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Nordahl KML, Fedulov V, Holm A, Haanes KA. Intraocular Adeno-Associated Virus-Mediated Transgene Endothelin-1 Delivery to the Rat Eye Induces Functional Changes Indicative of Retinal Ischemia-A Potential Chronic Glaucoma Model. Cells 2023; 12:1987. [PMID: 37566067 PMCID: PMC10417058 DOI: 10.3390/cells12151987] [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: 05/26/2023] [Revised: 07/19/2023] [Accepted: 07/25/2023] [Indexed: 08/12/2023] Open
Abstract
Endothelin-1 (ET-1) overactivity has been implicated as a factor contributing to glaucomatous neuropathy, and it has been utilized in animal models of retinal ischemia. The functional effects of long-term ET-1 exposure and possible compensatory mechanisms have, however, not been investigated. This was therefore the purpose of our study. ET-1 was delivered into rat eyes via a single intravitreal injection of 500 µM or via transgene delivery using an adeno-associated viral (AAV) vector. Retinal function was assessed using electroretinography (ERG) and the retinal expression of potentially compensatory genes was evaluated by means of qRT-PCR. Acute ET-1 delivery led to vasoconstriction and a significant reduction in the ERG response. AAV-ET-1 resulted in substantial transgene expression and ERG results similar to the acute ET-1 injections and comparable to other models of retinal ischemia. Compensatory changes were observed, including an increase in calcitonin gene-related peptide (CGRP) gene expression, which may both counterbalance the vasoconstrictive effects of ET-1 and provide neuroprotection. This chronic ET-1 ischemia model might be especially relevant to glaucoma research, mimicking the mild and repeated ischemic events in patients with long-term vascular dysfunction. The compensatory mechanisms, and particularly the role of vasodilatory CGRP in mitigating the retinal damage, warrant further investigation with the aim of evaluating new therapeutic strategies.
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Affiliation(s)
- Karin M. L. Nordahl
- Clinical Experimental Research, Glostrup Research Institute, Rigshospitalet, 2600 Glostrup, Denmark; (A.H.); (K.A.H.)
| | - Vadim Fedulov
- Clinical and Medical Affairs, Radiometer, 2700 Brønshøj, Denmark;
| | - Anja Holm
- Clinical Experimental Research, Glostrup Research Institute, Rigshospitalet, 2600 Glostrup, Denmark; (A.H.); (K.A.H.)
- Center for RNA Medicine, Department of Clinical Medicine, Aalborg University, 2450 Copenhagen, Denmark
| | - Kristian A. Haanes
- Clinical Experimental Research, Glostrup Research Institute, Rigshospitalet, 2600 Glostrup, Denmark; (A.H.); (K.A.H.)
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Chen YL, Ren Y, Rosa RH, Kuo L, Hein TW. Contributions of Sodium-Hydrogen Exchanger 1 and Mitogen-Activated Protein Kinases to Enhanced Retinal Venular Constriction to Endothelin-1 in Diabetes. Diabetes 2021; 70:2353-2363. [PMID: 34353852 PMCID: PMC8576499 DOI: 10.2337/db20-0889] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/01/2020] [Accepted: 07/28/2021] [Indexed: 11/13/2022]
Abstract
Diabetes elevates endothelin-1 (ET-1) in the vitreous and enhances constriction of retinal venules to this peptide. However, mechanisms contributing to ET-1-induced constriction of retinal venules are incompletely understood. We examined roles of sodium-hydrogen exchanger 1 (NHE1), protein kinase C (PKC), mitogen-activated protein kinases (MAPKs), and extracellular calcium (Ca2+) in retinal venular constriction to ET-1 and the impact of diabetes on these signaling molecules. Retinal venules were isolated from control pigs and pigs with streptozocin-induced diabetes for in vitro studies. ET-1-induced vasoconstriction was abolished in the absence of extracellular Ca2+ and sensitive to c-Jun N-terminal kinase (JNK) inhibitor SP600125 but unaffected by extracellular signal-regulated kinase (ERK) inhibitor PD98059, p38 kinase inhibitor SB203580, or broad-spectrum PKC inhibitor Gö 6983. Diabetes (after 2 weeks) enhanced venular constriction to ET-1, which was insensitive to PD98059 and Gö 6983 but was prevented by NHE1 inhibitor cariporide, SB203580, and SP600125. In conclusion, extracellular Ca2+ entry and activation of JNK, independent of ERK and PKC, mediate constriction of retinal venules to ET-1. Diabetes activates p38 MAPK and NHE1, which cause enhanced venular constriction to ET-1. Treatments targeting these vascular molecules may lessen retinal complications in early diabetes.
