However, the mechanism by which K(ATP) channel expression changes result in a beneficial effect on cardiac excitability and function remains to be established. Here, we demonstrate that an exercise-induced rise in K(ATP) channel expression enhanced the rate and magnitude of action potential shortening in response to heart rate acceleration. This adaptation in membrane excitability promoted significant reduction in cardiac energy consumption under escalating workloads. Genetic disruption of normal K(ATP) channel pore function abolished the exercise-related changes in action potential duration adjustment and caused increased cardiac energy consumption. Thus, an expression-driven enhancement in the K(ATP) channel-dependent membrane response to alterations in cardiac workload represents a previously unrecognized mechanism for adaptation to physical activity and a potential target for cardioprotection.
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Affiliation(s)
- Leonid V Zingman
- Department of Internal Medicine, University of Iowa, Carver College of Medicine, Iowa City, IA 52242, USA.
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45
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Jovanović S, Du Q, Mukhopadhyay S, Swingler R, Buckley R, McEachen J, Jovanović A. A patient suffering from hypokalemic periodic paralysis is deficient in skeletal muscle ATP-sensitive K channels. Clin Transl Sci 2010; 1:71-4. [PMID: 20396605 DOI: 10.1111/j.1752-8062.2008.00007.x] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
Hypokalemic periodic paralysis (HOPP) is a rare disease associated with attacks of muscle weakness and hypokalemia. In the present study, immunoprecipitation/Western blotting has shown that a HOPP patient was deficient in sarcolemmal K(ATP) channels. Real-time RT-PCR has revealed that HOPP has decreased mRNA levels of Kir6.2, a pore-forming K(ATP) channel subunit, without affecting the expression of other K(ATP) channel-forming proteins. Based on these findings, we conclude that HOPP could be associated with impaired expression of Kir6.2 which leads to deficiency in skeletal muscle K(ATP) channels, which may explain the symptoms and clinical signs of this disease.
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Affiliation(s)
- Sofija Jovanović
- Maternal and Child Health Sciences, Ninewells Hospital & Medical School, University of Dundee, Dundee, Scotland, UK
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46
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Flagg TP, Enkvetchakul D, Koster JC, Nichols CG. Muscle KATP channels: recent insights to energy sensing and myoprotection. Physiol Rev 2010; 90:799-829. [PMID: 20664073 DOI: 10.1152/physrev.00027.2009] [Citation(s) in RCA: 202] [Impact Index Per Article: 14.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
ATP-sensitive potassium (K(ATP)) channels are present in the surface and internal membranes of cardiac, skeletal, and smooth muscle cells and provide a unique feedback between muscle cell metabolism and electrical activity. In so doing, they can play an important role in the control of contractility, particularly when cellular energetics are compromised, protecting the tissue against calcium overload and fiber damage, but the cost of this protection may be enhanced arrhythmic activity. Generated as complexes of Kir6.1 or Kir6.2 pore-forming subunits with regulatory sulfonylurea receptor subunits, SUR1 or SUR2, the differential assembly of K(ATP) channels in different tissues gives rise to tissue-specific physiological and pharmacological regulation, and hence to the tissue-specific pharmacological control of contractility. The last 10 years have provided insights into the regulation and role of muscle K(ATP) channels, in large part driven by studies of mice in which the protein determinants of channel activity have been deleted or modified. As yet, few human diseases have been correlated with altered muscle K(ATP) activity, but genetically modified animals give important insights to likely pathological roles of aberrant channel activity in different muscle types.
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Affiliation(s)
- Thomas P Flagg
- Department of Cell Biology and Physiology, Washington University School of Medicine, St. Louis, Missouri 63110, USA.
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47
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Abstract
Abstract
Sarcolemmal ATP-sensitive K+ (KATP) channels are abundant in cardiac myocytes where they couple the cellular metabolic state with membrane excitability. Structurally, these channels are composed of Kir6.2, a pore-forming subunit, SUR2A, a regulatory subunit, and at least four accessory proteins. The activation of KATP channels occurs during ischaemia to promote cardiac viability under this adverse condition. Age-dependent changes in the myocardial susceptibility to ischaemia have been reported in experimental animals as well as in humans. Recent research has demonstrated that ageing is associated with a decrease in the number of cardiac sarcolemmal KATP channels in hearts from females, but not males. This alteration is likely to be due to an age-dependent decrease in the concentration of circulating estrogens. In the heart, SUR2A is the least expressed protein of all KATP channel-forming proteins. The consequence of this phenomenon is that the level of SUR2A is the main factor controlling the number of sarcolemmal KATP channels. Estrogens specifically up-regulate SUR2A and govern the number of sarcolemmal KATP channels, and this may explain the effect of decreasing estrogen levels on the heart. An age-dependent decrease in the number of sarcolemmal KATP channels generates a cardiac phenotype more sensitive to ischaemia, which seems to be responsible for the ageing-associated decrease in myocardial tolerance to stress that occurs in elderly women.
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Affiliation(s)
- Aleksandar Jovanović
- Maternal and Child Health Sciences, Tayside Institute of Child Health, Ninewells Hospital and Medical School, University of Dundee, Dundee, UK.
