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Sitinjak MC, Chen JK, Liu FL, Hou MH, Lin SM, Liu HJ, Wang CY. Antiviral effect of the viroporin inhibitors against Taiwan isolates of infectious bronchitis virus (IBV). Virus Res 2024; 349:199458. [PMID: 39187047 DOI: 10.1016/j.virusres.2024.199458] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2024] [Revised: 08/06/2024] [Accepted: 08/23/2024] [Indexed: 08/28/2024]
Abstract
Coronaviruses (CoVs) are significant animal and human pathogens, characterized by being enveloped RNA viruses with positive-sense single-stranded RNA. The Coronaviridae family encompasses four genera, among which gammacoronaviruses pose a major threat to the poultry industry, which infectious bronchitis virus (IBV) being the most prominent of these threats. Particularly, IBV adversely affects broiler growth and egg production, causing substantial losses. The IBV strains currently circulating in Taiwan include the IBV Taiwan-I (TW-I) serotype, IBV Taiwan-II (TW-II) serotype, and vaccine strains. Therefore, ongoing efforts have focused on developing novel vaccines and discovering antiviral agents. The envelope (E) proteins of CoVs accumulate in the endoplasmic reticulum-Golgi intermediate compartment prior to virus budding. These E proteins assemble into viroporins, exhibiting ion channel activity that leads to cell membrane disruption, making them attractive targets for antiviral therapy. In this study, we investigated the E proteins of IBV H-120, as well as IBV serotypes TW-I and TW-II. E protein expression resulted in inhibited bacteria growth, increased permeability of bacteria to β-galactosidase substrates, and blocked protein synthesis of bacteria by hygromycin B (HygB). Furthermore, in the presence of E proteins, HygB also impeded protein translation in DF-1 cells and damaged their membrane integrity. Collectively, these findings confirm the viroporin activity of the E proteins from IBV H-120, IBV serotype TW-I, and IBV serotype TW-II. Next, the viroporin inhibitors, 5-(N,N-hexamethylene) amiloride (HMA) and 4,4'-diisothiocyano stilbene-2,2'-disulphonic acid (DIDS) were used to inhibit the viroporin activities of the E proteins of IBV H-120, IBV serotype TW-I, and IBV serotype TW-II. In chicken embryos and chickens infected with IBV serotypes TW-I and IBV TW-II, no survivors were observed at 6 and 11 days post-infection (dpi), respectively. However, treatments with both DIDS and HMA increased the survival rates in infected chicken embryos and chickens and mitigated histopathological lesions in the trachea and kidney. Additionally, a 3D pentameric structure of the IBV E protein was constructed via homology modeling. As expected, both inhibitors were found to bind to the lipid-facing surface within the transmembrane domain of the E protein, inhibiting ion conduction. Taken together, our findings provide comprehensive evidence supporting the use of viroporin inhibitors as promising antiviral agents against IBV Taiwan isolates.
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Affiliation(s)
- Mikael Cristofer Sitinjak
- Department of Veterinary Medicine, College of Veterinary Medicine, National Chung Hsing University, 145 Xingda Road, Taichung 402, Taiwan
| | - Jui-Kai Chen
- Department of Veterinary Medicine, College of Veterinary Medicine, National Chung Hsing University, 145 Xingda Road, Taichung 402, Taiwan
| | - Fang-Lin Liu
- Department of Veterinary Medicine, College of Veterinary Medicine, National Chung Hsing University, 145 Xingda Road, Taichung 402, Taiwan
| | - Ming-Hon Hou
- Institute of Genomics and Bioinformatics and Department of Life Sciences, College of Life Science, National Chung Hsing University, 145 Xingda Road, Taichung 402, Taiwan
| | - Shan-Meng Lin
- Institute of Genomics and Bioinformatics and Department of Life Sciences, College of Life Science, National Chung Hsing University, 145 Xingda Road, Taichung 402, Taiwan
| | - Hung-Jen Liu
- Institute of Molecular Biology, College of Life Science, National Chung Hsing University, 145 Xingda Road, Taichung 402, Taiwan.; The iEGG and Animal Biotechnology Center, National Chung Hsing University, 250 Kuo Kuang Road, Taichung 40227, Taiwan
| | - Chi-Young Wang
- Department of Veterinary Medicine, College of Veterinary Medicine, National Chung Hsing University, 145 Xingda Road, Taichung 402, Taiwan.; The iEGG and Animal Biotechnology Center, National Chung Hsing University, 250 Kuo Kuang Road, Taichung 40227, Taiwan.
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2
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Raut S, Singh K, Sanghvi S, Loyo-Celis V, Varghese L, Singh E, Gururaja Rao S, Singh H. Chloride ions in health and disease. Biosci Rep 2024; 44:BSR20240029. [PMID: 38573803 PMCID: PMC11065649 DOI: 10.1042/bsr20240029] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2024] [Revised: 03/26/2024] [Accepted: 04/04/2024] [Indexed: 04/06/2024] Open
Abstract
Chloride is a key anion involved in cellular physiology by regulating its homeostasis and rheostatic processes. Changes in cellular Cl- concentration result in differential regulation of cellular functions such as transcription and translation, post-translation modifications, cell cycle and proliferation, cell volume, and pH levels. In intracellular compartments, Cl- modulates the function of lysosomes, mitochondria, endosomes, phagosomes, the nucleus, and the endoplasmic reticulum. In extracellular fluid (ECF), Cl- is present in blood/plasma and interstitial fluid compartments. A reduction in Cl- levels in ECF can result in cell volume contraction. Cl- is the key physiological anion and is a principal compensatory ion for the movement of the major cations such as Na+, K+, and Ca2+. Over the past 25 years, we have increased our understanding of cellular signaling mediated by Cl-, which has helped in understanding the molecular and metabolic changes observed in pathologies with altered Cl- levels. Here, we review the concentration of Cl- in various organs and cellular compartments, ion channels responsible for its transportation, and recent information on its physiological roles.
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Affiliation(s)
- Satish K. Raut
- Department of Physiology and Cell Biology, College of Medicine, The Ohio State University, Columbus, OH, U.S.A
| | - Kulwinder Singh
- Department of Physiology and Cell Biology, College of Medicine, The Ohio State University, Columbus, OH, U.S.A
| | - Shridhar Sanghvi
- Department of Physiology and Cell Biology, College of Medicine, The Ohio State University, Columbus, OH, U.S.A
- Department of Molecular Cellular and Developmental Biology, The Ohio State University, Columbus, OH, U.S.A
| | - Veronica Loyo-Celis
- Department of Physiology and Cell Biology, College of Medicine, The Ohio State University, Columbus, OH, U.S.A
| | - Liyah Varghese
- Department of Physiology and Cell Biology, College of Medicine, The Ohio State University, Columbus, OH, U.S.A
| | - Ekam R. Singh
- Department of Physiology and Cell Biology, College of Medicine, The Ohio State University, Columbus, OH, U.S.A
| | | | - Harpreet Singh
- Department of Physiology and Cell Biology, College of Medicine, The Ohio State University, Columbus, OH, U.S.A
- Department of Molecular Cellular and Developmental Biology, The Ohio State University, Columbus, OH, U.S.A
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3
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Salvagno M, Sterchele ED, Zaccarelli M, Mrakic-Sposta S, Welsby IJ, Balestra C, Taccone FS. Oxidative Stress and Cerebral Vascular Tone: The Role of Reactive Oxygen and Nitrogen Species. Int J Mol Sci 2024; 25:3007. [PMID: 38474253 DOI: 10.3390/ijms25053007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2024] [Revised: 02/29/2024] [Accepted: 03/02/2024] [Indexed: 03/14/2024] Open
Abstract
The brain's unique characteristics make it exceptionally susceptible to oxidative stress, which arises from an imbalance between reactive oxygen species (ROS) production, reactive nitrogen species (RNS) production, and antioxidant defense mechanisms. This review explores the factors contributing to the brain's vascular tone's vulnerability in the presence of oxidative damage, which can be of clinical interest in critically ill patients or those presenting acute brain injuries. The brain's high metabolic rate and inefficient electron transport chain in mitochondria lead to significant ROS generation. Moreover, non-replicating neuronal cells and low repair capacity increase susceptibility to oxidative insult. ROS can influence cerebral vascular tone and permeability, potentially impacting cerebral autoregulation. Different ROS species, including superoxide and hydrogen peroxide, exhibit vasodilatory or vasoconstrictive effects on cerebral blood vessels. RNS, particularly NO and peroxynitrite, also exert vasoactive effects. This review further investigates the neuroprotective effects of antioxidants, including superoxide dismutase (SOD), vitamin C, vitamin E, and the glutathione redox system. Various studies suggest that these antioxidants could be used as adjunct therapies to protect the cerebral vascular tone under conditions of high oxidative stress. Nevertheless, more extensive research is required to comprehensively grasp the relationship between oxidative stress and cerebrovascular tone, and explore the potential benefits of antioxidants as adjunctive therapies in critical illnesses and acute brain injuries.
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Affiliation(s)
- Michele Salvagno
- Department of Intensive Care, Hôpital Universitaire de Bruxelles (HUB), 1000 Brussels, Belgium
| | - Elda Diletta Sterchele
- Department of Intensive Care, Hôpital Universitaire de Bruxelles (HUB), 1000 Brussels, Belgium
| | - Mario Zaccarelli
- Department of Intensive Care, Hôpital Universitaire de Bruxelles (HUB), 1000 Brussels, Belgium
| | - Simona Mrakic-Sposta
- Institute of Clinical Physiology-National Research Council (CNR-IFC), 20133 Milan, Italy
| | - Ian James Welsby
- Department of Anesthesiology, Duke University Medical Center, Durham, NC 27710, USA
| | - Costantino Balestra
- Environmental, Occupational, Aging (Integrative) Physiology Laboratory, Haute Ecole Bruxelles-Brabant (HE2B), 1160 Brussels, Belgium
- Anatomical Research and Clinical Studies, Vrije Universiteit Brussels (VUB), 1050 Elsene, Belgium
- DAN Europe Research Division (Roseto-Brussels), 1160 Brussels, Belgium
- Motor Sciences Department, Physical Activity Teaching Unit, Université Libre de Bruxelles (ULB), 1050 Brussels, Belgium
| | - Fabio Silvio Taccone
- Department of Intensive Care, Hôpital Universitaire de Bruxelles (HUB), 1000 Brussels, Belgium
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Characterization of a Family of Scorpion Toxins Modulating Ca 2+-Activated Cl - Current in Vascular Myocytes. Toxins (Basel) 2022; 14:toxins14110780. [PMID: 36356031 PMCID: PMC9699600 DOI: 10.3390/toxins14110780] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2022] [Revised: 11/02/2022] [Accepted: 11/03/2022] [Indexed: 11/12/2022] Open
Abstract
The pharmacology of calcium-activated chloride current is not well developed. Peptides from scorpion venom present potent pharmacological actions on ionic conductance used to characterize the function of channels but can also be helpful to develop organic pharmacological tools. Using electrophysiological recording coupled with calcium measurement, we tested the potent effect of peptides extracted from Leuirus quinquestratus quinquestratus venom on the calcium-activated chloride current expressed in smooth muscle cells freshly dissociated from rat portal veins. We identified one peptide which selectively inhibited the chloride conductance without effects on either calcium signaling or calcium and potassium currents expressed in this cell type. The synthetic peptide had the same affinity, but the chemical modification of the amino acid sequence altered the efficiency to inhibit the calcium-activated chloride conductance.
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Goto K, Kitazono T. Chloride Ions, Vascular Function and Hypertension. Biomedicines 2022; 10:biomedicines10092316. [PMID: 36140417 PMCID: PMC9496098 DOI: 10.3390/biomedicines10092316] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2022] [Revised: 09/10/2022] [Accepted: 09/15/2022] [Indexed: 11/26/2022] Open
Abstract
Blood pressure is determined by cardiac output and systemic vascular resistance, and mediators that induce vasoconstriction will increase systemic vascular resistance and thus elevate blood pressure. While peripheral vascular resistance reflects a complex interaction of multiple factors, vascular ion channels and transporters play important roles in the regulation of vascular tone by modulating the membrane potential of vascular cells. In vascular smooth muscle cells, chloride ions (Cl−) are a type of anions accumulated by anion exchangers and the anion–proton cotransporter system, and efflux of Cl− through Cl− channels depolarizes the membrane and thereby triggers vasoconstriction. Among these Cl− regulatory pathways, emerging evidence suggests that upregulation of the Ca2+-activated Cl− channel TMEM16A in the vasculature contributes to the increased vascular contractility and elevated blood pressure in hypertension. A robust accumulation of intracellular Cl− in vascular smooth muscle cells through the increased activity of Na+–K+–2Cl− cotransporter 1 (NKCC1) during hypertension has also been reported. Thus, the enhanced activity of both TMEM16A and NKCC1 could act additively and sequentially to increase vascular contractility and hence blood pressure in hypertension. In this review, we discuss recent findings regarding the role of Cl− in the regulation of vascular tone and arterial blood pressure and its association with hypertension, with a particular focus on TMEM16A and NKCC1.
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Affiliation(s)
- Kenichi Goto
- Department of Health Sciences, Graduate School of Medical Sciences, Kyushu University, Fukuoka 812-8582, Japan
- Correspondence:
| | - Takanari Kitazono
- Department of Medicine and Clinical Science, Graduate School of Medical Sciences, Kyushu University, Fukuoka 812-8582, Japan
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6
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Gao M, Ma MM, Lu FT, Huang CC, Sun L, Lv XF, Zhang B, Wang GL, Guan YY. Low Chloride-Regulated ClC-5 Contributes to Arterial Smooth Muscle Cell Proliferation and Cerebrovascular Remodeling. Hypertension 2022; 79:e73-e85. [PMID: 35144478 DOI: 10.1161/hypertensionaha.121.18472] [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: 11/16/2022]
Abstract
BACKGROUND Low serum chloride (Cl-) level is considered an independent predictor of cardiovascular mortality associated with chronic hypertension. However, the underlying mechanisms are unknown. ClC-5, a member of the Cl- channel family, is sensitive to changes in intracellular and extracellular Cl- concentration and conducts outwardly rectifying Cl- currents. The aims of this study were to determine if ClC-5 is regulated by low extracellular Cl-, clarify its putative roles in hypertension-induced cerebrovascular remodeling, and elucidate the associated underlying mechanisms. METHODS Whole-cell patch technique, intracellular Cl- concentration measurements, flow cytometry, Western blot, Clcn5 knockdown (Clcn5-/y), and adenovirus-mediated ClC-5 overexpression mice, 2-kidney, 2-clip, and angiotensin II infusion-induced hypertensive models were used. RESULTS We found that low extracellular Cl- evoked a ClC-5-dependent Cl- current that was abolished by ClC-5 depletion in basilar artery smooth muscle cells. ClC-5 was upregulated in the arterial tissues of rats and patients with hypertension. Low Cl--induced current and ClC-5 protein expression positively correlated with basilar artery remodeling during hypertension. ClC-5 knockdown ameliorated hypertension-induced cerebrovascular remodeling and smooth muscle cell proliferation, whereas ClC-5 overexpression mice exhibited the opposite phenotype. ClC-5-dependent Cl- efflux induced by low extracellular Cl- activated WNK1 (lysine-deficient protein kinase 1) which, in turn, activated AKT, and culminated in basilar artery smooth muscle cell proliferation and vascular remodeling. CONCLUSIONS ClC-5 mediates low Cl--induced Cl- currents in basilar artery smooth muscle cells and regulates hypertension-induced cerebrovascular remodeling by promoting basilar artery smooth muscle cell proliferation via the WNK1/AKT signaling pathway.
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Affiliation(s)
- Min Gao
- Department of Pharmacology, Cardiac and Cerebral Vascular Research Center, Zhongshan School of Medicine (M.G., M.-M.M., F.-T.L., C.-C.H., L.S., X.-F.L., G.-L.W., Y.-Y.G.).,Department of Pharmacy, The Sixth Affiliated Hospital, Sun Yat-Sen University, Guangzhou, China. (M.G., C.-C.H.)
| | - Ming-Ming Ma
- Department of Pharmacology, Cardiac and Cerebral Vascular Research Center, Zhongshan School of Medicine (M.G., M.-M.M., F.-T.L., C.-C.H., L.S., X.-F.L., G.-L.W., Y.-Y.G.)
| | - Feng-Ting Lu
- Department of Pharmacology, Cardiac and Cerebral Vascular Research Center, Zhongshan School of Medicine (M.G., M.-M.M., F.-T.L., C.-C.H., L.S., X.-F.L., G.-L.W., Y.-Y.G.)
| | - Cheng-Cui Huang
- Department of Pharmacology, Cardiac and Cerebral Vascular Research Center, Zhongshan School of Medicine (M.G., M.-M.M., F.-T.L., C.-C.H., L.S., X.-F.L., G.-L.W., Y.-Y.G.).,Department of Pharmacy, The Sixth Affiliated Hospital, Sun Yat-Sen University, Guangzhou, China. (M.G., C.-C.H.)
| | - Lu Sun
- Department of Pharmacology, Cardiac and Cerebral Vascular Research Center, Zhongshan School of Medicine (M.G., M.-M.M., F.-T.L., C.-C.H., L.S., X.-F.L., G.-L.W., Y.-Y.G.).,Department of Pharmacy, The First Affiliated Hospital of USTC, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, China (L.S.)
| | - Xiao-Fei Lv
- Department of Pharmacology, Cardiac and Cerebral Vascular Research Center, Zhongshan School of Medicine (M.G., M.-M.M., F.-T.L., C.-C.H., L.S., X.-F.L., G.-L.W., Y.-Y.G.)
| | - Bin Zhang
- Guangdong Cardiovascular Institute, Guangdong Provincial People's Hospital, China (B.Z.)
| | - Guan-Lei Wang
- Department of Pharmacology, Cardiac and Cerebral Vascular Research Center, Zhongshan School of Medicine (M.G., M.-M.M., F.-T.L., C.-C.H., L.S., X.-F.L., G.-L.W., Y.-Y.G.)
| | - Yong-Yuan Guan
- Department of Pharmacology, Cardiac and Cerebral Vascular Research Center, Zhongshan School of Medicine (M.G., M.-M.M., F.-T.L., C.-C.H., L.S., X.-F.L., G.-L.W., Y.-Y.G.)
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7
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Kouyoumdzian NM, Kim G, Rudi MJ, Rukavina Mikusic NL, Fernández BE, Choi MR. Clues and new evidences in arterial hypertension: unmasking the role of the chloride anion. Pflugers Arch 2021; 474:155-176. [PMID: 34966955 DOI: 10.1007/s00424-021-02649-5] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2021] [Revised: 12/02/2021] [Accepted: 12/03/2021] [Indexed: 02/06/2023]
Abstract
The present review will focus on the role of chloride anion in cardiovascular disease, with special emphasis in the development of hypertensive disease and vascular inflammation. It is known that acute and chronic overload of sodium chloride increase blood pressure and have pro-inflammatory and pro-fibrotic effects on different target organs, but it is unknown how chloride may influence these processes. Chloride anion is the predominant anion in the extracellular fluid and its intracellular concentration is dynamically regulated. As the queen of the electrolytes, it is of crucial importance to understand the physiological mechanisms that regulate the cellular handling of this anion including the different transporters and cellular chloride channels, which exert a variety of functions, such as regulation of cellular proliferation, differentiation, migration, apoptosis, intracellular pH and cellular redox state. In this article, we will also review the relationship between dietary, serum and intracellular chloride and how these different sources of chloride in the organism are affected in hypertension and their impact on cardiovascular disease. Additionally, we will discuss the approach of potential strategies that affect chloride handling and its potential effect on cardiovascular system, including pharmacological blockade of chloride channels and non-pharmacological interventions by replacing chloride by another anion.
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Affiliation(s)
- Nicolás Martín Kouyoumdzian
- Universidad de Buenos Aires, CONICET, Instituto Alberto C. Taquini de Investigaciones en Medicina Traslacional (IATIMET), Buenos Aires, Argentina.
| | - Gabriel Kim
- Facultad de Farmacia Y Bioquímica, Departamento de Ciencias Biológicas, Cátedra de Anatomía e Histología, Universidad de Buenos Aires, Buenos Aires, Argentina
| | - María Julieta Rudi
- Facultad de Farmacia Y Bioquímica, Departamento de Ciencias Biológicas, Cátedra de Anatomía e Histología, Universidad de Buenos Aires, Buenos Aires, Argentina
| | - Natalia Lucía Rukavina Mikusic
- Facultad de Farmacia Y Bioquímica, Departamento de Ciencias Biológicas, Cátedra de Anatomía e Histología, Universidad de Buenos Aires, Buenos Aires, Argentina
| | | | - Marcelo Roberto Choi
- Universidad de Buenos Aires, CONICET, Instituto Alberto C. Taquini de Investigaciones en Medicina Traslacional (IATIMET), Buenos Aires, Argentina.,Facultad de Farmacia Y Bioquímica, Departamento de Ciencias Biológicas, Cátedra de Anatomía e Histología, Universidad de Buenos Aires, Buenos Aires, Argentina.,Instituto Universitario de Ciencias de La Salud, Fundación H.A. Barceló, Buenos Aires, Argentina
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8
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Lidington D, Wan H, Dinh DD, Ng C, Bolz SS. Circadian Rhythmicity in Cerebral Microvascular Tone Influences Subarachnoid Hemorrhage-Induced Injury. Stroke 2021; 53:249-259. [PMID: 34905942 PMCID: PMC8700310 DOI: 10.1161/strokeaha.121.036950] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Supplemental Digital Content is available in the text. Circadian rhythms influence the extent of brain injury following subarachnoid hemorrhage (SAH), but the mechanism is unknown. We hypothesized that cerebrovascular myogenic reactivity is rhythmic and explains the circadian variation in SAH-induced injury.
