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Hilgers RHP, Das KC. Redox Regulation of K + Channel: Role of Thioredoxin. Antioxid Redox Signal 2024. [PMID: 39099341 DOI: 10.1089/ars.2023.0416] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 08/06/2024]
Abstract
Significance: Potassium channels regulate the influx and efflux of K+ ions in various cell types that generate and propagate action potential associated with excitation, contraction, and relaxation of various cell types. Although redox active cysteines are critically important for channel activity, the redox regulation of K+ channels by thioredoxin (Trx) has not been systematically reviewed. Recent Advances: Redox regulation of K+ channel is now increasingly recognized as drug targets in the pathological condition of several cardiovascular disease processes. The role of Trx in regulation of these channels and its implication in pathological conditions have not been adequately reviewed. This review specifically focuses on the redox-regulatory role of Trx on K+ channel structure and function in physiological and pathophysiological conditions. Critical Issues: Ion channels, including K+ channel, have been implicated in the functioning of cardiomyocyte excitation-contraction coupling, vascular hyperpolarization, cellular proliferation, and neuronal stimulation in physiological and pathophysiological conditions. Although oxidation-reduction of ion channels is critically important in their function, the role of Trx, redox regulatory protein in regulation of these channels, and its implication in pathological conditions need to be studied to gain further insight into channel function. Future Directions: Future studies need to map all redox regulatory pathways in channel structure and function using novel mouse models and redox proteomic and signal transduction studies, which modulate various currents and altered excitability of relevant cells implicated in a pathological condition. We are yet at infancy of studies related to redox control of various K+ channels and structured and focused studies with novel animal models. Antioxid. Redox Signal. 00, 00-00.
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Affiliation(s)
- Rob H P Hilgers
- Department of Internal Medicine, Texas Tech University Health Sciences Center, Lubbock, Texas, USA
| | - Kumuda C Das
- Department of Internal Medicine, Texas Tech University Health Sciences Center, Lubbock, Texas, USA
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2
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Sun X, Lee HC, Lu T. Sorbs2 Deficiency and Vascular BK Channelopathy in Diabetes. Circ Res 2024; 134:858-871. [PMID: 38362769 PMCID: PMC10978258 DOI: 10.1161/circresaha.123.323538] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/16/2023] [Accepted: 02/02/2024] [Indexed: 02/17/2024]
Abstract
BACKGROUND Vascular large conductance Ca2+-activated K+ (BK) channel, composed of the α-subunit (BK-α) and the β1-subunit (BK-β1), is a key determinant of coronary vasorelaxation and its function is impaired in diabetic vessels. However, our knowledge of diabetic BK channel dysregulation is incomplete. The Sorbs2 (Sorbin homology [SoHo] and Src homology 3 [SH3] domains-containing protein 2), is ubiquitously expressed in arteries, but its role in vascular pathophysiology is unknown. METHODS The role of Sorbs2 in regulating vascular BK channel activity was determined using patch-clamp recordings, molecular biological techniques, and in silico analysis. RESULTS Sorbs2 is not only a cytoskeletal protein but also an RNA-binding protein that binds to BK channel proteins and BK-α mRNA, regulating BK channel expression and function in coronary smooth muscle cells. Molecular biological studies reveal that the SH3 domain of Sorbs2 is necessary for Sorbs2 interaction with BK-α subunits, while both the SH3 and SoHo domains of Sorbs2 interact with BK-β1 subunits. Deletion of the SH3 or SoHo domains abolishes the Sorbs2 effect on the BK-α/BK-β1 channel current density. Additionally, Sorbs2 is a target gene of the Nrf2 (nuclear factor erythroid-2-related factor 2), which binds to the promoter of Sorbs2 and regulates Sorbs2 expression in coronary smooth muscle cells. In vivo studies demonstrate that Sorbs2 knockout mice at 4 months of age display a significant decrease in BK channel expression and function, accompanied by impaired BK channel Ca2+-sensitivity and BK channel-mediated vasodilation in coronary arteries, without altering their body weights and blood glucose levels. Importantly, Sorbs2 expression is significantly downregulated in the coronary arteries of db/db type 2 diabetic mice. CONCLUSIONS Sorbs2, a downstream target of Nrf2, plays an important role in regulating BK channel expression and function in vascular smooth muscle cells. Vascular Sorbs2 is downregulated in diabetes. Genetic knockout of Sorbs2 manifests coronary BK channelopathy and vasculopathy observed in diabetic mice, independent of obesity and glucotoxicity.
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Affiliation(s)
- Xiaojing Sun
- The Department of Cardiovascular Medicine, Mayo Clinic, Rochester, MN
| | - Hon-Chi Lee
- The Department of Cardiovascular Medicine, Mayo Clinic, Rochester, MN
| | - Tong Lu
- The Department of Cardiovascular Medicine, Mayo Clinic, Rochester, MN
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3
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Awad EM, Ahmed ASF, El-Daly M, Amin AH, El-Tahawy NFG, Wagdy A, Hollenberg MD, Taye A. Dihydromyricetin protects against high glucose-induced endothelial dysfunction: Role of HIF-1α/ROR2/NF-κB. Biomed Pharmacother 2022; 153:113308. [PMID: 35752009 DOI: 10.1016/j.biopha.2022.113308] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2022] [Revised: 06/13/2022] [Accepted: 06/14/2022] [Indexed: 11/02/2022] Open
Abstract
OBJECTIVES Dihydromyricetin (DHM), a natural flavonoid isolated from vine tea with anti-inflammatory activity was evaluated for its ability to prevent vascular endothelial dysfunction caused by hyperglycaemia. METHODS Vasoconstrictor (phenylephrine-PE) and vasodilator (acetylcholine-ACh) responses were monitored for female rat aorta rings maintained in a bioassay organ bath for 3 h at 37 °C in either low (LG: 10 mM) or high (HG: 40 mM, to mimic hyperglycaemia) glucose-Krebs buffer in the absence or presence of 50 µM DHM. Tissues recovered from the organ bath at 3 h were fixed and analyzed for morphological changes and their expression of eNOS, iNOS, HIF-1α, GLUT1, ROR2 tyrosine kinase, NF-κB, TNF-α, Bax, Bcl2, caspase-3, and forindices of increased oxidative stress. KEY FINDINGS HG-incubated tissues showed increased PE-stimulated contractile response and decreased ACh-mediated endothelial vasodilation. DHM prevented both of these changes. Besides, HG incubation increased the immunoreactivity to iNOS, HIF-1α, GLUT1, ROR2, NF-κB, TNF-α, Bax, and active caspase-3, and decreased the expression of eNOS and Bcl2. Hyperglycaemia-like conditions also increased the indices of oxidative/nitrosative stress. These HG-induced changes, which were accompanied by an increase in tissue adventitial thickness and inflammatory cell infiltration, were all prevented by DHM. CONCLUSION Our data demonstrate an anti-inflammatory protective action of DHM to preserve vascular function in the setting of hyperglycaemia.
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Affiliation(s)
- Eman M Awad
- Department of Pharmacology and Toxicology, Faculty of Pharmacy, Minia University, Minia, Egypt
| | - Al-Shaimaa F Ahmed
- Department of Pharmacology and Toxicology, Faculty of Pharmacy, Minia University, Minia, Egypt.
| | - Mahmoud El-Daly
- Department of Pharmacology and Toxicology, Faculty of Pharmacy, Minia University, Minia, Egypt
| | - Ali H Amin
- Deanship of Scientific Research, Umm Al-Qura University, Makkah, Saudi Arabia; Department of Zoology, Faculty of Science, Mansoura University, Mansoura, Egypt.
| | - Nashwa F G El-Tahawy
- Department of Histology and Cell Biology, Faculty of Medicine, Minia University, Minia, Egypt
| | - AlShimaa Wagdy
- Department of Pathology, Faculty of Medicine, Minia University, Minia, Egypt
| | - Morley D Hollenberg
- Department of Medicine, Cumming School of Medicine, University of Calgary, Calgary AB T2N 4N1, Canada
| | - Ashraf Taye
- Department of Pharmacology and Toxicology, Faculty of Pharmacy, South Valley University, Qena, Egypt
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4
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Lu T, Lee HC. Coronary Large Conductance Ca 2+-Activated K + Channel Dysfunction in Diabetes Mellitus. Front Physiol 2021; 12:750618. [PMID: 34744789 PMCID: PMC8567020 DOI: 10.3389/fphys.2021.750618] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2021] [Accepted: 09/14/2021] [Indexed: 11/24/2022] Open
Abstract
Diabetes mellitus (DM) is an independent risk of macrovascular and microvascular complications, while cardiovascular diseases remain a leading cause of death in both men and women with diabetes. Large conductance Ca2+-activated K+ (BK) channels are abundantly expressed in arteries and are the key ionic determinant of vascular tone and organ perfusion. It is well established that the downregulation of vascular BK channel function with reduced BK channel protein expression and altered intrinsic BK channel biophysical properties is associated with diabetic vasculopathy. Recent efforts also showed that diabetes-associated changes in signaling pathways and transcriptional factors contribute to the downregulation of BK channel expression. This manuscript will review our current understandings on the molecular, physiological, and biophysical mechanisms that underlie coronary BK channelopathy in diabetes mellitus.
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Affiliation(s)
- Tong Lu
- Department of Cardiovascular Medicine, Mayo Clinic, Rochester, MN, United States
| | - Hon-Chi Lee
- Department of Cardiovascular Medicine, Mayo Clinic, Rochester, MN, United States
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5
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Torabi N, Noursadeghi E, Shayanfar F, Nazari M, Fahanik-Babaei J, Saghiri R, Khodagholi F, Eliassi A. Intranasal insulin improves the structure-function of the brain mitochondrial ATP-sensitive Ca 2+ activated potassium channel and respiratory chain activities under diabetic conditions. Biochim Biophys Acta Mol Basis Dis 2021; 1867:166075. [PMID: 33444710 DOI: 10.1016/j.bbadis.2021.166075] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2020] [Revised: 12/06/2020] [Accepted: 12/30/2020] [Indexed: 11/21/2022]
Abstract
Although it is well established that diabetes impairs mitochondrial respiratory chain activity, little is known of the effects of intranasal insulin (INI) on the mitochondrial respiratory chain and structure-function of mitoBKCa channel in diabetes. We have investigated this mechanism in an STZ-induced early type 2 diabetic model. Single ATP-sensitive mitoBKCa channel activity was considered in diabetic and INI-treated rats using a channel incorporated into the bilayer lipid membrane. Because mitoBKCa channels have been involved in mitochondrial respiratory chain activity, a study was undertaken to investigate whether the NADH, complexes I and IV, mitochondrial ROS production, and ΔΨm are altered in an early diabetic model. In this work, we provide evidence for a significant decrease in channel open probability and conductance in diabetic rats. Evidence has been shown that BKCa channel β2 subunits induce a left shift in the BKCa channel voltage dependent curve in low Ca2+ conditions,; our results indicated a significant decrease in mitoBKCa β2 subunits using Western blot analysis. Importantly, INI treatment improved mitoBKCa channel behaviors and β2 subunits expression up to ~70%. We found that early diabetes decreased activities of complex I and IV and increased NADH, ROS production, and ΔΨm. Surprisingly, INI modified the mitochondrial respiratory chain, ROS production, and ΔΨm up to ~70%. Our results thus demonstrate an INI improvement in respiratory chain activity and ROS production in brain mitochondrial preparations coming from the STZ early diabetic rat model, an effect potentially linked to INI improvement in mitoBKCa channel activity and channel β2 subunit expression.
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Affiliation(s)
- Nihad Torabi
- Neurophysiology Research Center, Shahid Beheshti University of Medical Sciences, Tehran, Iran; Department of Physiology, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - Elham Noursadeghi
- Neurophysiology Research Center, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - Farzad Shayanfar
- Department of Physiology, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - Maryam Nazari
- Department of Physiology, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - Javad Fahanik-Babaei
- Electrophysiology Research Center, Neuroscience Institute, Tehran University of Medical Sciences, Tehran, Iran
| | - Reza Saghiri
- Department of Biochemistry, Pasteur Institute of Iran, Tehran, Iran
| | - Fariba Khodagholi
- Neuroscience Research Center, Shahid Beheshti University of Medical Sciences, Evin, Tehran, Iran
| | - Afsaneh Eliassi
- Neurophysiology Research Center, Shahid Beheshti University of Medical Sciences, Tehran, Iran; Department of Physiology, Shahid Beheshti University of Medical Sciences, Tehran, Iran.
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6
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Sahranavard T, Carbone F, Montecucco F, Xu S, Al-Rasadi K, Jamialahmadi T, Sahebkar A. The role of potassium in atherosclerosis. Eur J Clin Invest 2021; 51:e13454. [PMID: 33216974 DOI: 10.1111/eci.13454] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/01/2020] [Revised: 11/04/2020] [Accepted: 11/15/2020] [Indexed: 12/15/2022]
Abstract
BACKGROUND Atherosclerosis (AS) is a chronic progressive inflammatory condition with a leading prevalence worldwide. Endothelial dysfunction leads to low-density lipoprotein trafficking into subendothelial space and the subsequent form of oxidized LDL (ox-LDL) within intimal layer, perpetuating the vicious cycle of endothelial dysfunction. K+ exerts beneficial effects in vascular wall by reducing LDL oxidization, vascular smooth muscle cells (VSMCs) proliferation, and free radical generation. K+ also modulates vascular tone through a regulatory effect on cell membrane potential. MATERIALS AND METHODS The most relevant papers on the association between 'potassium channels' and 'atherosclerosis' were selected among those deposited on PubMed from 1990 to 2020. RESULTS Here, we provide a short narrative review that elaborates on the role of K+ in atherosclerosis. This review also update the current knowledge about potential pharmacological agents targeting K+ channels with a special focus on pleiotropic activities of agents such as statins, sulfonylureas and dihydropyridines. CONCLUSION In this review, the mechanism of different K+ channels on vascular endothelium will be summarized, mainly focusing on their pathophysiological role in atherosclerosis and potential therapeutic application.