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Affiliation(s)
- Yen-Lin Chen
- Department of Medical Physiology, College of Medicine, Texas A&M University Health Science Center, Bryan, TX
| | - Yi Ren
- Department of Medical Physiology, College of Medicine, Texas A&M University Health Science Center, Bryan, TX
| | - Robert H Rosa
- Department of Medical Physiology, College of Medicine, Texas A&M University Health Science Center, Bryan, TX
- Department of Ophthalmology, Baylor Scott & White Eye Institute, Temple, TX
| | - Lih Kuo
- Department of Medical Physiology, College of Medicine, Texas A&M University Health Science Center, Bryan, TX
| | - Travis W Hein
- Department of Medical Physiology, College of Medicine, Texas A&M University Health Science Center, Bryan, TX
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Retinal blood flow dysregulation precedes neural retinal dysfunction in type 2 diabetic mice. Sci Rep 2021; 11:18401. [PMID: 34526573 PMCID: PMC8443656 DOI: 10.1038/s41598-021-97651-3] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2021] [Accepted: 08/27/2021] [Indexed: 11/23/2022] Open
Abstract
We investigated and compared the susceptibility of retinal blood flow regulation and neural function in mice developing type 2 diabetes. The longitudinal changes in retinal neuronal function and blood flow responses to a 10-min systemic hyperoxia and a 3-min flicker stimulation were evaluated every 2 weeks in diabetic db/db mice and nondiabetic controls (db/m) from age 8 to 20 weeks. The retinal blood flow and neural activity were assessed using laser speckle flowgraphy and electroretinography (ERG), respectively. The db/db mice had significantly higher blood glucose levels and body weight. The resting retinal blood flow was steady and comparable between two groups throughout the study. Hyperoxia elicited a consistent decrease, and flicker light an increase, in retinal blood flow in db/m mice independent of age. However, these flow responses were significantly diminished in db/db mice at 8 weeks old and then the mice became unresponsive to stimulations at 12 weeks. Subsequently, the ERG implicit time for oscillatory potential was significantly increased at 14 weeks of age while the a-wave and b-wave amplitudes and implicit times remained unchanged. The deficiencies of flow regulation and neurovascular coupling in the retina appear to precede neural dysfunction in the mouse with type 2 diabetes.
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Kamiya T, Omae T, Nakabayashi S, Takahashi K, Tanner A, Yoshida A. Effect of Rho Kinase Inhibitor Ripasudil (K-115) on Isolated Porcine Retinal Arterioles. J Ocul Pharmacol Ther 2020; 37:104-111. [PMID: 33351704 DOI: 10.1089/jop.2020.0082] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
Purpose: To investigate the vasorelaxation effect of ripasudil (K-115), a novel Rho-associated coiled-coil-containing protein kinase (ROCK) inhibitor, on isolated retinal arterioles. We determined whether the actions of ripasudil on the retinal microvascular diameter were dependent on the endothelium and/or potassium channels in the smooth muscle, with the goals of uncovering the signaling mechanisms required for this vasomotor activity and inhibiting the action of endothelin-1 (ET-1). Methods: In this in vitro study, we isolated porcine retinal arterioles, which were cannulated and pressurized without flow. We recorded diametric changes using videomicroscopic techniques. Results: In a dose-dependent (10 nM-30 μM) manner, retinal arterioles were relaxed in response to ripasudil [maximum % resting diameter, 160.3% ± 7.7% (mean ± standard error of the mean)]. The ripasudil-induced vasorelaxation was unaffected by endothelium removal, using nonselective potassium channel blocker tetraethylammonium, Ca2+-activated large-conductance potassium channel blocker iberiotoxin, voltage-gated potassium channel blocker 4-AP, ATP-sensitive potassium channel blocker glibenclamide, and inward rectifier potassium channel blocker BaCl2. Ripasudil prevented ET-1-caused vasoconstriction of the retinal arterioles regardless of the presence of endothelium to a similar extent. Conclusion: The ROCK inhibitor ripasudil elicits endothelium-independent relaxation and inhibits the action of ET-1 on the retinal arterioles. Determining the relaxation properties of ripasudil on the retinal microvasculature will likely support the development of potential therapies for glaucoma.
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Affiliation(s)
- Takayuki Kamiya
- Department of Ophthalmology, Asahikawa Medical University, Asahikawa, Japan
| | - Tsuneaki Omae
- Department of Ophthalmology, Asahikawa Medical University, Asahikawa, Japan
| | - Seigo Nakabayashi
- Department of Ophthalmology, Asahikawa Medical University, Asahikawa, Japan
| | - Kengo Takahashi
- Department of Ophthalmology, Asahikawa Medical University, Asahikawa, Japan
| | - Akira Tanner
- Department of Ophthalmology, Asahikawa Medical University, Asahikawa, Japan
| | - Akitoshi Yoshida
- Department of Ophthalmology, Asahikawa Medical University, Asahikawa, Japan
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Chen YL, Rosa RH, Kuo L, Hein TW. Hyperglycemia Augments Endothelin-1-Induced Constriction of Human Retinal Venules. Transl Vis Sci Technol 2020; 9:1. [PMID: 32879758 PMCID: PMC7442874 DOI: 10.1167/tvst.9.9.1] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2020] [Accepted: 06/17/2020] [Indexed: 02/06/2023] Open
Abstract
Purpose Endothelin-1 (ET-1) is a potent vasoactive factor implicated in development of diabetic retinopathy, which is commonly associated with retinal edema and hyperglycemia. Although the vasomotor activity of venules contributes to the regulation of tissue fluid homeostasis, responses of human retinal venules to ET-1 under euglycemia and hyperglycemia remain unknown and the ET-1 receptor subtype corresponding to vasomotor function has not been determined. Herein, we addressed these issues by examining the reactivity of isolated human retinal venules to ET-1, and results from porcine retinal venules were compared. Methods Retinal tissues were obtained from patients undergoing enucleation. Human and porcine retinal venules were isolated and pressurized to assess diameter changes in response to ET-1 after exposure to 5 mM control glucose or 25 mM high glucose for 2 hours. Results Both human and porcine retinal venules exposed to control glucose developed similar basal tone and constricted comparably to ET-1 in a concentration-dependent manner. ET-1–induced constrictions of human and porcine retinal venules were abolished by ETA receptor antagonist BQ123. During high glucose exposure, basal tone of human and porcine retinal venules was unaltered but ET-1–induced vasoconstrictions were enhanced. Conclusions ET-1 elicits comparable constriction of human and porcine retinal venules by activation of ETA receptors. In vitro hyperglycemia augments human and porcine retinal venular responses to ET-1. Translational Relevance Similarities in vasoconstriction to ET-1 between human and porcine retinal venules support the latter as an effective model of the human retinal microcirculation to help identify vascular targets for the treatment of retinal complications in patients with diabetes.
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Affiliation(s)
- Yen-Lin Chen
- Department of Medical Physiology, College of Medicine, Texas A&M University Health Science Center, Bryan, TX, USA
| | - Robert H Rosa
- Department of Medical Physiology, College of Medicine, Texas A&M University Health Science Center, Bryan, TX, USA.,Department of Ophthalmology, Baylor Scott & White Eye Institute, Temple, TX, USA
| | - Lih Kuo
- Department of Medical Physiology, College of Medicine, Texas A&M University Health Science Center, Bryan, TX, USA
| | - Travis W Hein
- Department of Medical Physiology, College of Medicine, Texas A&M University Health Science Center, Bryan, TX, USA
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Wright WS, Eshaq RS, Lee M, Kaur G, Harris NR. Retinal Physiology and Circulation: Effect of Diabetes. Compr Physiol 2020; 10:933-974. [PMID: 32941691 PMCID: PMC10088460 DOI: 10.1002/cphy.c190021] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
In this article, we present a discussion of diabetes and its complications, including the macrovascular and microvascular effects, with the latter of consequence to the retina. We will discuss the anatomy and physiology of the retina, including aspects of metabolism and mechanisms of oxygenation, with the latter accomplished via a combination of the retinal and choroidal blood circulations. Both of these vasculatures are altered in diabetes, with the retinal circulation intimately involved in the pathology of diabetic retinopathy. The later stages of diabetic retinopathy involve poorly controlled angiogenesis that is of great concern, but in our discussion, we will focus more on several alterations in the retinal circulation occurring earlier in the progression of disease, including reductions in blood flow and a possible redistribution of perfusion that may leave some areas of the retina ischemic and hypoxic. Finally, we include in this article a more recent area of investigation regarding the diabetic retinal vasculature, that is, the alterations to the endothelial surface layer that normally plays a vital role in maintaining physiological functions. © 2020 American Physiological Society. Compr Physiol 10:933-974, 2020.
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Affiliation(s)
- William S Wright
- Department of Biomedical Sciences, University of South Carolina School of Medicine Greenville, Greenville, South Carolina, USA
| | - Randa S Eshaq
- Department of Molecular and Cellular Physiology, Louisiana State University Health Shreveport, Shreveport, Louisiana, USA
| | - Minsup Lee
- Department of Molecular and Cellular Physiology, Louisiana State University Health Shreveport, Shreveport, Louisiana, USA
| | - Gaganpreet Kaur
- Department of Molecular and Cellular Physiology, Louisiana State University Health Shreveport, Shreveport, Louisiana, USA
| | - Norman R Harris
- Department of Molecular and Cellular Physiology, Louisiana State University Health Shreveport, Shreveport, Louisiana, USA
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Barabas P, Augustine J, Fernández JA, McGeown JG, McGahon MK, Curtis TM. Ion channels and myogenic activity in retinal arterioles. CURRENT TOPICS IN MEMBRANES 2020; 85:187-226. [PMID: 32402639 DOI: 10.1016/bs.ctm.2020.01.008] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Retinal pressure autoregulation is an important mechanism that protects the retina by stabilizing retinal blood flow during changes in arterial or intraocular pressure. Similar to other vascular beds, retinal pressure autoregulation is thought to be mediated largely through the myogenic response of small arteries and arterioles which constrict when transmural pressure increases or dilate when it decreases. Over recent years, we and others have investigated the signaling pathways underlying the myogenic response in retinal arterioles, with particular emphasis on the involvement of different ion channels expressed in the smooth muscle layer of these vessels. Here, we review and extend previous work on the expression and spatial distribution of the plasma membrane and sarcoplasmic reticulum ion channels present in retinal vascular smooth muscle cells (VSMCs) and discuss their contribution to pressure-induced myogenic tone in retinal arterioles. This includes new data demonstrating that several key players and modulators of the myogenic response show distinctively heterogeneous expression along the length of the retinal arteriolar network, suggesting differences in myogenic signaling between larger and smaller pre-capillary arterioles. Our immunohistochemical investigations have also highlighted the presence of actin-containing microstructures called myobridges that connect the retinal VSMCs to one another. Although further work is still needed, studies to date investigating myogenic mechanisms in the retina have contributed to a better understanding of how blood flow is regulated in this tissue. They also provide a basis to direct future research into retinal diseases where blood flow changes contribute to the pathology.
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Affiliation(s)
- Peter Barabas
- Wellcome-Wolfson Institute for Experimental Medicine, Queen's University of Belfast, Belfast, United Kingdom
| | - Josy Augustine
- Wellcome-Wolfson Institute for Experimental Medicine, Queen's University of Belfast, Belfast, United Kingdom
| | - José A Fernández
- Wellcome-Wolfson Institute for Experimental Medicine, Queen's University of Belfast, Belfast, United Kingdom
| | - J Graham McGeown
- Wellcome-Wolfson Institute for Experimental Medicine, Queen's University of Belfast, Belfast, United Kingdom
| | - Mary K McGahon
- Wellcome-Wolfson Institute for Experimental Medicine, Queen's University of Belfast, Belfast, United Kingdom
| | - Tim M Curtis
- Wellcome-Wolfson Institute for Experimental Medicine, Queen's University of Belfast, Belfast, United Kingdom.
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Chen YL, Ren Y, Xu W, Rosa RH, Kuo L, Hein TW. Constriction of Retinal Venules to Endothelin-1: Obligatory Roles of ETA Receptors, Extracellular Calcium Entry, and Rho Kinase. Invest Ophthalmol Vis Sci 2019; 59:5167-5175. [PMID: 30372743 PMCID: PMC6203175 DOI: 10.1167/iovs.18-25369] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Purpose Endothelin-1 (ET-1) is a potent vasoconstrictor peptide implicated in retinal venous pathologies such as diabetic retinopathy and retinal vein occlusion. However, underlying mechanisms contributing to venular constriction remain unknown. Thus, we examined the roles of ET-1 receptors, extracellular calcium (Ca2+), L-type voltage-operated calcium channels (L-VOCCs), Rho kinase (ROCK), and protein kinase C (PKC) in ET-1-induced constriction of retinal venules. Methods Porcine retinal venules were isolated and pressurized for vasoreactivity study using videomicroscopic techniques. Protein and mRNA were analyzed using molecular tools. Results Retinal venules developed basal tone and constricted concentration-dependently to ET-1. The ETA receptor (ETAR) antagonist BQ123 abolished venular constriction to ET-1, but ETB receptor (ETBR) antagonist BQ788 had no effect on vasoconstriction. The ETBR agonist sarafotoxin S6c did not elicit vasomotor activity. In the absence of extracellular Ca2+, venules lost basal tone and ET-1–induced constriction was nearly abolished. Although L-VOCC inhibitor nifedipine also reduced basal tone and blocked vasoconstriction to L-VOCC activator Bay K8644, constriction of venules to ET-1 remained. The ROCK inhibitor H-1152 but not PKC inhibitor Gö 6983 prevented ET-1-induced vasoconstriction. Protein and mRNA expressions of ETARs and ETBRs, along with ROCK1 and ROCK2 isoforms, were detected in retinal venules. Conclusions Extracellular Ca2+ entry via L-VOCCs is essential for developing and maintaining basal tone of porcine retinal venules. ET-1 causes significant constriction of retinal venules by activating ETARs and extracellular Ca2+ entry independent of L-VOCCs. Activation of ROCK signaling, without involvement of PKC, appears to mediate venular constriction to ET-1 in the porcine retina.
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Affiliation(s)
- Yen-Lin Chen
- Department of Medical Physiology, College of Medicine, Texas A&M University Health Science Center, Temple, Texas, United States
| | - Yi Ren
- Department of Medical Physiology, College of Medicine, Texas A&M University Health Science Center, Temple, Texas, United States
| | - Wenjuan Xu
- Department of Medical Physiology, College of Medicine, Texas A&M University Health Science Center, Temple, Texas, United States
| | - Robert H Rosa
- Department of Medical Physiology, College of Medicine, Texas A&M University Health Science Center, Temple, Texas, United States.,Ophthalmic Vascular Research Program, Department of Ophthalmology, Scott & White Eye Institute, Baylor Scott & White Health, Temple, Texas, United States
| | - Lih Kuo
- Department of Medical Physiology, College of Medicine, Texas A&M University Health Science Center, Temple, Texas, United States.,Ophthalmic Vascular Research Program, Department of Ophthalmology, Scott & White Eye Institute, Baylor Scott & White Health, Temple, Texas, United States
| | - Travis W Hein
- Department of Medical Physiology, College of Medicine, Texas A&M University Health Science Center, Temple, Texas, United States.,Ophthalmic Vascular Research Program, Department of Ophthalmology, Scott & White Eye Institute, Baylor Scott & White Health, Temple, Texas, United States
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Arfuzir NNN, Agarwal R, Iezhitsa I, Agarwal P, Ismail NM. Dose-Dependent Effects of Endothelin-1 on Retinal and Optic Nerve Morphology in Sprague Dawley Rats. NEUROCHEM J+ 2019. [DOI: 10.1134/s1819712419010045] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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Takahashi K, Omae T, Ono S, Kamiya T, Tanner A, Yoshida A. Thrombin-Induced Responses via Protease-Activated Receptor 1 Blocked by the Endothelium on Isolated Porcine Retinal Arterioles. Curr Eye Res 2018; 43:1374-1382. [PMID: 29966442 DOI: 10.1080/02713683.2018.1496266] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
Abstract
PURPOSE Thrombin, a serine protease, causes organ-specific responses to vessels. However, the mechanism by which thrombin affects the retinal microcirculation remains unclear. We examined the effects of thrombin on the retinal microvasculature and signaling mechanisms. METHODS Porcine retinal arterioles were isolated, cannulated, and pressurized (55 cmH2O) without flow in this in vitro study. Videomicroscopy techniques recorded changes in diameter in the retinal arterioles in response to thrombin at concentrations ranging from 0.001 to 20 mU/ml. RESULTS Extraluminal administration of thrombin induced concentration-dependent vascular responses, that is, vasoconstriction at low concentrations less than 5 mU/ml and vasorelaxation with high concentrations greater than 5 mU/ml. However, intraluminal administration of thrombin (5 mU/m) did not constrict the retinal arterioles; in denuded vessels, intraluminal administration constricted the retinal arterioles. Thrombin-induced vasoconstriction was significantly (p < 0.01) suppressed by pretreatment with a protein kinase C (PKC) inhibitor and a protease-activated receptor (PAR)-1 inhibitor but not by PAR-2 and PAR-4 inhibitors or denudation. A rho kinase (ROCK) inhibitor also suppressed thrombin-induced vasoconstriction (5 mU/ml) compared with sodium nitroprusside. Endothelial denudation and pretreatment with an endothelial nitric oxide (NO) synthase inhibitor suppressed vasorelaxation caused by a high concentration of thrombin. CONCLUSIONS A low concentration of thrombin causes vasoconstriction of smooth muscles via PAR-1, PKC, and ROCK, and a high concentration of thrombin possibly causes vasorelaxation of the retinal arterioles via nitric oxide synthase activation in the endothelium. The vascular endothelium might block signaling of thrombin-induced vasoconstriction in the retinal arterioles when administered intraluminally.
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Affiliation(s)
- Kengo Takahashi
- a Department of Ophthalmology , Asahikawa Medical University , Asahikawa , Japan
| | - Tsuneaki Omae
- a Department of Ophthalmology , Asahikawa Medical University , Asahikawa , Japan
| | - Shinji Ono
- a Department of Ophthalmology , Asahikawa Medical University , Asahikawa , Japan
| | | | - Akira Tanner
- a Department of Ophthalmology , Asahikawa Medical University , Asahikawa , Japan
| | - Akitoshi Yoshida
- a Department of Ophthalmology , Asahikawa Medical University , Asahikawa , Japan
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Bregar D, Cilenšek I, Mankoč S, Reschner A, Petrovič D, Globočnik Petrovič M. The joint effect of the endothelin receptor B gene (EDNRB) polymorphism rs10507875 and nitric oxide synthase 3 gene (NOS3) polymorphism rs869109213 in Slovenian patients with type 2 diabetes mellitus and diabetic retinopathy. Bosn J Basic Med Sci 2018; 18:80-86. [PMID: 28817788 DOI: 10.17305/bjbms.2017.2244] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2017] [Revised: 07/12/2017] [Accepted: 07/12/2017] [Indexed: 11/16/2022] Open
Abstract
Increasing evidence suggests that endothelin and nitric oxide synthase genes and their products exert biological effects on the vasculature via the nitric oxide or endothelin pathway. The aim of the study was to evaluate the association of rs10507875 and rs869109213 (alone or in interaction) with diabetic retinopathy (DR) in subjects with type 2 diabetes mellitus (T2DM). We genotyped the single nucleotide polymorphism rs10507875 of the endothelin receptor B gene (EDNRB) and variable number tandem repeats rs869109213 of the nitric oxide synthase 3 gene (NOS3) in 270 Slovenian patients with DR and T2DM and 256 controls with T2DM without clinical signs of DR. The genotyping was performed using either real-time polymerase chain reaction (PCR) or standard PCR. We found a significant association between the genotypes of NOS3 rs869109213 polymorphism and the risk of DR in the co-dominant model (4a4b genotype; 1.99-fold increased risk [1.09-3.65]; 95% confidence interval [CI]; p = 0.02), co-dominant model (4a4a genotype; 4.16-fold increased risk [1.03-16.74]; 95% CI; p = 0.04), and dominant model (4a4a and 4a4b genotypes; 2.22-fold increased risk [1.26-3.92]; 95% CI; p = 0.01) compared to the 4b4b genotype. Moreover, the joint effect of the two polymorphisms on DR risk was greater than the individual effect of each polymorphism in the analyzed genetic models. Additionally, adjusted odds ratio showed an increased risk in dominant × dominant (4.15-fold [1.40-12.26]; 95% CI; p = 0.01) and recessive × dominant (2.24-fold [1.25-4.01]; 95% CI; p = 0.02) genotype combinations of the two polymorphisms. In conclusion, our results indicate that NOS3 rs869109213 polymorphism alone or in a combination with EDNRB rs10507875 polymorphism may be associated with DR in Slovenian patients with T2DM.
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Affiliation(s)
- Dejan Bregar
- Institute of Histology and Embryology, Faculty of Medicine, University Ljubljana, Ljubljana, Slovenia.
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Tong JY, Golzan M, Georgevsky D, Williamson JP, Graham SL, Farah CS, Fraser CL. Quantitative Retinal Vascular Changes in Obstructive Sleep Apnea. Am J Ophthalmol 2017; 182:72-80. [PMID: 28734812 DOI: 10.1016/j.ajo.2017.07.012] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2017] [Revised: 07/11/2017] [Accepted: 07/12/2017] [Indexed: 11/25/2022]
Abstract
PURPOSE To examine the relationship between both static and dynamic retinal vascular caliber and the severity of obstructive sleep apnea (OSA). DESIGN Prospective cross-sectional study. METHODS Adult patients undergoing diagnostic polysomnography studies at a private Australian university teaching hospital were recruited. OSA severity was defined by the apnea-hypopnea index (AHI): severe >30, moderate >15-30, mild 5-15, and controls <5. Of 115 patients recruited (73 male; mean age 58 ± 13 years), there were 41 severe, 35 moderate, and 25 mild OSA patients and 14 controls. Static retinal vascular caliber was measured as the average diameter of retinal arterioles (CRAE) and venules (CRVE), and summarized as the arteriovenous ratio (AVR). Dynamic retinal vascular caliber was evaluated as the average pulsation amplitude of retinal arterioles (SRAP) and venules (SRVP). Comparisons across groups were performed using multivariate linear regression analysis. All results were adjusted for age, body mass index, and mean arterial pressure. RESULTS Increasing AHI was significantly associated with decreasing AVR (P = .008) and CRAE (P = .016). A significant relationship was demonstrated between increasing AHI and attenuated retinal vascular pulsation amplitude (arterioles P = .028; venules P < .0001). CONCLUSIONS Increasing OSA severity is independently associated with retinal arteriolar narrowing and attenuated vascular pulsation amplitude. The retinal vasculature is easily imaged, and may be a surrogate biomarker of cerebral and systemic vascular risk in patients with OSA requiring further comprehensive investigation.
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Khuu LA, Tayyari F, Sivak JM, Flanagan JG, Singer S, Brent MH, Huang D, Tan O, Hudson C. Aqueous humor endothelin-1 and total retinal blood flow in patients with non-proliferative diabetic retinopathy. Eye (Lond) 2017; 31:1443-1450. [PMID: 28548649 DOI: 10.1038/eye.2017.74] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2015] [Accepted: 03/14/2017] [Indexed: 12/16/2022] Open
Abstract
PurposeThe purpose of this study was to determine the association between aqueous ET-1 levels and total retinal blood flow (TRBF) in patients with non-insulin-dependent type 2 diabetes mellitus (T2DM) and early non-proliferative diabetic retinopathy (NPDR).Patients and methodsA total of 15 age-matched controls and 15 T2DM patients with NPDR were recruited into the study. Aqueous humor (~80-120 μl) was collected before cataract surgery to measure the levels of ET-1 using suspension multiplex array technology. Four weeks post surgery, six images were acquired to assess TRBF using the prototype RTVue Doppler FD-OCT (Optovue, Inc., Fremont, CA, USA) with a double circular scan protocol. At the same visit, forearm blood was collected to determine plasma glycosylated hemoglobin (A1c) levels.ResultsAqueous ET-1 was significantly elevated in the NPDR group compared with the control group (3.5±1.8 vs 2.2±0.8, P=0.02). TRBF was found to be significantly reduced in the NPDR group compared with the control group (34.5±9.1 vs 44.1±4.6 μl/min, P=0.002). TRBF and aqueous ET-1 were not correlated within the NPDR group (r=-0.24, P=0.22). In a multivariate analysis, high A1c was associated with reduced TRBF and aqueous ET-1 levels across control and NPDR groups (P<0.01).ConclusionAqueous ET-1 levels were increased while TRBF was reduced in patients with NPDR compared with the control group. Although not directly associated, the vasoconstrictory effects of ET-1 are consistent with a reduced TRBF observed in early DR. ET-1 dysregulation may contribute to a reduction in retinal blood flow during early DR.
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Affiliation(s)
- L-A Khuu
- Institute of Medical Science, University of Toronto, Toronto, ON, Canada.,Vision Science and Ophthalmology, Toronto Western Hospital, Toronto, ON, Canada
| | - F Tayyari
- School of Optometry and Vision Science, University of Waterloo, Waterloo, ON, Canada
| | - J M Sivak
- Institute of Medical Science, University of Toronto, Toronto, ON, Canada
| | - J G Flanagan
- Institute of Medical Science, University of Toronto, Toronto, ON, Canada.,Vision Science and Ophthalmology, Toronto Western Hospital, Toronto, ON, Canada.,School of Optometry and Vision Science, University of Waterloo, Waterloo, ON, Canada
| | - S Singer
- Vision Science and Ophthalmology, Toronto Western Hospital, Toronto, ON, Canada
| | - M H Brent
- Vision Science and Ophthalmology, Toronto Western Hospital, Toronto, ON, Canada
| | - D Huang
- Casey Eye Institute, Oregon Health and Science University, Portland, OR, USA
| | - O Tan
- Casey Eye Institute, Oregon Health and Science University, Portland, OR, USA
| | - C Hudson
- Institute of Medical Science, University of Toronto, Toronto, ON, Canada.,Vision Science and Ophthalmology, Toronto Western Hospital, Toronto, ON, Canada.,School of Optometry and Vision Science, University of Waterloo, Waterloo, ON, Canada
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Lin GM, Redline S, Klein R, Colangelo LA, Cotch MF, Wong TY, Klein BEK, Patel SR, Shea SJ, Liu K. Sex-Specific Association of Obstructive Sleep Apnea With Retinal Microvascular Signs: The Multi-Ethnic Study of Atherosclerosis. J Am Heart Assoc 2016; 5:JAHA.116.003598. [PMID: 27451457 PMCID: PMC5015394 DOI: 10.1161/jaha.116.003598] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Background Obstructive sleep apnea (OSA) is a common condition affecting more men than women. The relationship of OSA with microvascular disease is unclear, complicated by possible sex difference. Assessment of the relationship of OSA with retinal microvascular signs in men and women may provide insights into such a relationship. Methods and Results We examined the sex‐specific cross‐sectional association of OSA severity with retinal vascular calibers in 1808 participants, and with specific retinopathy signs in 1831 participants from a sample of 2060 participants aged 54 to 93 years who underwent successful polysomnography in the Multi‐Ethnic Study of Atherosclerosis, 2010–2012. OSA severity was defined by the apnea–hypopnea index (events/h) as none (<5), mild (5–14.9), moderate (15–29.9), and severe (≥30). As compared to no OSA, moderate/severe OSA in men was associated with retinal arteriolar narrowing (odds ratio [OR] and 95% CI for the narrowest quartile: 1.65 [1.00–2.71]) and retinal venular widening (1.80 [1.07–3.04] for the widest quartile), but not in women (odds ratio: 1.10 [0.67–1.81] and 0.91 [0.58–1.43], respectively) after adjusting for age, race/ethnicity, body mass index, pack‐years of cigarette smoking, alcohol intake, hypertension duration, diabetes mellitus duration, HbA1c levels, lipid profile, micro‐/macroalbuminuria, estimated glomerular filtration rate, β‐blockers use, antihypertensive therapy, and lipid‐lowering therapy. In contrast, severe OSA was associated with retinal microaneurysms in women, but not in men (odds ratio: 3.22 [1.16–8.97] and 0.59 [0.27–1.30], respectively). Conclusions The associations of OSA severity with retinal microvascular signs may differ by sex. Whether these findings were related to sex differences in OSA exposure needs further investigation.
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Affiliation(s)
- Gen-Min Lin
- Department of Preventive Medicine, Northwestern University, Chicago, IL Department of Medicine, Hualien Armed Forces General Hospital, Hualien, Taiwan Tri-Service General Hospital, National Defense Medical Center, Taipei, Taiwan
| | - Susan Redline
- Department of Medicine, Harvard Medical School, Boston, MA Brigham and Women's Hospital and Beth Israel Deaconess Medical Center, Boston, MA
| | - Ronald Klein
- Department of Ophthalmology and Visual Sciences, School of Medicine and Public Health, University of Wisconsin, Madison, WS
| | - