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Brennan S, Chen S, Makwana S, Esposito S, McGuinness LR, Alnaimi AIM, Sims MW, Patel M, Aziz Q, Ojake L, Roberts JA, Sharma P, Lodwick D, Tinker A, Barrett-Jolley R, Dart C, Rainbow RD. Identification and characterisation of functional K ir6.1-containing ATP-sensitive potassium channels in the cardiac ventricular sarcolemmal membrane. Br J Pharmacol 2024. [PMID: 38763521 DOI: 10.1111/bph.16390] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2023] [Revised: 02/21/2024] [Accepted: 03/18/2024] [Indexed: 05/21/2024] Open
Abstract
BACKGROUND AND PURPOSE The canonical Kir6.2/SUR2A ventricular KATP channel is highly ATP-sensitive and remains closed under normal physiological conditions. These channels activate only when prolonged metabolic compromise causes significant ATP depletion and then shortens the action potential to reduce contractile activity. Pharmacological activation of KATP channels is cardioprotective, but physiologically, it is difficult to understand how these channels protect the heart if they only open under extreme metabolic stress. The presence of a second KATP channel population could help explain this. Here, we characterise the biophysical and pharmacological behaviours of a constitutively active Kir6.1-containing KATP channel in ventricular cardiomyocytes. EXPERIMENTAL APPROACH Patch-clamp recordings from rat ventricular myocytes in combination with well-defined pharmacological modulators was used to characterise these newly identified K+ channels. Action potential recording, calcium (Fluo-4) fluorescence measurements and video edge detection of contractile function were used to assess functional consequences of channel modulation. KEY RESULTS Our data show a ventricular K+ conductance whose biophysical characteristics and response to pharmacological modulation were consistent with Kir6.1-containing channels. These Kir6.1-containing channels lack the ATP-sensitivity of the canonical channels and are constitutively active. CONCLUSION AND IMPLICATIONS We conclude there are two functionally distinct populations of ventricular KATP channels: constitutively active Kir6.1-containing channels that play an important role in fine-tuning the action potential and Kir6.2/SUR2A channels that activate with prolonged ischaemia to impart late-stage protection against catastrophic ATP depletion. Further research is required to determine whether Kir6.1 is an overlooked target in Comprehensive in vitro Proarrhythmia Assay (CiPA) cardiac safety screens.
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Affiliation(s)
- Sean Brennan
- Department of Cardiovascular and Metabolic Medicine and Liverpool Centre for Cardiovascular Science, University of Liverpool, Liverpool, UK
| | - Shen Chen
- Department of Cardiovascular Sciences, University of Leicester, Leicester, UK
| | - Samir Makwana
- Department of Cardiovascular Sciences, University of Leicester, Leicester, UK
| | - Simona Esposito
- Department of Cardiovascular and Metabolic Medicine and Liverpool Centre for Cardiovascular Science, University of Liverpool, Liverpool, UK
- Department of Cardiovascular Sciences, University of Leicester, Leicester, UK
| | - Lauren R McGuinness
- Department of Cardiovascular and Metabolic Medicine and Liverpool Centre for Cardiovascular Science, University of Liverpool, Liverpool, UK
| | - Abrar I M Alnaimi
- Department of Cardiovascular and Metabolic Medicine and Liverpool Centre for Cardiovascular Science, University of Liverpool, Liverpool, UK
- Department of Cardiac Technology, Imam Abdulrahman Bin Faisal University, Dammam, Saudi Arabia
| | - Mark W Sims
- Department of Cardiovascular Sciences, University of Leicester, Leicester, UK
| | - Manish Patel
- Department of Cardiovascular Sciences, University of Leicester, Leicester, UK
| | - Qadeer Aziz
- William Harvey Research Institute, Queen Mary University of London, London, UK
| | - Leona Ojake
- William Harvey Research Institute, Queen Mary University of London, London, UK
| | - James A Roberts
- Department of Cardiovascular and Metabolic Medicine and Liverpool Centre for Cardiovascular Science, University of Liverpool, Liverpool, UK
| | - Parveen Sharma
- Department of Cardiovascular and Metabolic Medicine and Liverpool Centre for Cardiovascular Science, University of Liverpool, Liverpool, UK
| | - David Lodwick
- Department of Cardiovascular Sciences, University of Leicester, Leicester, UK
| | - Andrew Tinker
- William Harvey Research Institute, Queen Mary University of London, London, UK
| | - Richard Barrett-Jolley
- Department of Musculoskeletal and Ageing Science, University of Liverpool, Liverpool, UK
| | - Caroline Dart
- Department of Biochemistry, Cell and Systems Biology, University of Liverpool, Liverpool, UK
| | - Richard D Rainbow
- Department of Cardiovascular and Metabolic Medicine and Liverpool Centre for Cardiovascular Science, University of Liverpool, Liverpool, UK
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Nichols CG. Personalized Therapeutics for K ATP-Dependent Pathologies. Annu Rev Pharmacol Toxicol 2023; 63:541-563. [PMID: 36170658 PMCID: PMC9868118 DOI: 10.1146/annurev-pharmtox-051921-123023] [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: 01/26/2023]
Abstract
Ubiquitously expressed throughout the body, ATP-sensitive potassium (KATP) channels couple cellular metabolism to electrical activity in multiple tissues; their unique assembly as four Kir6 pore-forming subunits and four sulfonylurea receptor (SUR) subunits has resulted in a large armory of selective channel opener and inhibitor drugs. The spectrum of monogenic pathologies that result from gain- or loss-of-function mutations in these channels, and the potential for therapeutic correction of these pathologies, is now clear. However, while available drugs can be effective treatments for specific pathologies, cross-reactivity with the other Kir6 or SUR subfamily members can result in drug-induced versions of each pathology and may limit therapeutic usefulness. This review discusses the background to KATP channel physiology, pathology, and pharmacology and considers the potential for more specific or effective therapeutic agents.