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Affiliation(s)
- Darcy Lidington
- Department of Physiology (D.L., H.W., D.D.D., C.N., S.-S.B.), University of Toronto, Canada.,Toronto Centre for Microvascular Medicine at The Ted Rogers Centre for Heart Research Translational Biology and Engineering Program (D.L., H.W., D.D.D., C.N., S-S.B.), University of Toronto, Canada
| | - Hoyee Wan
- Department of Physiology (D.L., H.W., D.D.D., C.N., S.-S.B.), University of Toronto, Canada.,Toronto Centre for Microvascular Medicine at The Ted Rogers Centre for Heart Research Translational Biology and Engineering Program (D.L., H.W., D.D.D., C.N., S-S.B.), University of Toronto, Canada
| | - Danny D Dinh
- Department of Physiology (D.L., H.W., D.D.D., C.N., S.-S.B.), University of Toronto, Canada.,Toronto Centre for Microvascular Medicine at The Ted Rogers Centre for Heart Research Translational Biology and Engineering Program (D.L., H.W., D.D.D., C.N., S-S.B.), University of Toronto, Canada
| | - Chloe Ng
- Department of Physiology (D.L., H.W., D.D.D., C.N., S.-S.B.), University of Toronto, Canada.,Toronto Centre for Microvascular Medicine at The Ted Rogers Centre for Heart Research Translational Biology and Engineering Program (D.L., H.W., D.D.D., C.N., S-S.B.), University of Toronto, Canada
| | - Steffen-Sebastian Bolz
- Department of Physiology (D.L., H.W., D.D.D., C.N., S.-S.B.), University of Toronto, Canada.,Toronto Centre for Microvascular Medicine at The Ted Rogers Centre for Heart Research Translational Biology and Engineering Program (D.L., H.W., D.D.D., C.N., S-S.B.), University of Toronto, Canada.,Heart & Stroke/Richard Lewar Centre of Excellence for Cardiovascular Research (S-S.B.), University of Toronto, Canada
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9
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Wray S, Prendergast C, Arrowsmith S. Calcium-Activated Chloride Channels in Myometrial and Vascular Smooth Muscle. Front Physiol 2021; 12:751008. [PMID: 34867456 PMCID: PMC8637852 DOI: 10.3389/fphys.2021.751008] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2021] [Accepted: 09/24/2021] [Indexed: 11/24/2022] Open
Abstract
In smooth muscle tissues, calcium-activated chloride channels (CaCC) provide the major anionic channel. Opening of these channels leads to chloride efflux and depolarization of the myocyte membrane. In this way, activation of the channels by a rise of intracellular [Ca2+], from a variety of sources, produces increased excitability and can initiate action potentials and contraction or increased tone. We now have a good mechanistic understanding of how the channels are activated and regulated, due to identification of TMEM16A (ANO1) as the molecular entity of the channel, but key questions remain. In reviewing these channels and comparing two distinct smooth muscles, myometrial and vascular, we expose the differences that occur in their activation mechanisms, properties, and control. We find that the myometrium only expresses “classical,” Ca2+-activated, and voltage sensitive channels, whereas both tonic and phasic blood vessels express classical, and non-classical, cGMP-regulated CaCC, which are voltage insensitive. This translates to more complex activation and regulation in vascular smooth muscles, irrespective of whether they are tonic or phasic. We therefore tentatively conclude that although these channels are expressed and functionally important in all smooth muscles, they are probably not part of the mechanisms governing phasic activity. Recent knockdown studies have produced unexpected functional results, e.g. no effects on labour and delivery, and tone increasing in some but decreasing in other vascular beds, strongly suggesting that there is still much to be explored concerning CaCC in smooth muscle.
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Affiliation(s)
- Susan Wray
- Department of Women and Children's Health, Institute of Life Course and Medical Sciences, University of Liverpool, Liverpool, United Kingdom
| | - Clodagh Prendergast
- Department of Women and Children's Health, Institute of Life Course and Medical Sciences, University of Liverpool, Liverpool, United Kingdom
| | - Sarah Arrowsmith
- Department of Life Sciences, Manchester Metropolitan University, Manchester, United Kingdom
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10
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Fancher IS. Cardiovascular mechanosensitive ion channels-Translating physical forces into physiological responses. CURRENT TOPICS IN MEMBRANES 2021; 87:47-95. [PMID: 34696889 DOI: 10.1016/bs.ctm.2021.07.001] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Cells and tissues are constantly exposed to mechanical stress. In order to respond to alterations in mechanical stimuli, specific cellular machinery must be in place to rapidly convert physical force into chemical signaling to achieve the desired physiological responses. Mechanosensitive ion channels respond to such physical stimuli in the order of microseconds and are therefore essential components to mechanotransduction. Our understanding of how these ion channels contribute to cellular and physiological responses to mechanical force has vastly expanded in the last few decades due to engineering ingenuities accompanying patch clamp electrophysiology, as well as sophisticated molecular and genetic approaches. Such investigations have unveiled major implications for mechanosensitive ion channels in cardiovascular health and disease. Therefore, in this chapter I focus on our present understanding of how biophysical activation of various mechanosensitive ion channels promotes distinct cell signaling events with tissue-specific physiological responses in the cardiovascular system. Specifically, I discuss the roles of mechanosensitive ion channels in mediating (i) endothelial and smooth muscle cell control of vascular tone, (ii) mechano-electric feedback and cell signaling pathways in cardiomyocytes and cardiac fibroblasts, and (iii) the baroreflex.
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Affiliation(s)
- Ibra S Fancher
- Department of Kinesiology and Applied Physiology, College of Health Sciences, University of Delaware, Newark, DE, United States.
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11
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Rapalino O, Pourvaziri A, Maher M, Jaramillo-Cardoso A, Edlow BL, Conklin J, Huang S, Westover B, Romero JM, Halpern E, Gupta R, Pomerantz S, Schaefer P, Gonzalez RG, Mukerji SS, Lev MH. Clinical, Imaging, and Lab Correlates of Severe COVID-19 Leukoencephalopathy. AJNR Am J Neuroradiol 2021; 42:632-638. [PMID: 33414226 DOI: 10.3174/ajnr.a6966] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2020] [Accepted: 10/28/2020] [Indexed: 12/15/2022]
Abstract
BACKGROUND AND PURPOSE Patients infected with the Severe Acute Respiratory Syndrome coronavirus 2 (SARS-CoV-2) can develop a spectrum of neurological disorders, including a leukoencephalopathy of variable severity. Our aim was to characterize imaging, lab, and clinical correlates of severe coronavirus disease 2019 (COVID-19) leukoencephalopathy, which may provide insight into the SARS-CoV-2 pathophysiology. MATERIALS AND METHODS Twenty-seven consecutive patients positive for SARS-CoV-2 who had brain MR imaging following intensive care unit admission were included. Seven (7/27, 26%) developed an unusual pattern of "leukoencephalopathy with reduced diffusivity" on diffusion-weighted MR imaging. The remaining patients did not exhibit this pattern. Clinical and laboratory indices, as well as neuroimaging findings, were compared between groups. RESULTS The reduced-diffusivity group had a significantly higher body mass index (36 versus 28 kg/m2, P < .01). Patients with reduced diffusivity trended toward more frequent acute renal failure (7/7, 100% versus 9/20, 45%; P = .06) and lower estimated glomerular filtration rate values (49 versus 85 mL/min; P = .06) at the time of MRI. Patients with reduced diffusivity also showed lesser mean values of the lowest hemoglobin levels (8.1 versus 10.2 g/dL, P < .05) and higher serum sodium levels (147 versus 139 mmol/L, P = .04) within 24 hours before MR imaging. The reduced-diffusivity group showed a striking and highly reproducible distribution of confluent, predominantly symmetric, supratentorial, and middle cerebellar peduncular white matter lesions (P < .001). CONCLUSIONS Our findings highlight notable correlations between severe COVID-19 leukoencephalopathy with reduced diffusivity and obesity, acute renal failure, mild hypernatremia, anemia, and an unusual brain MR imaging white matter lesion distribution pattern. Together, these observations may shed light on possible SARS-CoV-2 pathophysiologic mechanisms associated with leukoencephalopathy, including borderzone ischemic changes, electrolyte transport disturbances, and silent hypoxia in the setting of the known cytokine storm syndrome that accompanies severe COVID-19.
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Affiliation(s)
- O Rapalino
- From the Department of Radiology (O.R., A.P., M.M., A.J.-C., J.C., S.H., J.M.R., R.G., S.P., P.S., R.G.G., M.H.L.)
| | - A Pourvaziri
- From the Department of Radiology (O.R., A.P., M.M., A.J.-C., J.C., S.H., J.M.R., R.G., S.P., P.S., R.G.G., M.H.L.)
| | - M Maher
- From the Department of Radiology (O.R., A.P., M.M., A.J.-C., J.C., S.H., J.M.R., R.G., S.P., P.S., R.G.G., M.H.L.)
| | - A Jaramillo-Cardoso
- From the Department of Radiology (O.R., A.P., M.M., A.J.-C., J.C., S.H., J.M.R., R.G., S.P., P.S., R.G.G., M.H.L.)
| | | | - J Conklin
- From the Department of Radiology (O.R., A.P., M.M., A.J.-C., J.C., S.H., J.M.R., R.G., S.P., P.S., R.G.G., M.H.L.)
| | - S Huang
- From the Department of Radiology (O.R., A.P., M.M., A.J.-C., J.C., S.H., J.M.R., R.G., S.P., P.S., R.G.G., M.H.L.)
| | | | - J M Romero
- From the Department of Radiology (O.R., A.P., M.M., A.J.-C., J.C., S.H., J.M.R., R.G., S.P., P.S., R.G.G., M.H.L.)
| | - E Halpern
- Institute for Technology Assessment (E.H.), Massachusetts General Hospital, Boston, Massachusetts
| | - R Gupta
- From the Department of Radiology (O.R., A.P., M.M., A.J.-C., J.C., S.H., J.M.R., R.G., S.P., P.S., R.G.G., M.H.L.)
| | - S Pomerantz
- From the Department of Radiology (O.R., A.P., M.M., A.J.-C., J.C., S.H., J.M.R., R.G., S.P., P.S., R.G.G., M.H.L.)
| | - P Schaefer
- From the Department of Radiology (O.R., A.P., M.M., A.J.-C., J.C., S.H., J.M.R., R.G., S.P., P.S., R.G.G., M.H.L.)
| | - R G Gonzalez
- From the Department of Radiology (O.R., A.P., M.M., A.J.-C., J.C., S.H., J.M.R., R.G., S.P., P.S., R.G.G., M.H.L.)
| | | | - M H Lev
- From the Department of Radiology (O.R., A.P., M.M., A.J.-C., J.C., S.H., J.M.R., R.G., S.P., P.S., R.G.G., M.H.L.)
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12
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Barabas P, Augustine J, Fernández JA, McGeown JG, McGahon MK, Curtis TM. Ion channels and myogenic activity in retinal arterioles. CURRENT TOPICS IN MEMBRANES 2020; 85:187-226. [PMID: 32402639 DOI: 10.1016/bs.ctm.2020.01.008] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Retinal pressure autoregulation is an important mechanism that protects the retina by stabilizing retinal blood flow during changes in arterial or intraocular pressure. Similar to other vascular beds, retinal pressure autoregulation is thought to be mediated largely through the myogenic response of small arteries and arterioles which constrict when transmural pressure increases or dilate when it decreases. Over recent years, we and others have investigated the signaling pathways underlying the myogenic response in retinal arterioles, with particular emphasis on the involvement of different ion channels expressed in the smooth muscle layer of these vessels. Here, we review and extend previous work on the expression and spatial distribution of the plasma membrane and sarcoplasmic reticulum ion channels present in retinal vascular smooth muscle cells (VSMCs) and discuss their contribution to pressure-induced myogenic tone in retinal arterioles. This includes new data demonstrating that several key players and modulators of the myogenic response show distinctively heterogeneous expression along the length of the retinal arteriolar network, suggesting differences in myogenic signaling between larger and smaller pre-capillary arterioles. Our immunohistochemical investigations have also highlighted the presence of actin-containing microstructures called myobridges that connect the retinal VSMCs to one another. Although further work is still needed, studies to date investigating myogenic mechanisms in the retina have contributed to a better understanding of how blood flow is regulated in this tissue. They also provide a basis to direct future research into retinal diseases where blood flow changes contribute to the pathology.
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Affiliation(s)
- Peter Barabas
- Wellcome-Wolfson Institute for Experimental Medicine, Queen's University of Belfast, Belfast, United Kingdom
| | - Josy Augustine
- Wellcome-Wolfson Institute for Experimental Medicine, Queen's University of Belfast, Belfast, United Kingdom
| | - José A Fernández
- Wellcome-Wolfson Institute for Experimental Medicine, Queen's University of Belfast, Belfast, United Kingdom
| | - J Graham McGeown
- Wellcome-Wolfson Institute for Experimental Medicine, Queen's University of Belfast, Belfast, United Kingdom
| | - Mary K McGahon
- Wellcome-Wolfson Institute for Experimental Medicine, Queen's University of Belfast, Belfast, United Kingdom
| | - Tim M Curtis
- Wellcome-Wolfson Institute for Experimental Medicine, Queen's University of Belfast, Belfast, United Kingdom.