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Affiliation(s)
- Toktam Sahranavard
- Student Research Committee, Faculty of Medicine, Mashhad University of Medical Sciences, Mashhad, Iran
| | - Federico Carbone
- First Clinic of Internal Medicine, Department of Internal Medicine, University of Genoa School of Medicine, Genoa, Italy.,IRCCS Ospedale Policlinico San Martino Genoa-Italian Cardiovascular Network, Genoa, Italy
| | - Fabrizio Montecucco
- IRCCS Ospedale Policlinico San Martino Genoa-Italian Cardiovascular Network, Genoa, Italy.,First Clinic of Internal Medicine, Department of Internal Medicine, Centre of Excellence for Biomedical Research (CEBR), University of Genoa, Genoa, Italy
| | - Suowen Xu
- Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, China
| | | | - Tannaz Jamialahmadi
- Department of Food Science and Technology, Quchan Branch, Islamic Azad University, Quchan, Iran.,Department of Nutrition, Faculty of Medicine, Mashhad University of Medical Sciences, Mashhad, Iran
| | - Amirhossein Sahebkar
- Neurogenic Inflammation Research Center, Mashhad University of Medical Sciences, Mashhad, Iran.,Biotechnology Research Center, Pharmaceutical Technology Institute, Mashhad University of Medical Sciences, Mashhad, Iran.,Polish Mother's Memorial Hospital Research Institute (PMMHRI), Lodz, Poland
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7
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Xing H, Zhang Z, Shi G, He Y, Song Y, Liu Y, Harrington EO, Sellke FW, Feng J. Chronic Inhibition of mROS Protects Against Coronary Endothelial Dysfunction in Mice With Diabetes. Front Cell Dev Biol 2021; 9:643810. [PMID: 33681229 PMCID: PMC7930489 DOI: 10.3389/fcell.2021.643810] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2020] [Accepted: 01/29/2021] [Indexed: 11/13/2022] Open
Abstract
Diabetes is associated with coronary endothelial dysfunction. Persistent oxidative stress during diabetes contributes to coronary endothelial dysfunction. The mitochondria are main sources of reactive oxygen species (ROS) in diabetes, and mitochondria-targeted antioxidant mito-Tempo can prevent mitochondrial reactive oxygen species (mROS) generation in a variety of disorders. Inhibition/inactivation of small-conductance Ca2+-activated K+ (SK) channels contribute to diabetic downregulation of coronary endothelial function/relaxation. However, few investigated the role of mROS on endothelial dysfunction/vasodilation and endothelial SK channel downregulation in diabetes. The aim of present study was to investigate the chronic administration of mito-Tempo, on coronary vasodilation, and endothelial SK channel activity of mice with or without diabetes. Mito-Tempo (1 mg/kg/day) was applied to the mice with or without diabetes (n = 10/group) for 4 weeks. In vitro relaxation response of pre-contracted arteries was examined in the presence or absence of the vasodilatory agents. SK channel currents of the isolated mouse heart endothelial cells were measured using whole-cell patch clamp methods. At baseline, coronary endothelium-dependent relaxation responses to ADP and the selective SK channel activator NS309 and endothelial SK channel currents were decreased in diabetic mice compared with that in non-diabetic (ND) mice (p < 0.05). After a 4-week treatment with mito-Tempo, coronary endothelium-dependent relaxation response to ADP or NS309 and endothelial SK channel currents in the diabetic mice was significantly improved when compared with that in untreated diabetic mice (p < 0.05). Interestingly, coronary relaxation responses to ADP and NS309 and endothelial SK channel currents were not significantly changed in ND mice after mito-Tempo treatment, as compared to that of untreated control group. Chronic inhibition of endothelial mROS appears to improve coronary endothelial function/dilation and SK channel activity in diabetes, and mROS inhibitors may be a novel strategy to treat vascular complications in diabetes.
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Affiliation(s)
- Hang Xing
- Cardiothoracic Surgery Research Laboratory, Cardiovascular Research Center, Department of Surgery, Rhode Island Hospital, Alpert Medical School of Brown University, Providence, RI, United States
| | - Zhiqi Zhang
- Cardiothoracic Surgery Research Laboratory, Cardiovascular Research Center, Department of Surgery, Rhode Island Hospital, Alpert Medical School of Brown University, Providence, RI, United States
| | - Guangbin Shi
- Cardiothoracic Surgery Research Laboratory, Cardiovascular Research Center, Department of Surgery, Rhode Island Hospital, Alpert Medical School of Brown University, Providence, RI, United States
| | - Yixin He
- Cardiothoracic Surgery Research Laboratory, Cardiovascular Research Center, Department of Surgery, Rhode Island Hospital, Alpert Medical School of Brown University, Providence, RI, United States
| | - Yi Song
- Cardiothoracic Surgery Research Laboratory, Cardiovascular Research Center, Department of Surgery, Rhode Island Hospital, Alpert Medical School of Brown University, Providence, RI, United States
| | - Yuhong Liu
- Cardiothoracic Surgery Research Laboratory, Cardiovascular Research Center, Department of Surgery, Rhode Island Hospital, Alpert Medical School of Brown University, Providence, RI, United States
| | - Elizabeth O Harrington
- Vascular Research Laboratory, Providence VA Medical Center, Department of Medicine, Alpert Medical School of Brown University, Providence, RI, United States
| | - Frank W Sellke
- Cardiothoracic Surgery Research Laboratory, Cardiovascular Research Center, Department of Surgery, Rhode Island Hospital, Alpert Medical School of Brown University, Providence, RI, United States
| | - Jun Feng
- Cardiothoracic Surgery Research Laboratory, Cardiovascular Research Center, Department of Surgery, Rhode Island Hospital, Alpert Medical School of Brown University, Providence, RI, United States
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8
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Nieves-Cintrón M, Flores-Tamez VA, Le T, Baudel MMA, Navedo MF. Cellular and molecular effects of hyperglycemia on ion channels in vascular smooth muscle. Cell Mol Life Sci 2021; 78:31-61. [PMID: 32594191 PMCID: PMC7765743 DOI: 10.1007/s00018-020-03582-z] [Citation(s) in RCA: 26] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2019] [Revised: 06/10/2020] [Accepted: 06/22/2020] [Indexed: 12/13/2022]
Abstract
Diabetes affects millions of people worldwide. This devastating disease dramatically increases the risk of developing cardiovascular disorders. A hallmark metabolic abnormality in diabetes is hyperglycemia, which contributes to the pathogenesis of cardiovascular complications. These cardiovascular complications are, at least in part, related to hyperglycemia-induced molecular and cellular changes in the cells making up blood vessels. Whereas the mechanisms mediating endothelial dysfunction during hyperglycemia have been extensively examined, much less is known about how hyperglycemia impacts vascular smooth muscle function. Vascular smooth muscle function is exquisitely regulated by many ion channels, including several members of the potassium (K+) channel superfamily and voltage-gated L-type Ca2+ channels. Modulation of vascular smooth muscle ion channels function by hyperglycemia is emerging as a key contributor to vascular dysfunction in diabetes. In this review, we summarize the current understanding of how diabetic hyperglycemia modulates the activity of these ion channels in vascular smooth muscle. We examine underlying mechanisms, general properties, and physiological relevance in the context of myogenic tone and vascular reactivity.
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Affiliation(s)
- Madeline Nieves-Cintrón
- Department of Pharmacology, University of California Davis, One Shields Avenue, Davis, CA, 95616, USA
| | - Víctor A Flores-Tamez
- Department of Pharmacology, University of California Davis, One Shields Avenue, Davis, CA, 95616, USA
| | - Thanhmai Le
- Department of Pharmacology, University of California Davis, One Shields Avenue, Davis, CA, 95616, USA
| | | | - Manuel F Navedo
- Department of Pharmacology, University of California Davis, One Shields Avenue, Davis, CA, 95616, USA.
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9
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Liu Y, Kabakov AY, Xie A, Shi G, Singh AK, Sodha NR, Ehsan A, Usheva A, Agbortoko V, Koren G, Dudley SC, Sellke FW, Feng J. Metabolic regulation of endothelial SK channels and human coronary microvascular function. Int J Cardiol 2020; 312:1-9. [PMID: 32199682 PMCID: PMC7388214 DOI: 10.1016/j.ijcard.2020.03.028] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/29/2019] [Revised: 02/18/2020] [Accepted: 03/10/2020] [Indexed: 12/28/2022]
Abstract
BACKGROUND Diabetic (DM) inactivation of small conductance calcium-activated potassium (SK) channels contributes to coronary endothelial dysfunction. However, the mechanisms responsible for this down-regulation of endothelial SK channels are poorly understood. Thus, we hypothesized that the altered metabolic signaling in diabetes regulates endothelial SK channels and human coronary microvascular function. METHODS Human atrial tissue, coronary arterioles and coronary artery endothelial cells (HCAECs) obtained from DM and non-diabetic (ND) patients (n = 12/group) undergoing cardiac surgery were used to analyze metabolic alterations, endothelial SK channel function, coronary microvascular reactivity and SK gene/protein expression/localization. RESULTS The relaxation response of DM coronary arterioles to the selective SK channel activator SKA-31 and calcium ionophore A23187 was significantly decreased compared to that of ND arterioles (p < 0.05). Diabetes increases the level of NADH and the NADH/NAD+ ratio in human myocardium and HCAECs (p < 0.05). Increase in intracellular NADH (100 μM) in the HCAECs caused a significant decrease in endothelial SK channel currents (p < 0.05), whereas, intracellular application of NAD+ (500 μM) increased the endothelial SK channel currents (p < 0.05). Mitochondrial reactive oxygen species (mROS) of HCAECs and NADPH oxidase (NOX) and PKC protein expression in the human myocardium and coronary microvasculature were increased respectively (p < 0.05). CONCLUSIONS Diabetes is associated with metabolic changes in the human myocardium, coronary microvasculature and HCAECs. Endothelial SK channel function is regulated by the metabolite pyridine nucleotides, NADH and NAD+, suggesting that metabolic regulation of endothelial SK channels may contribute to coronary endothelial dysfunction in the DM patients with diabetes.
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Affiliation(s)
- Yuhong Liu
- Division of Cardiothoracic Surgery, Rhode Island Hospital, Alpert Medical School of Brown University, Providence, RI, United States of America
| | - Anatoli Y Kabakov
- Cardiovascular Research Center, Rhode Island Hospital, Alpert Medical School of Brown University, Providence, RI, United States of America
| | - An Xie
- Department of Medicine, Lillehei Heart Institute, University of Minnesota, Minneapolis, MN, United States of America
| | - Guangbin Shi
- Division of Cardiothoracic Surgery, Rhode Island Hospital, Alpert Medical School of Brown University, Providence, RI, United States of America
| | - Arun K Singh
- Division of Cardiothoracic Surgery, Rhode Island Hospital, Alpert Medical School of Brown University, Providence, RI, United States of America
| | - Neel R Sodha
- Division of Cardiothoracic Surgery, Rhode Island Hospital, Alpert Medical School of Brown University, Providence, RI, United States of America
| | - Afshin Ehsan
- Division of Cardiothoracic Surgery, Rhode Island Hospital, Alpert Medical School of Brown University, Providence, RI, United States of America
| | - Anny Usheva
- Division of Cardiothoracic Surgery, Rhode Island Hospital, Alpert Medical School of Brown University, Providence, RI, United States of America
| | - Vahid Agbortoko
- Division of Cardiothoracic Surgery, Rhode Island Hospital, Alpert Medical School of Brown University, Providence, RI, United States of America
| | - Gideon Koren
- Cardiovascular Research Center, Rhode Island Hospital, Alpert Medical School of Brown University, Providence, RI, United States of America
| | - Samuel C Dudley
- Department of Medicine, Lillehei Heart Institute, University of Minnesota, Minneapolis, MN, United States of America
| | - Frank W Sellke
- Division of Cardiothoracic Surgery, Rhode Island Hospital, Alpert Medical School of Brown University, Providence, RI, United States of America
| | - Jun Feng
- Division of Cardiothoracic Surgery, Rhode Island Hospital, Alpert Medical School of Brown University, Providence, RI, United States of America.
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10
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Coskun C, Buyuknacar HS, Cicek F, Gunay I. BK channel openers NS1619 and NS11021 reverse hydrogen peroxide-induced membrane potential changes in skeletal muscle. J Recept Signal Transduct Res 2020; 40:449-455. [PMID: 32326798 DOI: 10.1080/10799893.2020.1756324] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
Large conductance calcium-activated potassium (BK) channels play a crucial role in the repolarization and after-hyperpolarization phases of the cell membrane. The channel openers are also used in treatment of some diseases, including hypo/hyperkalemic periodic paralysis. However, little is known about the effects of BK channels and the channel activators on membrane potentials in skeletal muscle. In addition, the effects of reactive oxygen species (ROS) on BK channels in skeletal muscle are also unknown. Therefore, the aim of this study was to determine the effects of BK channel openers and ROS on membrane potentials in skeletal muscle fibers. For this purpose, resting membrane potentials and action potentials (AP) of frog gastrocnemius muscles were recorded in the presence of commonly used BK channel openers NS1619 and NS11021, H2O2 (a type of ROS), and both using intracellular microelectrode technique. The channel activators significantly and dose-dependently decreased amplitude and increased rise time of AP but did not impact repolarization. The presence of H2O2 plus NS1619 or NS11021 resulted in significant change because the channel openers completely reversed the deleterious effects of hydrogen peroxide on the repolarization phase of AP in skeletal muscle fibers. In the present study, the contributions of BK channel activation and the modulatory role of H2O2 on membrane potentials was demonstrated in skeletal muscle fibers, for the first time. Moreover, it should be noted that BK channel openers should be used in the treatment of reactive oxygen species-induced skeletal muscle diseases.
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Affiliation(s)
- Cagil Coskun
- Department of Biophysics, Faculty of Medicine, Cukurova University, Adana, Turkey
| | | | - Figen Cicek
- Department of Biophysics, Faculty of Medicine, Cukurova University, Adana, Turkey
| | - Ismail Gunay
- Department of Biophysics, Faculty of Medicine, Cukurova University, Adana, Turkey
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11
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Abstract
The microcirculation maintains tissue homeostasis through local regulation of blood flow and oxygen delivery. Perturbations in microvascular function are characteristic of several diseases and may be early indicators of pathological changes in the cardiovascular system and in parenchymal tissue function. These changes are often mediated by various reactive oxygen species and linked to disruptions in pathways such as vasodilation or angiogenesis. This overview compiles recent advances relating to redox regulation of the microcirculation by adopting both cellular and functional perspectives. Findings from a variety of vascular beds and models are integrated to describe common effects of different reactive species on microvascular function. Gaps in understanding and areas for further research are outlined. © 2020 American Physiological Society. Compr Physiol 10:229-260, 2020.
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Affiliation(s)
- Andrew O Kadlec
- Department of Physiology, Medical College of Wisconsin, Milwaukee, Wisconsin, USA.,Medical Scientist Training Program, Medical College of Wisconsin, Milwaukee, Wisconsin, USA.,Cardiovascular Center, Medical College of Wisconsin, Milwaukee, Wisconsin, USA
| | - David D Gutterman
- Department of Physiology, Medical College of Wisconsin, Milwaukee, Wisconsin, USA.,Department of Medicine-Division of Cardiology, Medical College of Wisconsin, Milwaukee, Wisconsin, USA.,Cardiovascular Center, Medical College of Wisconsin, Milwaukee, Wisconsin, USA
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12
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Zhu Y, Ye P, Chen SL, Zhang DM. Functional regulation of large conductance Ca 2+-activated K + channels in vascular diseases. Metabolism 2018; 83:75-80. [PMID: 29373813 DOI: 10.1016/j.metabol.2018.01.008] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/23/2017] [Revised: 01/03/2018] [Accepted: 01/18/2018] [Indexed: 12/17/2022]
Abstract
The large conductance Ca2+-activated potassium channels, the BK channels, is widely expressed in various tissues and activated in a Ca2+- and voltage-dependent manner. The activation of BK channels hyperpolarizes vascular smooth muscle cell membrane potential, resulting in vasodilation. Under pathophysiological conditions, such as diabetes mellitus and hypertension, impaired BK channel function exacerbates vascular vasodilation and leads to organ ischemia. The vascular BK channel is composed of 4 pore-forming subunits, BK-α together with 4 auxiliary subunits: β1 subunits (BK-β1) or γ1 subunits (BK-γ1). Recent studies have shown that down-regulation of the BK β1 subunit in diabetes mellitus induced vascular dysfunction; however, the molecular mechanism of these vascular diseases is not well understood. In this review, we summarize the potential mechanisms regarding BK channelopathy and the potential therapeutic targets of BK channels for vascular diseases.