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Affiliation(s)
- Colin G. Nichols
- Center for the Investigation of Membrane Excitability Diseases and Department of Cell Biology and Physiology, Washington University School of Medicine, St. Louis, Missouri, USA
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3
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Bercea C, Limbu R, Behnam K, Ng KE, Aziz Q, Tinker A, Tamagnini F, Cottrell GS, McNeish AJ. Omega-3 polyunsaturated fatty acid-induced vasodilation in mouse aorta and mesenteric arteries is not mediated by ATP-sensitive potassium channels. Front Physiol 2022; 13:1033216. [PMID: 36589427 PMCID: PMC9797959 DOI: 10.3389/fphys.2022.1033216] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2022] [Accepted: 11/30/2022] [Indexed: 12/23/2022] Open
Abstract
There is strong evidence that the omega-3 polyunsaturated fatty acids (n-3 PUFAs) docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA) have cardioprotective effects. n-3 PUFAs cause vasodilation in hypertensive patients, in part controlled by increased membrane conductance to potassium. As KATP channels play a major role in vascular tone regulation and are involved in hypertension, we aimed to verify whether n-3 PUFA-mediated vasodilation involved the opening of KATP channels. We used a murine model in which the KATP channel pore subunit, Kir6.1, is deleted in vascular smooth muscle. The vasomotor response of preconstricted arteries to physiologically relevant concentrations of DHA and EPA was measured using wire myography, using the channel blocker PNU-37883A. The effect of n-3 PUFAs on potassium currents in wild-type native smooth muscle cells was investigated using whole-cell patch clamping. DHA and EPA induced vasodilation in mouse aorta and mesenteric arteries; relaxations in the aorta were sensitive to KATP blockade with PNU-37883A. Endothelium removal didn't affect relaxation to EPA and caused a small but significant inhibition of relaxation to DHA. In the knock-out model, relaxations to DHA and EPA were unaffected by channel knockdown but were still inhibited by PNU-37883A, indicating that the action of PNU-37883A on relaxation may not reflect inhibition of KATP. In native aortic smooth muscle cells DHA failed to activate KATP currents. We conclude that DHA and EPA cause vasodilation in mouse aorta and mesenteric arteries. Relaxations in blocker-treated arteries from knock-out mice demonstrate that KATP channels are not involved in the n-3 PUFA-induced relaxation.
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Affiliation(s)
- Cristiana Bercea
- McNeish Laboratory, School of Chemistry, Food and Pharmacy, Department of Pharmacology, University of Reading, London, United Kingdom
- Tinker Laboratory, William Harvey Research Institute, Clinical Pharmacology and Precision Medicine, Queen Mary University, London, United Kingdom
| | - Roshan Limbu
- McNeish Laboratory, School of Chemistry, Food and Pharmacy, Department of Pharmacology, University of Reading, London, United Kingdom
| | - Kamila Behnam
- McNeish Laboratory, School of Chemistry, Food and Pharmacy, Department of Pharmacology, University of Reading, London, United Kingdom
| | - Keat-Eng Ng
- Tinker Laboratory, William Harvey Research Institute, Clinical Pharmacology and Precision Medicine, Queen Mary University, London, United Kingdom
| | - Qadeer Aziz
- Tinker Laboratory, William Harvey Research Institute, Clinical Pharmacology and Precision Medicine, Queen Mary University, London, United Kingdom
| | - Andrew Tinker
- Tinker Laboratory, William Harvey Research Institute, Clinical Pharmacology and Precision Medicine, Queen Mary University, London, United Kingdom
| | - Francesco Tamagnini
- McNeish Laboratory, School of Chemistry, Food and Pharmacy, Department of Pharmacology, University of Reading, London, United Kingdom
| | - Graeme S Cottrell
- McNeish Laboratory, School of Chemistry, Food and Pharmacy, Department of Pharmacology, University of Reading, London, United Kingdom
| | - Alister J McNeish
- McNeish Laboratory, School of Chemistry, Food and Pharmacy, Department of Pharmacology, University of Reading, London, United Kingdom
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Kir Channel Molecular Physiology, Pharmacology, and Therapeutic Implications. Handb Exp Pharmacol 2021; 267:277-356. [PMID: 34345939 DOI: 10.1007/164_2021_501] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
For the past two decades several scholarly reviews have appeared on the inwardly rectifying potassium (Kir) channels. We would like to highlight two efforts in particular, which have provided comprehensive reviews of the literature up to 2010 (Hibino et al., Physiol Rev 90(1):291-366, 2010; Stanfield et al., Rev Physiol Biochem Pharmacol 145:47-179, 2002). In the past decade, great insights into the 3-D atomic resolution structures of Kir channels have begun to provide the molecular basis for their functional properties. More recently, computational studies are beginning to close the time domain gap between in silico dynamic and patch-clamp functional studies. The pharmacology of these channels has also been expanding and the dynamic structural studies provide hope that we are heading toward successful structure-based drug design for this family of K+ channels. In the present review we focus on placing the physiology and pharmacology of this K+ channel family in the context of atomic resolution structures and in providing a glimpse of the promising future of therapeutic opportunities.
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Glück C, Ferrari KD, Binini N, Keller A, Saab AS, Stobart JL, Weber B. Distinct signatures of calcium activity in brain mural cells. eLife 2021; 10:e70591. [PMID: 34227466 PMCID: PMC8294852 DOI: 10.7554/elife.70591] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2021] [Accepted: 06/15/2021] [Indexed: 12/15/2022] Open
Abstract
Pericytes have been implicated in various neuropathologies, yet little is known about their function and signaling pathways in health. Here, we characterized calcium dynamics of cortical mural cells in anesthetized or awake Pdgfrb-CreERT2;Rosa26< LSL-GCaMP6s > mice and in acute brain slices. Smooth muscle cells (SMCs) and ensheathing pericytes (EPs), also named as terminal vascular SMCs, revealed similar calcium dynamics in vivo. In contrast, calcium signals in capillary pericytes (CPs) were irregular, higher in frequency, and occurred in cellular microdomains. In the absence of the vessel constricting agent U46619 in acute slices, SMCs and EPs revealed only sparse calcium signals, whereas CPs retained their spontaneous calcium activity. Interestingly, chemogenetic activation of neurons in vivo and acute elevations of extracellular potassium in brain slices strongly decreased calcium activity in CPs. We propose that neuronal activation and an extracellular increase in potassium suppress calcium activity in CPs, likely mediated by Kir2.2 and KATP channels.
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Affiliation(s)
- Chaim Glück
- Institute of Pharmacology and Toxicology, University of ZurichZürichSwitzerland
- Neuroscience Center Zurich, University and ETH ZurichZurichSwitzerland
| | - Kim David Ferrari
- Institute of Pharmacology and Toxicology, University of ZurichZürichSwitzerland
- Neuroscience Center Zurich, University and ETH ZurichZurichSwitzerland
| | - Noemi Binini
- Institute of Pharmacology and Toxicology, University of ZurichZürichSwitzerland
- Neuroscience Center Zurich, University and ETH ZurichZurichSwitzerland
| | - Annika Keller
- Neuroscience Center Zurich, University and ETH ZurichZurichSwitzerland
- Department of Neurosurgery, University of ZurichSchlierenSwitzerland
| | - Aiman S Saab
- Institute of Pharmacology and Toxicology, University of ZurichZürichSwitzerland
- Neuroscience Center Zurich, University and ETH ZurichZurichSwitzerland
| | - Jillian L Stobart
- Institute of Pharmacology and Toxicology, University of ZurichZürichSwitzerland
- Rady Faculty of Health Sciences, College of PharmacyWinnipegCanada
| | - Bruno Weber
- Institute of Pharmacology and Toxicology, University of ZurichZürichSwitzerland
- Neuroscience Center Zurich, University and ETH ZurichZurichSwitzerland
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Panou MM, Antoni M, Morgan EL, Loundras EA, Wasson CW, Welberry-Smith M, Mankouri J, Macdonald A. Glibenclamide inhibits BK polyomavirus infection in kidney cells through CFTR blockade. Antiviral Res 2020; 178:104778. [PMID: 32229236 PMCID: PMC7322401 DOI: 10.1016/j.antiviral.2020.104778] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2020] [Revised: 03/07/2020] [Accepted: 03/18/2020] [Indexed: 02/08/2023]
Abstract
BK polyomavirus (BKPyV) is a ubiquitous pathogen in the human population that is asymptomatic in healthy individuals, but can be life-threatening in those undergoing kidney transplant. To-date, no vaccines or anti-viral therapies are available to treat human BKPyV infections. New therapeutic strategies are urgently required. In this study, using a rational pharmacological screening regimen of known ion channel modulating compounds, we show that BKPyV requires cystic fibrosis transmembrane conductance regulator (CFTR) activity to infect primary renal proximal tubular epithelial cells. Disrupting CFTR function through treatment with the clinically available drug glibenclamide, the CFTR inhibitor CFTR172, or CFTR-silencing, all reduced BKPyV infection. Specifically, time of addition assays and the assessment of the exposure of VP2/VP3 minor capsid proteins indicated a role for CFTR during BKPyV transport to the endoplasmic reticulum, an essential step during the early stages of BKPyV infection. We thus establish CFTR as an important host-factor in the BKPyV life cycle and reveal CFTR modulators as potential anti-BKPyV therapies. BK polyomavirus (BKPyV) is life-threatening in those undergoing kidney transplant. BKPyV requires CFTR to infect primary kidney cells. Disrupting CFTR function pharmacologically reduces BKPyV infection. CFTR is required during BKPyV transport to the endoplasmic reticulum.
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Affiliation(s)
- Margarita-Maria Panou
- School of Molecular and Cellular Biology, Faculty of Biological Sciences and Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds, West Yorkshire, LS2 9JT, United Kingdom
| | - Michelle Antoni
- School of Molecular and Cellular Biology, Faculty of Biological Sciences and Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds, West Yorkshire, LS2 9JT, United Kingdom
| | - Ethan L Morgan
- School of Molecular and Cellular Biology, Faculty of Biological Sciences and Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds, West Yorkshire, LS2 9JT, United Kingdom
| | - Eleni-Anna Loundras
- School of Molecular and Cellular Biology, Faculty of Biological Sciences and Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds, West Yorkshire, LS2 9JT, United Kingdom
| | - Christopher W Wasson
- School of Molecular and Cellular Biology, Faculty of Biological Sciences and Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds, West Yorkshire, LS2 9JT, United Kingdom
| | | | - Jamel Mankouri
- School of Molecular and Cellular Biology, Faculty of Biological Sciences and Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds, West Yorkshire, LS2 9JT, United Kingdom.
| | - Andrew Macdonald
- School of Molecular and Cellular Biology, Faculty of Biological Sciences and Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds, West Yorkshire, LS2 9JT, United Kingdom.
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7
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Turzo M, Vaith J, Lasitschka F, Weigand MA, Busch CJ. Role of ATP-sensitive potassium channels on hypoxic pulmonary vasoconstriction in endotoxemia. Respir Res 2018; 19:29. [PMID: 29433570 PMCID: PMC5810061 DOI: 10.1186/s12931-018-0735-x] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2017] [Accepted: 02/05/2018] [Indexed: 02/12/2023] Open
Abstract
BACKGROUND ATP-regulated potassium channels (KATP) regulate pulmonary vascular tone and are involved in hypoxic pulmonary vasoconstriction (HPV). In patients with inflammation like sepsis or ARDS, HPV is impaired, resulting in a ventilation-perfusion mismatch and hypoxia. Since increase of vascular KATP channel Kir6.1 has been reported in animal models of endotoxemia, we studied the expression and physiological effects of Kir6.1 in murine endotoxemic lungs. We hypothesized that inhibition of overexpressed Kir6.1 increases HPV in endotoxemia. METHODS Mice (C57BL/6; n = 55) with (n = 27) and without (n = 28) endotoxemia (35 mg/kg LPS i.p. for 18 h) were analyzed for Kir6.1 gene as well as protein expression and HPV was examined in isolated perfused mouse lungs with and without selective inhibition of Kir6.1 with PNU-37883A. Pulmonary artery pressure (PAP) and pressure-flow curves during normoxic (FiO2 0.21) and hypoxic (FiO2 0.01) ventilation were obtained. HPV was quantified as the increase in perfusion pressure in response to hypoxic ventilation in mmHg of baseline perfusion pressure (ΔPAP) in the presence and absence of PNU-37883A. RESULTS Endotoxemia increases pulmonary Kir6.1 gene (+ 2.8 ± 0.3-fold) and protein expression (+ 2.1 ± 0.3-fold). Hypoxia increases HPV in lungs of control animals, while endotoxemia decreases HPV (∆PAP control: 9.2 ± 0.9 mmHg vs. LPS: 3.0 ± 0.7 mmHg, p < 0.05, means ± SEM). Inhibition of Kir6.1 with 1 μM PNU-37883A increases HPV in endotoxemia, while not increasing HPV in controls (∆PAP PNU control: 9.3 ± 0.7 mmHg vs. PNU LPS 8.3 ± 0.9 mmHg, p < 0.05, means ± SEM). CONCLUSION Endotoxemia increases pulmonary Kir6.1 gene and protein expression. Inhibition of Kir6.1 augments HPV in murine endotoxemic lungs.
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Affiliation(s)
- Maurizio Turzo
- Department of Anesthesiology, Heidelberg University Hospital, Im Neuenheimer Feld 110, 69120, Heidelberg, Germany
| | - Julian Vaith
- Department of Anesthesiology, Heidelberg University Hospital, Im Neuenheimer Feld 110, 69120, Heidelberg, Germany
| | - Felix Lasitschka
- Institute of Pathology, Heidelberg University Hospital, Heidelberg, Germany
| | - Markus A Weigand
- Department of Anesthesiology, Heidelberg University Hospital, Im Neuenheimer Feld 110, 69120, Heidelberg, Germany
| | - Cornelius J Busch
- Department of Anesthesiology, Heidelberg University Hospital, Im Neuenheimer Feld 110, 69120, Heidelberg, Germany.