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13
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Gururaja Rao S, Patel NJ, Singh H. Intracellular Chloride Channels: Novel Biomarkers in Diseases. Front Physiol 2020; 11:96. [PMID: 32116799 PMCID: PMC7034325 DOI: 10.3389/fphys.2020.00096] [Citation(s) in RCA: 70] [Impact Index Per Article: 17.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2019] [Accepted: 01/27/2020] [Indexed: 12/27/2022] Open
Abstract
Ion channels are integral membrane proteins present on the plasma membrane as well as intracellular membranes. In the human genome, there are more than 400 known genes encoding ion channel proteins. Ion channels are known to regulate several cellular, organellar, and physiological processes. Any mutation or disruption in their function can result in pathological disorders, both common or rare. Ion channels present on the plasma membrane are widely acknowledged for their role in various biological processes, but in recent years, several studies have pointed out the importance of ion channels located in intracellular organelles. However, ion channels located in intracellular organelles are not well-understood in the context of physiological conditions, such as the generation of cellular excitability and ionic homeostasis. Due to the lack of information regarding their molecular identity and technical limitations of studying them, intracellular organelle ion channels have thus far been overlooked as potential therapeutic targets. In this review, we focus on a novel class of intracellular organelle ion channels, Chloride Intracellular Ion Channels (CLICs), mainly documented for their role in cardiovascular, neurophysiology, and tumor biology. CLICs have a single transmembrane domain, and in cells, they exist in cytosolic as well as membranous forms. They are predominantly present in intracellular organelles and have recently been shown to be localized to cardiomyocyte mitochondria as well as exosomes. In fact, a member of this family, CLIC5, is the first mitochondrial chloride channel to be identified on the molecular level in the inner mitochondrial membrane, while another member, CLIC4, is located predominantly in the outer mitochondrial membrane. In this review, we discuss this unique class of intracellular chloride channels, their role in pathologies, such as cardiovascular, cancer, and neurodegenerative diseases, and the recent developments concerning their usage as theraputic targets.
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Affiliation(s)
- Shubha Gururaja Rao
- Department of Physiology and Cell Biology, The Ohio State University Wexner Medical Center, Columbus, OH, United States
| | - Neel J Patel
- Department of Cardiology, Hospital of the University of Pennsylvania, Philadelphia, PA, United States
| | - Harpreet Singh
- Department of Physiology and Cell Biology, The Ohio State University Wexner Medical Center, Columbus, OH, United States
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14
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Jensen AB, Joergensen HB, Dam VS, Kamaev D, Boedtkjer D, Füchtbauer EM, Aalkjaer C, Matchkov VV. Variable Contribution of TMEM16A to Tone in Murine Arterial Vasculature. Basic Clin Pharmacol Toxicol 2018; 123:30-41. [DOI: 10.1111/bcpt.12984] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2016] [Accepted: 01/31/2018] [Indexed: 01/02/2023]
Affiliation(s)
| | | | | | - Dmitrii Kamaev
- Department of Biomedicine; Aarhus University; Aarhus Denmark
| | - Donna Boedtkjer
- Department of Biomedicine; Aarhus University; Aarhus Denmark
- Department of Clinical Medicine; Aarhus University; Aarhus Denmark
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15
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Lukaszewicz KM, Durand MJ, Priestley JRC, Schmidt JR, Allen LA, Geurts AM, Lombard JH. Evaluation of Vascular Control Mechanisms Utilizing Video Microscopy of Isolated Resistance Arteries of Rats. J Vis Exp 2017. [PMID: 29286398 DOI: 10.3791/56133] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022] Open
Abstract
This protocol describes the use of in vitro television microscopy to evaluate vascular function in isolated cerebral resistance arteries (and other vessels), and describes techniques for evaluating tissue perfusion using Laser Doppler Flowmetry (LDF) and microvessel density utilizing fluorescently labeled Griffonia simplicifolia (GS1) lectin. Current methods for studying isolated resistance arteries at transmural pressures encountered in vivo and in the absence of parenchymal cell influences provide a critical link between in vivo studies and information gained from molecular reductionist approaches that provide limited insight into integrative responses at the whole animal level. LDF and techniques to selectively identify arterioles and capillaries with fluorescently-labeled GS1 lectin provide practical solutions to enable investigators to extend the knowledge gained from studies of isolated resistance arteries. This paper describes the application of these techniques to gain fundamental knowledge of vascular physiology and pathology in the rat as a general experimental model, and in a variety of specialized genetically engineered "designer" rat strains that can provide important insight into the influence of specific genes on important vascular phenotypes. Utilizing these valuable experimental approaches in rat strains developed by selective breeding strategies and new technologies for producing gene knockout models in the rat, will expand the rigor of scientific premises developed in knockout mouse models and extend that knowledge to a more relevant animal model, with a well understood physiological background and suitability for physiological studies because of its larger size.
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Affiliation(s)
| | | | | | - James R Schmidt
- Graduate Programs of Nurse Anesthesia, Texas Wesleyan University
| | | | - Aron M Geurts
- Department of Physiology, Medical College of Wisconsin
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16
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Cook DP, Adam RJ, Zarei K, Deonovic B, Stroik MR, Gansemer ND, Meyerholz DK, Au KF, Stoltz DA. CF airway smooth muscle transcriptome reveals a role for PYK2. JCI Insight 2017; 2:95332. [PMID: 28878137 DOI: 10.1172/jci.insight.95332] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2017] [Accepted: 07/27/2017] [Indexed: 12/17/2022] Open
Abstract
Abnormal airway smooth muscle function can contribute to cystic fibrosis (CF) airway disease. We previously found that airway smooth muscle from newborn CF pigs had increased basal tone, an increased bronchodilator response, and abnormal calcium handling. Since CF pigs lack airway infection and inflammation at birth, these findings suggest intrinsic airway smooth muscle dysfunction in CF. In this study, we tested the hypothesis that CFTR loss in airway smooth muscle would produce a distinct set of changes in the airway smooth muscle transcriptome that we could use to develop novel therapeutic targets. Total RNA sequencing of newborn wild-type and CF airway smooth muscle revealed changes in muscle contraction-related genes, ontologies, and pathways. Using connectivity mapping, we identified several small molecules that elicit transcriptional signatures opposite of CF airway smooth muscle, including NVP-TAE684, an inhibitor of proline-rich tyrosine kinase 2 (PYK2). In CF airway smooth muscle tissue, PYK2 phosphorylation was increased and PYK2 inhibition decreased smooth muscle contraction. In vivo NVP-TAE684 treatment of wild-type mice reduced methacholine-induced airway smooth muscle contraction. These findings suggest that studies in the newborn CF pig may provide an important approach to enhance our understanding of airway smooth muscle biology and for discovery of novel airway smooth muscle therapeutics for CF and other diseases of airway hyperreactivity.
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Affiliation(s)
- Daniel P Cook
- Department of Internal Medicine.,Department of Molecular Physiology and Biophysics, and
| | - Ryan J Adam
- Department of Biomedical Engineering, Roy J. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City, Iowa, USA
| | - Keyan Zarei
- Department of Biomedical Engineering, Roy J. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City, Iowa, USA
| | - Benjamin Deonovic
- Department of Biostatistics, College of Public Health, University of Iowa, Iowa City, Iowa, USA
| | | | | | - David K Meyerholz
- Department of Pathology, Roy J. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City, Iowa, USA
| | - Kin Fai Au
- Department of Internal Medicine.,Department of Biostatistics, College of Public Health, University of Iowa, Iowa City, Iowa, USA
| | - David A Stoltz
- Department of Internal Medicine.,Department of Molecular Physiology and Biophysics, and.,Department of Biomedical Engineering, Roy J. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City, Iowa, USA.,Pappajohn Biomedical Institute, University of Iowa, Iowa City, Iowa, USA
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17
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Aleksandrowicz M, Dworakowska B, Dolowy K, Kozniewska E. Restoration of the response of the middle cerebral artery of the rat to acidosis in hyposmotic hyponatremia by the opener of large-conductance calcium sensitive potassium channels (BK Ca). J Cereb Blood Flow Metab 2017; 37:3219-3230. [PMID: 28058990 PMCID: PMC5584697 DOI: 10.1177/0271678x16685575] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
Hyposmotic hyponatremia (the decrease of extracellular concentration of sodium ions from 145 to 121 mM and the decrease of hyposmolality from 300 to 250 mOsm/kg H2O) impairs response of the middle cerebral artery (MCA) to acetylcholine and NO donor (S-nitroso-N-acetyl-DL-penicillamine). Since acidosis activates a similar intracellular signaling pathway, the present study was designed to verify the hypothesis that the response of the MCA to acidosis is impaired during acute hyposmotic hyponatremia due to abnormal NO-related signal transduction in vascular smooth muscle cells. Studies performed on isolated, cannulated, and pressurized rat MCA revealed that hyposmotic hyponatremia impaired the response of the MCA to acidosis and this was associated with hyposmolality rather than with decreased sodium ion concentration. Response to acidosis was restored by the BKCa but not by the KATP channel activator. Patch-clamp electrophysiology performed on myocytes freshly isolated from MCAs, demonstrated that hyposmotic hyponatremia does not affect BKCa currents but decreases the voltage-dependency of the activation of the BKCa channels in the presence of a specific opener of these channels. Our study suggests that reduced sensitivity of BKCa channels in the MCA to agonists results in the lack of response of this artery to acidosis during acute hyposmotic hyponatremia.
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Affiliation(s)
- Marta Aleksandrowicz
- 1 Department of Neurosurgery, Mossakowski Medical Research Centre, Polish Academy of Sciences, Warsaw, Poland
| | - Beata Dworakowska
- 2 Department of Biophysics, Warsaw University of Life Sciences, Warsaw, Poland
| | - Krzysztof Dolowy
- 2 Department of Biophysics, Warsaw University of Life Sciences, Warsaw, Poland
| | - Ewa Kozniewska
- 1 Department of Neurosurgery, Mossakowski Medical Research Centre, Polish Academy of Sciences, Warsaw, Poland.,3 Department of Experimental and Clinical Physiology, Medical University of Warsaw, Warsaw, Poland
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18
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Jensen LJ, Nielsen MS, Salomonsson M, Sørensen CM. T-type Ca 2+ channels and autoregulation of local blood flow. Channels (Austin) 2017; 11:183-195. [PMID: 28055302 DOI: 10.1080/19336950.2016.1273997] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
L-type voltage gated Ca2+ channels are considered to be the primary source of calcium influx during the myogenic response. However, many vascular beds also express T-type voltage gated Ca2+ channels. Recent studies suggest that these channels may also play a role in autoregulation. At low pressures (40-80 mmHg) T-type channels affect myogenic responses in cerebral and mesenteric vascular beds. T-type channels also seem to be involved in skeletal muscle autoregulation. This review discusses the expression and role of T-type voltage gated Ca2+ channels in the autoregulation of several different vascular beds. Lack of specific pharmacological inhibitors has been a huge challenge in the field. Now the research has been strengthened by genetically modified models such as mice lacking expression of T-type voltage gated Ca2+ channels (CaV3.1 and CaV3.2). Hopefully, these new tools will help further elucidate the role of voltage gated T-type Ca2+ channels in autoregulation and vascular function.