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Affiliation(s)
- Yanrong Zhu
- Department of Cardiology, Nanjing First Hospital, Nanjing Medical University, Nanjing, Jiangsu 210006, China
| | - Peng Ye
- Department of Cardiology, Nanjing First Hospital, Nanjing Medical University, Nanjing, Jiangsu 210006, China
| | - Shao-Liang Chen
- Department of Cardiology, Nanjing First Hospital, Nanjing Medical University, Nanjing, Jiangsu 210006, China
| | - Dai-Min Zhang
- Department of Cardiology, Nanjing First Hospital, Nanjing Medical University, Nanjing, Jiangsu 210006, China.
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13
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Dopico AM, Bukiya AN, Jaggar JH. Calcium- and voltage-gated BK channels in vascular smooth muscle. Pflugers Arch 2018; 470:1271-1289. [PMID: 29748711 DOI: 10.1007/s00424-018-2151-y] [Citation(s) in RCA: 63] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2018] [Accepted: 04/27/2018] [Indexed: 02/04/2023]
Abstract
Ion channels in vascular smooth muscle regulate myogenic tone and vessel contractility. In particular, activation of calcium- and voltage-gated potassium channels of large conductance (BK channels) results in outward current that shifts the membrane potential toward more negative values, triggering a negative feed-back loop on depolarization-induced calcium influx and SM contraction. In this short review, we first present the molecular basis of vascular smooth muscle BK channels and the role of subunit composition and trafficking in the regulation of myogenic tone and vascular contractility. BK channel modulation by endogenous signaling molecules, and paracrine and endocrine mediators follows. Lastly, we describe the functional changes in smooth muscle BK channels that contribute to, or are triggered by, common physiological conditions and pathologies, including obesity, diabetes, and systemic hypertension.
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Affiliation(s)
- Alex M Dopico
- Department of Pharmacology, College of Medicine, The University of Tennessee Health Science Center, 71 South Manassas St., Memphis, TN, 38163, USA.
| | - Anna N Bukiya
- Department of Pharmacology, College of Medicine, The University of Tennessee Health Science Center, 71 South Manassas St., Memphis, TN, 38163, USA
| | - Jonathan H Jaggar
- Department of Physiology, College of Medicine, The University of Tennessee Health Science Center, Memphis, TN, USA
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Li Y, Wang XL, Sun X, Chai Q, Li J, Thompson B, Shen WK, Lu T, Lee HC. Regulation of vascular large-conductance calcium-activated potassium channels by Nrf2 signalling. Diab Vasc Dis Res 2017; 14:353-362. [PMID: 28429615 DOI: 10.1177/1479164117703903] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
BK channels are major ionic determinants of vasodilation. BK channel function is impaired in diabetic vessels due to accelerated proteolysis of its beta-1 (BK-β1) subunits in response to increased oxidative stress. The nuclear factor E2-related factor-2 (Nrf2) signalling pathway has emerged as a master regulator of cellular redox status, and we hypothesized that it plays a central role in regulating BK channel function in diabetic vessels. We found that Nrf2 expression was markedly reduced in db/db diabetic mouse aortas, and this was associated with significant downregulation of BK-β1. In addition, the muscle ring finger protein 1 (MuRF1), a known E-3 ligase targeting BK-β1 ubiquitination and proteasomal degradation, was significantly augmented. These findings were reproduced by knockdown of Nrf2 by siRNA in cultured human coronary artery smooth muscle cells. In contrast, adenoviral transfer of Nrf2 gene in these cells downregulated MuRF1 and upregulated BK-β1 expression. Activation of Nrf2 by dimethyl fumarate preserved BK-β1 expression and protected BK channel and vascular function in db/db coronary arteries. These results indicate that expression of BK-β1 is closely regulated by Nrf2 and vascular BK channel function can be restored by Nrf2 activation. Nrf2 should be considered a novel therapeutic target in the treatment of diabetic vasculopathy.
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Affiliation(s)
- Yong Li
- 1 Department of Cardiology, Affiliated Wujin Hospital of Jiangsu University, Changzhou, China
- 2 Department of Cardiovascular Medicine, Mayo Clinic, Rochester, MN, USA
| | - Xiao-Li Wang
- 2 Department of Cardiovascular Medicine, Mayo Clinic, Rochester, MN, USA
| | - Xiaojing Sun
- 2 Department of Cardiovascular Medicine, Mayo Clinic, Rochester, MN, USA
| | - Qiang Chai
- 2 Department of Cardiovascular Medicine, Mayo Clinic, Rochester, MN, USA
- 3 Department of Physiology, Institute of Basic Medicine, Shandong Academy of Medical Sciences, Jinan, P.R. China
| | - Jingchao Li
- 2 Department of Cardiovascular Medicine, Mayo Clinic, Rochester, MN, USA
- 4 Department of Emergency Medicine, Henan Provincial People's Hospital, Affiliated Hospital of Zhengzhou University, Zhengzhou, P.R. China
| | - Benjamin Thompson
- 2 Department of Cardiovascular Medicine, Mayo Clinic, Rochester, MN, USA
| | - Win-Kuang Shen
- 5 Department of Cardiovascular Medicine, Mayo Clinic, Scottsdale, AZ, USA
| | - Tong Lu
- 2 Department of Cardiovascular Medicine, Mayo Clinic, Rochester, MN, USA
| | - Hon-Chi Lee
- 2 Department of Cardiovascular Medicine, Mayo Clinic, Rochester, MN, USA
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15
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Feng X, Zhou X, Zhang W, Li X, He A, Liu B, Shi R, Wu L, Wu J, Zhu D, Li N, Sun M, Xu Z. Maternal high-sucrose diets altered vascular large-conductance Ca2+-activated K+ channels via reactive oxygen species in offspring rats†. Biol Reprod 2017; 96:1085-1095. [DOI: 10.1093/biolre/iox031] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2016] [Accepted: 04/13/2017] [Indexed: 12/22/2022] Open
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16
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Nishijima Y, Cao S, Chabowski DS, Korishettar A, Ge A, Zheng X, Sparapani R, Gutterman DD, Zhang DX. Contribution of K V1.5 Channel to Hydrogen Peroxide-Induced Human Arteriolar Dilation and Its Modulation by Coronary Artery Disease. Circ Res 2016; 120:658-669. [PMID: 27872049 DOI: 10.1161/circresaha.116.309491] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/06/2016] [Revised: 11/11/2016] [Accepted: 11/21/2016] [Indexed: 02/06/2023]
Abstract
RATIONALE Hydrogen peroxide (H2O2) regulates vascular tone in the human microcirculation under physiological and pathophysiological conditions. It dilates arterioles by activating large-conductance Ca2+-activated K+ channels in subjects with coronary artery disease (CAD), but its mechanisms of action in subjects without CAD (non-CAD) when compared with those with CAD remain unknown. OBJECTIVE We hypothesize that H2O2-elicited dilation involves different K+ channels in non-CAD versus CAD, resulting in an altered capacity for vasodilation during disease. METHODS AND RESULTS H2O2 induced endothelium-independent vasodilation in non-CAD adipose arterioles, which was reduced by paxilline, a large-conductance Ca2+-activated K+ channel blocker, and by 4-aminopyridine, a voltage-gated K+ (KV) channel blocker. Assays of mRNA transcripts, protein expression, and subcellular localization revealed that KV1.5 is the major KV1 channel expressed in vascular smooth muscle cells and is abundantly localized on the plasma membrane. The selective KV1.5 blocker diphenylphosphine oxide-1 and the KV1.3/1.5 blocker 5-(4-phenylbutoxy)psoralen reduced H2O2-elicited dilation to a similar extent as 4-aminopyridine, but the selective KV1.3 blocker phenoxyalkoxypsoralen-1 was without effect. In arterioles from CAD subjects, H2O2-induced dilation was significantly reduced, and this dilation was inhibited by paxilline but not by 4-aminopyridine, diphenylphosphine oxide-1, or 5-(4-phenylbutoxy)psoralen. KV1.5 cell membrane localization and diphenylphosphine oxide-1-sensitive K+ currents were markedly reduced in isolated vascular smooth muscle cells from CAD arterioles, although mRNA or total cellular protein expression was largely unchanged. CONCLUSIONS In human arterioles, H2O2-induced dilation is impaired in CAD, which is associated with a transition from a combined large-conductance Ca2+-activated K+- and KV (KV1.5)-mediated vasodilation toward a large-conductance Ca2+-activated K+-predominant mechanism of dilation. Loss of KV1.5 vasomotor function may play an important role in microvascular dysfunction in CAD or other vascular diseases.
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Affiliation(s)
- Yoshinori Nishijima
- From the Department of Medicine (Y.N., S.C., D.S.C., A.K., A.G., X.Z., D.D.G., D.X.Z.), Cardiovascular Center (Y.N., S.C., D.S.C., A.K., A.G., X.Z., D.D.G., D.X.Z.), Department of Pharmacology and Toxicology (D.S.C., A.K.), Division of Biostatistics (R.S.), Medical College of Wisconsin, and Zablocki Veterans Affairs Medical Center (D.D.G.), Milwaukee, WI
| | - Sheng Cao
- From the Department of Medicine (Y.N., S.C., D.S.C., A.K., A.G., X.Z., D.D.G., D.X.Z.), Cardiovascular Center (Y.N., S.C., D.S.C., A.K., A.G., X.Z., D.D.G., D.X.Z.), Department of Pharmacology and Toxicology (D.S.C., A.K.), Division of Biostatistics (R.S.), Medical College of Wisconsin, and Zablocki Veterans Affairs Medical Center (D.D.G.), Milwaukee, WI
| | - Dawid S Chabowski
- From the Department of Medicine (Y.N., S.C., D.S.C., A.K., A.G., X.Z., D.D.G., D.X.Z.), Cardiovascular Center (Y.N., S.C., D.S.C., A.K., A.G., X.Z., D.D.G., D.X.Z.), Department of Pharmacology and Toxicology (D.S.C., A.K.), Division of Biostatistics (R.S.), Medical College of Wisconsin, and Zablocki Veterans Affairs Medical Center (D.D.G.), Milwaukee, WI
| | - Ankush Korishettar
- From the Department of Medicine (Y.N., S.C., D.S.C., A.K., A.G., X.Z., D.D.G., D.X.Z.), Cardiovascular Center (Y.N., S.C., D.S.C., A.K., A.G., X.Z., D.D.G., D.X.Z.), Department of Pharmacology and Toxicology (D.S.C., A.K.), Division of Biostatistics (R.S.), Medical College of Wisconsin, and Zablocki Veterans Affairs Medical Center (D.D.G.), Milwaukee, WI
| | - Alyce Ge
- From the Department of Medicine (Y.N., S.C., D.S.C., A.K., A.G., X.Z., D.D.G., D.X.Z.), Cardiovascular Center (Y.N., S.C., D.S.C., A.K., A.G., X.Z., D.D.G., D.X.Z.), Department of Pharmacology and Toxicology (D.S.C., A.K.), Division of Biostatistics (R.S.), Medical College of Wisconsin, and Zablocki Veterans Affairs Medical Center (D.D.G.), Milwaukee, WI
| | - Xiaodong Zheng
- From the Department of Medicine (Y.N., S.C., D.S.C., A.K., A.G., X.Z., D.D.G., D.X.Z.), Cardiovascular Center (Y.N., S.C., D.S.C., A.K., A.G., X.Z., D.D.G., D.X.Z.), Department of Pharmacology and Toxicology (D.S.C., A.K.), Division of Biostatistics (R.S.), Medical College of Wisconsin, and Zablocki Veterans Affairs Medical Center (D.D.G.), Milwaukee, WI
| | - Rodney Sparapani
- From the Department of Medicine (Y.N., S.C., D.S.C., A.K., A.G., X.Z., D.D.G., D.X.Z.), Cardiovascular Center (Y.N., S.C., D.S.C., A.K., A.G., X.Z., D.D.G., D.X.Z.), Department of Pharmacology and Toxicology (D.S.C., A.K.), Division of Biostatistics (R.S.), Medical College of Wisconsin, and Zablocki Veterans Affairs Medical Center (D.D.G.), Milwaukee, WI
| | - David D Gutterman
- From the Department of Medicine (Y.N., S.C., D.S.C., A.K., A.G., X.Z., D.D.G., D.X.Z.), Cardiovascular Center (Y.N., S.C., D.S.C., A.K., A.G., X.Z., D.D.G., D.X.Z.), Department of Pharmacology and Toxicology (D.S.C., A.K.), Division of Biostatistics (R.S.), Medical College of Wisconsin, and Zablocki Veterans Affairs Medical Center (D.D.G.), Milwaukee, WI
| | - David X Zhang
- From the Department of Medicine (Y.N., S.C., D.S.C., A.K., A.G., X.Z., D.D.G., D.X.Z.), Cardiovascular Center (Y.N., S.C., D.S.C., A.K., A.G., X.Z., D.D.G., D.X.Z.), Department of Pharmacology and Toxicology (D.S.C., A.K.), Division of Biostatistics (R.S.), Medical College of Wisconsin, and Zablocki Veterans Affairs Medical Center (D.D.G.), Milwaukee, WI.
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Ellinsworth DC, Sandow SL, Shukla N, Liu Y, Jeremy JY, Gutterman DD. Endothelium-Derived Hyperpolarization and Coronary Vasodilation: Diverse and Integrated Roles of Epoxyeicosatrienoic Acids, Hydrogen Peroxide, and Gap Junctions. Microcirculation 2016; 23:15-32. [PMID: 26541094 DOI: 10.1111/micc.12255] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2015] [Accepted: 11/01/2015] [Indexed: 12/22/2022]
Abstract
Myocardial perfusion and coronary vascular resistance are regulated by signaling metabolites released from the local myocardium that act either directly on the VSMC or indirectly via stimulation of the endothelium. A prominent mechanism of vasodilation is EDH of the arteriolar smooth muscle, with EETs and H(2)O(2) playing important roles in EDH in the coronary microcirculation. In some cases, EETs and H(2)O(2) are released as transferable hyperpolarizing factors (EDHFs) that act directly on the VSMCs. By contrast, EETs and H(2)O(2) can also promote endothelial KCa activity secondary to the amplification of extracellular Ca(2+) influx and Ca(2+) mobilization from intracellular stores, respectively. The resulting endothelial hyperpolarization may subsequently conduct to the media via myoendothelial gap junctions or potentially lead to the release of a chemically distinct factor(s). Furthermore, in human isolated coronary arterioles dilator signaling involving EETs and H(2)O(2) may be integrated, being either complimentary or inhibitory depending on the stimulus. With an emphasis on the human coronary microcirculation, this review addresses the diverse and integrated mechanisms by which EETs and H(2)O(2) regulate vessel tone and also examines the hypothesis that myoendothelial microdomain signaling facilitates EDH activity in the human heart.