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48
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Du Q, Jovanović S, Sukhodub A, Jovanović A. Infection with AV-SUR2A protects H9C2 cells against metabolic stress: a mechanism of SUR2A-mediated cytoprotection independent from the K(ATP) channel activity. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2010; 1803:405-15. [PMID: 20123112 PMCID: PMC2881534 DOI: 10.1016/j.bbamcr.2010.01.018] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/15/2009] [Revised: 12/18/2009] [Accepted: 01/22/2010] [Indexed: 11/17/2022]
Abstract
Transgenic mice overexpressing SUR2A, a subunit of ATP-sensitive K(+) (K(ATP)) channels, acquire resistance to myocardial ischaemia. However, the mechanism of SUR2A-mediated cytoprotection is yet to be fully understood. Adenoviral SUR2A construct (AV-SUR2A) increased SUR2A expression, number of K(ATP) channels and subsarcolemmal ATP in glycolysis-sensitive manner in H9C2 cells. It also increased K(+) current in response to chemical hypoxia, partially preserved subsarcolemmal ATP and increased cell survival. Kir6.2AFA, a mutant form of Kir6.2 with largely decreased K(+) conductance, abolished the effect of SUR2A on K(+) current, did not affect SUR2A-induced increase in subsarcolemmal ATP and partially inhibited SUR2A-mediated cytoprotection. Infection with 193gly-M-LDH, an inactive mutant of muscle lactate dehydrogenase, abolished the effect of SUR2A on K(+) current, subsarcolemmal ATP and cell survival; the effect of 193gly-M-LDH on cell survival was significantly more pronounced than those of Kir6.2AFA. We conclude that AV-SUR2A increases resistance to metabolic stress in H9C2 cells by increasing the number of sarcolemmal K(ATP) channels and subsarcolemmal ATP.
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Affiliation(s)
| | | | | | - Aleksandar Jovanović
- Corresponding author. Division of Medical Sciences/MACHS, Ninewells
Hospital and Medical School, University of Dundee, Dundee, DD1 9SY, Scotland,
UK. Tel.: +44 1382 496 269; fax: +44 1382 632 597.
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49
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Sukhodub A, Du Q, Jovanović S, Jovanović A. Nicotinamide-rich diet protects the heart against ischaemia-reperfusion in mice: a crucial role for cardiac SUR2A. Pharmacol Res 2010; 61:564-70. [PMID: 20083200 PMCID: PMC2859200 DOI: 10.1016/j.phrs.2010.01.008] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/22/2009] [Revised: 01/11/2010] [Accepted: 01/11/2010] [Indexed: 11/15/2022]
Abstract
It is a consensus view that a strategy to increase heart resistance to ischaemia-reperfusion is a warranted. Here, based on our previous study, we have hypothesized that a nicotinamide-rich diet could increase myocardial resistance to ischaemia-reperfusion. Therefore, the purpose of this study was to determine whether nicotinamide-rich diet would increase heart resistance to ischaemia-reperfusion and what is the underlying mechanism. Experiments have been done on mice on control and nicotinamide-rich diet (mice were a week on nicotinamide-rich diet) as well as on transgenic mice overexpressing SUR2A (SUR2A mice), a regulatory subunit of cardioprotective ATP-sensitive K(+) (K(ATP)) channels and their littermate controls (WT). The levels of mRNA in heart tissue were measured by real-time RT-PCR, whole heart and single cell resistance to ischaemia-reperfusion and severe hypoxia was measured by TTC staining and laser confocal microscopy, respectively. Nicotinamide-rich diet significantly decreased the size of myocardial infarction induced by ischaemia-reperfusion (from 42.5+/-4.6% of the area at risk zone in mice on control diet to 26.8+/-1.8% in mice on nicotinamide-rich diet, n=6-12, P=0.031). The cardioprotective effect of nicotinamide-rich diet was associated with 11.46+/-1.22 times (n=6) increased mRNA levels of SUR2A in the heart. HMR1098, a selective inhibitor of the sarcolemmal K(ATP) channels opening, abolished cardioprotection afforded by nicotinamide-rich diet. Transgenic mice with a sole increase in SUR2A expression had also increased cardiac resistance to ischaemia-reperfusion. We conclude that nicotinamide-rich diet up-regulate SUR2A and increases heart resistance to ischaemia-reperfusion.
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Affiliation(s)
- Andriy Sukhodub
- Division of Medical Sciences, Centre for Cardiovascular and Lung Biology, Ninewells Hospital & Medical School, University of Dundee, Dundee DD1 9SY, UK
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50
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M-LDH physically associated with sarcolemmal K ATP channels mediates cytoprotection in heart embryonic H9C2 cells. Int J Biochem Cell Biol 2009; 41:2295-301. [PMID: 19464385 PMCID: PMC2758067 DOI: 10.1016/j.biocel.2009.05.012] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2009] [Revised: 04/24/2009] [Accepted: 05/17/2009] [Indexed: 11/21/2022]
Abstract
Muscle form of lactate dehydrogenase (M-LDH) physically associate with KATP channel subunits, Kir6.2 and SUR2A, and is an integral part of the ATP-sensitive K+ (KATP) channel protein complex in the heart. Here, we have shown that concomitant introduction of viral constructs containing truncated and mutated forms of M-LDH (ΔM-LDH) and 193gly-M-LDH respectively, generate a phenotype of rat heart embryonic H9C2 cells that do not contain functional M-LDH as a part of the KATP channel protein complex. The K+ current was increased in wild type cells, but not in cells expressing ΔM-LDH/193gly-M-LDH, when they were exposed to chemical hypoxia induced by 2,4 dinitrophenol (DNP; 10 mM). At the same time, the outcome of chemical hypoxia was much worse in ΔM-LDH/193gly-M-LDH phenotype than in the control one, and that was associated with increased loss of intracellular ATP in cells infected with ΔM-LDH/193gly-M-LDH. On the other hand, cells expressing Kir6.2AFA, a Kir6.2 mutant that abolishes KATP channel conductance without affecting intracellular ATP levels, survived chemical hypoxia much better than cells expressing ΔM-LDH/193gly-M-LDH. Based on the obtained results, we conclude that M-LDH physically associated with Kir6.2/SUR2A regulates the activity of sarcolemmal KATP channels as well as an intracellular ATP production during metabolic stress, both of which are important for cell survival.
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