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Affiliation(s)
- Lars Jørn Jensen
- a Departments of Veterinary Clinical and Animal Sciences , University of Copenhagen , Copenhagen , Denmark
| | - Morten Schak Nielsen
- b Department of Biomedical Sciences, Faculty of Health and Medical Sciences , University of Copenhagen , Copenhagen , Denmark
| | - Max Salomonsson
- b Department of Biomedical Sciences, Faculty of Health and Medical Sciences , University of Copenhagen , Copenhagen , Denmark
| | - Charlotte Mehlin Sørensen
- b Department of Biomedical Sciences, Faculty of Health and Medical Sciences , University of Copenhagen , Copenhagen , Denmark
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Toth P, Tarantini S, Csiszar A, Ungvari Z. Functional vascular contributions to cognitive impairment and dementia: mechanisms and consequences of cerebral autoregulatory dysfunction, endothelial impairment, and neurovascular uncoupling in aging. Am J Physiol Heart Circ Physiol 2017; 312:H1-H20. [PMID: 27793855 PMCID: PMC5283909 DOI: 10.1152/ajpheart.00581.2016] [Citation(s) in RCA: 324] [Impact Index Per Article: 46.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/07/2016] [Revised: 10/10/2016] [Accepted: 10/26/2016] [Indexed: 12/16/2022]
Abstract
Increasing evidence from epidemiological, clinical and experimental studies indicate that age-related cerebromicrovascular dysfunction and microcirculatory damage play critical roles in the pathogenesis of many types of dementia in the elderly, including Alzheimer's disease. Understanding and targeting the age-related pathophysiological mechanisms that underlie vascular contributions to cognitive impairment and dementia (VCID) are expected to have a major role in preserving brain health in older individuals. Maintenance of cerebral perfusion, protecting the microcirculation from high pressure-induced damage and moment-to-moment adjustment of regional oxygen and nutrient supply to changes in demand are prerequisites for the prevention of cerebral ischemia and neuronal dysfunction. This overview discusses age-related alterations in three main regulatory paradigms involved in the regulation of cerebral blood flow (CBF): cerebral autoregulation/myogenic constriction, endothelium-dependent vasomotor function, and neurovascular coupling responses responsible for functional hyperemia. The pathophysiological consequences of cerebral microvascular dysregulation in aging are explored, including blood-brain barrier disruption, neuroinflammation, exacerbation of neurodegeneration, development of cerebral microhemorrhages, microvascular rarefaction, and ischemic neuronal dysfunction and damage. Due to the widespread attention that VCID has captured in recent years, the evidence for the causal role of cerebral microvascular dysregulation in cognitive decline is critically examined.
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Affiliation(s)
- Peter Toth
- Department of Geriatric Medicine, Reynolds Oklahoma Center on Aging, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma
- Department of Neurosurgery and Szentagothai Research Center, University of Pecs, Pecs, Hungary; and
| | - Stefano Tarantini
- Department of Geriatric Medicine, Reynolds Oklahoma Center on Aging, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma
| | - Anna Csiszar
- Department of Geriatric Medicine, Reynolds Oklahoma Center on Aging, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma
- Department of Medical Physics and Informatics, University of Szeged, Szeged, Hungary
| | - Zoltan Ungvari
- Department of Geriatric Medicine, Reynolds Oklahoma Center on Aging, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma;
- Department of Medical Physics and Informatics, University of Szeged, Szeged, Hungary
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Boedtkjer E, Matchkov VV, Boedtkjer DMB, Aalkjaer C. Negative News: Cl− and HCO3− in the Vascular Wall. Physiology (Bethesda) 2016; 31:370-83. [DOI: 10.1152/physiol.00001.2016] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
Cl− and HCO3− are the most prevalent membrane-permeable anions in the intra- and extracellular spaces of the vascular wall. Outwardly directed electrochemical gradients for Cl− and HCO3− permit anion channel opening to depolarize vascular smooth muscle and endothelial cells. Transporters and channels for Cl− and HCO3− also modify vascular contractility and structure independently of membrane potential. Transport of HCO3− regulates intracellular pH and thereby modifies the activity of enzymes, ion channels, and receptors. There is also evidence that Cl− and HCO3− transport proteins affect gene expression and protein trafficking. Considering the extensive implications of Cl− and HCO3− in the vascular wall, it is critical to understand how these ions are transported under physiological conditions and how disturbances in their transport can contribute to disease development. Recently, sensing mechanisms for Cl− and HCO3− have been identified in the vascular wall where they modify ion transport and vasomotor function, for instance, during metabolic disturbances. This review discusses current evidence that transport (e.g., via NKCC1, NBCn1, Ca2+-activated Cl− channels, volume-regulated anion channels, and CFTR) and sensing (e.g., via WNK and RPTPγ) of Cl− and HCO3− influence cardiovascular health and disease.
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Affiliation(s)
| | | | - Donna M. B. Boedtkjer
- Department of Biomedicine, Aarhus University, Denmark
- Department of Clinical Medicine, Aarhus University, Denmark; and
| | - Christian Aalkjaer
- Department of Biomedicine, Aarhus University, Denmark
- Department of Biomedical Sciences, University of Copenhagen, Copenhagen, Denmark
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22
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Dam VS, Boedtkjer DMB, Aalkjaer C, Matchkov V. The bestrophin- and TMEM16A-associated Ca(2+)- activated Cl(–) channels in vascular smooth muscles. Channels (Austin) 2015; 8:361-9. [PMID: 25478625 PMCID: PMC4203738 DOI: 10.4161/chan.29531] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
The presence of Ca2+-activated Cl– currents (ICl(Ca)) in vascular smooth muscle cells (VSMCs) is well established. ICl(Ca) are supposedly important for arterial contraction by linking changes in [Ca2+]i and membrane depolarization. Bestrophins and some members of the TMEM16 protein family were recently associated with ICl(Ca). Two distinct ICl(Ca) are characterized in VSMCs; the cGMP-dependent ICl(Ca) dependent upon bestrophin expression and the ‘classical’ Ca2+-activated Cl– current, which is bestrophin-independent. Interestingly, TMEM16A is essential for both the cGMP-dependent and the classical ICl(Ca). Furthermore, TMEM16A has a role in arterial contraction while bestrophins do not. TMEM16A’s role in the contractile response cannot be explained however only by a simple suppression of the depolarization by Cl– channels. It is suggested that TMEM16A expression modulates voltage-gated Ca2+ influx in a voltage-independent manner and recent studies also demonstrate a complex role of TMEM16A in modulating other membrane proteins.
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23
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Matchkov VV, Boedtkjer DM, Aalkjaer C. The role of Ca2+ activated Cl− channels in blood pressure control. Curr Opin Pharmacol 2015; 21:127-37. [DOI: 10.1016/j.coph.2015.02.003] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2014] [Revised: 02/02/2015] [Accepted: 02/04/2015] [Indexed: 12/17/2022]
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Abstract
Intrarenal autoregulatory mechanisms maintain renal blood flow (RBF) and glomerular filtration rate (GFR) independent of renal perfusion pressure (RPP) over a defined range (80-180 mmHg). Such autoregulation is mediated largely by the myogenic and the macula densa-tubuloglomerular feedback (MD-TGF) responses that regulate preglomerular vasomotor tone primarily of the afferent arteriole. Differences in response times allow separation of these mechanisms in the time and frequency domains. Mechanotransduction initiating the myogenic response requires a sensing mechanism activated by stretch of vascular smooth muscle cells (VSMCs) and coupled to intracellular signaling pathways eliciting plasma membrane depolarization and a rise in cytosolic free calcium concentration ([Ca(2+)]i). Proposed mechanosensors include epithelial sodium channels (ENaC), integrins, and/or transient receptor potential (TRP) channels. Increased [Ca(2+)]i occurs predominantly by Ca(2+) influx through L-type voltage-operated Ca(2+) channels (VOCC). Increased [Ca(2+)]i activates inositol trisphosphate receptors (IP3R) and ryanodine receptors (RyR) to mobilize Ca(2+) from sarcoplasmic reticular stores. Myogenic vasoconstriction is sustained by increased Ca(2+) sensitivity, mediated by protein kinase C and Rho/Rho-kinase that favors a positive balance between myosin light-chain kinase and phosphatase. Increased RPP activates MD-TGF by transducing a signal of epithelial MD salt reabsorption to adjust afferent arteriolar vasoconstriction. A combination of vascular and tubular mechanisms, novel to the kidney, provides for high autoregulatory efficiency that maintains RBF and GFR, stabilizes sodium excretion, and buffers transmission of RPP to sensitive glomerular capillaries, thereby protecting against hypertensive barotrauma. A unique aspect of the myogenic response in the renal vasculature is modulation of its strength and speed by the MD-TGF and by a connecting tubule glomerular feedback (CT-GF) mechanism. Reactive oxygen species and nitric oxide are modulators of myogenic and MD-TGF mechanisms. Attenuated renal autoregulation contributes to renal damage in many, but not all, models of renal, diabetic, and hypertensive diseases. This review provides a summary of our current knowledge regarding underlying mechanisms enabling renal autoregulation in health and disease and methods used for its study.
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Affiliation(s)
- Mattias Carlström
- Department of Medicine, Division of Nephrology and Hypertension and Hypertension, Kidney and Vascular Research Center, Georgetown University, Washington, District of Columbia; Department of Physiology and Pharmacology, Karolinska Institutet, Stockholm, Sweden; and Department of Cell Biology and Physiology, UNC Kidney Center, and McAllister Heart Institute, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
| | - Christopher S Wilcox
- Department of Medicine, Division of Nephrology and Hypertension and Hypertension, Kidney and Vascular Research Center, Georgetown University, Washington, District of Columbia; Department of Physiology and Pharmacology, Karolinska Institutet, Stockholm, Sweden; and Department of Cell Biology and Physiology, UNC Kidney Center, and McAllister Heart Institute, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
| | - William J Arendshorst
- Department of Medicine, Division of Nephrology and Hypertension and Hypertension, Kidney and Vascular Research Center, Georgetown University, Washington, District of Columbia; Department of Physiology and Pharmacology, Karolinska Institutet, Stockholm, Sweden; and Department of Cell Biology and Physiology, UNC Kidney Center, and McAllister Heart Institute, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
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25
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Takano T, Nakano K, Doki T, Hohdatsu T. Differential effects of viroporin inhibitors against feline infectious peritonitis virus serotypes I and II. Arch Virol 2015; 160:1163-70. [PMID: 25701212 PMCID: PMC7086594 DOI: 10.1007/s00705-015-2370-x] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2014] [Accepted: 02/12/2015] [Indexed: 12/21/2022]
Abstract
Feline infectious peritonitis virus (FIP virus: FIPV), a feline coronavirus of the family Coronaviridae, causes a fatal disease called FIP in wild and domestic cat species. The genome of coronaviruses encodes a hydrophobic transmembrane protein, the envelope (E) protein. The E protein possesses ion channel activity. Viral proteins with ion channel activity are collectively termed “viroporins”. Hexamethylene amiloride (HMA), a viroporin inhibitor, can inhibit the ion channel activity of the E protein and replication of several coronaviruses. However, it is not clear whether HMA and other viroporin inhibitors affect replication of FIPV. We examined the effect of HMA and other viroporin inhibitors (DIDS [4,4′-disothiocyano-2,2′-stilbenedisulphonic acid] and amantadine) on infection by FIPV serotypes I and II. HMA treatment drastically decreased the titers of FIPV serotype I strains Black and KU-2 in a dose-dependent manner, but it only slightly decreased the titer of FIPV serotype II strain 79-1146. In contrast, DIDS treatment decreased the titer of FIPV serotype II strain 79-1146 in dose-dependent manner, but it only slightly decreased the titers of FIPV serotype I strains Black and KU-2. We investigated whether there is a difference in ion channel activity of the E protein between viral serotypes using E. coli cells expressing the E protein of FIPV serotypes I and II. No difference was observed, suggesting that a viroporin other than the E protein influences the differences in the actions of HMA and DIDS on FIPV serotypes I and II.
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Affiliation(s)
- Tomomi Takano
- Laboratory of Veterinary Infectious Disease, School of Veterinary Medicine, Kitasato University, Towada, Aomori, 034-8628, Japan
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The hidden hand of chloride in hypertension. Pflugers Arch 2015; 467:595-603. [PMID: 25619794 PMCID: PMC4325190 DOI: 10.1007/s00424-015-1690-8] [Citation(s) in RCA: 58] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2014] [Revised: 12/03/2014] [Accepted: 12/05/2014] [Indexed: 01/10/2023]
Abstract
Among the environmental factors that affect blood pressure, dietary sodium chloride has been studied the most, and there is general consensus that increased sodium chloride intake increases blood pressure. There is accruing evidence that chloride may have a role in blood pressure regulation which may perhaps be even more important than that of Na+. Though more than 85 % of Na+ is consumed as sodium chloride, there is evidence that Na+ and Cl− concentrations do not go necessarily hand in hand since they may originate from different sources. Hence, elucidating the role of Cl− as an independent player in blood pressure regulation will have clinical and public health implications in addition to advancing our understanding of electrolyte-mediated blood pressure regulation. In this review, we describe the evidence that support an independent role for Cl− on hypertension and cardiovascular health.
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Hübner CA, Schroeder BC, Ehmke H. Regulation of vascular tone and arterial blood pressure: role of chloride transport in vascular smooth muscle. Pflugers Arch 2015; 467:605-14. [DOI: 10.1007/s00424-014-1684-y] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2014] [Revised: 12/24/2014] [Accepted: 12/29/2014] [Indexed: 01/01/2023]
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Bulley S, Jaggar JH. Cl⁻ channels in smooth muscle cells. Pflugers Arch 2014; 466:861-72. [PMID: 24077695 DOI: 10.1007/s00424-013-1357-2] [Citation(s) in RCA: 70] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2013] [Revised: 09/09/2013] [Accepted: 09/09/2013] [Indexed: 10/26/2022]
Abstract
In smooth muscle cells (SMCs), the intracellular chloride ion (Cl−) concentration is high due to accumulation by Cl−/HCO3− exchange and Na+–K+–Cl− cotransportation. The equilibrium potential for Cl− (ECl) is more positive than physiological membrane potentials (Em), with Cl− efflux inducing membrane depolarization. Early studies used electrophysiology and nonspecific antagonists to study the physiological relevance of Cl− channels in SMCs. More recent reports have incorporated molecular biological approaches to identify and determine the functional significance of several different Cl− channels. Both "classic" and cGMP-dependent calcium (Ca2+)-activated (ClCa) channels and volume-sensitive Cl− channels are present, with TMEM16A/ANO1, bestrophins, and ClC-3, respectively, proposed as molecular candidates for these channels. The cystic fibrosis transmembrane conductance regulator (CFTR) has also been described in SMCs. This review will focus on discussing recent progress made in identifying each of these Cl− channels in SMCs, their physiological functions, and contribution to diseases that modify contraction, apoptosis, and cell proliferation.
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Gonzales AL, Earley S. Regulation of cerebral artery smooth muscle membrane potential by Ca²⁺-activated cation channels. Microcirculation 2013; 20:337-47. [PMID: 23116477 DOI: 10.1111/micc.12023] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2012] [Accepted: 10/26/2012] [Indexed: 12/24/2022]
Abstract
Arterial tone is dependent on the depolarizing and hyperpolarizing currents regulating membrane potential and governing the influx of Ca²⁺ needed for smooth muscle contraction. Several ion channels have been proposed to contribute to membrane depolarization, but the underlying molecular mechanisms are not fully understood. In this review, we will discuss the historical and physiological significance of the Ca²⁺-activated cation channel, TRPM4, in regulating membrane potential of cerebral artery smooth muscle cells. As a member of the recently described transient receptor potential super family of ion channels, TRPM4 possesses the biophysical properties and upstream cellular signaling and regulatory pathways that establish it as a major physiological player in smooth muscle membrane depolarization.
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Affiliation(s)
- Albert L Gonzales
- Vascular Physiology Research Group, Department of Biomedical Sciences, Colorado State University, Fort Collins, Colorado, USA
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30
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Edwards A, Layton AT. Calcium dynamics underlying the myogenic response of the renal afferent arteriole. Am J Physiol Renal Physiol 2013; 306:F34-48. [PMID: 24173354 DOI: 10.1152/ajprenal.00317.2013] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
The renal afferent arteriole reacts to an elevation in blood pressure with an increase in muscle tone and a decrease in luminal diameter. This effect, known as the myogenic response, is believed to stabilize glomerular filtration and to protect the glomerulus from systolic blood pressure increases, especially in hypertension. To study the mechanisms underlying the myogenic response, we developed a mathematical model of intracellular Ca(2+) signaling in an afferent arteriole smooth muscle cell. The model represents detailed transmembrane ionic transport, intracellular Ca(2+) dynamics, the kinetics of myosin light chain phosphorylation, and the mechanical behavior of the cell. It assumes that the myogenic response is initiated by pressure-induced changes in the activity of nonselective cation channels. Our model predicts spontaneous vasomotion at physiological luminal pressures and KCl- and diltiazem-induced diameter changes comparable to experimental findings. The time-periodic oscillations stem from the dynamic exchange of Ca(2+) between the cytosol and the sarcoplasmic reticulum, coupled to the stimulation of Ca(2+)-activated potassium (KCa) and chloride (ClCa) channels, and the modulation of voltage-activated L-type channels; blocking sarco/endoplasmic reticulum Ca(2+) pumps, ryanodine receptors (RyR), KCa, ClCa, or L-type channels abolishes these oscillations. Our results indicate that the profile of the myogenic response is also strongly dependent on the conductance of ClCa and L-type channels, as well as the activity of plasmalemmal Ca(2+) pumps. Furthermore, inhibition of KCa is not necessary to induce myogenic contraction. Lastly, our model suggests that the kinetic behavior of L-type channels results in myogenic kinetics that are substantially faster during constriction than during dilation, consistent with in vitro observations (Loutzenhiser R, Bidani A, Chilton L. Circ. Res. 90: 1316-1324, 2002).
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Affiliation(s)
- Aurélie Edwards
- Dept. of Mathematics, Duke Univ., Box 90320, Durham, NC 27708-0320.
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Pires PW, Dams Ramos CM, Matin N, Dorrance AM. The effects of hypertension on the cerebral circulation. Am J Physiol Heart Circ Physiol 2013; 304:H1598-614. [PMID: 23585139 DOI: 10.1152/ajpheart.00490.2012] [Citation(s) in RCA: 250] [Impact Index Per Article: 22.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
Maintenance of brain function depends on a constant blood supply. Deficits in cerebral blood flow are linked to cognitive decline, and they have detrimental effects on the outcome of ischemia. Hypertension causes alterations in cerebral artery structure and function that can impair blood flow, particularly during an ischemic insult or during periods of low arterial pressure. This review will focus on the historical discoveries, novel developments, and knowledge gaps in 1) hypertensive cerebral artery remodeling, 2) vascular function with emphasis on myogenic reactivity and endothelium-dependent dilation, and 3) blood-brain barrier function. Hypertensive artery remodeling results in reduction in the lumen diameter and an increase in the wall-to-lumen ratio in most cerebral arteries; this is linked to reduced blood flow postischemia and increased ischemic damage. Many factors that are increased in hypertension stimulate remodeling; these include the renin-angiotensin-aldosterone system and reactive oxygen species levels. Endothelial function, vital for endothelium-mediated dilation and regulation of myogenic reactivity, is impaired in hypertension. This is a consequence of alterations in vasodilator mechanisms involving nitric oxide, epoxyeicosatrienoic acids, and ion channels, including calcium-activated potassium channels and transient receptor potential vanilloid channel 4. Hypertension causes blood-brain barrier breakdown by mechanisms involving inflammation, oxidative stress, and vasoactive circulating molecules. This exposes neurons to cytotoxic molecules, leading to neuronal loss, cognitive decline, and impaired recovery from ischemia. As the population ages and the incidence of hypertension, stroke, and dementia increases, it is imperative that we gain a better understanding of the control of cerebral artery function in health and disease.
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Affiliation(s)
- Paulo W Pires
- Department of Pharmacology and Toxicology, Michigan State University, East Lansing, MI 48824, USA
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Li XZ, Ma KT, Guan BC, Li L, Zhao L, Zhang ZS, Si JQ, Jiang ZG. Fenamates block gap junction coupling and potentiate BKCa channels in guinea pig arteriolar cells. Eur J Pharmacol 2013; 703:74-82. [PMID: 23420003 PMCID: PMC3615131 DOI: 10.1016/j.ejphar.2013.02.004] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2012] [Revised: 02/01/2013] [Accepted: 02/06/2013] [Indexed: 10/27/2022]
Abstract
We determined the actions of the fenamates, flufenamic acid (FFA) and niflumic acid (NFA), on gap junction-mediated intercellular coupling between vascular smooth muscle cells (VSMC) in situ of acutely isolated arteriole segments from the three vascular beds: the spiral modiolar artery (SMA), anterior inferior cerebellar artery (AICA) and mesenteric artery (MA), and on non-junctional membrane channels in dispersed VSMCs. Conventional whole-cell recording methods were used. FFA reversibly suppressed the input conductance (Ginput) or increased the input resistance (Rinput) in a concentration dependent manner, with slightly different IC50s for the SMA, AICA and MA segments (26, 33 and 56 μM respectively, P>0.05). Complete electrical isolation of the recorded VSMC was normally reached at ≥ 300 μM. NFA had a similar effect on gap junction among VSMCs with an IC50 of 40, 48 and 62 μM in SMA, AICA and MA segments, respectively. In dispersed VSMCs, FFA and NFA increased outward rectifier K(+)-current mediated by the big conductance calcium-activated potassium channel (BKCa) in a concentration-dependent manner, with a similar EC50 of ∼300 μM for both FFA and NFA in the three vessels. Iberiotoxin, a selective blocker of the BKCa, suppressed the enhancement of the BKCa by FFA and NFA. The KV blocker 4-AP had no effect on the fenamates-induced K(+)-current enhancement. We conclude that FFA and NFA blocked the vascular gap junction mediated electrical couplings uniformly in arterioles of the three vascular beds, and complete electrical isolation of the recorded VSMC is obtained at ≧300μM; FFA and NFA also activate BKCa channels in the arteriolar smooth muscle cells in addition to their known inhibitory effects on chloride channels.
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Affiliation(s)
- Xin-Zhi Li
- Department of Physiology, Tongji Medical College of Huazhong University of Science and Technology, Wuhan 430030, P.R. China
- The Key Laboratory of Xinjiang Endemic and Ethnic Diseases, Medical College of Shihezi University, Shihezi, 832002, P.R. China
| | - Ke-Tao Ma
- The Key Laboratory of Xinjiang Endemic and Ethnic Diseases, Medical College of Shihezi University, Shihezi, 832002, P.R. China
| | - Bing-Cai Guan
- Department of Pharmacology, Hebei Medical University, Shijiazhuang, 050017, P.R. China
| | - Li Li
- The Key Laboratory of Xinjiang Endemic and Ethnic Diseases, Medical College of Shihezi University, Shihezi, 832002, P.R. China
| | - Lei Zhao
- The Key Laboratory of Xinjiang Endemic and Ethnic Diseases, Medical College of Shihezi University, Shihezi, 832002, P.R. China
| | - Zhong-Shuang Zhang
- The Key Laboratory of Xinjiang Endemic and Ethnic Diseases, Medical College of Shihezi University, Shihezi, 832002, P.R. China
| | - Jun-Qiang Si
- Department of Physiology, Tongji Medical College of Huazhong University of Science and Technology, Wuhan 430030, P.R. China
- The Key Laboratory of Xinjiang Endemic and Ethnic Diseases, Medical College of Shihezi University, Shihezi, 832002, P.R. China
| | - Zhi-Gen Jiang
- Oregon Hearing Research Center, NRC04, Oregon Health and Science University, Portland, OR, 97239 USA
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How the airway smooth muscle in cystic fibrosis reacts in proinflammatory conditions: implications for airway hyper-responsiveness and asthma in cystic fibrosis. THE LANCET RESPIRATORY MEDICINE 2013; 1:137-47. [PMID: 24429094 DOI: 10.1016/s2213-2600(12)70058-9] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Among patients with cystic fibrosis there is a high prevalence (40-70%) of asthma signs and symptoms such as cough and wheezing and airway hyper-responsiveness to inhaled histamine or methacholine. Whether these abnormal airway responses are due to a primary deficiency in the cystic fibrosis transmembrane conductance regulator (CFTR) or are secondary to the inflammatory environment in the cystic fibrosis lungs is not clear. A role for the CFTR in smooth muscle function is emerging, and alterations in contractile signalling have been reported in CFTR-deficient airway smooth muscle. Persistent bacterial infection, especially with Pseudomonas aeruginosa, stimulates interleukin-8 release from the airway epithelium, resulting in neutrophilic inflammation. Increased neutrophilia and skewing of CFTR-deficient T-helper cells to type 2 helper T cells creates an inflammatory environment characterised by high concentrations of tumour necrosis factor α, interleukin-8, and interleukin-13, which might all contribute to increased contractility of airway smooth muscle in cystic fibrosis. An emerging role of interleukin-17, which is raised in patients with cystic fibrosis, in airway smooth muscle proliferation and hyper-responsiveness is apparent. Increased understanding of the molecular mechanisms responsible for the altered smooth muscle physiology in patients with cystic fibrosis might provide insight into airway dysfunction in this disease.
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Abstract
Vascular remodeling of cerebral arterioles, including proliferation, migration, and apoptosis of vascular smooth muscle cells (VSMCs), is the major cause of changes in the cross-sectional area and diameter of the arteries and sudden interruption of blood flow or hemorrhage in the brain, ie, stroke. Accumulating evidence strongly supports an important role for chloride (Cl(-)) channels in vascular remodeling and stroke. At least three Cl(-) channel genes are expressed in VSMCs: 1) the TMEM16A (or Ano1), which may encode the calcium-activated Cl(-) channels (CACCs); 2) the CLC-3 Cl(-) channel and Cl(-)/H(+) antiporter, which is closely related to the volume-regulated Cl(-) channels (VRCCs); and 3) the cystic fibrosis transmembrane conductance regulator (CFTR), which encodes the PKA- and PKC-activated Cl(-) channels. Activation of the CACCs by agonist-induced increase in intracellular Ca(2+) causes membrane depolarization, vasoconstriction, and inhibition of VSMC proliferation. Activation of VRCCs by cell volume increase or membrane stretch promotes the production of reactive oxygen species, induces proliferation and inhibits apoptosis of VSMCs. Activation of CFTR inhibits oxidative stress and may prevent the development of hypertension. In addition, Cl(-) current mediated by gamma-aminobutyric acid (GABA) receptor has also been implicated a role in ischemic neuron death. This review focuses on the functional roles of Cl(-) channels in the development of stroke and provides a perspective on the future directions for research and the potential to develop Cl(-) channels as new targets for the prevention and treatment of stroke.
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Matchkov VV, Secher Dam V, Bødtkjer DMB, Aalkjær C. Transport and Function of Chloride in Vascular Smooth Muscles. J Vasc Res 2013; 50:69-87. [DOI: 10.1159/000345242] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2012] [Accepted: 10/16/2012] [Indexed: 12/12/2022] Open
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Bulley S, Neeb ZP, Burris SK, Bannister JP, Thomas-Gatewood CM, Jangsangthong W, Jaggar JH. TMEM16A/ANO1 channels contribute to the myogenic response in cerebral arteries. Circ Res 2012; 111:1027-36. [PMID: 22872152 DOI: 10.1161/circresaha.112.277145] [Citation(s) in RCA: 110] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
RATIONALE Pressure-induced arterial depolarization and constriction (the myogenic response) is a smooth muscle cell (myocyte)-specific mechanism that controls regional organ blood flow and systemic blood pressure. Several different nonselective cation channels contribute to pressure-induced depolarization, but signaling mechanisms involved are unclear. Similarly uncertain is the contribution of anion channels to the myogenic response and physiological functions and mechanisms of regulation of recently discovered transmembrane 16A (TMEM16A), also termed Anoctamin 1, chloride (Cl(-)) channels in arterial myocytes. OBJECTIVE To investigate the hypothesis that myocyte TMEM16A channels control membrane potential and contractility and contribute to the myogenic response in cerebral arteries. METHODS AND RESULTS Cell swelling induced by hyposmotic bath solution stimulated Cl(-) currents in arterial myocytes that were blocked by TMEM16A channel inhibitory antibodies, RNAi-mediated selective TMEM16A channel knockdown, removal of extracellular calcium (Ca(2+)), replacement of intracellular EGTA with BAPTA, a fast Ca(2+) chelator, and Gd(3+) and SKF-96365, nonselective cation channel blockers. In contrast, nimodipine, a voltage-dependent Ca(2+) channel inhibitor, or thapsigargin, which depletes intracellular Ca(2+) stores, did not alter swelling-activated TMEM16A currents. Pressure-induced (-40 mm Hg) membrane stretch activated ion channels in arterial myocyte cell-attached patches that were inhibited by TMEM16A antibodies and were of similar amplitude to recombinant TMEM16A channels. TMEM16A knockdown reduced intravascular pressure-induced depolarization and vasoconstriction but did not alter depolarization-induced (60 mmol/L K(+)) vasoconstriction. CONCLUSIONS Membrane stretch activates arterial myocyte TMEM16A channels, leading to membrane depolarization and vasoconstriction. Data also provide a mechanism by which a local Ca(2+) signal generated by nonselective cation channels stimulates TMEM16A channels to induce myogenic constriction.
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Affiliation(s)
- Simon Bulley
- Department of Physiology, University of Tennessee Health Science Center, Memphis, TN 38163, USA
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Koller A, Toth P. Contribution of flow-dependent vasomotor mechanisms to the autoregulation of cerebral blood flow. J Vasc Res 2012; 49:375-89. [PMID: 22739136 PMCID: PMC3586555 DOI: 10.1159/000338747] [Citation(s) in RCA: 85] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2011] [Accepted: 04/04/2012] [Indexed: 11/19/2022] Open
Abstract
Regulation of cerebral blood flow (CBF) is the result of multilevel mechanisms to maintain the appropriate blood supply to the brain while having to comply with the limited space available in the cranium. The latter requirement is ensured by the autoregulation of CBF, in which the pressure-sensitive myogenic response is known to play a pivotal role. However, in vivo increases in pressure are accompanied by increases in flow; yet the effects of flow on the vasomotor tone of cerebral vessels are less known. Earlier studies showed flow-sensitive dilation and/or constriction or both, but no clear picture emerged. Recently, the important role of flow-sensitive mechanism(s) eliciting the constriction of cerebral vessels has been demonstrated. This review focuses on the effect of hemodynamic forces (especially intraluminal flow) on the vasomotor tone of cerebral vessels and the underlying cellular and molecular mechanisms. A novel concept of autoregulation of CBF is proposed, suggesting that (in certain areas of the cerebrovascular tree) pressure- and flow-induced constrictions together maintain an effective autoregulation, and that alterations in these mechanisms may contribute to the development of cerebrovascular disorders. Future studies are warranted to explore the signals, the details of signaling processes and the in vivo importance of these mechanisms.
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Affiliation(s)
- Akos Koller
- Department of Pathophysiology and Gerontology, Medical School, University of Pécs, Pécs, Hungary.
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Abstract
Mechanosensation and -transduction are important for physiological processes like the senses of touch, hearing, and balance. The mechanisms underlying the translation of mechanical stimuli into biochemical information by activating various signaling pathways play a fundamental role in physiology and pathophysiology but are only poorly understood. Recently, G protein-coupled receptors (GPCRs), which are essential for the conversion of light, olfactory and gustatory stimuli, as well as of primary messengers like hormones and neurotransmitters into cellular signals and which play distinct roles in inflammation, cell growth, and differentiation, have emerged as potential mechanosensors. The first candidate for a mechanosensitive GPCR was the angiotensin-II type-1 (AT(1)) receptor. Agonist-independent mechanical receptor activation of AT(1) receptors induces an active receptor conformation that appears to differ from agonist-induced receptor conformations and entails the activation of G proteins. Mechanically induced AT(1) receptor activation plays an important role for myogenic vasoconstriction and for the initiation of cardiac hypertrophy. A growing body of evidence suggests that other GPCRs are involved in mechanosensation as well. These findings highlight physiologically relevant, ligand-independent functions of GPCRs and add yet another facet to the polymodal activation spectrum of this ubiquitous protein family.
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Affiliation(s)
- Ursula Storch
- Walther-Straub-Institute of Pharmacology and Toxicology, University of Munich, Germany
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Anfinogenova Y, Brett SE, Walsh MP, Harraz OF, Welsh DG. Do TRPC-like currents and G protein-coupled receptors interact to facilitate myogenic tone development? Am J Physiol Heart Circ Physiol 2011; 301:H1378-88. [DOI: 10.1152/ajpheart.00460.2011] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
The objective of this study was to determine whether Gq/11-coupled receptor activation can enhance the mechanosensitivity of a canonical transient receptor potential (TRPC)-like current and consequently the myogenic responsiveness of rat anterior cerebral arteries. Initial patch-clamp experiments revealed the presence of a basal cation current in isolated smooth muscle cells that displayed evidence of double rectification, which was blocked by trivalent cations (Gd3+ and La3+). PCR analysis identified the expression of TRPC1, 3, 6 and 7 mRNA and, characteristic of TRPC-like current, the whole-cell conductance was insensitive to a Na+-dependent transport (amiloride), TRP vanilloid (ruthenium red), and chloride channel (DIDS, niflumic acid, and flufenamate) inhibitors. One notable exception was tamoxifen, which elicited a dual effect, blocking or activating the TRPC-like current at 1 and 10 μM, respectively. This TRPC-like current was augmented by constrictor agonists (uridine 5′-triphosphate and U46619) or hyposmotic challenge (303 to 223 mOsm/l), a mechanical stimulus. Although each stimulus was effective alone, smooth muscle cells pretreated with agonist did not augment the whole-cell response to hyposmotic challenge. Consistent with these electrophysiological recordings, functional experiments revealed that neither UTP nor U46619 enhanced the sensitivity of intact cerebral arteries to hyposmotic challenge or elevated intravascular pressure. In summary, this study found no evidence that Gq/11-coupled receptor activation augments the mechanosensitivity of a TRPC-like current and consequently the myogenic responsiveness of anterior cerebral arteries.
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Affiliation(s)
| | | | - Michael P. Walsh
- Biochemistry and Molecular Biology, Hotchkiss Brain and Libin Cardiovascular Institutes, University of Calgary, Alberta, Canada
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Abstract
ClC-3 is a member of the ClC voltage-gated chloride (Cl(-)) channel superfamily. Recent studies have demonstrated the abundant expression and pleiotropy of ClC-3 in cardiac atrial and ventricular myocytes, vascular smooth muscle cells, and endothelial cells. ClC-3 Cl(-) channels can be activated by increase in cell volume, direct stretch of β1-integrin through focal adhesion kinase and many active molecules or growth factors including angiotensin II and endothelin-1-mediated signaling pathways, Ca(2+)/calmodulin-dependent protein kinase II and reactive oxygen species. ClC-3 may function as a key component of the volume-regulated Cl(-) channels, a superoxide anion transport and/or NADPH oxidase interaction partner, and a regulator of many other transporters. ClC-3 has been implicated in the regulation of electrical activity, cell volume, proliferation, differentiation, migration, apoptosis and intracellular pH. This review will highlight the major findings and recent advances in the study of ClC-3 Cl(-) channels in the cardiovascular system and discuss their important roles in cardiac and vascular remodeling during hypertension, myocardial hypertrophy, ischemia/reperfusion, and heart failure.
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Du RH, Tang YB, Zhou JG, Guan YY. Effects of Tween 80 on volume-regulated chloride channel and cell proliferation in rat basilar artery smooth muscle cell. J Pharm Pharmacol 2011; 63:253-60. [DOI: 10.1111/j.2042-7158.2010.01209.x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Abstract
Objectives
We have previously found that volume-regulated chloride current (VRCC) is involved in cell cycle progression and cell proliferation. This study was to examine the effect of Tween 80, a nonionic surfactant, on VRCC and cell proliferation in rat basilar artery smooth muscle cells (BASMCs).
Methods
VRCC was recorded using a whole-cell patch clamp. Cell proliferation and cell cycle were determined by CCK-8, cell count and flow cytometry.
Key findings
The results showed that endothelin-1 promotes cell cycle transition from the G0/G1 phase to the S phase and significantly increases VRCC in BASMCs. The effect of Tween 80 on VRCC is reversible and concentration dependent. However, this chemical has no effect on the calcium-activated chloride channel. Tween 80 also concentration-dependently inhibits BASMCs proliferation and arrests cells in the G1/S checkpoint. The antiproliferative effect is paralleled with the inhibitory effect on VRCC.
Conclutision
Our study demonstrates that the inhibitory effect of Tween 80 on VRCC contributes importantly to arrest of the cell cycle and prevention of cell proliferation.
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Affiliation(s)
- Ren-Hong Du
- Department of Pharmacology, Zhongshan School of Medicine, and Vascular Research Center, Sun Yat-Sen University, Guangzhou, China
| | - Yong-Bo Tang
- Department of Pharmacology, Zhongshan School of Medicine, and Vascular Research Center, Sun Yat-Sen University, Guangzhou, China
| | - Jia-Guo Zhou
- Department of Pharmacology, Zhongshan School of Medicine, and Vascular Research Center, Sun Yat-Sen University, Guangzhou, China
| | - Yong-Yuan Guan
- Department of Pharmacology, Zhongshan School of Medicine, and Vascular Research Center, Sun Yat-Sen University, Guangzhou, China
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Namkung W, Thiagarajah JR, Phuan PW, Verkman AS. Inhibition of Ca2+-activated Cl- channels by gallotannins as a possible molecular basis for health benefits of red wine and green tea. FASEB J 2010; 24:4178-86. [PMID: 20581223 DOI: 10.1096/fj.10-160648] [Citation(s) in RCA: 154] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
TMEM16A was found recently to be a calcium-activated Cl(-) channel (CaCC). CaCCs perform important functions in cell physiology, including regulation of epithelial secretion, cardiac and neuronal excitability, and smooth muscle contraction. CaCC modulators are of potential utility for treatment of hypertension, diarrhea, and cystic fibrosis. Screening of drug and natural product collections identified tannic acid as an inhibitor of TMEM16A, with IC(50) ∼ 6 μM and ∼100% inhibition at higher concentrations. Tannic acid inhibited CaCCs in multiple cell types but did not affect CFTR Cl(-) channels. Structure-activity analysis indicated the requirement of gallic or digallic acid substituents on a macromolecular scaffold (gallotannins), as are present in green tea and red wine. Other polyphenolic components of teas and wines, including epicatechin, catechin, and malvidin-3-glucoside, poorly inhibited CaCCs. Remarkably, a 1000-fold dilution of red wine and 100-fold dilution of green tea inhibited CaCCs by >50%. Tannic acid, red wine, and green tea inhibited arterial smooth muscle contraction and intestinal Cl(-) secretion. Gallotannins are thus potent CaCC inhibitors whose biological activity provides a potential molecular basis for the cardioprotective and antisecretory benefits of red wine and green tea.
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Affiliation(s)
- Wan Namkung
- Department of Medicine , University of California, San Francisco, CA 94143-0521, USA
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CLC-3 chloride channels in the pulmonary vasculature. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2010; 661:237-47. [PMID: 20204734 DOI: 10.1007/978-1-60761-500-2_15] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/24/2023]
Abstract
Volume-sensitive outwardly rectifying anion channels (VSOACs) are expressed in pulmonary artery smooth muscle cells (PASMCs) and have been implicated in cell proliferation, growth, apoptosis and protection against oxidative stress. In this chapter, we review the properties of native VSOACs in PASMCs, and consider the evidence that ClC-3, a member of the ClC superfamily of voltage dependent Cl- channels, may be responsible for native VSOACs in PASMCs. Finally, we examine whether or not native VSOACs and heterologously expressed ClC-3 channels function as bona fide chloride channels or as chloride/proton antiporters.
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Tang YB, Zhou JG, Guan YY. Volume-regulated chloride channels and cerebral vascular remodelling. Clin Exp Pharmacol Physiol 2010; 37:238-42. [DOI: 10.1111/j.1440-1681.2008.05137.x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
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Guan Z, Pollock JS, Cook AK, Hobbs JL, Inscho EW. Effect of epithelial sodium channel blockade on the myogenic response of rat juxtamedullary afferent arterioles. Hypertension 2009; 54:1062-9. [PMID: 19720952 DOI: 10.1161/hypertensionaha.109.137992] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
The mechanotransduction mechanism underlying the myogenic response is poorly understood, but evidence implicates participation of epithelial sodium channel (ENaC)-like proteins. Therefore, the role of ENaC on the afferent arteriolar myogenic response was investigated in vitro using the blood-perfused juxtamedullary nephron technique. Papillectomy was used to isolate myogenic influences by eliminating tubuloglomerular feedback signals. Autoregulatory responses were assessed by manipulating perfusion pressure in 30-mm Hg steps. Under control conditions, arteriolar diameter increased by 15% from 13.0+/-1.3 to 14.7+/-1.2 microm (P<0.05) after reducing perfusion pressure from 100 to 70 mm Hg. Diameter decreased to 11.3+/-1.1 and 10.6+/-1.0 microm after increasing pressure to 130 and 160 mm Hg (88+/-1 and 81+/-2% of control diameter, P<0.05), respectively. Pressure-mediated autoregulatory responses were significantly inhibited by superfusion of 10 micromol/L amiloride (102+/-2, 97+/-4, and 94+/-3% of control diameter), or 10 micromol/L benzamil (106+/-5, 100+/-3, and 103+/-3% of control diameter), and when perfusing with blood containing 5 micromol/L amiloride (106+/-2, 97+/-4, and 97+/-4% of control diameter). Vasoconstrictor responses to 55 mmol/L KCl were preserved as diameters decreased by 67+/-4, 55+/-8, and 60+/-4% in afferent arterioles superfused with amiloride or benzamil, and perfused with amiloride, respectively. These responses were similar to responses obtained from control afferent arterioles (64+/-6%, P>0.05). Immunofluorescence revealed expression of the alpha, beta, and gamma subunits of ENaC in freshly isolated preglomerular microvascular smooth muscle cells. These results demonstrate that selective ENaC inhibitors attenuate afferent arteriolar myogenic responses and suggest that ENaC may function as mechanosensitive ion channels initiating pressure-dependent myogenic responses in rat juxtamedullary afferent arterioles.
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Affiliation(s)
- Zhengrong Guan
- Department of Physiology, Medical College of Georgia, Augusta, GA 30912, USA
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Hill MA, Meininger GA, Davis MJ, Laher I. Therapeutic potential of pharmacologically targeting arteriolar myogenic tone. Trends Pharmacol Sci 2009; 30:363-74. [PMID: 19541373 DOI: 10.1016/j.tips.2009.04.008] [Citation(s) in RCA: 69] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2009] [Revised: 04/28/2009] [Accepted: 04/28/2009] [Indexed: 01/05/2023]
Abstract
The arteriolar myogenic response, which is defined as vasoconstriction to increases in intraluminal pressure and, conversely, dilation to a reduction in pressure, is key in the setting of vascular resistance, local control of microvascular blood flow through autoregulation, and in the control of capillary hydrostatic pressure. Although considerable progress has been made in the quest for understanding the underlying sensory apparatus and cellular mechanisms, fundamental questions remain - particularly if this pathway is to be considered as a target for novel strategies of pharmacological intervention. We propose that an ability to 're-set' myogenic tone would enable modification of systemic vascular resistance and pressure while at the same time preserving existing interactions with neurohumoral regulatory mechanisms. The challenge, therefore, is to identify steps unique to the myogenic signaling pathway to enable specific pharmacological targeting.
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Affiliation(s)
- Michael A Hill
- Dalton Cardiovascular Research Center and Department of Medical Pharmacology and Physiology, University of Missouri, Columbia, MO 65211, USA.
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McGahon MK, Needham MA, Scholfield CN, McGeown JG, Curtis TM. Ca2+-activated Cl- current in retinal arteriolar smooth muscle. Invest Ophthalmol Vis Sci 2008; 50:364-71. [PMID: 18775864 DOI: 10.1167/iovs.08-2524] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
PURPOSE To characterize the biophysical, pharmacologic, and functional properties of the Ca(2+)-activated Cl(-) current in retinal arteriolar myocytes. METHODS Whole-cell perforated patch-clamp recordings were made from myocytes within intact isolated arteriolar segments. Arteriolar tone was assessed using pressure myography. RESULTS Depolarizing of voltage steps to -40 mV and greater activated an L-type Ca(2+) current (I(Ca(L))) that was followed by a sustained current. Large tail currents (I(tail)) were observed on stepping back to -80 mV. The sustained current and I(tail) reversed close to 0 mV in symmetrical Cl(-) concentrations. The ion selectivity sequence for I(tail) was I(-)> Cl(-)> glucuronate. Outward I(tail) was sensitive to the Cl(-) channel blockers 9-anthracene-carboxylic acid (9-AC; 1 mM), 4-acetamido-4'-isothiocyanatostilbene-2,2'-disulfonic acid (SITS; 1 mM), and disodium 4,4'-diisothiocyanatostilbene-2,2'-disulfonate (DIDS; 1 mM), but only DIDS produced a substantial (78%) block of inward tail currents at -100 mV. I(tail) was decreased in magnitude when the normal bathing medium was substituted with Ca(2+)-free solution or if I(Ca(L)) was inhibited by 1 microM nimodipine. Caffeine (10 mM) produced large transient currents that reversed close to the Cl(-) equilibrium potential and were blocked by 1 mM DIDS or 100 microM tetracaine. DIDS had no effect on basal vascular tone in pressurized arterioles but dramatically reduced the level of vasoconstriction observed in the presence of 10 nM endothelin-1. CONCLUSIONS Retinal arteriolar myocytes have I(Cl(Ca)), which may be activated by Ca(2+) entry through L-type Ca(2+) channels or Ca(2+) release from intracellular stores. This current appears to contribute to agonist-induced retinal vasoconstriction.
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Affiliation(s)
- Mary K McGahon
- Centre for Vision and Vascular Sciences, School of Medicine and Dentistry, The Queen's University of Belfast, Institute of Clinical Sciences, The Royal Victoria Hospital, United Kingdom
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