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Affiliation(s)
| | - Shaun L Sandow
- Faculty of Science, Health, Education and Engineering, University of the Sunshine Coast, Maroochydore, Queensland, Australia
| | - Nilima Shukla
- Bristol Heart Institute, University of Bristol, Bristol, UK
| | - Yanping Liu
- Division of Research Infrastructure, National Center for Research Resources, National Institutes of Health, Bethesda, Maryland, USA
| | - Jamie Y Jeremy
- Bristol Heart Institute, University of Bristol, Bristol, UK
| | - David D Gutterman
- Division of Cardiovascular Medicine, Departments of Medicine, Physiology and Pharmacology, Medical College of Wisconsin, Milwaukee, Wisconsin, USA
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18
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Gutterman DD, Chabowski DS, Kadlec AO, Durand MJ, Freed JK, Ait-Aissa K, Beyer AM. The Human Microcirculation: Regulation of Flow and Beyond. Circ Res 2016; 118:157-72. [PMID: 26837746 DOI: 10.1161/circresaha.115.305364] [Citation(s) in RCA: 187] [Impact Index Per Article: 23.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
The microcirculation is responsible for orchestrating adjustments in vascular tone to match local tissue perfusion with oxygen demand. Beyond this metabolic dilation, the microvasculature plays a critical role in modulating vascular tone by endothelial release of an unusually diverse family of compounds including nitric oxide, other reactive oxygen species, and arachidonic acid metabolites. Animal models have provided excellent insight into mechanisms of vasoregulation in health and disease. However, there are unique aspects of the human microcirculation that serve as the focus of this review. The concept is put forth that vasculoparenchymal communication is multimodal, with vascular release of nitric oxide eliciting dilation and preserving normal parenchymal function by inhibiting inflammation and proliferation. Likewise, in disease or stress, endothelial release of reactive oxygen species mediates both dilation and parenchymal inflammation leading to cellular dysfunction, thrombosis, and fibrosis. Some pathways responsible for this stress-induced shift in mediator of vasodilation are proposed. This paradigm may help explain why microvascular dysfunction is such a powerful predictor of cardiovascular events and help identify new approaches to treatment and prevention.
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Affiliation(s)
- David D Gutterman
- From the Cardiovascular Center (A.M.B., A.O.K., D.D.G., D.S.C., J.K.F., K.A.-A., M.J.D.), Departments of Medicine (A.M.B., A.O.K., D.D.G., D.S.C., J.K.F., K.A.-A.), Pharmacology and Toxicology (D.S.C., J.K.F.), Physiology (A.M.B., A.O.K.), Physical Medicine and Rehabilitation (M.J.D.), and Anesthesiology (J.K.F.), Medical College of Wisconsin, Milwaukee.
| | - Dawid S Chabowski
- From the Cardiovascular Center (A.M.B., A.O.K., D.D.G., D.S.C., J.K.F., K.A.-A., M.J.D.), Departments of Medicine (A.M.B., A.O.K., D.D.G., D.S.C., J.K.F., K.A.-A.), Pharmacology and Toxicology (D.S.C., J.K.F.), Physiology (A.M.B., A.O.K.), Physical Medicine and Rehabilitation (M.J.D.), and Anesthesiology (J.K.F.), Medical College of Wisconsin, Milwaukee
| | - Andrew O Kadlec
- From the Cardiovascular Center (A.M.B., A.O.K., D.D.G., D.S.C., J.K.F., K.A.-A., M.J.D.), Departments of Medicine (A.M.B., A.O.K., D.D.G., D.S.C., J.K.F., K.A.-A.), Pharmacology and Toxicology (D.S.C., J.K.F.), Physiology (A.M.B., A.O.K.), Physical Medicine and Rehabilitation (M.J.D.), and Anesthesiology (J.K.F.), Medical College of Wisconsin, Milwaukee
| | - Matthew J Durand
- From the Cardiovascular Center (A.M.B., A.O.K., D.D.G., D.S.C., J.K.F., K.A.-A., M.J.D.), Departments of Medicine (A.M.B., A.O.K., D.D.G., D.S.C., J.K.F., K.A.-A.), Pharmacology and Toxicology (D.S.C., J.K.F.), Physiology (A.M.B., A.O.K.), Physical Medicine and Rehabilitation (M.J.D.), and Anesthesiology (J.K.F.), Medical College of Wisconsin, Milwaukee
| | - Julie K Freed
- From the Cardiovascular Center (A.M.B., A.O.K., D.D.G., D.S.C., J.K.F., K.A.-A., M.J.D.), Departments of Medicine (A.M.B., A.O.K., D.D.G., D.S.C., J.K.F., K.A.-A.), Pharmacology and Toxicology (D.S.C., J.K.F.), Physiology (A.M.B., A.O.K.), Physical Medicine and Rehabilitation (M.J.D.), and Anesthesiology (J.K.F.), Medical College of Wisconsin, Milwaukee
| | - Karima Ait-Aissa
- From the Cardiovascular Center (A.M.B., A.O.K., D.D.G., D.S.C., J.K.F., K.A.-A., M.J.D.), Departments of Medicine (A.M.B., A.O.K., D.D.G., D.S.C., J.K.F., K.A.-A.), Pharmacology and Toxicology (D.S.C., J.K.F.), Physiology (A.M.B., A.O.K.), Physical Medicine and Rehabilitation (M.J.D.), and Anesthesiology (J.K.F.), Medical College of Wisconsin, Milwaukee
| | - Andreas M Beyer
- From the Cardiovascular Center (A.M.B., A.O.K., D.D.G., D.S.C., J.K.F., K.A.-A., M.J.D.), Departments of Medicine (A.M.B., A.O.K., D.D.G., D.S.C., J.K.F., K.A.-A.), Pharmacology and Toxicology (D.S.C., J.K.F.), Physiology (A.M.B., A.O.K.), Physical Medicine and Rehabilitation (M.J.D.), and Anesthesiology (J.K.F.), Medical College of Wisconsin, Milwaukee
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Krishnamoorthy-Natarajan G, Koide M. BK Channels in the Vascular System. INTERNATIONAL REVIEW OF NEUROBIOLOGY 2016; 128:401-38. [PMID: 27238270 DOI: 10.1016/bs.irn.2016.03.017] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Autoregulation of blood flow is essential for the preservation of organ function to ensure continuous supply of oxygen and essential nutrients and removal of metabolic waste. This is achieved by controlling the diameter of muscular arteries and arterioles that exhibit a myogenic response to changes in arterial blood pressure, nerve activity and tissue metabolism. Large-conductance voltage and Ca(2+)-dependent K(+) channels (BK channels), expressed exclusively in smooth muscle cells (SMCs) in the vascular wall of healthy arteries, play a critical role in regulating the myogenic response. Activation of BK channels by intracellular, local, and transient ryanodine receptor-mediated "Ca(2+) sparks," provides a hyperpolarizing influence on the SMC membrane potential thereby decreasing the activity of voltage-dependent Ca(2+) channels and limiting Ca(2+) influx to promote SMC relaxation and vasodilation. The BK channel α subunit, a large tetrameric protein with each monomer consisting of seven-transmembrane domains, a long intracellular C-terminal tail and an extracellular N-terminus, associates with the β1 and γ subunits in vascular SMCs. The BK channel is regulated by factors originating within the SMC or from the endothelium, perivascular nerves and circulating blood, that significantly alter channel gating properties, Ca(2+) sensitivity and expression of the α and/or β1 subunit. The BK channel thus serves as a central receiving dock that relays the effects of the changes in several such concomitant autocrine and paracrine factors and influences cardiovascular health. This chapter describes the primary mechanism of regulation of myogenic response by BK channels and the alterations to this mechanism wrought by different vasoactive mediators.
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Affiliation(s)
| | - M Koide
- University of Vermont, Burlington, VT, United States
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20
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Bilodeau C, Bardou O, Maillé É, Berthiaume Y, Brochiero E. Deleterious impact of hyperglycemia on cystic fibrosis airway ion transport and epithelial repair. J Cyst Fibros 2016; 15:43-51. [DOI: 10.1016/j.jcf.2015.04.002] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2014] [Revised: 04/07/2015] [Accepted: 04/10/2015] [Indexed: 02/08/2023]
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21
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Hermann A, Sitdikova GF, Weiger TM. Oxidative Stress and Maxi Calcium-Activated Potassium (BK) Channels. Biomolecules 2015; 5:1870-911. [PMID: 26287261 PMCID: PMC4598779 DOI: 10.3390/biom5031870] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2015] [Revised: 07/17/2015] [Accepted: 07/20/2015] [Indexed: 01/13/2023] Open
Abstract
All cells contain ion channels in their outer (plasma) and inner (organelle) membranes. Ion channels, similar to other proteins, are targets of oxidative impact, which modulates ion fluxes across membranes. Subsequently, these ion currents affect electrical excitability, such as action potential discharge (in neurons, muscle, and receptor cells), alteration of the membrane resting potential, synaptic transmission, hormone secretion, muscle contraction or coordination of the cell cycle. In this chapter we summarize effects of oxidative stress and redox mechanisms on some ion channels, in particular on maxi calcium-activated potassium (BK) channels which play an outstanding role in a plethora of physiological and pathophysiological functions in almost all cells and tissues. We first elaborate on some general features of ion channel structure and function and then summarize effects of oxidative alterations of ion channels and their functional consequences.
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Affiliation(s)
- Anton Hermann
- Department of Cell Biology, Division of Cellular and Molecular Neurobiology, University of Salzburg, Salzburg 5020, Austria.
| | - Guzel F Sitdikova
- Department of Physiology of Man and Animals, Kazan Federal University, Kazan 420008, Russia.
| | - Thomas M Weiger
- Department of Cell Biology, Division of Cellular and Molecular Neurobiology, University of Salzburg, Salzburg 5020, Austria.
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22
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Molecular mechanism underlying β1 regulation in voltage- and calcium-activated potassium (BK) channels. Proc Natl Acad Sci U S A 2015; 112:4809-14. [PMID: 25825713 DOI: 10.1073/pnas.1504378112] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
Being activated by depolarizing voltages and increases in cytoplasmic Ca(2+), voltage- and calcium-activated potassium (BK) channels and their modulatory β-subunits are able to dampen or stop excitatory stimuli in a wide range of cellular types, including both neuronal and nonneuronal tissues. Minimal alterations in BK channel function may contribute to the pathophysiology of several diseases, including hypertension, asthma, cancer, epilepsy, and diabetes. Several gating processes, allosterically coupled to each other, control BK channel activity and are potential targets for regulation by auxiliary β-subunits that are expressed together with the α (BK)-subunit in almost every tissue type where they are found. By measuring gating currents in BK channels coexpressed with chimeras between β1 and β3 or β2 auxiliary subunits, we were able to identify that the cytoplasmic regions of β1 are responsible for the modulation of the voltage sensors. In addition, we narrowed down the structural determinants to the N terminus of β1, which contains two lysine residues (i.e., K3 and K4), which upon substitution virtually abolished the effects of β1 on charge movement. The mechanism by which K3 and K4 stabilize the voltage sensor is not electrostatic but specific, and the α (BK)-residues involved remain to be identified. This is the first report, to our knowledge, where the regulatory effects of the β1-subunit have been clearly assigned to a particular segment, with two pivotal amino acids being responsible for this modulation.
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23
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Brain mitochondrial ATP-insensitive large conductance Ca⁺²-activated K⁺ channel properties are altered in a rat model of amyloid-β neurotoxicity. Exp Neurol 2015; 269:8-16. [PMID: 25828534 DOI: 10.1016/j.expneurol.2014.12.024] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2014] [Revised: 12/01/2014] [Accepted: 12/20/2014] [Indexed: 12/22/2022]
Abstract
Mitochondrial dysfunction is a hallmark of amyloid-beta (Aβ)-induced neuronal toxicity in Alzheimer's disease (AD). However, the underlying mechanism of how Aβ affects mitochondrial function remains uncertain. Because mitochondrial potassium channels have been involved in several mitochondrial functions including cytoprotection, apoptosis and calcium homeostasis, a study was undertaken to investigate whether the gating behavior of the mitochondrial ATP- and ChTx-insensitive-IbTx-sensitive Ca(2+)-activated potassium channel (mitoBKCa) is altered in a rat model of Aβ neurotoxicity. Aβ1-42 (4 μg/μl) was intracerebroventricularly injected in male Wistar rats (220-250 g). Brain Aβ accumulation was confirmed two weeks later on the basis of an immunohistochemistry staining assay, and physiological impacts measured in passive avoidance task cognitive performance experiments. Brain mitochondrial inner membranes were then extracted and membrane vesicles prepared for channel incorporation into bilayer lipid. Purity of the cell fraction was confirmed by Western blot using specific markers of mitochondria, plasma membrane, endoplasmic reticulum, and Golgi. Our results first provide evidence for differences in mitoBKCa ion permeation properties with channels coming from Aβ vesicle preparations characterized by an inward rectifying I-V curve, in contrast to control mitoBKCa channels which showed a linear I-V relationship under the same ionic conditions (200 mM cis/50mM trans). More importantly the open probability of channels from Aβ vesicles appeared 1.5 to 2.5 smaller compared to controls, the most significant decrease being observed at depolarizing potentials (30 mV to 50 mV). Because BKCa-β4 subunit has been documented to shift the BKCa channel voltage dependence curve, a Western blot analysis was undertaken where expression of mitoBKCa α and β4 subunits was estimated using anti-α and β4 subunit antibodies. Our results indicated a significant increase in mitoBKCa-β4 subunit expression coupled to a decrease in the expression of α subunit. Our results thus demonstrate a modification in the mitoBKCa channel gating properties in membrane preparations coming from a rat model of Aβ neurotoxicity, an effect potentially linked to a change in mitoBKCa-β4 and -α subunits expression or increased ROS production due to an enhanced Aβ mitochondrial accumulation. Our results may provide new insights into the cellular mechanisms underlying mitochondrial dysfunctions in Aβ neurotoxicity.
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Yi F, Ling TY, Lu T, Wang XL, Li J, Claycomb WC, Shen WK, Lee HC. Down-regulation of the small conductance calcium-activated potassium channels in diabetic mouse atria. J Biol Chem 2015; 290:7016-26. [PMID: 25605734 DOI: 10.1074/jbc.m114.607952] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
The small conductance Ca(2+)-activated K(+) (SK) channels have recently been found to be expressed in the heart, and genome-wide association studies have shown that they are implicated in atrial fibrillation. Diabetes mellitus is an independent risk factor of atrial fibrillation, but the ionic mechanism underlying this relationship remains unclear. We hypothesized that SK channel function is abnormal in diabetes mellitus, leading to altered cardiac electrophysiology. We found that in streptozotocin-induced diabetic mice, the expression of SK2 and SK3 isoforms was down-regulated by 85 and 92%, respectively, whereas that of SK1 was not changed. SK currents from isolated diabetic mouse atrial myocytes were significantly reduced compared with controls. The resting potentials of isolated atrial preparations were similar between control and diabetic mice, but action potential durations were significantly prolonged in the diabetic atria. Exposure to apamin significantly prolonged action potential durations in control but not in diabetic atria. Production of reactive oxygen species was significantly increased in diabetic atria and in high glucose-cultured HL-1 cells, whereas exposure of HL-1 cells in normal glucose culture to H2O2 reduced the expression of SK2 and SK3. Tyrosine nitration in SK2 and SK3 was significantly increased by high glucose culture, leading to accelerated channel turnover. Treatment with Tiron prevented these changes. Our results suggest that increased oxidative stress in diabetes results in SK channel-associated electrical remodeling in diabetic atria and may promote arrhythmogenesis.
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Affiliation(s)
- Fu Yi
- From the Department of Internal Medicine, Division of Cardiovascular Diseases, Mayo Clinic, Rochester, Minnesota 55905, Department of Cardiovascular Diseases, Xijing Hospital, Fourth Military Medical University, Xi'an 710032, China
| | - Tian-You Ling
- From the Department of Internal Medicine, Division of Cardiovascular Diseases, Mayo Clinic, Rochester, Minnesota 55905, Department of Cardiology, Ruijin Hospital, Shanghai JiaoTong University School of Medicine, Shanghai 200025, China
| | - Tong Lu
- From the Department of Internal Medicine, Division of Cardiovascular Diseases, Mayo Clinic, Rochester, Minnesota 55905
| | - Xiao-Li Wang
- From the Department of Internal Medicine, Division of Cardiovascular Diseases, Mayo Clinic, Rochester, Minnesota 55905
| | - Jingchao Li
- From the Department of Internal Medicine, Division of Cardiovascular Diseases, Mayo Clinic, Rochester, Minnesota 55905, Department of Emergency Medicine, Henan Provincial People's Hospital, Affiliated Hospital of Zhengzhou University, Zhengzhou 450003, Henan, China
| | - William C Claycomb
- Department of Biochemistry and Molecular Biology, Louisiana State University Health Sciences Center, New Orleans, Louisiana 70112, and
| | - Win-Kuang Shen
- Department of Internal Medicine, Division of Cardiovascular Diseases, Mayo Clinic, Phoenix, Arizona 85255
| | - Hon-Chi Lee
- From the Department of Internal Medicine, Division of Cardiovascular Diseases, Mayo Clinic, Rochester, Minnesota 55905,
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25
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Impairment of brain mitochondrial charybdotoxin- and ATP-insensitive BK channel activities in diabetes. Neuromolecular Med 2014; 16:862-71. [PMID: 25344764 DOI: 10.1007/s12017-014-8334-6] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2014] [Accepted: 10/17/2014] [Indexed: 12/22/2022]
Abstract
Existing evidence indicates an impairment of mitochondrial functions and alterations in potassium channel activities in diabetes. Because mitochondrial potassium channels have been involved in several mitochondrial functions including cytoprotection, apoptosis and calcium homeostasis, a study was carried out to consider whether the gating behavior of the mitochondrial ATP- and ChTx-insensitive Ca(2+)-activated potassium channel (mitoBKCa) is altered in a streptozotocin (STZ) model of diabetes. Using ion channel incorporation of brain mitochondrial inner membrane into the bilayer lipid membrane, we provide in this work evidence for modifications of the mitoBKCa ion permeation properties with channels from vesicles preparations coming from diabetic rats characterized by a significant decrease in conductance. More importantly, the open probability of channels from diabetic rats was reduced 1.5-2.5 fold compared to control, the most significant decrease being observed at depolarizing potentials. Because BKCa β4 subunit has been documented to left shift the BKCa channel voltage dependence curve in high Ca(2+) conditions, a Western blot analysis was undertaken where the expression of mitoBKCa α and β4 subunits was estimated using of anti-α and β4 subunit antibodies. Our results indicated a significant decrease in mitoBKCa β4 subunit expression coupled to a decrease in the expression of α subunit, an observation compatible with the observed decrease in Ca(2+) sensitivity. Our results thus demonstrate a modification in the mitoBKCa channel gating properties in membrane preparations coming from STZ model of diabetic rats, an effect potentially linked to a change in mitoBKCa β4 and α subunits expression and/or to an increase in reactive oxygen species production in high glucose conditions.
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26
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Abstract
SIGNIFICANCE Voltage-gated K+ channels are a large family of K+-selective ion channel protein complexes that open on membrane depolarization. These K+ channels are expressed in diverse tissues and their function is vital for numerous physiological processes, in particular of neurons and muscle cells. Potentially reversible oxidative regulation of voltage-gated K+ channels by reactive species such as reactive oxygen species (ROS) represents a contributing mechanism of normal cellular plasticity and may play important roles in diverse pathologies including neurodegenerative diseases. RECENT ADVANCES Studies using various protocols of oxidative modification, site-directed mutagenesis, and structural and kinetic modeling provide a broader phenomenology and emerging mechanistic insights. CRITICAL ISSUES Physicochemical mechanisms of the functional consequences of oxidative modifications of voltage-gated K+ channels are only beginning to be revealed. In vivo documentation of oxidative modifications of specific amino-acid residues of various voltage-gated K+ channel proteins, including the target specificity issue, is largely absent. FUTURE DIRECTIONS High-resolution chemical and proteomic analysis of ion channel proteins with respect to oxidative modification combined with ongoing studies on channel structure and function will provide a better understanding of how the function of voltage-gated K+ channels is tuned by ROS and the corresponding reducing enzymes to meet cellular needs.
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Affiliation(s)
- Nirakar Sahoo
- 1 Department of Biophysics, Center for Molecular Biomedicine, Friedrich Schiller University Jena and Jena University Hospital , Jena, Germany
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27
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Nausch B, Rode F, Jørgensen S, Nardi A, Korsgaard MPG, Hougaard C, Bonev AD, Brown WD, Dyhring T, Strøbæk D, Olesen SP, Christophersen P, Grunnet M, Nelson MT, Rønn LCB. NS19504: a novel BK channel activator with relaxing effect on bladder smooth muscle spontaneous phasic contractions. J Pharmacol Exp Ther 2014; 350:520-30. [PMID: 24951278 DOI: 10.1124/jpet.113.212662] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Large-conductance Ca(2+)-activated K(+) channels (BK, KCa1.1, MaxiK) are important regulators of urinary bladder function and may be an attractive therapeutic target in bladder disorders. In this study, we established a high-throughput fluorometric imaging plate reader-based screening assay for BK channel activators and identified a small-molecule positive modulator, NS19504 (5-[(4-bromophenyl)methyl]-1,3-thiazol-2-amine), which activated the BK channel with an EC50 value of 11.0 ± 1.4 µM. Hit validation was performed using high-throughput electrophysiology (QPatch), and further characterization was achieved in manual whole-cell and inside-out patch-clamp studies in human embryonic kidney 293 cells expressing hBK channels: NS19504 caused distinct activation from a concentration of 0.3 and 10 µM NS19504 left-shifted the voltage activation curve by 60 mV. Furthermore, whole-cell recording showed that NS19504 activated BK channels in native smooth muscle cells from guinea pig urinary bladder. In guinea pig urinary bladder strips, NS19504 (1 µM) reduced spontaneous phasic contractions, an effect that was significantly inhibited by the specific BK channel blocker iberiotoxin. In contrast, NS19504 (1 µM) only modestly inhibited nerve-evoked contractions and had no effect on contractions induced by a high K(+) concentration consistent with a K(+) channel-mediated action. Collectively, these results show that NS19504 is a positive modulator of BK channels and provide support for the role of BK channels in urinary bladder function. The pharmacologic profile of NS19504 indicates that this compound may have the potential to reduce nonvoiding contractions associated with spontaneous bladder overactivity while having a minimal effect on normal voiding.
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Affiliation(s)
- Bernhard Nausch
- NeuroSearch A/S, Ballerup, Denmark (F.R., S.J., A.N., M.P.G.K., C.H., W.D.B., T.D., D.S., S.-P.O., P.C., M.G., L.C.B.R.); University of Vermont, Department of Pharmacology, Burlington, Vermont (B.N., A.D.B., M.T.N.); and Institute of Cardiovascular Sciences, University of Manchester, Manchester, United Kingdom (M.T.N.)
| | - Frederik Rode
- NeuroSearch A/S, Ballerup, Denmark (F.R., S.J., A.N., M.P.G.K., C.H., W.D.B., T.D., D.S., S.-P.O., P.C., M.G., L.C.B.R.); University of Vermont, Department of Pharmacology, Burlington, Vermont (B.N., A.D.B., M.T.N.); and Institute of Cardiovascular Sciences, University of Manchester, Manchester, United Kingdom (M.T.N.)
| | - Susanne Jørgensen
- NeuroSearch A/S, Ballerup, Denmark (F.R., S.J., A.N., M.P.G.K., C.H., W.D.B., T.D., D.S., S.-P.O., P.C., M.G., L.C.B.R.); University of Vermont, Department of Pharmacology, Burlington, Vermont (B.N., A.D.B., M.T.N.); and Institute of Cardiovascular Sciences, University of Manchester, Manchester, United Kingdom (M.T.N.)
| | - Antonio Nardi
- NeuroSearch A/S, Ballerup, Denmark (F.R., S.J., A.N., M.P.G.K., C.H., W.D.B., T.D., D.S., S.-P.O., P.C., M.G., L.C.B.R.); University of Vermont, Department of Pharmacology, Burlington, Vermont (B.N., A.D.B., M.T.N.); and Institute of Cardiovascular Sciences, University of Manchester, Manchester, United Kingdom (M.T.N.)
| | - Mads P G Korsgaard
- NeuroSearch A/S, Ballerup, Denmark (F.R., S.J., A.N., M.P.G.K., C.H., W.D.B., T.D., D.S., S.-P.O., P.C., M.G., L.C.B.R.); University of Vermont, Department of Pharmacology, Burlington, Vermont (B.N., A.D.B., M.T.N.); and Institute of Cardiovascular Sciences, University of Manchester, Manchester, United Kingdom (M.T.N.)
| | - Charlotte Hougaard
- NeuroSearch A/S, Ballerup, Denmark (F.R., S.J., A.N., M.P.G.K., C.H., W.D.B., T.D., D.S., S.-P.O., P.C., M.G., L.C.B.R.); University of Vermont, Department of Pharmacology, Burlington, Vermont (B.N., A.D.B., M.T.N.); and Institute of Cardiovascular Sciences, University of Manchester, Manchester, United Kingdom (M.T.N.)
| | - Adrian D Bonev
- NeuroSearch A/S, Ballerup, Denmark (F.R., S.J., A.N., M.P.G.K., C.H., W.D.B., T.D., D.S., S.-P.O., P.C., M.G., L.C.B.R.); University of Vermont, Department of Pharmacology, Burlington, Vermont (B.N., A.D.B., M.T.N.); and Institute of Cardiovascular Sciences, University of Manchester, Manchester, United Kingdom (M.T.N.)
| | - William D Brown
- NeuroSearch A/S, Ballerup, Denmark (F.R., S.J., A.N., M.P.G.K., C.H., W.D.B., T.D., D.S., S.-P.O., P.C., M.G., L.C.B.R.); University of Vermont, Department of Pharmacology, Burlington, Vermont (B.N., A.D.B., M.T.N.); and Institute of Cardiovascular Sciences, University of Manchester, Manchester, United Kingdom (M.T.N.)
| | - Tino Dyhring
- NeuroSearch A/S, Ballerup, Denmark (F.R., S.J., A.N., M.P.G.K., C.H., W.D.B., T.D., D.S., S.-P.O., P.C., M.G., L.C.B.R.); University of Vermont, Department of Pharmacology, Burlington, Vermont (B.N., A.D.B., M.T.N.); and Institute of Cardiovascular Sciences, University of Manchester, Manchester, United Kingdom (M.T.N.)
| | - Dorte Strøbæk
- NeuroSearch A/S, Ballerup, Denmark (F.R., S.J., A.N., M.P.G.K., C.H., W.D.B., T.D., D.S., S.-P.O., P.C., M.G., L.C.B.R.); University of Vermont, Department of Pharmacology, Burlington, Vermont (B.N., A.D.B., M.T.N.); and Institute of Cardiovascular Sciences, University of Manchester, Manchester, United Kingdom (M.T.N.)
| | - Søren-Peter Olesen
- NeuroSearch A/S, Ballerup, Denmark (F.R., S.J., A.N., M.P.G.K., C.H., W.D.B., T.D., D.S., S.-P.O., P.C., M.G., L.C.B.R.); University of Vermont, Department of Pharmacology, Burlington, Vermont (B.N., A.D.B., M.T.N.); and Institute of Cardiovascular Sciences, University of Manchester, Manchester, United Kingdom (M.T.N.)
| | - Palle Christophersen
- NeuroSearch A/S, Ballerup, Denmark (F.R., S.J., A.N., M.P.G.K., C.H., W.D.B., T.D., D.S., S.-P.O., P.C., M.G., L.C.B.R.); University of Vermont, Department of Pharmacology, Burlington, Vermont (B.N., A.D.B., M.T.N.); and Institute of Cardiovascular Sciences, University of Manchester, Manchester, United Kingdom (M.T.N.)
| | - Morten Grunnet
- NeuroSearch A/S, Ballerup, Denmark (F.R., S.J., A.N., M.P.G.K., C.H., W.D.B., T.D., D.S., S.-P.O., P.C., M.G., L.C.B.R.); University of Vermont, Department of Pharmacology, Burlington, Vermont (B.N., A.D.B., M.T.N.); and Institute of Cardiovascular Sciences, University of Manchester, Manchester, United Kingdom (M.T.N.)
| | - Mark T Nelson
- NeuroSearch A/S, Ballerup, Denmark (F.R., S.J., A.N., M.P.G.K., C.H., W.D.B., T.D., D.S., S.-P.O., P.C., M.G., L.C.B.R.); University of Vermont, Department of Pharmacology, Burlington, Vermont (B.N., A.D.B., M.T.N.); and Institute of Cardiovascular Sciences, University of Manchester, Manchester, United Kingdom (M.T.N.)
| | - Lars C B Rønn
- NeuroSearch A/S, Ballerup, Denmark (F.R., S.J., A.N., M.P.G.K., C.H., W.D.B., T.D., D.S., S.-P.O., P.C., M.G., L.C.B.R.); University of Vermont, Department of Pharmacology, Burlington, Vermont (B.N., A.D.B., M.T.N.); and Institute of Cardiovascular Sciences, University of Manchester, Manchester, United Kingdom (M.T.N.)
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28
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Satoh K, Godo S, Saito H, Enkhjargal B, Shimokawa H. Dual roles of vascular-derived reactive oxygen species--with a special reference to hydrogen peroxide and cyclophilin A. J Mol Cell Cardiol 2014; 73:50-6. [PMID: 24406688 DOI: 10.1016/j.yjmcc.2013.12.022] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/11/2013] [Revised: 12/27/2013] [Accepted: 12/28/2013] [Indexed: 12/21/2022]
Abstract
Reactive oxygen species (ROS) have been considered to play a major role in the pathogenesis of cardiovascular diseases. However, this notion needs to be revised since recent evidence indicates that vascular-derived hydrogen peroxide (H2O2) serves as an important signaling molecule in the cardiovascular system at its low physiological concentrations. At low concentrations, H2O2 can act as a second messenger, transducing the oxidative signal into biological responses through post-translational protein modification. These structural changes ultimately lead to altered cellular function. Intracellular redox status is closely regulated by the balance between oxidant and antioxidant systems and their imbalance can cause oxidative or reductive stress, leading to cellular damage and dysregulation. For example, excessive H2O2 deteriorates vascular functions and promotes vascular disease through multiple pathways. Furthermore, cyclophilin A (CyPA) has been shown to be secreted from vascular smooth muscle cells and to augment the destructive effects of ROS, linking it to the development of many cardiovascular diseases. Thus, it is important to understand the H2O2 signaling and the roles of downstream effectors such as CyPA in the vascular system in order to develop new therapeutic strategies for cardiovascular diseases. In this review, we will discuss the dual roles of vascular-derived H2O2 in mediating vascular functions (physiological roles) and promoting vascular diseases (pathological roles), with particular emphasis on the function of CyPA. This article is part of a Special Issue entitled "Redox Signalling in the Cardiovascular System".
