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Márquez M, Muñoz M, Córdova A, Puebla M, Figueroa XF. Connexin 40-Mediated Regulation of Systemic Circulation and Arterial Blood Pressure. J Vasc Res 2023; 60:87-100. [PMID: 37331352 DOI: 10.1159/000531035] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2022] [Accepted: 05/05/2023] [Indexed: 06/20/2023] Open
Abstract
Vascular system is a complex network in which different cell types and vascular segments must work in concert to regulate blood flow distribution and arterial blood pressure. Although paracrine/autocrine signaling is involved in the regulation of vasomotor tone, direct intercellular communication via gap junctions plays a central role in the control and coordination of vascular function in the microvascular network. Gap junctions are made up by connexin (Cx) proteins, and among the four Cxs expressed in the cardiovascular system (Cx37, Cx40, Cx43, and Cx45), Cx40 has emerged as a critical signaling pathway in the vessel wall. This Cx is predominantly found in the endothelium, but it is involved in the development of the cardiovascular system and in the coordination of endothelial and smooth muscle cell function along the length of the vessels. In addition, Cx40 participates in the control of vasomotor tone through the transmission of electrical signals from the endothelium to the underlying smooth muscle and in the regulation of arterial blood pressure by renin-angiotensin system in afferent arterioles. In this review, we discuss the participation of Cx40-formed channels in the development of cardiovascular system, control and coordination of vascular function, and regulation of arterial blood pressure.
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Affiliation(s)
- Mónica Márquez
- Departamento de Fisiología, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Matías Muñoz
- Departamento de Fisiología, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Alexandra Córdova
- Departamento de Fisiología, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Mariela Puebla
- Departamento de Fisiología, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Xavier F Figueroa
- Departamento de Fisiología, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Santiago, Chile
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Burboa PC, Puebla M, Gaete PS, Durán WN, Lillo MA. Connexin and Pannexin Large-Pore Channels in Microcirculation and Neurovascular Coupling Function. Int J Mol Sci 2022; 23:ijms23137303. [PMID: 35806312 PMCID: PMC9266979 DOI: 10.3390/ijms23137303] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2022] [Revised: 06/27/2022] [Accepted: 06/28/2022] [Indexed: 01/27/2023] Open
Abstract
Microcirculation homeostasis depends on several channels permeable to ions and/or small molecules that facilitate the regulation of the vasomotor tone, hyperpermeability, the blood–brain barrier, and the neurovascular coupling function. Connexin (Cxs) and Pannexin (Panxs) large-pore channel proteins are implicated in several aspects of vascular physiology. The permeation of ions (i.e., Ca2+) and key metabolites (ATP, prostaglandins, D-serine, etc.) through Cxs (i.e., gap junction channels or hemichannels) and Panxs proteins plays a vital role in intercellular communication and maintaining vascular homeostasis. Therefore, dysregulation or genetic pathologies associated with these channels promote deleterious tissue consequences. This review provides an overview of current knowledge concerning the physiological role of these large-pore molecule channels in microcirculation (arterioles, capillaries, venules) and in the neurovascular coupling function.
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Affiliation(s)
- Pía C. Burboa
- Department of Pharmacology, Physiology and Neuroscience, New Jersey Medical School, Rutgers University, 185 South Orange Avenue, Newark, NJ 07103, USA; (P.C.B.); (W.N.D.)
- Departamento de Morfología y Función, Facultad de Salud y Ciencias Sociales, Sede Santiago Centro, Universidad de las Américas, Avenue República 71, Santiago 8370040, Chile;
| | - Mariela Puebla
- Departamento de Morfología y Función, Facultad de Salud y Ciencias Sociales, Sede Santiago Centro, Universidad de las Américas, Avenue República 71, Santiago 8370040, Chile;
| | - Pablo S. Gaete
- Department of Physiology and Membrane Biology, University of California at Davis, Davis, CA 95616, USA;
| | - Walter N. Durán
- Department of Pharmacology, Physiology and Neuroscience, New Jersey Medical School, Rutgers University, 185 South Orange Avenue, Newark, NJ 07103, USA; (P.C.B.); (W.N.D.)
- Rutgers School of Graduate Studies, 185 South Orange Avenue, Newark, NJ 07103, USA
| | - Mauricio A. Lillo
- Department of Pharmacology, Physiology and Neuroscience, New Jersey Medical School, Rutgers University, 185 South Orange Avenue, Newark, NJ 07103, USA; (P.C.B.); (W.N.D.)
- Correspondence:
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Targeting Endothelial Connexin37 Reduces Angiogenesis and Decreases Tumor Growth. Int J Mol Sci 2022; 23:ijms23062930. [PMID: 35328350 PMCID: PMC8948817 DOI: 10.3390/ijms23062930] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2022] [Revised: 02/28/2022] [Accepted: 03/03/2022] [Indexed: 12/13/2022] Open
Abstract
Connexin37 (Cx37) and Cx40 form intercellular channels between endothelial cells (EC), which contribute to the regulation of the functions of vessels. We previously documented the participation of both Cx in developmental angiogenesis and have further shown that loss of Cx40 decreases the growth of different tumors. Here, we report that loss of Cx37 reduces (1) the in vitro proliferation of primary human EC; (2) the vascularization of subcutaneously implanted matrigel plugs in Cx37−/− mice or in WT using matrigel plugs supplemented with a peptide targeting Cx37 channels; (3) tumor angiogenesis; and (4) the growth of TC-1 and B16 tumors, resulting in a longer mice survival. We further document that Cx37 and Cx40 function in a collaborative manner to promote tumor growth, inasmuch as the injection of a peptide targeting Cx40 into Cx37−/− mice decreased the growth of TC-1 tumors to a larger extent than after loss of Cx37. This loss did not alter vessel perfusion, mural cells coverage and tumor hypoxia compared to tumors grown in WT mice. The data show that Cx37 is relevant for the control of EC proliferation and growth in different tumor models, suggesting that it may be a target, alone or in combination with Cx40, in the development of anti-tumoral treatments.
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Schmidt K, de Wit C. Endothelium-Derived Hyperpolarizing Factor and Myoendothelial Coupling: The in vivo Perspective. Front Physiol 2021; 11:602930. [PMID: 33424626 PMCID: PMC7786115 DOI: 10.3389/fphys.2020.602930] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2020] [Accepted: 11/30/2020] [Indexed: 12/11/2022] Open
Abstract
The endothelium controls vascular tone adopting blood flow to tissue needs. It releases chemical mediators [e.g., nitric oxide (NO), prostaglandins (PG)] and exerts appreciable dilation through smooth muscle hyperpolarization, thus termed endothelium-dependent hyperpolarization (EDH). Initially, EDH was attributed to release of a factor, but later it was suggested that smooth muscle hyperpolarization might be derived from radial spread of an initial endothelial hyperpolarization through heterocellular channels coupling these vascular cells. The channels are indeed present and formed by connexins that enrich in gap junctions (GJ). In vitro data suggest that myoendothelial coupling underlies EDH-type dilations as evidenced by blocking experiments as well as simultaneous, merely identical membrane potential changes in endothelial and smooth muscle cells (SMCs), which is indicative of coupling through ohmic resistors. However, connexin-deficient animals do not display any attenuation of EDH-type dilations in vivo, and endothelial and SMCs exhibit distinct and barely superimposable membrane potential changes exerted by different means in vivo. Even if studied in the exact same artery EDH-type dilation exhibits distinct features in vitro and in vivo: in isometrically mounted vessels, it is rather weak and depends on myoendothelial coupling through connexin40 (Cx40), whereas in vivo as well as in vitro under isobaric conditions it is powerful and independent of myoendothelial coupling through Cx40. It is concluded that EDH-type dilations are distinct and a significant dependence on myoendothelial coupling in vitro does not reflect the situation under physiologic conditions in vivo. Myoendothelial coupling may act as a backup mechanism that is uncovered in the absence of the powerful EDH-type response and possibly reflects a situation in a pathophysiologic environment.
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Affiliation(s)
- Kjestine Schmidt
- Institut für Physiologie, Universität zu Lübeck, Lübeck, Germany.,Deutsches Zentrum für Herz-Kreislauf-Forschung (DZHK) e.V. (German Center for Cardiovascular Research), Partner Site Hamburg/Kiel/Lübeck, Lübeck, Germany
| | - Cor de Wit
- Institut für Physiologie, Universität zu Lübeck, Lübeck, Germany.,Deutsches Zentrum für Herz-Kreislauf-Forschung (DZHK) e.V. (German Center for Cardiovascular Research), Partner Site Hamburg/Kiel/Lübeck, Lübeck, Germany
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5
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Huang MN, Nicholson LT, Batich KA, Swartz AM, Kopin D, Wellford S, Prabhakar VK, Woroniecka K, Nair SK, Fecci PE, Sampson JH, Gunn MD. Antigen-loaded monocyte administration induces potent therapeutic antitumor T cell responses. J Clin Invest 2020; 130:774-788. [PMID: 31661470 DOI: 10.1172/jci128267] [Citation(s) in RCA: 44] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2019] [Accepted: 10/22/2019] [Indexed: 12/20/2022] Open
Abstract
Efficacy of dendritic cell (DC) cancer vaccines is classically thought to depend on their antigen-presenting cell (APC) activity. Studies show, however, that DC vaccine priming of cytotoxic T lymphocytes (CTLs) requires the activity of endogenous DCs, suggesting that exogenous DCs stimulate antitumor immunity by transferring antigens (Ags) to endogenous DCs. Such Ag transfer functions are most commonly ascribed to monocytes, implying that undifferentiated monocytes would function equally well as a vaccine modality and need not be differentiated to DCs to be effective. Here, we used several murine cancer models to test the antitumor efficacy of undifferentiated monocytes loaded with protein or peptide Ag. Intravenously injected monocytes displayed antitumor activity superior to DC vaccines in several cancer models, including aggressive intracranial glioblastoma. Ag-loaded monocytes induced robust CTL responses via Ag transfer to splenic CD8+ DCs in a manner independent of monocyte APC activity. Ag transfer required cell-cell contact and the formation of connexin 43-containing gap junctions between monocytes and DCs. These findings demonstrate the existence of an efficient gap junction-mediated Ag transfer pathway between monocytes and CD8+ DCs and suggest that administration of tumor Ag-loaded undifferentiated monocytes may serve as a simple and efficacious immunotherapy for the treatment of human cancers.
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Affiliation(s)
- Min-Nung Huang
- Department of Immunology.,Division of Cardiology, Department of Medicine
| | | | - Kristen A Batich
- School of Medicine.,Department of Pathology.,Preston Robert Tisch Brain Tumor Center
| | - Adam M Swartz
- Department of Pathology.,Preston Robert Tisch Brain Tumor Center
| | | | | | | | - Karolina Woroniecka
- School of Medicine.,Department of Pathology.,Preston Robert Tisch Brain Tumor Center
| | - Smita K Nair
- Department of Pathology.,Preston Robert Tisch Brain Tumor Center.,Department of Neurosurgery, and.,Department of Surgery, Duke University Medical Center, Durham, North Carolina, USA
| | - Peter E Fecci
- Department of Pathology.,Preston Robert Tisch Brain Tumor Center.,Department of Neurosurgery, and
| | - John H Sampson
- Department of Pathology.,Preston Robert Tisch Brain Tumor Center.,Department of Neurosurgery, and
| | - Michael D Gunn
- Department of Immunology.,Division of Cardiology, Department of Medicine
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Yang L, Yan J, Zhang JA, Zhou XH, Fang C, Zeng EM, Tang B, Duan J, Lu GH, Hong T. The important role of connexin 43 in subarachnoid hemorrhage-induced cerebral vasospasm. J Transl Med 2019; 17:433. [PMID: 31888653 PMCID: PMC6936071 DOI: 10.1186/s12967-019-02190-1] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2019] [Accepted: 12/23/2019] [Indexed: 12/23/2022] Open
Abstract
Background Gap junctions are involved in the development of cerebral vasospasm (CVS) after subarachnoid hemorrhage (SAH). However, the specific roles and regulatory functions of related connexin isoforms remain unknown. The aim of this study was to investigate the importance of connexin 43 (Cx43) in CVS and determine whether Cx43 alterations are modulated via the protein kinase C (PKC) signaling transduction pathway. Methods Oxyhemoglobin (OxyHb)-induced smooth muscle cells of basilar arterial and second-injection model in rat were used as CVS models in vitro and in vivo. In addition, dye transfer assays were used for gap junction-mediated intercellular communication (GJIC) observation in vitro and delayed cerebral ischemia (DCI) was observed in vivo by perfusion-weighted imaging (PWI) and intravital fluorescence microscopy. Results Increase in Cx43 mediated the development of SAH-induced CVS was found in both in vitro and in vivo CVS models. Enhanced GJIC was observed in vitro CVS model, this effect and increased Cx43 were reversed by preincubation with specific PKC inhibitors (chelerythrine or GF 109203X). DCI was observed in vivo on day 7 after SAH. However, DCI was attenuated by pretreatment with Cx43 siRNA or PKC inhibitors, and the increased Cx43 expression in vivo was also reversed by Cx43 siRNA or PKC inhibitors. Conclusions These data provide strong evidence that Cx43 plays an important role in CVS and indicate that changes in Cx43 expression may be mediated by the PKC pathway. The current findings suggest that Cx43 and the PKC pathway are novel targets for developing treatments for SAH-induced CVS.
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Affiliation(s)
- Le Yang
- Department of Neurosurgery, The First Affiliated Hospital of Nanchang University, 17 Yong Wai Zheng Street, Nanchang, China
| | - Jian Yan
- Department of Neurosurgery, The First Affiliated Hospital of Nanchang University, 17 Yong Wai Zheng Street, Nanchang, China
| | - Jin-An Zhang
- Department of Neurosurgery, The First Affiliated Hospital of Nanchang University, 17 Yong Wai Zheng Street, Nanchang, China
| | - Xin-Hui Zhou
- Department of Neurosurgery, The First Affiliated Hospital of Nanchang University, 17 Yong Wai Zheng Street, Nanchang, China
| | - Chao Fang
- Department of Neurosurgery, The First Affiliated Hospital of Nanchang University, 17 Yong Wai Zheng Street, Nanchang, China
| | - Er-Ming Zeng
- Department of Neurosurgery, The First Affiliated Hospital of Nanchang University, 17 Yong Wai Zheng Street, Nanchang, China
| | - Bin Tang
- Department of Neurosurgery, The First Affiliated Hospital of Nanchang University, 17 Yong Wai Zheng Street, Nanchang, China
| | - Jian Duan
- Department of Neurosurgery, The First Affiliated Hospital of Nanchang University, 17 Yong Wai Zheng Street, Nanchang, China
| | - Guo-Hui Lu
- Department of Neurosurgery, The First Affiliated Hospital of Nanchang University, 17 Yong Wai Zheng Street, Nanchang, China
| | - Tao Hong
- Department of Neurosurgery, The First Affiliated Hospital of Nanchang University, 17 Yong Wai Zheng Street, Nanchang, China.
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7
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Htet M, Nally JE, Shaw A, Foote BE, Martin PE, Dempsie Y. Connexin 43 Plays a Role in Pulmonary Vascular Reactivity in Mice. Int J Mol Sci 2018; 19:E1891. [PMID: 29954114 PMCID: PMC6073802 DOI: 10.3390/ijms19071891] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2018] [Revised: 06/07/2018] [Accepted: 06/20/2018] [Indexed: 11/25/2022] Open
Abstract
Pulmonary arterial hypertension (PAH) is a chronic condition characterized by vascular remodeling and increased vaso-reactivity. PAH is more common in females than in males (~3:1). Connexin (Cx)43 has been shown to be involved in cellular communication within the pulmonary vasculature. Therefore, we investigated the role of Cx43 in pulmonary vascular reactivity using Cx43 heterozygous (Cx43+/−) mice and 37,43Gap27, which is a pharmacological inhibitor of Cx37 and Cx43. Contraction and relaxation responses were studied in intra-lobar pulmonary arteries (IPAs) derived from normoxic mice and hypoxic mice using wire myography. IPAs from male Cx43+/− mice displayed a small but significant increase in the contractile response to endothelin-1 (but not 5-hydroxytryptamine) under both normoxic and hypoxic conditions. There was no difference in the contractile response to endothelin-1 (ET-1) or 5-hydroxytryptamine (5-HT) in IPAs derived from female Cx43+/−mice compared to wildtype mice. Relaxation responses to methacholine (MCh) were attenuated in IPAs from male and female Cx43+/− mice or by pre-incubation of IPAs with 37,43Gap27. Nω-Nitro-L-arginine methyl ester (l-NAME) fully inhibited MCh-induced relaxation. In conclusion, Cx43 is involved in nitric oxide (NO)-induced pulmonary vascular relaxation and plays a gender-specific and agonist-specific role in pulmonary vascular contractility. Therefore, reduced Cx43 signaling may contribute to pulmonary vascular dysfunction.
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Affiliation(s)
- Myo Htet
- Department of Life Sciences, School of Health and Life Sciences, Glasgow Caledonian University, Glasgow G4 0BA, UK.
| | - Jane E Nally
- Department of Life Sciences, School of Health and Life Sciences, Glasgow Caledonian University, Glasgow G4 0BA, UK.
| | - Andrew Shaw
- Department of Life Sciences, School of Health and Life Sciences, Glasgow Caledonian University, Glasgow G4 0BA, UK.
| | - Bradley E Foote
- Department of Life Sciences, School of Health and Life Sciences, Glasgow Caledonian University, Glasgow G4 0BA, UK.
| | - Patricia E Martin
- Department of Life Sciences, School of Health and Life Sciences, Glasgow Caledonian University, Glasgow G4 0BA, UK.
| | - Yvonne Dempsie
- Department of Life Sciences, School of Health and Life Sciences, Glasgow Caledonian University, Glasgow G4 0BA, UK.
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Molica F, Figueroa XF, Kwak BR, Isakson BE, Gibbins JM. Connexins and Pannexins in Vascular Function and Disease. Int J Mol Sci 2018; 19:ijms19061663. [PMID: 29874791 PMCID: PMC6032213 DOI: 10.3390/ijms19061663] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2018] [Revised: 05/28/2018] [Accepted: 05/31/2018] [Indexed: 12/24/2022] Open
Abstract
Connexins (Cxs) and pannexins (Panxs) are ubiquitous membrane channel forming proteins that are critically involved in many aspects of vascular physiology and pathology. The permeation of ions and small metabolites through Panx channels, Cx hemichannels and gap junction channels confers a crucial role to these proteins in intercellular communication and in maintaining tissue homeostasis. This review provides an overview of current knowledge with respect to the pathophysiological role of these channels in large arteries, the microcirculation, veins, the lymphatic system and platelet function. The essential nature of these membrane proteins in vascular homeostasis is further emphasized by the pathologies that are linked to mutations and polymorphisms in Cx and Panx genes.
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Affiliation(s)
- Filippo Molica
- Department of Pathology and Immunology, University of Geneva, CH-1211 Geneva, Switzerland.
| | - Xavier F Figueroa
- Departamento de Fisiología, Faculdad de Ciencias Biológicas, Pontifica Universidad Católica de Chile, Santiago 8330025, Chile.
| | - Brenda R Kwak
- Department of Pathology and Immunology, University of Geneva, CH-1211 Geneva, Switzerland.
| | - Brant E Isakson
- Robert M. Berne Cardiovascular Research Center, University of Virginia School of Medicine, Charlottesville, VA 22908, USA.
- Department of Molecular Physiology and Biophysics, University of Virginia School of Medicine, Charlottesville, VA 22908, USA.
| | - Jonathan M Gibbins
- Institute for Cardiovascular & Metabolic Research, School of Biological Sciences, Harborne Building, University of Reading, Reading RG6 6AS, UK.
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Mishra JS, More AS, Hankins GDV, Kumar S. Hyperandrogenemia reduces endothelium-derived hyperpolarizing factor-mediated relaxation in mesenteric artery of female rats. Biol Reprod 2018; 96:1221-1230. [PMID: 28486649 DOI: 10.1093/biolre/iox043] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2017] [Accepted: 05/08/2017] [Indexed: 01/05/2023] Open
Abstract
Women with polycystic ovary syndrome (PCOS) are often presented with hyperandrogenemia along with vascular dysfunction and elevated blood pressure. In animal models of PCOS, anti-androgen treatment decreased blood pressure, indicating a key role for androgens in the development of hypertension. However, the underlying androgen-mediated mechanism that contributes to increased blood pressure is not known. This study determined whether elevated androgens affect endothelium-derived hyperpolarizing factor (EDHF)-mediated vascular relaxation responses through alteration in function of gap junctional proteins. Female rats were implanted with placebo or dihydrotestosterone (DHT) pellets (7.5 mg, 90-day release). After 12 weeks of DHT exposure, blood pressure was assessed through carotid arterial catheter and endothelium-dependent mesenteric arterial EDHF relaxation using wire myograph. Connexin expression in mesenteric arteries was also examined. Elevated DHT significantly increased mean arterial pressure and decreased endothelium-dependent EDHF-mediated acetylcholine relaxation. Inhibition of Cx40 did not have any effect, while inhibition of Cx37 decreased EDHF relaxation to a similar magnitude in both controls and DHT females. On the other hand, inhibition of Cx43 significantly attenuated EDHF relaxation in mesenteric arteries of controls but not DHT females. Elevated DHT did not alter Cx37 or Cx40, but decreased Cx43 mRNA and protein levels in mesenteric arteries. In vitro exposure of DHT to cultured mesenteric artery smooth muscle cells dose-dependently downregulated Cx43 expression. In conclusion, increased blood pressure in hyperandrogenic females is due, at least in part, to decreased EDHF-mediated vascular relaxation responses. Decreased Cx43 expression and activity may play a role in contributing to androgen-induced decrease in EDHF function.
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Affiliation(s)
- Jay S Mishra
- Division of Reproductive Endocrinology, Department of Obstetrics and Gynecology, University of Texas Medical Branch at Galveston, Texas, USA
| | - Amar S More
- Division of Reproductive Endocrinology, Department of Obstetrics and Gynecology, University of Texas Medical Branch at Galveston, Texas, USA
| | - Gary D V Hankins
- Division of Reproductive Endocrinology, Department of Obstetrics and Gynecology, University of Texas Medical Branch at Galveston, Texas, USA
| | - Sathish Kumar
- Division of Reproductive Endocrinology, Department of Obstetrics and Gynecology, University of Texas Medical Branch at Galveston, Texas, USA
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Mohanty I, Parija SC, Suklabaidya S, Rattan S. Acidosis potentiates endothelium-dependent vasorelaxation and gap junction communication in the superior mesenteric artery. Eur J Pharmacol 2018. [PMID: 29524386 DOI: 10.1016/j.ejphar.2018.03.004] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Extracellular pH is an important physiological determinant of vascular tone that is normally maintained within 7.35-7.45. Any change outside this range leads to severe pathological repercussions. We investigated the unknown effects of extracellular acidosis on relaxation in the superior mesenteric artery (SMA) of goat. SMA rings were employed to maintain isometric contractions at extracellular pH (pHo) 7.4 and 6.8. We analyzed the effect of acidosis (pHo 6.8) compared to physiological pH (pHo 7.4) on three signaling mediators of endothelium-dependent hyperpolarization: nitric oxide (NO), prostaglandin I2 (PGI2), and myoendothelial gap junctions (MEGJ). NO and cyclic guanosine monophosphate (cGMP) levels were compared between normal and acidic pH. Quantitative real-time PCR (qPCR) studies determined the change in expression of vascular connexin (Cx), Cx37, Cx40, and Cx43. Under acidosis, acetyl choline-induced relaxation was augmented in an endothelium-dependent manner via eNOS-NO-cGMP signaling. Conversely, at normal pH, acetyl choline-induced vasorelaxation was mediated primarily via COX-PGI2 pathway. The functional activity of MEGJ was increased under acidosis as evident from increased sensitivity of connexin blockers and upregulated gene and protein expression of connexins. In conclusion, acetyl choline-induced augmented vasorelaxation under acidosis is mediated by NOS-NO-cGMP, with a partial role of MEGJ as EDH mediators in the SMA. Present data suggest a novel role of connexin as therapeutic targets to attenuate the detrimental effect of acidosis on vascular tone.
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Affiliation(s)
- Ipsita Mohanty
- Department of Medicine, Division of Gastroenterology and Hepatology, Jefferson Medical College, Thomas Jefferson University, Philadelphia, PA, United States; Department of Pharmacology and Toxicology, College of Veterinary Sciences and Animal Husbandry, Orissa University of Agriculture and Technology, Bhubaneswar 751003, Odisha, India
| | - Subas Chandra Parija
- Department of Pharmacology and Toxicology, College of Veterinary Sciences and Animal Husbandry, Orissa University of Agriculture and Technology, Bhubaneswar 751003, Odisha, India
| | - Sujit Suklabaidya
- Tumor Microenvironment and Animal Models Laboratory, Institute of Life Sciences, Bhubaneswar, Odisha, India
| | - Satish Rattan
- Department of Medicine, Division of Gastroenterology and Hepatology, Jefferson Medical College, Thomas Jefferson University, Philadelphia, PA, United States.
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Looft-Wilson RC, Goodell CR, Mutch CA, Mutchler SM, Miller KL, Guraya M. Increased myoendothelial feedback is associated with increased connexin37 and IK1 channel expression in mesenteric arteries of diet-induced hyperhomocysteinemic mice. Microcirculation 2017; 24. [PMID: 28857417 DOI: 10.1111/micc.12398] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2017] [Accepted: 08/24/2017] [Indexed: 12/16/2022]
Abstract
OBJECTIVE Previously, we found that diet-induced HHcy in mice caused decreased eNOS expression and signaling in mesenteric arteries, but greatly enhanced non-NOS, non-prostacyclin-dependent vasodilation, which involves MEJ communication. To further assess whether HHcy enhances MEJ communication, this study examined endothelium-dependent attenuation of phenylephrine-induced vasoconstriction (myoendothelial feedback) and key molecules involved. METHODS Myoendothelial feedback was examined in isolated mouse mesenteric arteries, after 6-weeks diet-induced HHcy, using pressure myography. Gap junction (Cx37, Cx40, Cx43), NOS (eNOS, nNOS, iNOS), and potassium channel (IK1) protein expression were measured with immunoblots, and connexin mRNAs with real-time PCR. Contribution of nNOS + iNOS to vasomotor responses was assessed using the drug TRIM. RESULTS Myoendothelial feedback was significantly (P < .05) enhanced in HHcy arteries compared to control, coincident with significantly greater Cx37 and IK1 protein and Cx37 mRNA. Cx43 protein, but not mRNA, was significantly less in HHcy, and Cx40 was not different. eNOS protein was significantly less in HHcy. nNOS and iNOS were not different. TRIM had little effect on vasomotor function. CONCLUSIONS Diet-induced HHcy enhanced myoendothelial feedback, and increased Cx37 and IK1 expression may contribute. nNOS or iNOS did not upregulate to compensate for decreased eNOS, and they had little involvement in vasomotor function.
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Affiliation(s)
- Robin C Looft-Wilson
- Department of Kinesiology and Health Sciences, The College of William & Mary, Williamsburg, VA, USA
| | - Cara R Goodell
- Department of Kinesiology and Health Sciences, The College of William & Mary, Williamsburg, VA, USA
| | - Christina A Mutch
- Department of Kinesiology and Health Sciences, The College of William & Mary, Williamsburg, VA, USA
| | - Stephanie M Mutchler
- Department of Kinesiology and Health Sciences, The College of William & Mary, Williamsburg, VA, USA
| | - Kayla L Miller
- Department of Kinesiology and Health Sciences, The College of William & Mary, Williamsburg, VA, USA
| | - Monique Guraya
- Department of Kinesiology and Health Sciences, The College of William & Mary, Williamsburg, VA, USA
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Jain M, Frobert A, Valentin J, Cook S, Giraud MN. The Rabbit Model of Accelerated Atherosclerosis: A Methodological Perspective of the Iliac Artery Balloon Injury. J Vis Exp 2017. [PMID: 28994792 DOI: 10.3791/55295] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022] Open
Abstract
Acute coronary syndrome resulting from coronary occlusion following atherosclerotic plaque development and rupture is the leading cause of death in the industrialized world. New Zealand White (NZW) rabbits are widely used as an animal model for the study of atherosclerosis. They develop spontaneous lesions when fed with atherogenic diet; however, this requires long time of 4 - 8 months. To further enhance and accelerate atherogenesis, a combination of atherogenic diet and mechanical endothelial injury is often employed. The presented procedure for inducing atherosclerotic plaques in rabbits uses a balloon catheter to disrupt the endothelium in the left iliac artery of NZW rabbits fed with atherogenic diet. Such mechanical damage caused by the balloon catheter induces a chain of inflammatory reactions initiating neointimal lipid accumulation in a time dependent fashion. Atherosclerotic plaque following balloon injury show neointimal thickening with extensive lipid infiltration, high smooth muscle cell content and presence of macrophage derived foam cells. This technique is simple, reproducible and produces plaque of controlled length within the iliac artery. The whole procedure is completed within 20 - 30 min. The procedure is safe with low mortality and also offers high success in obtaining substantial intimal lesions. The procedure of balloon catheter induced arterial injury results in atherosclerosis within two weeks. This model can be used for investigating the disease pathology, diagnostic imaging and to evaluate new therapeutic strategies.
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Affiliation(s)
- Manish Jain
- Cardiology, Department of Medicine, University of Fribourg
| | | | | | - Stéphane Cook
- Cardiology, Department of Medicine, University of Fribourg
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Ellinsworth DC, Sandow SL, Shukla N, Liu Y, Jeremy JY, Gutterman DD. Endothelium-Derived Hyperpolarization and Coronary Vasodilation: Diverse and Integrated Roles of Epoxyeicosatrienoic Acids, Hydrogen Peroxide, and Gap Junctions. Microcirculation 2016; 23:15-32. [PMID: 26541094 DOI: 10.1111/micc.12255] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2015] [Accepted: 11/01/2015] [Indexed: 12/22/2022]
Abstract
Myocardial perfusion and coronary vascular resistance are regulated by signaling metabolites released from the local myocardium that act either directly on the VSMC or indirectly via stimulation of the endothelium. A prominent mechanism of vasodilation is EDH of the arteriolar smooth muscle, with EETs and H(2)O(2) playing important roles in EDH in the coronary microcirculation. In some cases, EETs and H(2)O(2) are released as transferable hyperpolarizing factors (EDHFs) that act directly on the VSMCs. By contrast, EETs and H(2)O(2) can also promote endothelial KCa activity secondary to the amplification of extracellular Ca(2+) influx and Ca(2+) mobilization from intracellular stores, respectively. The resulting endothelial hyperpolarization may subsequently conduct to the media via myoendothelial gap junctions or potentially lead to the release of a chemically distinct factor(s). Furthermore, in human isolated coronary arterioles dilator signaling involving EETs and H(2)O(2) may be integrated, being either complimentary or inhibitory depending on the stimulus. With an emphasis on the human coronary microcirculation, this review addresses the diverse and integrated mechanisms by which EETs and H(2)O(2) regulate vessel tone and also examines the hypothesis that myoendothelial microdomain signaling facilitates EDH activity in the human heart.
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Affiliation(s)
| | - Shaun L Sandow
- Faculty of Science, Health, Education and Engineering, University of the Sunshine Coast, Maroochydore, Queensland, Australia
| | - Nilima Shukla
- Bristol Heart Institute, University of Bristol, Bristol, UK
| | - Yanping Liu
- Division of Research Infrastructure, National Center for Research Resources, National Institutes of Health, Bethesda, Maryland, USA
| | - Jamie Y Jeremy
- Bristol Heart Institute, University of Bristol, Bristol, UK
| | - David D Gutterman
- Division of Cardiovascular Medicine, Departments of Medicine, Physiology and Pharmacology, Medical College of Wisconsin, Milwaukee, Wisconsin, USA
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14
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Schmidt K, Windler R, de Wit C. Communication Through Gap Junctions in the Endothelium. ADVANCES IN PHARMACOLOGY (SAN DIEGO, CALIF.) 2016; 77:209-40. [PMID: 27451099 DOI: 10.1016/bs.apha.2016.04.004] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
A swarm of fish displays a collective behavior (swarm behavior) and moves "en masse" despite the huge number of individual animals. In analogy, organ function is supported by a huge number of cells that act in an orchestrated fashion and this applies also to vascular cells along the vessel length. It is obvious that communication is required to achieve this vital goal. Gap junctions with their modular bricks, connexins (Cxs), provide channels that interlink the cytosol of adjacent cells by a pore sealed against the extracellular space. This allows the transfer of ions and charge and thereby the travel of membrane potential changes along the vascular wall. The endothelium provides a low-resistance pathway that depends crucially on connexin40 which is required for long-distance conduction of dilator signals in the microcirculation. The experimental evidence for membrane potential changes synchronizing vascular behavior is manifold but the functional verification of a physiologic role is still open. Other molecules may also be exchanged that possibly contribute to the synchronization (eg, Ca(2+)). Recent data suggest that vascular Cxs have more functions than just facilitating communication. As pharmacological tools to modulate gap junctions are lacking, Cx-deficient mice provide currently the standard to unravel their vascular functions. These include arteriolar dilation during functional hyperemia, hypoxic pulmonary vasoconstriction, vascular collateralization after ischemia, and feedback inhibition on renin secretion in the kidney.
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Affiliation(s)
- K Schmidt
- Institut für Physiologie, Universität zu Lübeck, Lübeck, Germany; Deutsches Zentrum für Herz-Kreislauf-Forschung (DZHK) e.V. (German Center for Cardiovascular Research), Partner Site Hamburg/Kiel/Lübeck, Lübeck, Germany
| | - R Windler
- Institut für Physiologie, Universität zu Lübeck, Lübeck, Germany; Deutsches Zentrum für Herz-Kreislauf-Forschung (DZHK) e.V. (German Center for Cardiovascular Research), Partner Site Hamburg/Kiel/Lübeck, Lübeck, Germany
| | - C de Wit
- Institut für Physiologie, Universität zu Lübeck, Lübeck, Germany; Deutsches Zentrum für Herz-Kreislauf-Forschung (DZHK) e.V. (German Center for Cardiovascular Research), Partner Site Hamburg/Kiel/Lübeck, Lübeck, Germany.
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15
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Yang Q, He GW, Underwood MJ, Yu CM. Cellular and molecular mechanisms of endothelial ischemia/reperfusion injury: perspectives and implications for postischemic myocardial protection. Am J Transl Res 2016; 8:765-777. [PMID: 27158368 PMCID: PMC4846925] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2015] [Accepted: 11/24/2015] [Indexed: 06/05/2023]
Abstract
Ischemia/reperfusion (I/R) injury is a major cause of myocardial damage. Despite continuous efforts, minimizing I/R injury still represents a great challenge in standard medical treatments of ischemic heart disease, i.e., thrombolytic therapy, primary percutaneous coronary intervention, and coronary arterial bypass grafting. Development of effective interventions and strategies to prevent or reduce myocardial I/R injury is therefore of great clinical significance. Endothelial dysfunction plays a significant role in myocardial I/R injury, which renders endothelial cells an attractive target for postischemic myocardial protection. The rapidly evolving knowledge of the mechanisms of endothelial I/R injury helps broaden perspective for future development of novel strategies targeting endothelium for alleviating myocardial I/R damage. This review provides a comprehensive summary of the cellular and molecular mechanisms of endothelial I/R injury. Current perspectives and future directions for developing endothelium targeting therapeutics for postischemic myocardial protection are further discussed.
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Affiliation(s)
- Qin Yang
- Division of Cardiology, Department of Medicine and Therapeutics, Institute of Vascular Medicine, Li Ka Shing Institute of Health Sciences, Institute of Innovative Medicine, Faculty of Medicine, The Chinese University of Hong Kong; The Chinese University of Hong Kong Shenzhen Research InstituteHong Kong
- TEDA International Cardiovascular HospitalTianjin, China
| | - Guo-Wei He
- TEDA International Cardiovascular HospitalTianjin, China
- Hangzhou Normal University & Zhejiang UniversityHangzhou, China
| | - Malcolm John Underwood
- Division of Cardiothoracic Surgery, Department of Surgery, The Chinese University of Hong KongHong Kong
| | - Cheuk-Man Yu
- Division of Cardiology, Department of Medicine and Therapeutics, Institute of Vascular Medicine, Li Ka Shing Institute of Health Sciences, Institute of Innovative Medicine, Faculty of Medicine, The Chinese University of Hong Kong; The Chinese University of Hong Kong Shenzhen Research InstituteHong Kong
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16
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Dominguez Rieg JA, Burt JM, Ruth P, Rieg T. P2Y₂ receptor activation decreases blood pressure via intermediate conductance potassium channels and connexin 37. Acta Physiol (Oxf) 2015; 213:628-41. [PMID: 25545736 PMCID: PMC4442688 DOI: 10.1111/apha.12446] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2014] [Revised: 10/14/2014] [Accepted: 12/17/2014] [Indexed: 02/06/2023]
Abstract
AIMS Nucleotides are important paracrine regulators of vascular tone. We previously demonstrated that activation of P2Y₂ receptors causes an acute, NO-independent decrease in blood pressure, indicating this signalling pathway requires an endothelial-derived hyperpolarization (EDH) response. To define the mechanisms by which activation of P2Y₂ receptors initiates EDH and vasodilation, we studied intermediate-conductance (KCa3.1, expressed in endothelial cells) and big-conductance potassium channels (KCa1.1, expressed in smooth muscle cells) as well as components of the myoendothelial gap junction, connexins 37 and 40 (Cx37, Cx40), all hypothesized to be part of the EDH response. METHODS We compared the effects of a P2Y₂/₄ receptor agonist in wild-type (WT) mice and in mice lacking KCa3.1, KCa1.1, Cx37 or Cx40 under anaesthesia, while monitoring intra-arterial blood pressure and heart rate. RESULTS Acute activation of P2Y₂/₄ receptors (0.01-3 mg kg(-1) body weight i.v.) caused a biphasic blood pressure response characterized by a dose-dependent and rapid decrease in blood pressure in WT (maximal response % of baseline at 3 mg kg(-1) : -38 ± 1%) followed by a consecutive increase in blood pressure (+44 ± 11%). The maximal responses in KCa3.1(-/-) and Cx37(-/-) were impaired (-13 ± 5, +17 ± 7 and -27 ± 1, +13 ± 3% respectively), whereas the maximal blood pressure decrease in response to acetylcholine at 3 μg kg(-1) was not significantly different (WT: -53 ± 3%; KCa3.1(-/-) : -52 ± 3; Cx37(-/-) : -53 ± 3%). KCa1.1(-/-) and Cx40(-/-) showed an identical biphasic response to P2Y2/4 receptor activation compared to WT. CONCLUSIONS The data suggest that the P2Y2/4 receptor activation elicits blood pressure responses via distinct mechanisms involving KCa3.1 and Cx37.
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MESH Headings
- Animals
- Blood Pressure/drug effects
- Connexins/deficiency
- Connexins/genetics
- Connexins/metabolism
- Dose-Response Relationship, Drug
- Endothelial Cells/drug effects
- Endothelial Cells/metabolism
- Heart Rate/drug effects
- Inosine/analogs & derivatives
- Inosine/pharmacology
- Intermediate-Conductance Calcium-Activated Potassium Channels/deficiency
- Intermediate-Conductance Calcium-Activated Potassium Channels/genetics
- Intermediate-Conductance Calcium-Activated Potassium Channels/metabolism
- Large-Conductance Calcium-Activated Potassium Channel alpha Subunits/genetics
- Large-Conductance Calcium-Activated Potassium Channel alpha Subunits/metabolism
- Male
- Mice, 129 Strain
- Mice, Inbred C57BL
- Mice, Knockout
- Muscle, Smooth, Vascular/drug effects
- Muscle, Smooth, Vascular/metabolism
- Myocytes, Smooth Muscle/drug effects
- Myocytes, Smooth Muscle/metabolism
- Nitric Oxide Synthase Type III/genetics
- Nitric Oxide Synthase Type III/metabolism
- Purinergic P2Y Receptor Agonists
- Receptors, Purinergic P2Y2/drug effects
- Receptors, Purinergic P2Y2/metabolism
- Signal Transduction/drug effects
- Uridine Triphosphate/analogs & derivatives
- Uridine Triphosphate/pharmacology
- Vasodilation/drug effects
- Gap Junction alpha-4 Protein
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Affiliation(s)
- J. A. Dominguez Rieg
- Department of Basic Sciences, Bastyr University California, San Diego, CA, USA
- VA San Diego Healthcare System, San Diego, CA, USA
| | - J. M. Burt
- Department of Physiology, University of Arizona, Tucson, AZ, USA
| | - P. Ruth
- Department of Pharmacology, Toxicology and Clinical Pharmacy, University of Tübingen, Tübingen, Germany
| | - T. Rieg
- VA San Diego Healthcare System, San Diego, CA, USA
- Division of Nephrology-Hypertension, Department of Medicine, University of California San Diego, La Jolla, CA, USA
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17
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Morel S. Multiple roles of connexins in atherosclerosis- and restenosis-induced vascular remodelling. J Vasc Res 2014; 51:149-61. [PMID: 24853725 DOI: 10.1159/000362122] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2013] [Accepted: 03/01/2014] [Indexed: 12/19/2022] Open
Abstract
Endothelial dysfunction is the initial step in atherosclerotic plaque development in large- and medium-sized arteries. This progressive disease, which starts during childhood, is characterized by the accumulation of lipids, macrophages, neutrophils, T lymphocytes and smooth muscle cells in the intima of the vessels. Erosion and rupture of the atherosclerotic plaque may induce myocardial infarction and cerebrovascular accidents, which are responsible for a large percentage of sudden deaths. The most common treatment for atherosclerosis is angioplasty and stent implantation, but these surgical interventions favour a vascular reaction called restenosis and the associated de-endothelialization increases the risk of thrombosis. This review provides an overview of the role of connexins, a large family of transmembrane proteins, in vascular remodelling associated with atherosclerosis and restenosis. The connexins expressed in the vascular wall are Cx37, Cx40, Cx43 and Cx45; their expressions vary with vascular territory and species. Connexins form hemichannels or gap junction channels, allowing the exchange of ions and small metabolites between the cytosol and extracellular space or between neighbouring cells, respectively. Connexins have important roles in vascular physiology; they support radial and longitudinal cell-to-cell communication in the vascular wall, and significant changes in their expression patterns have been described during atherosclerosis and restenosis.
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Affiliation(s)
- Sandrine Morel
- Department of Pathology and Immunology, Faculty of Medicine, University of Geneva, Geneva, Switzerland
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18
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Billaud M, Lohman AW, Johnstone SR, Biwer LA, Mutchler S, Isakson BE. Regulation of cellular communication by signaling microdomains in the blood vessel wall. Pharmacol Rev 2014; 66:513-69. [PMID: 24671377 DOI: 10.1124/pr.112.007351] [Citation(s) in RCA: 82] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
It has become increasingly clear that the accumulation of proteins in specific regions of the plasma membrane can facilitate cellular communication. These regions, termed signaling microdomains, are found throughout the blood vessel wall where cellular communication, both within and between cell types, must be tightly regulated to maintain proper vascular function. We will define a cellular signaling microdomain and apply this definition to the plethora of means by which cellular communication has been hypothesized to occur in the blood vessel wall. To that end, we make a case for three broad areas of cellular communication where signaling microdomains could play an important role: 1) paracrine release of free radicals and gaseous molecules such as nitric oxide and reactive oxygen species; 2) role of ion channels including gap junctions and potassium channels, especially those associated with the endothelium-derived hyperpolarization mediated signaling, and lastly, 3) mechanism of exocytosis that has considerable oversight by signaling microdomains, especially those associated with the release of von Willebrand factor. When summed, we believe that it is clear that the organization and regulation of signaling microdomains is an essential component to vessel wall function.
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Affiliation(s)
- Marie Billaud
- Dept. of Molecular Physiology and Biophysics, University of Virginia School of Medicine, PO Box 801394, Charlottesville, VA 22902.
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19
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Ellinsworth DC, Shukla N, Fleming I, Jeremy JY. Interactions between thromboxane A₂, thromboxane/prostaglandin (TP) receptors, and endothelium-derived hyperpolarization. Cardiovasc Res 2014; 102:9-16. [PMID: 24469536 DOI: 10.1093/cvr/cvu015] [Citation(s) in RCA: 54] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Endothelium-dependent smooth muscle hyperpolarization (EDH) increasingly predominates over endothelium-derived nitric oxide (NO) as a participant in vasodilation as vessel size decreases. Its underlying nature is highly variable between vessel types, species, disease states, and exact experimental conditions, and is variably mediated by one or more transferable endothelium-derived hyperpolarizing factors and/or the electrotonic spread of endothelial hyperpolarization into the media via gap junctions. Although generally regarded (and studied) as a mechanism that is independent of NO and prostanoids, evidence has emerged that the endothelium-derived contracting factor and prostanoid thromboxane A2 can modulate several signalling components central to EDH, and therefore potentially curtail vasodilation through mechanisms that are distinct from those putatively involved in direct smooth muscle contraction. Notably, vascular production of thromboxane A2 is elevated in a number of cardiovascular disease states that promote endothelial dysfunction. This review will therefore discuss the mechanisms through which thromboxane A2 interacts with and modulates EDH, and will also consider the implications of such cross-talk in vasodilator control in health and disease.
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Affiliation(s)
- David C Ellinsworth
- Bristol Heart Institute, University of Bristol, Queens Building Level 7, Upper Maudlin St, Bristol Royal Infirmary, Upper Maudlin Street, Bristol BS2 8HW, UK
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20
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Makino A, Firth AL, Yuan JXJ. Endothelial and smooth muscle cell ion channels in pulmonary vasoconstriction and vascular remodeling. Compr Physiol 2013; 1:1555-602. [PMID: 23733654 DOI: 10.1002/cphy.c100023] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
The pulmonary circulation is a low resistance and low pressure system. Sustained pulmonary vasoconstriction and excessive vascular remodeling often occur under pathophysiological conditions such as in patients with pulmonary hypertension. Pulmonary vasoconstriction is a consequence of smooth muscle contraction. Many factors released from the endothelium contribute to regulating pulmonary vascular tone, while the extracellular matrix in the adventitia is the major determinant of vascular wall compliance. Pulmonary vascular remodeling is characterized by adventitial and medial hypertrophy due to fibroblast and smooth muscle cell proliferation, neointimal proliferation, intimal, and plexiform lesions that obliterate the lumen, muscularization of precapillary arterioles, and in situ thrombosis. A rise in cytosolic free Ca(2+) concentration ([Ca(2+)]cyt) in pulmonary artery smooth muscle cells (PASMC) is a major trigger for pulmonary vasoconstriction, while increased release of mitogenic factors, upregulation (or downregulation) of ion channels and transporters, and abnormalities in intracellular signaling cascades are key to the remodeling of the pulmonary vasculature. Changes in the expression, function, and regulation of ion channels in PASMC and pulmonary arterial endothelial cells play an important role in the regulation of vascular tone and development of vascular remodeling. This article will focus on describing the ion channels and transporters that are involved in the regulation of pulmonary vascular function and structure and illustrating the potential pathogenic role of ion channels and transporters in the development of pulmonary vascular disease.
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Affiliation(s)
- Ayako Makino
- Department of Medicine, The University of Illinois at Chicago, Chicago, Illinois, USA
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21
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Radtke J, Schmidt K, Wulff H, Köhler R, de Wit C. Activation of KCa3.1 by SKA-31 induces arteriolar dilatation and lowers blood pressure in normo- and hypertensive connexin40-deficient mice. Br J Pharmacol 2013; 170:293-303. [PMID: 23734697 PMCID: PMC3834754 DOI: 10.1111/bph.12267] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2012] [Revised: 05/06/2013] [Accepted: 05/22/2013] [Indexed: 11/28/2022] Open
Abstract
BACKGROUND AND PURPOSE The calcium-activated potassium channel KCa3.1 is expressed in the vascular endothelium where its activation causes endothelial hyperpolarization and initiates endothelium-derived hyperpolarization (EDH)-dependent dilatation. Here, we investigated whether pharmacological activation of KCa3.1 dilates skeletal muscle arterioles and whether myoendothelial gap junctions formed by connexin40 (Cx40) are required for EDH-type dilatations and pressure depressor responses in vivo. EXPERIMENTAL APPROACH We performed intravital microscopy in the cremaster muscle microcirculation and blood pressure telemetry in Cx40-deficient mice. KEY RESULTS In wild-type mice, the KCa3.1-activator SKA-31 induced pronounced concentration-dependent arteriolar EDH-type dilatations, amounting to ∼40% of maximal dilatation, and enhanced the effects of ACh. These responses were absent in mice devoid of KCa3.1 channels. In contrast, SKA-31-induced dilatations were not attenuated in mice with endothelial cells deficient in Cx40 (Cx40(fl/fl):Tie2-Cre). In isolated endothelial cell clusters, SKA-31 induced hyperpolarizations of similar magnitudes (by ∼38 mV) in Cx40(fl/fl):Tie2-Cre, ubiquitous Cx40-deficient mice (Cx40(-/-)) and controls (Cx40(fl/fl)), which were reversed by the specific KCa3.1-blocker TRAM-34. In normotensive wild-type and Cx40(fl/fl):Tie2-Cre as well as in hypertensive Cx40(-/-) animals, i.p. injections of SKA-31 (30 and 100 mg·kg(-1)) decreased arterial pressure by ∼32 mmHg in all genotypes. The depressor response to 100 mg·kg(-1) SKA-31 was associated with a decrease in heart rate. CONCLUSIONS AND IMPLICATIONS We conclude that endothelial hyperpolarization evoked by pharmacological activation of KCa3.1 channels induces EDH-type arteriolar dilatations that are independent of endothelial Cx40 and Cx40-containing myoendothelial gap junctions. As SKA-31 reduced blood pressure in hypertensive Cx40-deficient mice, KCa3.1 activators may be useful drugs for severe treatment-resistant hypertension.
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Affiliation(s)
- Josephine Radtke
- Institut für Physiologie, Universität zu Lübeck, Lübeck, Germany; DZHK (German Centre for Cardiovascular Research), partner site Hamburg/Kiel/Lübeck, Lübeck, Germany
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22
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Edwards DH. Local, integrated control of blood flow: Professor Tudor Griffith Memorial. Auton Neurosci 2013; 178:4-8. [PMID: 23522722 DOI: 10.1016/j.autneu.2013.02.023] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2012] [Revised: 02/07/2013] [Accepted: 02/24/2013] [Indexed: 11/24/2022]
Abstract
Professor Tudor Griffith was one of the founding members of the European Study Group on Cardiovascular Oscillations, and hosted the 1st ESGCO Conference in Cardiff, Wales in 2000. Tudor was a passionate scientist, who managed to combine his enthusiasm for vascular biology with his background in physics, to make key and insightful advances to our knowledge and understanding of the integrated vascular control mechanisms that co-ordinate blood flow in tissue perfusion. He had a particular interest in the endothelium, the monolayer of cells that lines the entire cardiovascular system and which is in prime position to sense a wide variety of modulatory stimuli, both chemical and mechanical. Over the last 20 years Tudor produced a series of research papers in which he used chaos theory to analyse the behaviour of arteries that underpins vasomotion. The research led to the development of mathematical models that were able to predict calcium oscillations in vascular smooth muscle with a view to predicting events in a complete virtual artery. This article will review the field in which he worked, with an obvious emphasis on his contribution.
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Affiliation(s)
- David H Edwards
- Institute of Molecular and Experimental Medicine, Wales Heart Research Institute, School of Medicine, Cardiff University, Heath Park, Cardiff CF14 4XN, United Kingdom.
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23
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Edwards DH, Li Y, Ellinsworth DC, Griffith TM. The effect of inorganic arsenic on endothelium-dependent relaxation: role of NADPH oxidase and hydrogen peroxide. Toxicology 2013; 306:50-8. [PMID: 23384446 PMCID: PMC3639371 DOI: 10.1016/j.tox.2013.01.019] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2012] [Revised: 01/09/2013] [Accepted: 01/26/2013] [Indexed: 10/29/2022]
Abstract
Chronic arsenic ingestion predisposes to vascular disease, but underlying mechanisms are poorly understood. In the present study we have analyzed the effects of short-term arsenite exposure on vascular function and endothelium-dependent relaxation. Endothelium-dependent relaxations, nitric oxide (NO) and endothelium derived hyperpolarizing factor (EDHF)-type, were studied in rabbit iliac artery and aortic rings using the G protein-coupled receptor agonist acetylcholine (ACh) and by cyclopiazonic acid (CPA), which promotes store-operated Ca(2+) entry by inhibiting the endothelial SERCA pump. Production of reactive oxygen species (ROS) in the endothelium of rabbit aortic valve leaflets and endothelium-denuded RIA and aortic rings was assessed by imaging of dihydroethidium. In the iliac artery, exposure to 100 μM arsenite for 30 min potentiated EDHF-type relaxations evoked by both CPA and ACh. Potentiation was prevented by catalase, the catalase/superoxide dismutase mimetic manganese porphyrin and the NADPH oxidase inhibitor apocynin. By contrast in aortic rings, that exhibited negligible EDHF-type responses, endothelium-dependent NO-mediated relaxations evoked by CPA and ACh were unaffected by arsenite. Arsenite induced apocynin-sensitive increases in ROS production in the aortic valve endothelium, but not in the media and adventitia of the iliac artery and aorta. Our results suggest that arsenite can potentiate EDHF-type relaxations via a mechanism that is dependent on hydrogen peroxide, thus demonstrating that dismutation of the superoxide anion generated by NADPH oxidase can potentially offset loss of NO bioavailability under conditions of reduced eNOS activity. By contrast, selective increases in endothelial ROS production following exposure to arsenite failed to modify relaxations mediated by endogenous NO.
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Affiliation(s)
- David H Edwards
- Ionic Cell Signalling Group, Wales Heart Research Institute, Institute of Molecular and Experimental Medicine, School of Medicine, Cardiff University, Heath Park, Cardiff CF14 4XN, UK.
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25
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Taylor MS, Francis M, Qian X, Solodushko V. Dynamic Ca(2+) signal modalities in the vascular endothelium. Microcirculation 2012; 19:423-9. [PMID: 22443172 DOI: 10.1111/j.1549-8719.2012.00180.x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
The endothelium is vital to normal vasoregulation. Although acute vasodilation associated with broad endothelial Ca(2+) elevation is well known, the control and targeting of Ca(2+) -dependent signals in the endothelium are poorly understood. Recent studies have revealed localized IP(3) -motivated Ca(2+) events occurring basally along the intima that may provide the fundamental basis for various endothelial influences. Here, we provide an overview of dynamic endothelial Ca(2+) signals and discuss the potential role of these signals in constant endothelial control of arterial tone and the titration of functional responses in vivo. In particular, we focus on the functional architecture contributing to the properties and ultimate impact of these signals, and explore new avenues in evaluating their prevalence and specific modalities in intact tissue. Finally, we discuss spatial and temporal effector recruitment through modification of these inherent signals. It is suggested that endothelial Ca(2+) signaling is a continuum in which the specific framework of store-release components and cellular targets along the endothelium allows for differential modes of Ca(2+) signal expansion and distinctive profiles of effector recruitment. The precise composition and distribution of these inherent components may underlie dynamic endothelial control and specialized functions of different vascular beds.
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Affiliation(s)
- Mark S Taylor
- Department of Physiology, University of South Alabama College of Medicine, Mobile, Alabama 36688, USA.
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26
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Evans WH, Bultynck G, Leybaert L. Manipulating connexin communication channels: use of peptidomimetics and the translational outputs. J Membr Biol 2012; 245:437-49. [PMID: 22886208 PMCID: PMC3456916 DOI: 10.1007/s00232-012-9488-5] [Citation(s) in RCA: 73] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2012] [Accepted: 07/07/2012] [Indexed: 12/22/2022]
Abstract
Gap junctions are key components underpinning multicellularity. They provide cell to cell channel pathways that enable direct intercellular communication and cellular coordination in tissues and organs. The channels are constructed of a family of connexin (Cx) membrane proteins. They oligomerize inside the cell, generating hemichannels (connexons) composed of six subunits arranged around a central channel. After transfer to the plasma membrane, arrays of Cx hemichannels (CxHcs) interact and couple with partners in neighboring attached cells to generate gap junctions. Cx channels have been studied using a range of technical approaches. Short peptides corresponding to sequences in the extra- and intracellular regions of Cxs were used first to generate epitope-specific antibodies that helped studies on the organization and functions of gap junctions. Subsequently, the peptides themselves, especially Gap26 and -27, mimetic peptides derived from each of the two extracellular loops of connexin43 (Cx43), a widely distributed Cx, have been extensively applied to block Cx channels and probe the biology of cell communication. The development of a further series of short peptides mimicking sequences in the intracellular loop, especially the extremity of the intracellular carboxyl tail of Cx43, followed. The primary inhibitory action of the peptidomimetics occurs at CxHcs located at unapposed regions of the cell's plasma membrane, followed by inhibition of cell coupling occurring across gap junctions. CxHcs respond to a range of environmental conditions by increasing their open probability. Peptidomimetics provide a way to block the actions of CxHcs with some selectivity. Furthermore, they are increasingly applied to address the pathological consequences of a range of environmental stresses that are thought to influence Cx channel operation. Cx peptidomimetics show promise as candidates in developing new therapeutic approaches for containing and reversing damage inflicted on CxHcs, especially in hypoxia and ischemia in the heart and in brain functions.
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Affiliation(s)
- W Howard Evans
- Institute of Infection and Immunity, Cardiff University School of Medicine, Heath Park, Cardiff, Wales CF14 4XN, UK.
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Boettcher M, de Wit C. Distinct endothelium-derived hyperpolarizing factors emerge in vitro and in vivo and are mediated in part via connexin 40-dependent myoendothelial coupling. Hypertension 2011; 57:802-8. [PMID: 21357279 DOI: 10.1161/hypertensionaha.110.165894] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The endothelium-derived hyperpolarizing factor (EDHF) contributes critically to the regulation of vascular tone. Its dependency on direct signaling through myoendothelial gap junctions composed of connexins (Cx) is controversially discussed. We studied the impact of Cx40 in EDHF-type dilations in vivo and in vitro (wire and pressure myography) in small arteries (A. gracilis) using different Cx40-deficient mouse models. Acetylcholine induced prominent EDHF-type dilations (inhibition of NO synthase and cyclooxygenase) of ≈90% (maximum effect) in wild-type and Cx40-deficient vessels (Cx40-/-) in vitro under isobaric conditions. In contrast, under isometric conditions, EDHF-type relaxations were nearly abrogated in Cx40-/- (9±3%) but only slightly reduced in wild-type vessels (45±4%; P<0.05). Vessels expressing Cx45 instead of Cx40 exhibited similarly reduced relaxations (13±1%), demonstrating that Cx45 cannot replace Cx40 functionally. The necessity of Cx40 in EDHF-type dilations under isometric conditions was verified by the attenuation in vessels being specifically deficient for Cx40 in endothelial cells (Cx40fl:TIE2-Cre: 17±3%; Cx40-floxed controls: 67±6%; P<0.05). Nevertheless, EDHF-type dilations were Cx40 independent when studied isobarically. The EDHF-type dilation in vivo resembled the isobaric situation, being virtually Cx40 independent and similar powerful. Distinct EDHF mechanisms can be distinguished by their Cx40 dependency. A powerful EDHF is present in vivo and in vitro under isobaric conditions but is lacking in wire myography (isometric conditions). Herein, a less potent EDHF depends on Cx40 and may represent signaling through myoendothelial gap junctions. We suggest that distinct EDHFs (even in the same artery) explain partially the controversy on the role of myoendothelial gap junctions in EDHF signaling.