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Molecular analysis of ATP-sensitive K(+) channel subunits expressed in mouse portal vein. Vascul Pharmacol 2015; 75:29-39. [PMID: 26163942 DOI: 10.1016/j.vph.2015.06.018] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2015] [Revised: 06/16/2015] [Accepted: 06/29/2015] [Indexed: 11/23/2022]
Abstract
BACKGROUND Several combinations of inwardly rectifying K(+) channel 6.x family pore-forming (KIR6.x) subunits associated with sulphonylurea receptor (SUR.x) subunits have been detected among ATP-sensitive K(+) (KATP) channels. It remains to be established which of these is expressed in native vascular smooth muscle. METHODS Pharmacological and electrophysiological properties of KATP channels in mouse portal vein were investigated using tension measurements and patch-clamp techniques. Molecular biological analyses were also performed to investigate the structural properties of these channels. RESULTS Spontaneous contractions in mouse portal vein were reversibly reduced by pinacidil and MCC-134, and the pinacidil-induced relaxation was antagonized by glibenclamide and U-37883A. In cell-attached mode, pinacidil activated glibenclamide-sensitive K(+) channels with a conductance (35 pS) similar to that of KIR6.1. RT-PCR analysis revealed the expression of KIR6.1, KIR6.2 and SUR2B transcripts. Using real-time PCR methods, the quantitative expression of KIR6.1 was much greater than that of KIR6.2. Immunohistochemical studies indicated the presence of KIR6.1 and SUR2B proteins in the smooth muscle layers of mouse portal vein and in single smooth muscle cells dispersed from mouse portal vein. CONCLUSIONS The results indicate that native KATP channels in mouse portal vein are likely to be composed of a heterocomplex of KIR6.1 and SUR2B subunits.
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Umaru B, Pyriochou A, Kotsikoris V, Papapetropoulos A, Topouzis S. ATP-sensitive potassium channel activation induces angiogenesis in vitro and in vivo. J Pharmacol Exp Ther 2015; 354:79-87. [PMID: 25977483 DOI: 10.1124/jpet.114.222000] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2014] [Accepted: 05/13/2015] [Indexed: 12/19/2022] Open
Abstract
Intense research is conducted to identify new molecular mechanisms of angiogenesis. Previous studies have shown that the angiogenic effects of hydrogen sulfide (H2S) depend on the activation of ATP-sensitive potassium channels (KATP) and that C-type natriuretic peptide (CNP), which can act through KATP, promotes endothelial cell growth. We therefore investigated whether direct KATP activation induces angiogenic responses and whether it is required for the endothelial responses to CNP or vascular endothelial growth factor (VEGF). Chick chorioallantoic membrane (CAM) angiogenesis was similarly enhanced by the direct KATP channel activator 2-nicotinamidoethyl acetate (SG-209) and by CNP or VEGF. The KATP inhibitors glibenclamide and 5-hydroxydecanoate (5-HD) reduced basal and abolished CNP-induced CAM angiogenesis. In vitro, the direct KATP openers nicorandil and SG-209 and the polypeptides VEGF and CNP increased proliferation and migration in bEnd.3 mouse endothelial cells. In addition, VEGF and CNP induced cord-like formation on Matrigel by human umbilical vein endothelial cells (HUVECs). All these in vitro endothelial responses were effectively abrogated by glibenclamide or 5-HD. In HUVECs, a small-interfering RNA-mediated decrease in the expression of the inwardly rectifying potassium channel (Kir) 6.1 subunit impaired cell migration and network morphogenesis in response to either SG-209 or CNP. We conclude that 1) direct pharmacologic activation of KATP induces angiogenic effects in vitro and in vivo, 2) angiogenic responses to CNP and VEGF depend on KATP activation and require the expression of the Kir6.1 KATP subunit, and 3) KATP activation may underpin angiogenesis to a variety of vasoactive stimuli, including H2S, VEGF, and CNP.
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Affiliation(s)
- Bukar Umaru
- Laboratory of Molecular Pharmacology, Department of Pharmacy, University of Patras, Rio-Patras, Greece (B.U., A.Py., V.K., S.T.); and Department of Pharmacy, National and Kapodistrian University of Athens, Athens, Greece (A.Pa.)
| | - Anastasia Pyriochou
- Laboratory of Molecular Pharmacology, Department of Pharmacy, University of Patras, Rio-Patras, Greece (B.U., A.Py., V.K., S.T.); and Department of Pharmacy, National and Kapodistrian University of Athens, Athens, Greece (A.Pa.)
| | - Vasileios Kotsikoris
- Laboratory of Molecular Pharmacology, Department of Pharmacy, University of Patras, Rio-Patras, Greece (B.U., A.Py., V.K., S.T.); and Department of Pharmacy, National and Kapodistrian University of Athens, Athens, Greece (A.Pa.)
| | - Andreas Papapetropoulos
- Laboratory of Molecular Pharmacology, Department of Pharmacy, University of Patras, Rio-Patras, Greece (B.U., A.Py., V.K., S.T.); and Department of Pharmacy, National and Kapodistrian University of Athens, Athens, Greece (A.Pa.)
| | - Stavros Topouzis
- Laboratory of Molecular Pharmacology, Department of Pharmacy, University of Patras, Rio-Patras, Greece (B.U., A.Py., V.K., S.T.); and Department of Pharmacy, National and Kapodistrian University of Athens, Athens, Greece (A.Pa.)
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Sato K, Chino D, Nishioka N, Kanai K, Aoki M, Obara K, Miyauchi S, Tanaka Y. Pharmacological evidence showing significant roles for potassium channels and CYP epoxygenase metabolites in the relaxant effects of docosahexaenoic acid on the rat aorta contracted with U46619. Biol Pharm Bull 2013; 37:394-403. [PMID: 24369179 DOI: 10.1248/bpb.b13-00746] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Docosahexaenoic acid (DHA) shows more pronounced relaxation when blood vessel is contracted with prostanoid receptor agonists than other stimulants. The present study was carried out to obtain information on the mechanisms underlying prostanoid receptor-selective relaxant action of DHA, particularly focusing on the possible roles for K(+) channels and its CYP epoxygenase (EOX) metabolites. In endothelium-denuded rat thoracic aorta, DHA (10(-5) M) almost completely relaxed U46619 (a thromboxane A2 (TP) receptor agonist)-contracted muscle without substantially affecting noradrenaline (NA)-induced contraction. DHA-induced relaxation was not affected by a large conductance, calcium- and voltage-activated K(+) (BK) channels inhibitor iberiotoxin (IbTX, 10(-7) M) but was almost abolished by high-KCl (8×10(-2) M) or 10(-2) M tetraethylammonium (TEA) which non-selectively inhibits K(+) channel activity. DHA also prominently relaxed U46619-contracted aorta even in the presence of CYP inhibitors (SKF525A or miconazole, each at 10(-5) M). However, in the presence of these CYP inhibitors, the relaxant action of DHA was not affected by 10(-2) M TEA. In supporting a significant role for CYP EOX metabolites in the blood vessel relaxation to DHA, 16,17-epoxy docosapentaenoic acid (16,17-EpDPE), but not 19,20-EpDPE, showed a potent relaxation in U46619-contracted aorta, and this action was significantly attenuated by 10(-2) M TEA. The present findings suggest that the relaxant action of DHA shown in the rat aorta contracted through the stimulation with TP receptor is generated by DHA itself and its CYP EOX metabolites. The relaxant effect of DHA metabolites seems to be partly triggered by the activation of K(+) channels though the role for BK channel is insignificant.
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Affiliation(s)
- Kyosuke Sato
- Department of Pharmacology, Toho University School of Pharmaceutical Sciences
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Yu L, Jin X, Cui N, Wu Y, Shi Z, Zhu D, Jiang C. Rosiglitazone selectively inhibits K(ATP) channels by acting on the K(IR) 6 subunit. Br J Pharmacol 2013; 167:26-36. [PMID: 22394376 DOI: 10.1111/j.1476-5381.2012.01934.x] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
BACKGROUND AND PURPOSE Rosiglitazone is an anti-diabetic drug acting as an insulin sensitizer. We recently found that rosiglitazone also inhibits the vascular isoform of ATP-sensitive K(+) channels and compromises vasodilatory effects of β-adrenoceptor activation and pinacidil. As its potency for the channel inhibition is in the micromolar range, rosiglitazone may be used as an effective K(ATP) channel inhibitor for research and therapeutic purposes. Therefore, we performed experiments to determine whether other isoforms of K(ATP) channels are also sensitive to rosiglitazone and what their sensitivities are. EXPERIMENTAL APPROACH K(IR) 6.1/SUR2B, K(IR) 6.2/SUR1, K(IR) 6.2/SUR2A, K(IR) 6.2/SUR2B and K(IR) 6.2ΔC36 channels were expressed in HEK293 cells and were studied using patch-clamp techniques. KEY RESULTS Rosiglitazone inhibited all isoforms of K(ATP) channels in excised patches and in the whole-cell configuration. Its IC(50) was 10 µmol·L(-1) for the K(IR) 6.1/SUR2B channel and ∼45 µmol·L(-1) for K(IR) 6.2/SURx channels. Rosiglitazone also inhibited K(IR) 6.2ΔC36 channels in the absence of the sulphonylurea receptor (SUR) subunit, with potency (IC(50) = 45 µmol·L(-1) ) almost identical to that for K(IR) 6.2/SURx channels. Single-channel kinetic analysis showed that the channel inhibition was mediated by augmentation of the long-lasting closures without affecting the channel open state and unitary conductance. In contrast, rosiglitazone had no effect on K(IR) 1.1, K(IR) 2.1 and K(IR) 4.1 channels, suggesting that the channel inhibitory effect is selective for K(IR) 6.x channels. CONCLUSIONS AND IMPLICATIONS These results suggest a novel K(ATP) channel inhibitor that acts on the pore-forming K(IR) 6.x subunit, affecting the channel gating.
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Affiliation(s)
- Lei Yu
- Department of Biology, Georgia State University, Atlanta, Georgia 30302-4010, USA.
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Mar GY, Chou MT, Chung HH, Chiu NH, Chen MF, Cheng JT. Changes of imidazoline receptors in spontaneously hypertensive rats. Int J Exp Pathol 2012; 94:17-24. [PMID: 23176371 DOI: 10.1111/iep.12000] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2012] [Revised: 07/13/2012] [Indexed: 12/27/2022] Open
Abstract
The role of imidazoline receptors in the regulation of vascular function remains unclear. In this study, we evaluated the effect of agmatine, an imidazoline receptor agonist, on systolic blood pressure (SBP) in spontaneously hypertensive rats (SHRs) and investigated the expressions of imidazoline receptors by Western blot. The isometric tension of aortic rings isolated from male SHRs was also estimated. Agmatine decreased SBP in a dose-dependent manner in SHRs but not in the normal group [Wistar-Kyoto (WKY) rats]. This reduction in SBP in SHRs was abolished by BU224, a selective antagonist of imidazoline I(2) -receptors. Higher expression of imidazoline receptors in SHR was observed. Moreover, agmatine-induced relaxation in isolated aortic rings precontracted with phenylephrine or KCl. This relaxation was also abolished by BU224 but was not modified by efaroxan, an imidazoline I(1) -receptor antagonist. Agmatine-induced relaxation was also attenuated by PNU 37883, a selective blocker of vascular ATP-sensitive potassium (K(ATP) ) channels. Additionally, vasodilatation by agmatine was reduced by an inhibitor of protein kinase A (PKA). We suggest that agmatine can lower blood pressure in SHRs through activation of the peripheral imidazoline I(2) -receptor, which is expressed more highly in SHRs.
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Affiliation(s)
- Guang-Yuan Mar
- Department of Cardiology, Kaohsiung Veterans General Hospital, Kaohsiung City, Taiwan
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Collin S, Sennoun N, Dron AG, de la Bourdonnaye M, Montemont C, Asfar P, Lacolley P, Meziani F, Levy B. Vascular ATP-sensitive potassium channels are over-expressed and partially regulated by nitric oxide in experimental septic shock. Intensive Care Med 2011; 37:861-9. [DOI: 10.1007/s00134-011-2169-5] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2010] [Accepted: 02/08/2011] [Indexed: 10/18/2022]
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Aziz Q, Thomas A, Khambra T, Tinker A. Phenformin has a direct inhibitory effect on the ATP-sensitive potassium channel. Eur J Pharmacol 2010; 634:26-32. [PMID: 20188727 DOI: 10.1016/j.ejphar.2010.02.023] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2009] [Revised: 01/29/2010] [Accepted: 02/14/2010] [Indexed: 11/17/2022]
Abstract
The biguanides, phenformin and metformin, are used in the treatment of type II diabetes mellitus, as well as being routinely used in studies investigating AMPK activity. We used the patch-clamp technique and rubidium flux assays to determine the role of these drugs in ATP-sensitive K+ channel (K(ATP)) regulation in cell lines expressing the cloned components of K(ATP) and the current natively expressed in vascular smooth muscle cells (VSMCs). Phenformin but not metformin inhibits a number of variants of K(ATP) including the cloned equivalents of currents present in vascular and non-vascular smooth muscle (Kir6.1/SUR2B and Kir6.2/SUR2B) and pancreatic beta-cells (Kir6.2/SUR1). However it does not inhibit the current potentially present in cardiac myocytes (Kir6.2/SUR2A). The highest affinity interaction is seen with Kir6.1/SUR2B (IC50=0.55 mM) and it also inhibits the current in native vascular smooth muscle cells. The extent and rate of inhibition are similar to that seen with the known K(ATP) blocker PNU 37883A. Additionally, phenformin inhibited the current elicited through the Kir6.2DeltaC26 (functional without SUR) channel with an IC50 of 1.78 mM. Phenformin reduced the open probability of Kir6.1/SUR2B channels by approximately 90% in inside-out patches. These findings suggest that phenformin interacts directly with the pore-forming Kir6.0 subunit however the sulphonylurea receptor is able to significantly modulate the affinity. It is likely to block from the intracellular side of the channel in a manner analogous to that of PNU 37883A.
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Affiliation(s)
- Qadeer Aziz
- Department of Medicine, University College London, Rayne Institute, 5 University Street, London, WC1E 6JJ, United Kingdom
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Tei A, Nejime N, Tada Y, Kagota S, Tanabe Y, Hashimoto M, Shinozuka K. Effects of nicorandil on sympathetic neurotransmission in rat caudal artery. Clin Exp Pharmacol Physiol 2010; 37:619-23. [PMID: 20132237 DOI: 10.1111/j.1440-1681.2010.05366.x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
1. We examined the effects of nicorandil, an ATP-sensitive potassium (K(ATP)) channel opener and nitric oxide donor, on the release of noradrenaline from vascular sympathetic nerves. This effect was compared to the effect on vascular smooth muscle. 2. Caudal artery preparations from Wistar rats were electrically stimulated (1 Hz, 0.5-ms duration) and noradrenaline release in the artery was detected using an high-pressure liquid chromatography-electrochemical detection technique. The pharmacological properties of the prejunctional effect of nicorandil were determined using the nonselective K(ATP) channel blocker glibenclamide, the pancreatic beta-cell and brain-type K(ATP) channel blocker tolbutamide, and the smooth muscle-type K(ATP) channel blocker PNU-37883A. 3. Nicorandil inhibited the electrical stimulation-evoked noradrenaline release in a concentration-dependent manner. This inhibitory effect was abolished by 1 micromol/L glibenclamide and 10 micromol/L tolbutamide, but was not affected by 10 micromol/L PNU-37883A or 0.3 micromol/L ODQ. Nicorandil did not affect the noradrenaline transporter uptake 1 in the adrenergic nerve terminals. 4. Nicorandil produced a relaxation response in a concentration-dependent manner in the caudal artery pre-contracted with 0.3 micromol/L noradrenaline. This relaxation response was significantly diminished in the presence of 1 micromol/L glibenclamide, 10 micromol/L PNU-37883A and 0.3 micromol/L ODQ but not by 10 micromol/L tolbutamide. 5. These findings suggest that nicorandil inhibits noradrenaline release via the K(ATP) channels of sympathetic nerves. These channels may be pharmacologically different from those of vascular smooth muscle.
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Affiliation(s)
- Ami Tei
- Department of Pharmacology and Pharmaceutics, School of Pharmaceutical Sciences, Mukogawa Women's University, Nishinomiya 663-8179, Japan
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Guo LY, Liu P. Research progress in the mechanism of renal vasoconstriction in hepatorenal syndrome. Shijie Huaren Xiaohua Zazhi 2008; 16:982-986. [DOI: 10.11569/wcjd.v16.i9.982] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Hepatorenal syndrome (HRS) is defined as the development of renal failure in patients with severe liver disease in the absence of any other identifiable cause of renal pathology. The hallmark of HRS is renal vasoconstriction. The cause of renal vasoconstriction may involve several factors: activation of renal nervous system, imbalance of renal vasoactive mediators and molecular mechanism. In this review, we summarize the above progress.
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K(ATP) channel expression and pharmacological in vivo and in vitro studies of the K(ATP) channel blocker PNU-37883A in rat middle meningeal arteries. Br J Pharmacol 2008; 154:72-81. [PMID: 18332850 DOI: 10.1038/bjp.2008.86] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
BACKGROUND AND PURPOSE Dilatation of cerebral and dural arteries causes a throbbing, migraine-like pain, indicating that these structures are involved in migraine. Clinical trials suggest that adenosine 5'-triphosphate-sensitive K(+) (K(ATP)) channel opening may cause migraine by dilatating intracranial arteries, including the middle meningeal artery (MMA). We studied the K(ATP) channel expression profile in rat MMA and examined the potential inhibitory effects of the K(ATP) channel blocker PNU-37883A on K(ATP) channel opener-induced relaxation of the rat MMA, using the three K(ATP) channel openers levcromakalim, pinacidil and P-1075. EXPERIMENTAL APPROACH mRNA and protein expression of K(ATP) channel subunits in the rat MMA were studied by quantitative real-time PCR and western blotting, respectively. The in vivo and in vitro effects of the K(ATP) channel drugs on rat MMA were studied in the genuine closed cranial window model and in myograph baths, respectively. KEY RESULTS Expression studies indicate that inwardly rectifying K(+) (Kir)6.1/sulphonylurea receptor (SUR)2B is the major K(ATP) channel complex in rat MMA. PNU-37883A (0.5 mg kg(-1)) significantly inhibited the in vivo dilatory effect of levcromakalim (0.025 mg kg(-1)), pinacidil (0.38 mg kg(-1)) and P-1075 (0.016 mg kg(-1)) in rat MMA. In vitro PNU-37883A significantly inhibited the dilatory responses of the three K(ATP) channel openers in rat MMA at 10(-7) and 3 x 10(-7) M. CONCLUSIONS AND IMPLICATIONS We suggest that Kir6.1/SUR2B is the major functional K(ATP) channel complex in the rat MMA. Furthermore, we demonstrate the potent in vivo and in vitro blocking potentials of PNU-37883A on K(ATP) channel opener-induced relaxation of the rat MMA.
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Berlinck RGS, Burtoloso ACB, Kossuga MH. The chemistry and biology of organic guanidine derivatives. Nat Prod Rep 2008; 25:919-54. [DOI: 10.1039/b507874c] [Citation(s) in RCA: 151] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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