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Affiliation(s)
- Kimio Satoh
- Department of Cardiovascular Medicine, Tohoku University Graduate School of Medicine, Sendai, Japan
| | - Shigeo Godo
- Department of Cardiovascular Medicine, Tohoku University Graduate School of Medicine, Sendai, Japan
| | - Hiroki Saito
- Department of Cardiovascular Medicine, Tohoku University Graduate School of Medicine, Sendai, Japan
| | - Budbazar Enkhjargal
- Department of Cardiovascular Medicine, Tohoku University Graduate School of Medicine, Sendai, Japan
| | - Hiroaki Shimokawa
- Department of Cardiovascular Medicine, Tohoku University Graduate School of Medicine, Sendai, Japan.
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29
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Xiao D, Hu XQ, Huang X, Zhou J, Wilson SM, Yang S, Zhang L. Chronic hypoxia during gestation enhances uterine arterial myogenic tone via heightened oxidative stress. PLoS One 2013; 8:e73731. [PMID: 24066066 PMCID: PMC3774750 DOI: 10.1371/journal.pone.0073731] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2013] [Accepted: 07/19/2013] [Indexed: 11/25/2022] Open
Abstract
Chronic hypoxia during gestation has profound adverse effects on the adaptation of uteroplacental circulation in pregnancy. Yet, the underlying mechanisms are not fully understood. The present study tested the hypothesis that enhanced production of reactive oxygen species (ROS) in uterine arteries plays a critical role in the maladaptation of uterine circulation associated with chronic hypoxia. Uterine arteries were isolated from nonpregnant and near-term pregnant sheep maintained at sea level (~300 m) or exposed to high-altitude (3801 m) hypoxia for 110 days. Hypoxia significantly increased ROS production in uterine arteries of pregnant, but not nonpregnant, sheep. This was associated with a significant increase in NADPH oxidase (Nox) 2, but not Nox1 or Nox4, protein abundance and total Nox activity in uterine arteries of pregnant animals. Chronic hypoxia significantly increased pressure-dependent uterine arterial myogenic tone in pregnant sheep, which was abrogated by a Nox inhibitor apocynin. Additionally, the hypoxia-induced increase in myogenic reactivity of uterine arteries to phorbol 12,13-dibutyrate in pregnant sheep was blocked by apocynin and tempol. In consistence with the myogenic responses, the hypoxia-mediated down-regulation of BKCa channel activity in uterine arteries of pregnant animals was reversed by apocynin. The findings suggest that heightened oxidative stress in uterine arteries plays a key role in suppressing the BKCa channel activity, resulting in increased myogenic reactivity and maladaptation of uteroplacental circulation caused by chronic hypoxia during gestation.
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Affiliation(s)
- Daliao Xiao
- Center for Perinatal Biology, Division of Pharmacology, Department of Basic Sciences, Loma Linda University School of Medicine, Loma Linda, California, United States of America
| | - Xiang-Qun Hu
- Center for Perinatal Biology, Division of Pharmacology, Department of Basic Sciences, Loma Linda University School of Medicine, Loma Linda, California, United States of America
| | - Xiaohui Huang
- Center for Perinatal Biology, Division of Pharmacology, Department of Basic Sciences, Loma Linda University School of Medicine, Loma Linda, California, United States of America
| | - Jianjun Zhou
- Department of Obstetrics and Gynecology, Nanjing Drum Tower Hospital, Nanjing University Medical School, Nanjing, China
| | - Sean M. Wilson
- Center for Perinatal Biology, Division of Pharmacology, Department of Basic Sciences, Loma Linda University School of Medicine, Loma Linda, California, United States of America
| | - Shumei Yang
- Department of Chemistry and Biochemistry, California State University, San Bernardino, California, United States of America
| | - Lubo Zhang
- Center for Perinatal Biology, Division of Pharmacology, Department of Basic Sciences, Loma Linda University School of Medicine, Loma Linda, California, United States of America
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30
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Tucker K, Cho S, Thiebaud N, Henderson MX, Fadool DA. Glucose sensitivity of mouse olfactory bulb neurons is conveyed by a voltage-gated potassium channel. J Physiol 2013; 591:2541-61. [PMID: 23478133 DOI: 10.1113/jphysiol.2013.254086] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
The olfactory bulb has recently been proposed to serve as a metabolic sensor of internal chemistry, particularly that modified by metabolism. Because the voltage-dependent potassium channel Kv1.3 regulates a large proportion of the outward current in olfactory bulb neurons and gene-targeted deletion of the protein produces a phenotype of resistance to diet-induced obesity in mice, we hypothesized that this channel may play a role in translating energy availability into a metabolic signal. Here we explored the ability of extracellular glucose concentration to modify evoked excitability of the mitral neurons that principally regulate olfactory coding and processing of olfactory information. Using voltage-clamp electrophysiology of heterologously expressed Kv1.3 channels in HEK 293 cells, we found that Kv1.3 macroscopic currents responded to metabolically active (d-) rather than inactive (l-) glucose with a response profile that followed a bell-shaped curve. Olfactory bulb slices stimulated with varying glucose concentrations showed glucose-dependent mitral cell excitability as evaluated by current-clamp electrophysiology. While glucose could be either excitatory or inhibitory, the majority of the sampled neurons displayed a decreased firing frequency in response to elevated glucose concentration that was linked to increased latency to first spike and decreased action potential cluster length. Unlike modulation attributed to phosphorylation, glucose modulation of mitral cells was rapid, less than one minute, and was reversible within the time course of a patch recording. Moreover, we report that modulation targets properties of spike firing rather than action potential shape, involves synaptic activity of glutamate or GABA signalling circuits, and is dependent upon Kv1.3 expression. Given the rising incidence of metabolic disorders attributed to weight gain, changes in neuronal excitability in brain regions regulating sensory perception of food are of consequence.
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Affiliation(s)
- Kristal Tucker
- Florida State University, 319 Stadium Drive, 3008 King Life Sciences, Tallahassee, FL 32306, USA
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Murata T, Dietrich HH, Xiang C, Dacey RG. G protein-coupled estrogen receptor agonist improves cerebral microvascular function after hypoxia/reoxygenation injury in male and female rats. Stroke 2013; 44:779-85. [PMID: 23362079 DOI: 10.1161/strokeaha.112.678177] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
BACKGROUND AND PURPOSE Reduced risk and severity of stroke in adult females are thought to depend on normal levels of endogenous estrogen, which is a known neuro- and vasoprotective agent in experimental cerebral ischemia. Recently, a novel G protein-coupled estrogen receptor (GPER, formerly GPR30) has been identified and may mediate the vasomotor and -protective effects of estrogen. However, the signaling mechanisms associated with GPER in the cerebral microcirculation remain unclear. We investigated the mechanism of GPER-mediated vasoreactivity and also its vasoprotective effect after hypoxia/reoxygenation (H/RO) injury. METHODS Rat cerebral penetrating arterioles from both sexes were isolated, cannulated, and pressurized. Vessel diameters were recorded by computer-aided videomicroscopy. To investigate vasomotor mechanism of the GPER agonist (G-1), several inhibitors with or without endothelial impairment were tested. Ischemia/reperfusion injury was simulated using H/RO. Vasomotor responses to adenosine triphophate after H/RO were measured with or without G-1 and compared with controls. RESULTS G-1 produced a vasodilatory response, which was partially dependent on endothelium-derived nitric oxide (NO) but not arachidonic acid cascades and endothelial hyperpolarization factor. Attenuation of G-1-vasodilation by the NO synthase inhibitor and endothelium-impairment were greater in vessels from female than male animals. G-1 treatment after H/RO injury fully restored arteriolar dilation to adenosine triphophate compared with controls. CONCLUSIONS GPER agonist elicited dilation, which was partially caused by endothelial NO pathway and induced by direct relaxation of smooth muscle cells. Further, GPER agonist restored vessel function of arterioles after H/RO injury and may play an important role in the ability of estrogen to protect the cerebrovasculature against ischemia/reperfusion injury.
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Affiliation(s)
- Takahiro Murata
- Department of Neurological Surgery, Washington University School of Medicine, St. Louis, MO 63110, USA
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32
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Rueda A, Fernández-Velasco M, Benitah JP, Gómez AM. Abnormal Ca2+ spark/STOC coupling in cerebral artery smooth muscle cells of obese type 2 diabetic mice. PLoS One 2013; 8:e53321. [PMID: 23301060 PMCID: PMC3536748 DOI: 10.1371/journal.pone.0053321] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2012] [Accepted: 11/30/2012] [Indexed: 01/19/2023] Open
Abstract
Diabetes is a major risk factor for stroke. However, the molecular mechanisms involved in cerebral artery dysfunction found in the diabetic patients are not completely elucidated. In cerebral artery smooth muscle cells (CASMCs), spontaneous and local increases of intracellular Ca2+ due to the opening of ryanodine receptors (Ca2+ sparks) activate large conductance Ca2+-activated K+ (BK) channels that generate spontaneous transient outward currents (STOCs). STOCs have a key participation in the control of vascular myogenic tone and blood pressure. Our goal was to investigate whether alterations in Ca(2+) spark and STOC activities, measured by confocal microscopy and patch-clamp technique, respectively, occur in isolated CASMCs of an experimental model of type-2 diabetes (db/db mouse). We found that mean Ca(2+) spark amplitude, duration, size and rate-of-rise were significantly smaller in Fluo-3 loaded db/db compared to control CASMCs, with a subsequent decrease in the total amount of Ca(2+) released through Ca(2+) sparks in db/db CASMCs, though Ca(2+) spark frequency remained. Interestingly, the frequency of large-amplitude Ca(2+) sparks was also significantly reduced in db/db cells. In addition, the frequency and amplitude of STOCs were markedly reduced at all voltages tested (from -50 to 0 mV) in db/db CASMCs. The latter correlates with decreased BK channel β1/α subunit ratio found in db/db vascular tissues. Taken together, Ca(2+) spark alterations lead to inappropriate BK channels activation in CASMCs of db/db mice and this condition is aggravated by the decrease in the BK β1 subunit/α subunit ratio which underlies the significant reduction of Ca(2+) spark/STOC coupling in CASMCs of diabetic animals.
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Affiliation(s)
- Angélica Rueda
- Departamento de Bioquímica, Centro de Investigación y de Estudios Avanzados del IPN, México City, México
- Inserm, U-637; Université de Montpellier 1, Université de Montpellier 2, Montpellier, France
- * E-mail: (AMG); (AR)
| | - María Fernández-Velasco
- Inserm, U-637; Université de Montpellier 1, Université de Montpellier 2, Montpellier, France
- Instituto de Investigación Hospital Universitario La Paz (IdiPAZ), Madrid, Spain
| | - Jean-Pierre Benitah
- Inserm, U769; Université de Paris-Sud, IFR141, Labex Lermit, Châtenay-Malabry, France
| | - Ana María Gómez
- Inserm, U769; Université de Paris-Sud, IFR141, Labex Lermit, Châtenay-Malabry, France
- * E-mail: (AMG); (AR)
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Wang Z, Yue P, Lin DH, Wang WH. Carbon monoxide stimulates Ca2+ -dependent big-conductance K channels in the cortical collecting duct. Am J Physiol Renal Physiol 2012; 304:F543-52. [PMID: 23235481 DOI: 10.1152/ajprenal.00530.2012] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
We used the patch-clamp technique to examine the role of carbon monoxide (CO) in regulating Ca(2+)-activated big-conductance K (BK) channels in the principal cell of the cortical collecting duct (CCD). Application of CORM3 or CORM2, a CO donor, activated BK channels in the CCD, whereas adding inactivated CORM2/3 had no effect. Superfusion of the CCD with CO-bubbled bath solution also activated the BK channels in the cell-attached patches. The effect of CO on BK channels was not dependent on nitric oxide synthase (NOS) because the effect of CORM3 was also observed in the CCD treated with l-NAME, an agent that inhibits the NOS. Adding a membrane-permeable cGMP analog, 8-bromo-cGMP, significantly increased the BK channel in the CCD. However, inhibition of soluble guanylate cyclase failed to abolish the stimulatory effect of CORM3 on BK channels. Moreover, inhibition of cGMP-dependent protein kinase G did not block the stimulatory effect of CORM3 on the BK channels, suggesting that the stimulatory effect of CO on the BK channels was, at least partially, induced by a cGMP-independent mechanism. Western blot demonstrated that heme oxygenase type 1 (HO-1) and HO-2 were expressed in the kidney. Moreover, a high-K (HK) intake increased the expression of HO-1 but not HO-2 in the kidney. A HK intake also increased renal HO activity defined by NADPH-dependent CO generation following addition of heme in the cell lysate from renal cortex and outer medulla. The role of HO in regulating BK channel activity in the CCD was also suggested by experiments in which application of hemin increased the BK channels. The stimulatory effect of hemin on the BK channels was blocked by SnMP, a HO inhibitor. But, adding CORM3 was still able to activate the BK channels in the presence of SnMP. We conclude that CO activates the BK channels, at least partially, through a NO-cGMP-independent pathway and that HO plays a role in mediating the effect of HK intake on the BK channels in the CCD.
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Affiliation(s)
- Zhijian Wang
- Dept. of Pharmacology, New York Medical College, Valhalla, NY 10595, USA
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Müller PM, Gnügge R, Dhayade S, Thunemann M, Krippeit-Drews P, Drews G, Feil R. H₂O₂ lowers the cytosolic Ca²⁺ concentration via activation of cGMP-dependent protein kinase Iα. Free Radic Biol Med 2012; 53:1574-83. [PMID: 22922339 DOI: 10.1016/j.freeradbiomed.2012.08.011] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/09/2012] [Revised: 08/06/2012] [Accepted: 08/07/2012] [Indexed: 11/21/2022]
Abstract
The cGMP-dependent protein kinase I (cGKI) is a key mediator of cGMP signaling, but the specific functions of its two isoforms, cGKIα and cGKIβ, are poorly understood. Recent studies indicated a novel cGMP-independent role for cGKIα in redox sensing. To dissect the effects of oxidative stress on the cGKI isoforms, we used mouse embryonic fibroblasts and vascular smooth muscle cells (VSMCs) expressing both, one, or none of them. In cGKIα-expressing cells, but not in cells expressing only cGKIβ, incubation with H₂O₂ induced the formation of a disulfide bond between the two identical subunits of the dimeric enzyme. Oxidation of cGKIα was associated with increased phosphorylation of its substrate, vasodilator-stimulated phosphoprotein. H₂O₂ did not stimulate cGMP production, indicating that it activates cGKIα directly via oxidation. Interestingly, there was a mutual influence of H₂O₂ and cGMP on cGKI activity and disulfide bond formation, respectively; preoxidation of the kinase with H₂O₂ slightly impaired its activation by cGMP, whereas preactivation of the enzyme with cGMP attenuated its oxidation by H₂O₂. To evaluate the functional relevance of the noncanonical H₂O₂-cGKIα pathway, we studied the regulation of the cytosolic Ca²⁺ concentration ([Ca²⁺](i)). H₂O₂ suppressed norepinephrine-induced Ca²⁺ transients in cGKIα-expressing VSMCs and, to a lower extent, in VSMCs expressing only cGKIβ or none of the isoforms. Thus, H₂O₂ lowers [Ca²⁺](i) mainly via a cGKIα-dependent pathway. These results indicate that oxidative stress selectively targets the cGKIα isoform, which then modulates cellular processes in a cGMP-independent manner. A decrease in [Ca²⁺](i) in VSMCs via activation of cGKIα might be a major mechanism of H₂O₂-induced vasodilation.
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MESH Headings
- Animals
- Blotting, Western
- Calcium/metabolism
- Cells, Cultured
- Cyclic GMP/metabolism
- Cyclic GMP-Dependent Protein Kinase Type I/metabolism
- Cytosol/metabolism
- Disulfides/metabolism
- Embryo, Mammalian/cytology
- Embryo, Mammalian/drug effects
- Embryo, Mammalian/enzymology
- Female
- Fibroblasts/cytology
- Fibroblasts/drug effects
- Fibroblasts/enzymology
- Hydrogen Peroxide/pharmacology
- Mice
- Mice, Inbred C57BL
- Muscle, Smooth, Vascular/cytology
- Muscle, Smooth, Vascular/drug effects
- Muscle, Smooth, Vascular/enzymology
- Oxidants/pharmacology
- Signal Transduction
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Affiliation(s)
- Paul Markus Müller
- Interfakultäres Institut für Biochemie, University of Tübingen, 72076 Tübingen, Germany
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Hu XQ, Zhang L. Function and regulation of large conductance Ca(2+)-activated K+ channel in vascular smooth muscle cells. Drug Discov Today 2012; 17:974-87. [PMID: 22521666 PMCID: PMC3414640 DOI: 10.1016/j.drudis.2012.04.002] [Citation(s) in RCA: 77] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2012] [Revised: 03/06/2012] [Accepted: 04/05/2012] [Indexed: 12/23/2022]
Abstract
Large conductance Ca(2+)-activated K(+) (BK(Ca)) channels are abundantly expressed in vascular smooth muscle cells. Activation of BK(Ca) channels leads to hyperpolarization of cell membrane, which in turn counteracts vasoconstriction. Therefore, BK(Ca) channels have an important role in regulation of vascular tone and blood pressure. The activity of BK(Ca) channels is subject to modulation by various factors. Furthermore, the function of BK(Ca) channels are altered in both physiological and pathophysiological conditions, such as pregnancy, hypertension and diabetes, which has dramatic impacts on vascular tone and hemodynamics. Consequently, compounds and genetic manipulation that alter activity and expression of the channel might be of therapeutic interest.
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Affiliation(s)
- Xiang-Qun Hu
- Center for Perinatal Biology, Division of Pharmacology, Department of Basic Sciences, Loma Linda University School of Medicine, Loma Linda, CA 92350, USA.
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Lu T, Chai Q, Yu L, d'Uscio LV, Katusic ZS, He T, Lee HC. Reactive oxygen species signaling facilitates FOXO-3a/FBXO-dependent vascular BK channel β1 subunit degradation in diabetic mice. Diabetes 2012; 61:1860-8. [PMID: 22586590 PMCID: PMC3379647 DOI: 10.2337/db11-1658] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Activity of the vascular large conductance Ca(2+)-activated K(+) (BK) channel is tightly regulated by its accessory β(1) subunit (BK-β(1)). Downregulation of BK-β(1) expression in diabetic vessels is associated with upregulation of the forkhead box O subfamily transcription factor-3a (FOXO-3a)-dependent F-box-only protein (FBXO) expression. However, the upstream signaling regulating this process is unclear. Overproduction of reactive oxygen species (ROS) is a common finding in diabetic vasculopathy. We hypothesized that ROS signaling cascade facilitates the FOXO-3a/FBXO-mediated BK-β(1) degradation and leads to diabetic BK channel dysfunction. Using cellular biology, patch clamp, and videomicroscopy techniques, we found that reduced BK-β(1) expression in streptozotocin (STZ)-induced diabetic mouse arteries and in human coronary smooth muscle cells (SMCs) cultured with high glucose was attributable to an increase in protein kinase C (PKC)-β and NADPH oxidase expressions and accompanied by attenuation of Akt phosphorylation and augmentation of atrogin-1 expression. Treatment with ruboxistaurin (a PKCβ inhibitor) or with GW501516 (a peroxisome proliferator-activated receptor δ activator) reduced atrogin-1 expression and restored BK channel-mediated coronary vasodilation in diabetic mice. Our results suggested that oxidative stress inhibited Akt signaling and facilitated the FOXO-3a/FBXO-dependent BK-β(1) degradation in diabetic vessels. Suppression of the FOXO-3a/FBXO pathway prevented vascular BK-β(1) degradation and protected coronary function in diabetes.
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Affiliation(s)
- Tong Lu
- Department of Internal Medicine, Mayo Clinic, Rochester, Minnesota, USA.
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Zhang DX, Borbouse L, Gebremedhin D, Mendoza SA, Zinkevich NS, Li R, Gutterman DD. H2O2-induced dilation in human coronary arterioles: role of protein kinase G dimerization and large-conductance Ca2+-activated K+ channel activation. Circ Res 2011; 110:471-80. [PMID: 22158710 DOI: 10.1161/circresaha.111.258871] [Citation(s) in RCA: 127] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
RATIONALE Hydrogen peroxide (H(2)O(2)) serves as a key endothelium-derived hyperpolarizing factor mediating flow-induced dilation in human coronary arterioles (HCAs). The precise mechanisms by which H(2)O(2) elicits smooth muscle hyperpolarization are not well understood. An important mode of action of H(2)O(2) involves the oxidation of cysteine residues in its target proteins, including protein kinase G (PKG)-Iα, thereby modulating their activities. OBJECTIVE Here we hypothesize that H(2)O(2) dilates HCAs through direct oxidation and activation of PKG-Iα leading to the opening of the large-conductance Ca(2+)-activated K(+) (BK(Ca)) channel and subsequent smooth muscle hyperpolarization. METHODS AND RESULTS Flow and H(2)O(2) induced pressure gradient/concentration-dependent vasodilation in isolated endothelium-intact and -denuded HCAs, respectively. The dilation was largely abolished by iberiotoxin, a BK(Ca) channel blocker. The PKG inhibitor Rp-8-Br-PET-cGMP also markedly inhibited flow- and H(2)O(2)-induced dilation, whereas the soluble guanylate cyclase inhibitor ODQ had no effect. Treatment of coronary smooth muscle cells (SMCs) with H(2)O(2) elicited dose-dependent, reversible dimerization of PKG-Iα, and induced its translocation to the plasma membrane. Patch-clamp analysis identified a paxilline-sensitive single-channel K(+) current with a unitary conductance of 246-pS in freshly isolated coronary SMCs. Addition of H(2)O(2) into the bath solution significantly increased the probability of BK(Ca) single-channel openings recorded from cell-attached patches, an effect that was blocked by the PKG-Iα inhibitor DT-2. H(2)O(2) exhibited an attenuated stimulatory effect on BK(Ca) channel open probability in inside-out membrane patches. CONCLUSIONS H(2)O(2) dilates HCAs through a novel mechanism involving protein dimerization and activation of PKG-Iα and subsequent opening of smooth muscle BK(Ca) channels.
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Affiliation(s)
- David X Zhang
- Department of Medicine, Cardiovascular Center, Medical College of Wisconsin, Milwaukee, 53226, USA.
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Chang H, Ma YG, Wang YY, Song Z, Li Q, Yang N, Zhao HZ, Feng HZ, Chang YM, Ma J, Yu ZB, Xie MJ. High glucose alters apoptosis and proliferation in HEK293 cells by inhibition of cloned BK Ca channel. J Cell Physiol 2011; 226:1660-75. [PMID: 21413024 DOI: 10.1002/jcp.22497] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
It has been reported that diabetic vascular dysfunction is associated with impaired function of large conductance Ca(2+) -activated K(+) (BK(Ca) ) channels. However, it is unclear whether impaired BK(Ca) channel directly participates in regulating diabetic vascular remodeling by altering cell growth in response to hyperglycemia. In the present study, we investigated the specific role of BK(Ca) channel in controlling apoptosis and proliferation under high glucose concentration (25 mM). The cDNA encoding the α+β1 subunit of BK(Ca) channel, hSloα+β1, was transiently transfected into human embryonic kidney 293 (HEK293) cells. Cloned BK(Ca) currents were recorded by both whole-cell and cell-attached patch clamp techniques. Cell apoptosis was assessed with immunocytochemistry and analysis of fragmented DNA by agarose gel electrophoresis. Cell proliferation was investigated by flow cytometry assays, MTT test, and immunocytochemistry. In addition, the expression of anti-apoptotic protein Bcl-2, intracellular Ca(2+) , and mitochondrial membrane potential (Δψm) were also examined to investigate the possible mechanisms. Our results indicate that inhibition of cloned BK(Ca) channels might be responsible for hyperglycemia-altered apoptosis and proliferation in HEK-hSloα+β1 cells. However, activation of BK(Ca) channel by NS1619 or Tamoxifen significantly induced apoptosis and suppressed proliferation in HEK-hSloα+β1 cells under hyperglycemia condition. When rat cerebral smooth muscle cells were cultured in hyperglycemia, similar findings were observed. Moreover, the possible mechanisms underlying the activation of BK(Ca) channel were associated with decreased expression of Bcl-2, elevation of intracellular Ca(2+) , and a concomitant depolarization of Δψm in HEK-hSloα+β1 cells. In conclusion, cloned BK(Ca) channel directly regulated apoptosis and proliferation of HEK293 cell under hyperglycemia condition.
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Affiliation(s)
- Hui Chang
- Department of Aerospace Physiology, Key Laboratory of Aerospace Medicine of Ministry of Education, Fourth Military Medical University, Xi'an, Shaanxi Province, China
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Liu B, Sun X, Zhu Y, Gan L, Xu H, Yang X. Biphasic effects of H(2)O(2) on BK(Ca) channels. Free Radic Res 2011; 44:1004-12. [PMID: 20560834 DOI: 10.3109/10715762.2010.495126] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
The inhibitory or activating effect of H(2)O(2) on large conductance calcium and voltage-dependent potassium (BK(Ca)) channels has been reported. However, the mechanism by which this occurs is unclear. In this paper, BK(Ca) channels encoded by mouse Slo were expressed in HEK 293 cells and BK(Ca) channel activity was measured by electrophysiology. The results showed that H(2)O(2) inhibited BK(Ca) channel activity in inside-out patches but enhanced BK(Ca) channel activity in cell-attached patches. The inhibition by H(2)O(2) in inside-out patches may be due to oxidative modification of cysteine residues in BK(Ca) channels or other membrane proteins that regulate BK(Ca) channel function. PI3K/AKT signaling modulates the H(2)O(2)-induced BK(Ca) channel activation in cell-attached patches. BK(Ca) channels and PI3K signaling pathway were involved in H(2)O(2)-induced vasodilation and H(2)O(2)-induced vasodilation by PI3K pathway was mainly due to modulation of BK(Ca) channel activity.
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Affiliation(s)
- Bo Liu
- Huazhong University of Science and Technology, Wuhan, PR China
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Liu Y, Bubolz AH, Mendoza S, Zhang DX, Gutterman DD. H2O2 is the transferrable factor mediating flow-induced dilation in human coronary arterioles. Circ Res 2011; 108:566-73. [PMID: 21233456 DOI: 10.1161/circresaha.110.237636] [Citation(s) in RCA: 140] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
RATIONALE Endothelial derived hydrogen peroxide (H(2)O(2)) is a necessary component of the pathway regulating flow-mediated dilation (FMD) in human coronary arterioles (HCAs). However, H(2)O(2) has never been shown to be the endothelium-dependent transferrable hyperpolarization factor (EDHF) in response to shear stress. OBJECTIVE We examined the hypothesis that H(2)O(2) serves as the EDHF in HCAs to shear stress. METHODS AND RESULTS Two HCAs were cannulated in series (a donor intact vessel upstream and endothelium-denuded detector vessel downstream). Diameter changes to flow were examined in the absence and presence of polyethylene glycol catalase (PEG-CAT). The open state probability of large conductance Ca(2+)-activated K(+) (BK(Ca)) channels in smooth muscle cells downstream from the perfusate from an endothelium-intact arteriole was examined by patch clamping. In some experiments, a cyanogen bromide-activated resin column bound with CAT was used to remove H(2)O(2) from the donor vessel. When flow proceeds from donor to detector, both vessels dilate (donor:68±7%; detector: 45±11%). With flow in the opposite direction, only the donor vessel dilates. PEG-CAT contacting only the detector vessel blocked FMD in that vessel (6±4%) but not in donor vessel (61±13%). Paxilline inhibited dilation of endothelium-denuded HCAs to H(2)O(2). Effluent from donor vessels elicited K(+) channel opening in an iberiotoxin- or PEG-CAT-sensitive fashion in cell-attached patches but had little effect on channel opening on inside-out patches. Vasodilation of detector vessels was diminished when exposed to effluent from CAT-column. CONCLUSIONS Flow induced endothelial production of H(2)O(2), which acts as the transferrable EDHF activating BK(Ca) channels on the smooth muscle cells.
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Affiliation(s)
- Yanping Liu
- Office of Research, Medical College of Wisconsin, 8701 Watertown Plank Rd, Milwaukee, WI 53226, USA
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Lin YL, Dai ZK, Lin RJ, Chu KS, Chen IJ, Wu JR, Wu BN. Baicalin, a flavonoid from Scutellaria baicalensis Georgi, activates large-conductance Ca2+-activated K+ channels via cyclic nucleotide-dependent protein kinases in mesenteric artery. PHYTOMEDICINE : INTERNATIONAL JOURNAL OF PHYTOTHERAPY AND PHYTOPHARMACOLOGY 2010; 17:760-70. [PMID: 20171070 DOI: 10.1016/j.phymed.2010.01.003] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/17/2009] [Accepted: 01/18/2010] [Indexed: 05/24/2023]
Abstract
Baicalin isolated from Scutellaria baicalensis is a traditional Chinese herbal medicine used for cardiovascular dysfunction. The ionic mechanism of the vasorelaxant effects of baicalin remains unclear. We investigated whether baicalin relaxes mesenteric arteries (MAs) via large-conductance Ca2+-activated K+ (BK(Ca)) channel activation and voltage-dependent Ca2+ channel (VDCC) inhibition. The contractility of MA was determined by dual wire myograph. BK(Ca) channels and VDCCs were measured using whole-cell recordings in single myocytes, enzymatically dispersed from rat MAs. Baicalin (10-100 microM) attenuated 80 mM KCl-contracted MA in a concentration-related manner. L-NAME (30 microM) and indomethacin (10 microM) little affected baicalin (100 microM)-induced vasorelaxations. Contractions induced by iberiotoxin (IbTX, 0.1 microM), Bay K8644 (0.1 microM) or PMA (10 microM) were abolished by baicalin 100 microM. In MA myocytes, baicalin (0.3-30 microM) enhanced BK(Ca) channel activity in a concentration-dependent manner. Increased BK(Ca) currents were abolished by IbTX (0.1 microM). Baicalin-mediated (30 microM) BK(Ca) current activation was significantly attenuated by an adenylate cyclase inhibitor (SQ 22536, 10 microM), a soluble guanylate cyclase inhibitor (ODQ, 10 microM), competitive antagonists of cAMP and cGMP (Rp-cAMP, 100 microM and Rp-cGMP, 100 microM), and cAMP- and cGMP-dependent protein kinase inhibitors (KT5720, 0.3 microM and KT5823, 0.3 microM). Perfusate with PMA (0.1 microM) abolished baicalin-enhanced BK(Ca) currents. Additionally, baicalin (0.3-30 microM) reduced the amplitude of VDCC currents in a concentration-dependent manner and abolished VDCC activator Bay K8644-enhanced (0.1 microM) currents. Baicalin produced MA relaxation by activating BK(Ca) and inhibiting VDCC channels by endothelium-independent mechanisms and by stimulating the cGMP/PKG and cAMP/PKA pathways.
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Affiliation(s)
- Yi-Ling Lin
- Department of Pharmacology, College of Medicine, Kaohsiung Medical University, 100 Shih-Chuan 1st Road, Kaohsiung 807, Taiwan
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Ding H, Triggle CR. Endothelial dysfunction in diabetes: multiple targets for treatment. Pflugers Arch 2010; 459:977-94. [PMID: 20238124 DOI: 10.1007/s00424-010-0807-3] [Citation(s) in RCA: 71] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2010] [Revised: 02/13/2010] [Accepted: 02/16/2010] [Indexed: 12/20/2022]
Abstract
Robert Furchgott's discovery of the obligatory role that the endothelium plays in the regulation of vascular tone has proved to be a major advance in terms of our understanding of the cellular basis of diabetic vascular disease. Endothelial dysfunction, as defined by a reduction in the vasodilatation response to an endothelium-dependent vasodilator (such as acetylcholine) or to flow-mediated vasodilatation, is an early indicator for the development of the micro- and macroangipathy that is associated with diabetes. In diabetes, hyperglycaemia plays a key role in the initiation and development of endothelial dysfunction; however, the cellular mechanisms involved as well as the importance of dyslipidaemia and co-morbidities such as hypertension and obesity remain incompletely understood. In this review, we discuss the mechanisms whereby hyperglycaemia, oxidative stress and dyslipidaemia can alter endothelial function and highlight their effects on endothelial nitric oxide synthase (eNOS), the endothelium-dependent hyperpolarising factor (EDHF) pathway(s), as well as on the role of endothelium-derived contracting factors (EDCFs) and adipocyte-derived vasoactive factors such as adipose-derived relaxing factor (ADRF).
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Affiliation(s)
- Hong Ding
- Department of Pharmacology & Medical Education, Weill Cornell Medical College in Qatar, P.O. Box 24144, Education City, Doha, Qatar
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Lu T, Zhang DM, Wang XL, He T, Wang RX, Chai Q, Katusic ZS, Lee HC. Regulation of coronary arterial BK channels by caveolae-mediated angiotensin II signaling in diabetes mellitus. Circ Res 2010; 106:1164-73. [PMID: 20167931 DOI: 10.1161/circresaha.109.209767] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
RATIONALE The large conductance Ca(2+)-activated K(+) (BK) channel, a key determinant of vascular tone, is regulated by angiotensin II (Ang II) type 1 receptor signaling. Upregulation of Ang II functions and downregulation of BK channel activities have been reported in diabetic vessels. However, the molecular mechanisms underlying Ang II-mediated BK channel modulation, especially in diabetes mellitus, have not been thoroughly examined. OBJECTIVES The aim in this study was to determine whether caveolae-targeting facilitates BK channel dysfunction in diabetic vessels. METHODS AND RESULTS Using patch clamp techniques and molecular biological approaches, we found that BK channels, Ang II type 1 receptor, G(alphaq/11) (G protein q/11 alpha subunit), nonphagocytic NAD(P)H oxidases (NOX-1), and c-Src kinases (c-Src) were colocalized in the caveolae of rat arterial smooth muscle cells and the integrity of caveolae in smooth muscle cells was critical for Ang II-mediated BK channel regulation. Most importantly, membrane microdomain targeting of these proteins was upregulated in the caveolae of streptozotocin-induced rat diabetic vessels, leading to enhanced Ang II-induced redox-mediated BK channel modification and causing BK channel and coronary dysfunction. The absence of caveolae abolished the effects of Ang II on vascular BK channel activity and preserved BK channel function in diabetes. CONCLUSIONS These results identified a molecular scheme of receptor/enzyme/channel/caveolae microdomain complex that facilitates the development of vascular BK channel dysfunction in diabetes.
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Affiliation(s)
- Tong Lu
- Division of Cardiovascular Diseases, Department of Internal Medicine, Mayo Clinic, 200 First Street SW, Rochester, MN 55905, USA.
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44
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Dunn KM, Nelson MT. Calcium and diabetic vascular dysfunction. Focus on “Elevated Ca2+ sparklet activity during acute hyperglycemia and diabetes in cerebral arterial smooth muscle cells”. Am J Physiol Cell Physiol 2010; 298:C203-5. [DOI: 10.1152/ajpcell.00499.2009] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Affiliation(s)
- Kathryn M. Dunn
- Department of Pharmacology, University of Vermont College of Medicine, Burlington, Vermont
| | - Mark T. Nelson
- Department of Pharmacology, University of Vermont College of Medicine, Burlington, Vermont
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Li H, Jiang LS, Dai LY. High glucose potentiates collagen synthesis and bone morphogenetic protein-2-induced early osteoblast gene expression in rat spinal ligament cells. Endocrinology 2010; 151:63-74. [PMID: 19915165 DOI: 10.1210/en.2009-0833] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Type 2 diabetes mellitus (T2DM) is an independent risk factor for ossification of the posterior longitudinal ligament, but the mechanism is unclear. We isolated cells from rat cervical spine ligaments and studied the effects of high glucose on expression of osteoblast genes to provide insight into molecular mechanism. Using these cells, high glucose stimulated the synthesis of type I collagen and significantly potentiated expression of early osteoblast genes (Runx2; alkaline phosphatase, ALP; and osteopontin, OP) induced by bone morphogenetic protein-2 (BMP-2). Notably, these effects of high glucose were fully mimicked and augmented by H(2)O(2), although blocked by the reactive oxygen species inhibitor N-acetyl cysteine. Furthermore, exposure of these cells to high glucose significantly suppressed the phosphorylation of p38MAPK while enhancing the phosphorylation of protein kinase C (PKC) in the cells. Consistent with these observations, an inhibitor of p38 augmented the potentiation of high glucose on BMP-2-induced early osteogenic gene expression, whereas the PKC inhibitor repressed the effect of high glucose on type I collagen synthesis of the cells. In conclusion, high glucose, via production of reactive oxygen species, subsequent activation of PKC, and inhibition of p38, enhances type I collagen synthesis and expression of early osteogenesis genes induced by BMP-2 in rat spinal ligament cells. Hyperglycemia may play an important role in the onset or progression of ossification of the posterior longitudinal ligament by promoting the responsiveness of ligament cells to osteogenic differentiation.
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Affiliation(s)
- Hai Li
- Department of Orthopedic Surgery, Xinhua Hospital, Shanghai Jiaotong University School of Medicine, 200092 Shanghai, China
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Gao Y, Yang Y, Guan Q, Pang X, Zhang H, Zeng D. IL-1beta modulate the Ca(2+)-activated big-conductance K channels (BK) via reactive oxygen species in cultured rat aorta smooth muscle cells. Mol Cell Biochem 2009; 338:59-68. [PMID: 19949838 DOI: 10.1007/s11010-009-0338-4] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2009] [Accepted: 11/19/2009] [Indexed: 10/20/2022]
Abstract
The large conductance Ca(2+)-activated K(+) (BK) channel, abundantly expressed in vascular smooth muscle cells, plays a critical role in controlling vascular tone. Activation of BK channels leads to membrane hyperpolarization and promotes vasorelaxation. BK channels are activated either by elevation of the intracellular Ca(2+) concentration or by membrane depolarization. It is also regulated by a diversity of vasodilators and vasoconstrictors. Interleukin-1beta (IL-1beta) is one of the cytokines that play important roles in the development and progression of a variety of cardiovascular diseases. The effects of IL-1beta on vascular reactivity are controversial, and little is known about the modulation of BK channel function by IL-1beta. In this study, we investigated how IL-1beta modulates BK channel function in cultured arterial smooth muscle cells (ASMCs), and examined the role of H(2)O(2) in the process. We demonstrated that IL-1beta had biphasic effects on BK channel function and membrane potential of ASMCs, that is both concentration and time dependent. IL-1beta increased BK channel-dependent K(+) current and hyperpolarized ASMCs when applied for 30 min. While long-term (24-48 h) treatment of IL-1beta resulted in decreased expression of alpha-subunit of BK channel, suppressed BK channel activity, decreased BK channel-dependent K(+) current and depolarization of the cells. H(2)O(2) scavenger catalase completely abolished the early effect of IL-1beta, while it only partly diminished the long-term effect of IL-1beta. These results may provide important molecular mechanisms for therapeutic strategies targeting BK channel in inflammation-related diseases.
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Affiliation(s)
- Yuan Gao
- Department of Cardiology, the First Affiliated Hospital, China Medical University, Heping District, Shengyang, People's Republic of China
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Hreiche R, Plante I, David LP, Simard C, Turgeon J, Drolet B. Impact of glucose concentration on cardiac ventricular repolarization under IKr/IKs blocking agents. J Mol Cell Cardiol 2009; 47:210-20. [DOI: 10.1016/j.yjmcc.2009.02.004] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/15/2008] [Revised: 01/21/2009] [Accepted: 02/05/2009] [Indexed: 12/12/2022]
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Dong L, Xie MJ, Zhang P, Ji LL, Liu WC, Dong MQ, Gao F. Rotenone partially reverses decreased BK Ca currents in cerebral artery smooth muscle cells from streptozotocin-induced diabetic mice. Clin Exp Pharmacol Physiol 2009; 36:e57-64. [PMID: 19515065 DOI: 10.1111/j.1440-1681.2009.05222.x] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
1. Reactive oxygen species (ROS) cause vascular complications and impair vasodilation in diabetes mellitus. Large-conductance Ca(2+)-activated potassium channels (BK(Ca)) modulate vascular tone and play an important negative feedback role in vasoconstriction. In the present study, we tested the hypothesis that ROS regulate the function of BK(Ca) in diabetic cerebral artery smooth muscle cells. 2. Diabetes was induced in male BALB/c mice by injection of streptozotocin (STZ; 180 mg/kg, i.p., dissolved in sterile saline). Control and diabetic mice were treated with 12.7 micromol/L rotenone, an inhibitor of the mitochondrial electron transport chain complex I, or placebo every other day for 5 weeks. The whole-cell patch clamp-technique and functional vasomotor methods were used to record BK(Ca) currents and myogenic tone of cerebral artery smooth muscle cells. 3. In the diabetic group, there was a significant decrease in spontaneous transient outward currents in cerebral artery smooth muscle cells compared with control. Although the currents were only moderately increased in rotenone-treated diabetic mice, they remained significantly lower than in the control group. Furthermore, the macroscopic BK(Ca) currents that were decreased in diabetic mice were partially recovered in rotenone-treated diabetic mice (P < 0.05 vs untreated diabetic group). 4. The posterior cerebral artery from diabetic mice had a significantly higher myogenic tone than the control group, but this impaired contraction was partially reversed in the rotenone-treated diabetic group (P < 0.05 vs untreated diabetic group). 5. The H(2)O(2) concentration was significantly increased in cerebral arteries from diabetic mice compared with control. This increase in H(2)O(2) was significantly blunted by rotenone treatment. 6. In conclusion, rotenone partially reverses the decreased macroscopic BK(Ca) currents in STZ-induced Type 1 diabetic mice and this reversal of BK(Ca) currents may be related to the inhibitory effects of rotenone on H(2)O(2) production. Reactive oxygen species, particularly H(2)O(2), are important regulators of BK(Ca) channels and myogenic tone in diabetic cerebral artery.
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Affiliation(s)
- Ling Dong
- Department of Physiology, Fourth Military Medical University, Xi'an 710032, China
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Hou S, Heinemann SH, Hoshi T. Modulation of BKCa channel gating by endogenous signaling molecules. Physiology (Bethesda) 2009; 24:26-35. [PMID: 19196649 DOI: 10.1152/physiol.00032.2008] [Citation(s) in RCA: 109] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Large-conductance Ca(2+)- and voltage-activated K(+) (BK(Ca), MaxiK, or Slo1) channels are expressed in almost every tissue in our body and participate in many critical functions such as neuronal excitability, vascular tone regulation, and neurotransmitter release. The functional versatility of BK(Ca) channels owes in part to the availability of a spectacularly wide array of biological modulators of the channel function. In this review, we focus on modulation of BK(Ca) channels by small endogenous molecules, emphasizing their molecular mechanisms. The mechanistic information available from studies on the small naturally occurring modulators is expected to contribute to our understanding of the physiological and pathophysiological roles of BK(Ca) channels.
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Affiliation(s)
- Shangwei Hou
- Department of Physiology, University of Pennsylvania, Philadelphia, Pennsylvania, USA
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Félétou M. Calcium-activated potassium channels and endothelial dysfunction: therapeutic options? Br J Pharmacol 2009; 156:545-62. [PMID: 19187341 DOI: 10.1111/j.1476-5381.2009.00052.x] [Citation(s) in RCA: 191] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022] Open
Abstract
The three subtypes of calcium-activated potassium channels (K(Ca)) of large, intermediate and small conductance (BK(Ca), IK(Ca) and SK(Ca)) are present in the vascular wall. In healthy arteries, BK(Ca) channels are preferentially expressed in vascular smooth muscle cells, while IK(Ca) and SK(Ca) are preferentially located in endothelial cells. The activation of endothelial IK(Ca) and SK(Ca) contributes to nitric oxide (NO) generation and is required to elicit endothelium-dependent hyperpolarizations. In the latter responses, the hyperpolarization of the smooth muscle cells is evoked either via electrical coupling through myo-endothelial gap junctions or by potassium ions, which by accumulating in the intercellular space activate the inwardly rectifying potassium channel Kir2.1 and/or the Na(+)/K(+)-ATPase. Additionally, endothelium-derived factors such as cytochrome P450-derived epoxyeicosatrienoic acids and under some circumstances NO, prostacyclin, lipoxygenase products and hydrogen peroxide (H(2)O(2)) hyperpolarize and relax the underlying smooth muscle cells by activating BK(Ca). In contrast, cytochrome P450-derived 20-hydroxyeicosatetraenoic acid and various endothelium-derived contracting factors inhibit BK(Ca). Aging and cardiovascular diseases are associated with endothelial dysfunctions that can involve a decrease in NO bioavailability, alterations of EDHF-mediated responses and/or enhanced production of endothelium-derived contracting factors. Because potassium channels are involved in these endothelium-dependent responses, activation of endothelial and/or smooth muscle K(Ca) could prevent the occurrence of endothelial dysfunction. Therefore, direct activators of these potassium channels or compounds that regulate their activity or their expression may be of some therapeutic interest. Conversely, blockers of IK(Ca) may prevent restenosis and that of BK(Ca) channels sepsis-dependent hypotension.
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Affiliation(s)
- Michel Félétou
- Department of Angiology, Institut de Recherches Servier, Suresnes, France.
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