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Affiliation(s)
- Markus Boettcher
- Physiologie Institut, Universität zu Lübeck, Ratzeburger Allee 160, 23538 Lübeck, Germany
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Morton JS, Rueda-Clausen CF, Davidge ST. Flow-mediated vasodilation is impaired in adult rat offspring exposed to prenatal hypoxia. J Appl Physiol (1985) 2011; 110:1073-82. [DOI: 10.1152/japplphysiol.01174.2010] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
There is now a demonstrated association between low birth weight and increased mortality later in life. Changes in fetal development may program the cardiovascular system and lead to an increased risk of cardiovascular diseases later in life. In addition, aging is a risk factor for vascular endothelial-dependent dysfunction. However, the impact of being born intrauterine growth restricted (IUGR) on the normal aging mechanisms of vascular dysfunction is not clear. We hypothesized that IUGR would cause changes in vascular function that would affect the mechanisms of flow-induced vasodilation later in life in an age- or sex-dependent manner. To create an IUGR model, pregnant Sprague-Dawley rats were placed in a hypoxic (11.5% O2) or control (room air, 21% O2) environment from days 15 to 21 of pregnancy. Both male and female offspring were investigated at 4 or 12 mo of age. Vascular function was assessed in small mesenteric arteries using flow-induced vasodilation, a physiological stimuli of vasodilation, in a pressure myograph. Flow-induced vasodilation was unaffected at a young age, but was significantly reduced in aging IUGR compared with aging controls ( P < 0.05). Underlying vasodilator mechanisms were altered such that nitric oxide-mediated vasodilation was abolished in both young adult and aging IUGR males and females and in aging control females ( P > 0.05). Endothelium-derived hyperpolarizing factor-mediated vasodilation was maintained in all groups ( P < 0.01). A change in the mechanisms of vasodilation occurring at an earlier age in IUGR offspring may predispose them to develop cardiovascular diseases as an aging adult.
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Affiliation(s)
- J. S. Morton
- Departments of 1Obstetrics and Gynaecology and
- Women and Children's Health Research Institute and the Cardiovascular Research Centre, Edmonton, Alberta, Canada
| | - C. F. Rueda-Clausen
- Physiology, University of Alberta, and
- Women and Children's Health Research Institute and the Cardiovascular Research Centre, Edmonton, Alberta, Canada
| | - S. T. Davidge
- Departments of 1Obstetrics and Gynaecology and
- Physiology, University of Alberta, and
- Women and Children's Health Research Institute and the Cardiovascular Research Centre, Edmonton, Alberta, Canada
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29
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Abstract
Gap junctions are aggregates of intercellular channels that permit direct cell-cell transfer of ions and small molecules. Initially described as low-resistance ion pathways joining excitable cells (nerve and muscle), gap junctions are found joining virtually all cells in solid tissues. Their long evolutionary history has permitted adaptation of gap-junctional intercellular communication to a variety of functions, with multiple regulatory mechanisms. Gap-junctional channels are composed of hexamers of medium-sized families of integral proteins: connexins in chordates and innexins in precordates. The functions of gap junctions have been explored by studying mutations in flies, worms, and humans, and targeted gene disruption in mice. These studies have revealed a wide diversity of function in tissue and organ biology.
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de Wit C, Griffith TM. Connexins and gap junctions in the EDHF phenomenon and conducted vasomotor responses. Pflugers Arch 2010; 459:897-914. [PMID: 20379740 DOI: 10.1007/s00424-010-0830-4] [Citation(s) in RCA: 125] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2010] [Accepted: 03/16/2010] [Indexed: 12/21/2022]
Abstract
It is becoming increasingly evident that electrical signaling via gap junctions plays a central role in the physiological control of vascular tone via two related mechanisms (1) the endothelium-derived hyperpolarizing factor (EDHF) phenomenon, in which radial transmission of hyperpolarization from the endothelium to subjacent smooth muscle promotes relaxation, and (2) responses that propagate longitudinally, in which electrical signaling within the intimal and medial layers of the arteriolar wall orchestrates mechanical behavior over biologically large distances. In the EDHF phenomenon, the transmitted endothelial hyperpolarization is initiated by the activation of Ca(2+)-activated K(+) channels channels by InsP(3)-induced Ca(2+) release from the endoplasmic reticulum and/or store-operated Ca(2+) entry triggered by the depletion of such stores. Pharmacological inhibitors of direct cell-cell coupling may thus attenuate EDHF-type smooth muscle hyperpolarizations and relaxations, confirming the participation of electrotonic signaling via myoendothelial and homocellular smooth muscle gap junctions. In contrast to isolated vessels, surprisingly little experimental evidence argues in favor of myoendothelial coupling acting as the EDHF mechanism in arterioles in vivo. However, it now seems established that the endothelium plays the leading role in the spatial propagation of arteriolar responses and that these involve poorly understood regenerative mechanisms. The present review will focus on the complex interactions between the diverse cellular signaling mechanisms that contribute to these phenomena.
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Affiliation(s)
- Cor de Wit
- Institut für Physiologie, Universität zu Lübeck, Ratzeburger Allee 160, 23538, Lübeck, Germany.
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Morton JS, Rueda-Clausen CF, Davidge ST. Mechanisms of endothelium-dependent vasodilation in male and female, young and aged offspring born growth restricted. Am J Physiol Regul Integr Comp Physiol 2010; 298:R930-8. [PMID: 20053962 DOI: 10.1152/ajpregu.00641.2009] [Citation(s) in RCA: 65] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Numerous epidemiological studies have shown that cardiovascular dysfunction in adult life may be programmed by compromised growth in utero. Aging is a risk factor for vascular endothelial-dependent dysfunction. After birth, the impact of intrauterine growth restriction (IUGR) on normal aging mechanisms of vascular dysfunction is not known. We hypothesized that IUGR would cause changes in vascular function that would affect the mechanisms of endothelium-dependent vasodilation later in life in an age- or sex-dependent manner. To create an IUGR model, pregnant Sprague-Dawley rats were placed in a hypoxic (12% O(2)) or control (room air, 21% O(2)) environment from days 15 to 21 of the pregnancy, and both male and female offspring were investigated at 4 or 12 mo of age. Endothelial function was assessed in small mesenteric arteries using methacholine (MCh)-induced vasodilation in a wire myograph system. The involvement of nitric oxide (NO), prostaglandins, and endothelium-derived hyperpolarizing factor (EDHF) was assessed using the inhibitors N(omega)-nitro-l-arginine methyl ester hydrochloride, meclofenamate, or a combination of apamin and TRAM-34 (SK(Ca) and IK(Ca) blockers), respectively. EDHF-induced vasodilation was further investigated by using inhibitors of P450 epoxygenases [N-methylsulfonyl-6-(2-propargyloxyphenyl) hexanamide] and gap junctions (18alpha-glycyrrhetinic acid). NO-mediated vasodilation was significantly reduced in aged controls and both young and aged IUGR females. EDHF-mediated vasodilation was maintained in all groups; however, an additional involvement of gap junctions was found in females exposed to hypoxia in utero, which may represent a compensatory mechanism. A change in the mechanisms of vasodilation occurring at an earlier age in IUGR offspring may predispose them to adult cardiovascular diseases.
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Affiliation(s)
- J S Morton
- Department of Obstetrics, 232 Heritage Medical Research Centre, University of Alberta, Edmonton, AB, T6G 2S2, Canada
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32
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Garry A, Edwards DH, Fallis IF, Jenkins RL, Griffith TM. Ascorbic acid and tetrahydrobiopterin potentiate the EDHF phenomenon by generating hydrogen peroxide. Cardiovasc Res 2009; 84:218-26. [PMID: 19592567 PMCID: PMC2761203 DOI: 10.1093/cvr/cvp235] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/13/2009] [Revised: 07/01/2009] [Accepted: 07/02/2009] [Indexed: 12/11/2022] Open
Abstract
AIMS Our objective was to investigate whether pro-oxidant properties of ascorbic acid (AA) and tetrahydrobiopterin (BH(4)) modulate endothelium-dependent, electrotonically mediated arterial relaxation. METHODS AND RESULTS In studies with rabbit iliac artery (RIA) rings, NO-independent, endothelium-derived hyperpolarizing factor (EDHF)-type relaxations evoked by the sarcoplasmic endoplasmic reticulum Ca(2+)-ATPase inhibitor cyclopiazonic acid and the G protein-coupled agonist acetylcholine (ACh) were enhanced by AA (1 mM) and BH(4) (200 microM), which generated buffer concentrations of H(2)O(2) in the range of 40-80 microM. Exogenous H(2)O(2) potentiated cyclopiazonic acid (CPA)- and ACh-evoked relaxations with a threshold of 10-30 microM, and potentiation by AA and BH(4) was abolished by catalase, which destroyed H(2)O(2) generated by oxidation of these agents in the organ chamber. Adventitial application of H(2)O(2) also enhanced EDHF-type dilator responses evoked by CPA and ACh in RIA segments perfused intraluminally with H(2)O(2)-free buffer, albeit with reduced efficacy. In RIA rings, both control relaxations and their potentiation by H(2)O(2) were overcome by blockade of gap junctions by connexin-mimetic peptides (YDKSFPISHVR and SRPTEK) targeted to the first and second extracellular loops of the dominant vascular connexins expressed in the RIA. Superoxide dismutase attenuated the potentiation of EDHF-type relaxations by BH(4), but not AA, consistent with findings demonstrating a differential role for superoxide anions in the generation of H(2)O(2) by the two agents. CONCLUSION Pro-oxidant effects of AA and BH(4) can enhance the EDHF phenomenon by generating H(2)O(2), which has previously been shown to amplify electrotonic hyperpolarization-mediated relaxation by facilitating Ca(2+) release from endothelial stores.
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Affiliation(s)
- Ambroise Garry
- Department of Diagnostic Radiology, Wales Heart Research Institute, School of Medicine, Cardiff University, Heath Park, Cardiff CF14 4XN, UK
| | - David H. Edwards
- Department of Diagnostic Radiology, Wales Heart Research Institute, School of Medicine, Cardiff University, Heath Park, Cardiff CF14 4XN, UK
| | - Ian F. Fallis
- School of Chemistry, Cardiff University, Main Building, Park Place, Cardiff CF10 3AT, UK
| | - Robert L. Jenkins
- School of Chemistry, Cardiff University, Main Building, Park Place, Cardiff CF10 3AT, UK
| | - Tudor M. Griffith
- Department of Diagnostic Radiology, Wales Heart Research Institute, School of Medicine, Cardiff University, Heath Park, Cardiff CF14 4XN, UK
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D'hondt C, Ponsaerts R, De Smedt H, Bultynck G, Himpens B. Pannexins, distant relatives of the connexin family with specific cellular functions? Bioessays 2009; 31:953-74. [PMID: 19644918 DOI: 10.1002/bies.200800236] [Citation(s) in RCA: 131] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Intercellular communication (IC) is mediated by gap junctions (GJs) and hemichannels, which consist of proteins. This has been particularly well documented for the connexin (Cx) family. Initially, Cxs were thought to be the only proteins capable of GJ formation in vertebrates. About 10 years ago, however, a new GJ-forming protein family related to invertebrate innexins (Inxs) was discovered in vertebrates, and named the pannexin (Panx) family. Panxs, which are structurally similar to Cxs, but evolutionarily distinct, have been shown to be co-expressed with Cxs in vertebrates. Both protein families show distinct properties and have their own particular function. Identification of the mechanisms that control Panx channel gating is a major challenge for future work. In this review, we focus on the specific properties and role of Panxs in normal and pathological conditions.
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Affiliation(s)
- Catheleyne D'hondt
- Laboratory of Molecular and Cellular Signalling, KULeuven, Campus Gasthuisberg O/N, Leuven, Belgium
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López D, Rodríguez-Sinovas A, Agulló E, García A, Sánchez JA, García-Dorado D. Replacement of connexin 43 by connexin 32 in a knock-in mice model attenuates aortic endothelium-derived hyperpolarizing factor-mediated relaxation. Exp Physiol 2009; 94:1088-97. [PMID: 19617266 DOI: 10.1113/expphysiol.2009.048413] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Previous studies demonstrated that intercellular communication through endothelial, smooth muscle or myoendothelial connexin channels contributes to the control of vascular tone. At least four connexin types are present in the arterial wall. The aim of the present work was to assess the role played by connexin 43 (Cx43)-formed gap junctions on vessel function. Aortic reactivity to noradrenaline, acetylcholine and sodium nitroprusside, and endothelium-derived hyperpolarizing factor (EDHF)-mediated relaxations, were analysed in a Cx43KI32 mouse model in which the coding region of Cx43 was replaced by that of connexin 32 (Cx32). Aortic rings were placed in organ baths containing a Krebs solution oxygenated at 37 degrees C (pH 7.4). Confocal images of aortic rings confirmed connexin substitution in mutant mice. In control conditions, replacement of Cx43 by Cx32 in homozygous mutant mice did not modify endothelium-independent contractile responses to noradrenaline, or relaxations in response to sodium nitroprusside (endothelium independent) or acetylcholine (endothelium dependent). However, residual endothelium-dependent relaxations in response to acetylcholine after nitric oxide synthase and cyclooxygenase inhibition (EDHF type) were significantly reduced in homozygous Cx43KI32 mice (maximal effect values: 4.86 +/- 0.37% of noradrenaline precontraction versus 7.06 +/- 0.31% in wild-type, n = 8, P < 0.05). This attenuation was mimicked by treatment of rings from wild-type animals with the connexin-mimetic peptide (37,43)Gap27 (5 x 10(-6)m). In conclusion, replacement of Cx43 by Cx32 attenuates EDHF-mediated relaxations in mice aortic rings, suggesting that they are, at least in part, dependent on Cx43-formed gap junctions. In contrast, aortic responses to tested endothelium-independent agonists were not modified in knock-in animals.
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Affiliation(s)
- Diego López
- Institut de Recerca Hospitals Vall d'Hebron, Hospital Universitario Vall d'Hebron, Passeig Vall d'Hebron 119, 08035 Barcelona, Spain
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Yi FX, Boeldt DS, Gifford SM, Sullivan JA, Grummer MA, Magness RR, Bird IM. Pregnancy enhances sustained Ca2+ bursts and endothelial nitric oxide synthase activation in ovine uterine artery endothelial cells through increased connexin 43 function. Biol Reprod 2009; 82:66-75. [PMID: 19741206 DOI: 10.1095/biolreprod.109.078253] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/01/2022] Open
Abstract
Endothelium-mediated vasodilation is specifically enhanced in uterine circulation during pregnancy, and production of nitric oxide (NO) is increased in response to a wide array of agonists. Uterine artery endothelial cells from nonpregnant (NP-UAECs) or pregnant (P-UAECs) ewes maintained in culture still show a pregnancy-enhanced difference in ATP-stimulated endothelial NO synthase (eNOS; official symbol NOS3) activation, even though NOS3 protein, purinergic receptors, and associated cell signaling proteins are expressed at equal levels. We have also shown that the pregnancy-enhanced endothelial cell NO response to ATP requires an enhanced and sustained capacitative entry phase that is likely mediated via canonical transient receptor potential protein/inositol 1,4,5-trisphosphate receptor type 2 interaction. In this study, we now show by simultaneous video imaging of individual Fura-2-loaded cells that the pregnancy-enhanced capacitative entry phase is not continuous and equal in all cells, but is in fact mediated as a series of periodic [Ca(2+)](i) bursts within individual cells. Not only does pregnancy increase the number of bursts over a longer time period in individual cells, but also a greater proportion of cells exhibit this burst activity, and at high cell density this occurs in a synchronous manner. The mediator of cell synchronization is connexin 43 (Cx43) gap junctions because 1) Cx43 is readily detectable by Western blot analysis in UAECs, whereas Cx40 and Cx37 are weakly detected or absent, and 2) pregnancy-specific enhancement of [Ca(2+)](i) bursts by ATP is blocked by inhibitory loop peptides selective to Cx43 ((43,37)GAP27) but not by a scrambled control peptide or (40)GAP27 or (40,37)GAP26 peptides, which are specific to Cx40 or Cx37. The relationship between Ca(2+) bursts and NOS3 activation is further established by the finding that (43,37)GAP27 inhibits ATP-stimulated NOS3 activation but has no effect on cell mitogenesis. We conclude that it is pregnancy-enhanced gap junction communication between cells that underlies pregnancy enhancement of capacitative entry via TRPC3 and, in turn, NOS3 activation. Such improved gap junction function allows greater and more sustained [Ca(2+)](i) responses to agents such as ATP within a single cell, as well as the additional recruitment of greater numbers of cells to the response in a coordinated and synchronous manner to support enhanced NO production.
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Affiliation(s)
- Fu-Xian Yi
- Department of Obstetrics & Gynecology, Perinatal Research Laboratories, University of Wisconsin, Madison, Wisconsin 53715, USA
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Dubyak GR. Both sides now: multiple interactions of ATP with pannexin-1 hemichannels. Focus on "A permeant regulating its permeation pore: inhibition of pannexin 1 channels by ATP". Am J Physiol Cell Physiol 2009; 296:C235-41. [PMID: 19179656 DOI: 10.1152/ajpcell.00639.2008] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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37
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de Wit C, Boettcher M, Schmidt VJ. Signaling across Myoendothelial Gap Junctions—Fact or fiction? ACTA ACUST UNITED AC 2009; 15:231-45. [DOI: 10.1080/15419060802440260] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
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Fernandez-Rodriguez S, Edwards DH, Newton B, Griffith TM. Attenuated store-operated Ca2+ entry underpins the dual inhibition of nitric oxide and EDHF-type relaxations by iodinated contrast media. Cardiovasc Res 2009; 84:470-8. [DOI: 10.1093/cvr/cvp239] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
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Brisset AC, Isakson BE, Kwak BR. Connexins in vascular physiology and pathology. Antioxid Redox Signal 2009; 11:267-82. [PMID: 18834327 PMCID: PMC2819334 DOI: 10.1089/ars.2008.2115] [Citation(s) in RCA: 136] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/12/2008] [Revised: 06/06/2008] [Accepted: 07/10/2008] [Indexed: 12/13/2022]
Abstract
Cellular interaction in blood vessels is maintained by multiple communication pathways, including gap junctions. They consist of intercellular channels ensuring direct interaction between endothelial and smooth muscle cells and the synchronization of their behavior along the vascular wall. Gap-junction channels arise from the docking of two hemichannels or connexons, formed by the assembly of six connexins, and achieve direct cellular communication by allowing the transport of small metabolites, second messengers, and ions between two adjacent cells. Physiologic variations in connexin expression are observed along the vascular tree, with most common connexins being Cx37, Cx40, and Cx43. Changes in the level of expression of connexins have been correlated to the development of vascular disease, such as hypertension, atherosclerosis, or restenosis. Recent studies on connexin-deficient mice highlighted key roles of these communication pathways in the development of these pathologies and confirmed the need for targeted pharmacologic approaches for their prevention and treatment. The aim of this issue is to review the current knowledge on the implication of gap junctions in vascular function and most common cardiovascular diseases.
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Affiliation(s)
- Anne C. Brisset
- Division of Cardiology, Geneva University Hospitals, Geneva, Switzerland
- Department of Pediatrics, Geneva University Hospitals, Geneva, Switzerland
| | - Brant E. Isakson
- Department of Molecular Physiology and Biological Physics, Robert M. Berne Cardiovascular Research Center, University of Virginia School of Medicine, Charlottesville, Virginia
| | - Brenda R. Kwak
- Division of Cardiology, Geneva University Hospitals, Geneva, Switzerland
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40
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Abstract
Direct intercellular communication via gap junctions is critical in the control and coordination of vascular function. In the cardiovascular system, gap junctions are made up of one or more of four connexin proteins: Cx37, Cx40, Cx43, and Cx45. The expression of more than one gap-junction protein in the vasculature is not redundant. Rather, vascular connexins work in concert, first during the development of the cardiovascular system, and then in integrating smooth muscle and endothelial cell function, and in coordinating cell function along the length of the vessel wall. In addition, connexin-based channels have emerged as an important signaling pathway in the astrocyte-mediated neurovascular coupling. Direct electrical communication between endothelial cells and vascular smooth muscle cells via gap junctions is thought to play a relevant role in the control of vasomotor tone, providing the signaling pathway known as endothelium-derived hyperpolarizing factor (EDHF). Consistent with the importance of gap junctions in the regulation of vasomotor tone and arterial blood pressure, the expression of connexins is altered in diseases associated with vascular complications. In this review, we discuss the participation of connexin-based channels in the control of vascular function in physiologic and pathologic conditions, with a special emphasis on hypertension and diabetes.
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Affiliation(s)
- Xavier F Figueroa
- Departamento de Ciencias Fisiológicas, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Santiago, Chile.
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Markos F, Ruane-O'Hora T, Snow HM, Kelly R, Wainwright C, Skene K, Drake-Holland AJ, Noble MIM. Dilatation in the femoral vascular bed does not cause retrograde relaxation of the iliac artery in the anaesthetized pig. Acta Physiol (Oxf) 2008; 194:207-13. [PMID: 18577181 DOI: 10.1111/j.1748-1716.2008.01882.x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
AIM We tested the hypothesis that dilatation of a feeding artery may be elicited by transmission of a signal through the tissue of the arterial wall from a vasodilated peripheral vascular bed. METHODS In eight pentobarbital anaesthetized pigs, acetylcholine (ACh, an endothelium-dependent vasodilator) was injected intra-arterially above (upstream) and below (downstream) a test segment of the left iliac artery, the diameter of which was measured continuously by sonomicrometry. RESULTS Under control conditions, ACh injections upstream and downstream of the test segment caused dilatation. Downstream injection dilated the peripheral arterioles, resulting in increased blood flow and proximal dilatation. This is a shear stress, nitric oxide (NO)-dependent response. The experiment was then repeated after applying a stenosis to prevent the increased flow caused by downstream injection of ACh; the stenosis was placed either above the site of diameter measurement to allow retrograde conduction, or below that site to prevent distally injected ACh reaching the measurement site. Under these conditions, downstream injection of ACh had a minimal effect on the shear stress of the test segment with no increase in test segment diameter. This was not due to endothelial damage or dysfunction as injection of ACh upstream still caused a large increase in test segment diameter. CONCLUSIONS Our results indicate that dilatation of the feeding artery of a vasodilated bed is caused by increased shear stress within the feeding artery and not via a signal transmitted through the arterial wall from below.
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Affiliation(s)
- F Markos
- Department of Physiology, University College Cork, Cork, Ireland.
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Young EJ, Hill MA, Wiehler WB, Triggle CR, Reid JJ. Reduced EDHF responses and connexin activity in mesenteric arteries from the insulin-resistant obese Zucker rat. Diabetologia 2008; 51:872-81. [PMID: 18324386 DOI: 10.1007/s00125-008-0934-y] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/07/2007] [Accepted: 12/17/2007] [Indexed: 01/18/2023]
Abstract
AIMS/HYPOTHESIS The objective of this study was to examine the effect of insulin resistance on endothelium-derived hyperpolarising factor (EDHF) and small mesenteric artery endothelial function using 25-week-old insulin-resistant obese Zucker rats (OZRs) and lean littermate control rats (LZRs). The involvement of gap junctions and their connexin subunits in the EDHF relaxation response was also assessed. METHODS Mesenteric arteries were evaluated using the following assays: (1) endothelial function by pressure myography, with internal diameter recorded using video microscopy; (2) connexin protein levels by western blotting; and (3) Cx mRNA expression by real-time PCR. RESULTS Relaxations in response to acetylcholine were significantly smaller in mesenteric arteries from the OZRs than the LZRs, whereas there was no difference in relaxations in response to levcromakalim. Responses to acetylcholine were not altered by nitric oxide inhibitors, but were abolished by charybdotoxin in combination with apamin, which blocked the EDHF component of the response. 40Gap27 significantly attenuated the response to acetylcholine in the LZRs, but had no effect in the OZRs. Connexin 40 protein and Cx40 mRNA levels in mesenteric vascular homogenates were significantly smaller in the OZRs than in the LZRs, with no difference in connexin 43 or Cx43 mRNA levels. CONCLUSIONS/INTERPRETATION These findings demonstrate that endothelial dysfunction in mesenteric arteries from the insulin-resistant OZRs can be attributed to a defect in EDHF. The results also suggest that the defective EDHF is at least partly related to an impairment of connexin 40-associated gap junctions, through a decrease in connexin 40 protein and Cx40 mRNA expression in the OZRs.
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Affiliation(s)
- E J Young
- School of Medical Sciences, RMIT University, Melbourne, Victoria, Australia.
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Berhane Y, Bailey SR, Putignano C, Elliott J. Characterization of agonist-induced endothelium-dependent vasodilatory responses in the vascular bed of the equine digit. J Vet Pharmacol Ther 2008; 31:1-8. [PMID: 18177312 DOI: 10.1111/j.1365-2885.2007.00912.x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The role of endothelium-derived relaxing factors was studied in the regulation of vascular responses in the Krebs perfused equine isolated digit. Perfusion pressure was recorded in response to bolus doses of 5-hydroxytryptamine (6 nmol) alone or co-administered with carbachol (CCh; 0.2 micromol), bradykinin (BK; 0.2 nmol), substance P (SP; 0.2 nmol) or sodium nitroprusside (SNP; 0.2 micromol). N(omega)-Nitro-L-Arginine methyl ester hydrochloride (L-NAME; 300 microm) caused partial but significant inhibition of CCh-induced vasodilatory response, whereas BK and SP-induced responses were resistant to L-NAME. High potassium (K(+), 30 mm) and the cytochrome P-450 (CYP) epoxygenase inhibitor, clotrimazole (10 microm) plus L-NAME (100 microm), completely abolished the CCh, BK and SP-induced vasodilatory responses, whereas the response to SNP was unaffected. In contrast, the L-NAME-resistant proportion of CCh, BK and SP-induced vasodilatory response was not inhibited by the highly selective CYP2C9 inhibitor, sulphaphenazole (10 microm). The cyclo-oxygenase inhibitor, ibuprofen (10 microm) did not affect the CCh, BK and SP-induced responses. These data demonstrate that CCh, BK and SP-induced relaxation in the equine digit involve a combination of the NO and endothelium-derived hyperpolarizing factor (EDHF) pathways. These results do not support the evidence for the involvement of CYP-derived epoxyeicosatrienoic acids and the exact nature of EDHF in the equine digit remains to be established.
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Affiliation(s)
- Y Berhane
- Department of Veterinary Basic Sciences, Royal Veterinary College, London, UK.
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Edwards DH, Chaytor AT, Bakker LM, Griffith TM. Modulation of gap-junction-dependent arterial relaxation by ascorbic acid. J Vasc Res 2007; 44:410-22. [PMID: 17587861 DOI: 10.1159/000104254] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2006] [Accepted: 03/19/2007] [Indexed: 11/19/2022] Open
Abstract
AIMS To investigate whether ascorbic acid (AA) can influence endothelium-dependent relaxation by modulating the spread of endothelial hyperpolarization through the arterial wall via gap junctions. METHODS Force development and membrane potential were monitored by myography and sharp electrode techniques in isolated rabbit iliac arteries. RESULTS AA prevented the ability of the gap junction blocker 2-aminoethoxydiphenyl borate to inhibit endothelium-dependent relaxations and subintimal smooth muscle hyperpolarizations evoked by cyclopiazonic acid in the presence of nitric oxide (NO) synthase and cyclooxygenase blockade. AA also prevented the ability of a connexin-mimetic peptide targeted against Cx37 and Cx40 (37,40Gap 26) to attenuate the transmission of endothelial hyperpolarization to subintimal smooth muscle, and a peptide targeted against Cx43 (43Gap 26) to attenuate the spread of subintimal hyperpolarization to subadventitial smooth muscle and the associated mechanical relaxation. Parallel studies with endothelium-denuded preparations demonstrated that AA and cyclopiazonic acid both depressed relaxation evoked by the NO donor MAHMA NONOate. CONCLUSIONS The data suggest that AA can modulate arterial function through a previously unrecognized ability to preserve electrotonic signalling via myoendothelial and homocellular smooth muscle gap junctions under conditions where cell coupling is depressed. Underlying mechanisms do not involve amplification of 'residual' NO activity by AA.
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Affiliation(s)
- David H Edwards
- Department of Diagnostic Radiology, Wales Heart Research Institute, Cardiff University, Cardiff, UK
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Daniel EE, Yazbi AE, Mannarino M, Galante G, Boddy G, Livergant J, Oskouei TE. Do gap junctions play a role in nerve transmissions as well as pacing in mouse intestine? Am J Physiol Gastrointest Liver Physiol 2007; 292:G734-45. [PMID: 17122366 DOI: 10.1152/ajpgi.00428.2006] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Varicosities of nitrergic and other nerves end on deep muscular plexus interstitial cells of Cajal or on CD34-positive, c-kit-negative fibroblast-like cells. Both cell types connect to outer circular muscle by gap junctions, which may transmit nerve messages to muscle. We tested the hypotheses that gap junctions transmit pacing messages from interstitial cells of Cajal of the myenteric plexus. Effects of inhibitors of gap junction conductance were studied on paced contractions and nerve transmissions in small segments of circular muscle of mouse intestine. Using electrical field stimulation parameters (50 V/cm, 5 pps, and 0.5 ms) which evoke near maximal responses to nitrergic, cholinergic, and apamin-sensitive nerve stimulation, we isolated inhibitory responses to nitrergic nerves, inhibitory responses to apamin-sensitive nerves and excitatory responses to cholinergic nerves. 18beta-Glycyrrhetinic acid (10, 30, and 100 microM), octanol (0.1, 0.3, and 1 mM) and gap peptides (300 microM of (40)Gap27, (43)Gap26, (37,43)Gap27) all failed to abolish neurotransmission. 18beta-Glycyrrhetinic acid inhibited frequencies of paced contractions, likely owing to inhibition of l-type Ca(2+) channels in smooth muscle, but octanol or gap peptides did not. 18beta-Glycyrrhetinic acid and octanol, but not gap peptides, reduced the amplitudes of spontaneous and nerve-induced contractions. These reductions paralleled reductions in contractions to exogenous carbachol. Additional experiments with gap peptides in both longitudinal and circular muscle segments after N(G)-nitro-l-arginine and TTX revealed no effects on pacing frequencies. We conclude that gap junction coupling may not be necessary for pacing or nerve transmission to the circular muscle of the mouse intestine.
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Affiliation(s)
- E E Daniel
- Department of Pharmacology, University of Alberta, Edmonton, Alberta, Canada.
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Lavoie B, Balemba OB, Nelson MT, Ward SM, Mawe GM. Morphological and physiological evidence for interstitial cell of Cajal-like cells in the guinea pig gallbladder. J Physiol 2007; 579:487-501. [PMID: 17204499 PMCID: PMC2075389 DOI: 10.1113/jphysiol.2006.122861] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Gallbladder smooth muscle (GBSM) exhibits spontaneous rhythmic electrical activity, but the origin and propagation of this activity are not understood. We used morphological and physiological approaches to determine whether interstitial cells of Cajal (ICC) are present in the guinea pig extrahepatic biliary tree. Light microscopic studies involving Kit tyrosine kinase immunohistochemistry and laser confocal imaging of Ca(2+) transients revealed ICC-like cells in the gallbladder. One type of ICC-like cell had elongated cell bodies with one or two primary processes and was observed mainly along GBSM bundles and nerve fibres. The other type comprised multipolar cells that were located at the origin and intersection of muscle bundles. Electron microscopy revealed ICC-like cells that were rich in mitochondria, caveolae and smooth endoplasmic reticulum and formed close appositions between themselves and with GBSM cells. Rhythmic Ca(2+) flashes, which represent Ca(2+) influx during action potentials, were synchronized in any given GBSM bundle and associated ICC-like cells. Gap junction uncouplers (1-octanol, carbenoxolone, 18beta-glycyrrhetinic acid and connexin mimetic peptide) eliminated or greatly reduced Ca(2+) flashes in GBSM, but they persisted in ICC-like cells, whereas the Kit tyrosine kinase inhibitor, imanitib mesylate, eliminated or reduced action potentials and Ca(2+) flashes in both cell types, as well as associated tissue contractions. This study provides morphological and physiological evidence for the existence of ICC-like cells in the gallbladder and presents data supporting electrical coupling between ICC-like and GBSM cells. The results support a role for ICC-like cells in the generation and propagation of spontaneous rhythmicity, and hence, the excitability of gallbladder.
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Affiliation(s)
- Brigitte Lavoie
- Department of Anatomy, University of Vermont College of Medicine, Burlington, VT 05405, USA
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Affiliation(s)
- Xavier F Figueroa
- Unidad de Regulación Neurohumoral, Departamento de Ciencias Fisiológicas, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Santiago, Chile
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Matchkov VV, Rahman A, Bakker LM, Griffith TM, Nilsson H, Aalkjaer C. Analysis of effects of connexin-mimetic peptides in rat mesenteric small arteries. Am J Physiol Heart Circ Physiol 2006; 291:H357-67. [PMID: 16428342 DOI: 10.1152/ajpheart.00681.2005] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Synthetic peptides homologous to the extracellular loops of the major vascular connexins represent a novel class of gap junction blockers that have been used to assess the role of direct cellular communication in arteries and veins. However, the specificity of action of such peptides on the coupling between smooth muscle cells (SMCs) has not yet been fully characterized. Isolated third-order rat mesenteric arteries were therefore studied with respect to isometric tension (myography), intracellular Ca2+ concentration ([Ca2+]i) (Ca2+ -sensitive dyes), membrane potential, and input resistance (sharp intracellular glass electrodes). Confocal imaging was used for visualization of [Ca2+]i events in individual SMCs in the arterial wall and membrane currents (patch clamp) measured in individual SMCs isolated from the same arteries. A triple peptide combination (37,43Gap 27 + 40Gap 27 + 43Gap 26) increased intercellular resistance (measured as input resistance) in intact arterial segments without affecting the membrane conductance of individual cells and also interrupted electrical coupling between pairs of rat aortic A7r5 myocytes. In intact arterial segments, the peptides desynchronized [Ca2+]i transients in individual SMCs and abolished vasomotion without suppressing Ca2+ transients in individual cells. They also depolarized SMCs, increased [Ca2+]i, and attenuated acetylcholine-induced, endothelium-dependent smooth muscle hyperpolarization. Experiments with endothelium-denuded arteries suggested that the depolarization produced by the peptides under basal conditions was in part secondary to electrical uncoupling of the endothelium from SMCs with loss of a tonic hyperpolarizing effect of the endothelium. Taken together, the results indicate that connexin-mimetic peptides block electrical signaling in rat mesenteric small arteries without exerting major nonjunctional effects.
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Affiliation(s)
- Vladimir V Matchkov
- The Water and Salt Research Center, Institute of Physiology and Biophysics, University of Aarhus, Aarhus, Denmark.
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Correction. Proc Natl Acad Sci U S A 2005. [DOI: 10.1073/pnas.0505943102] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
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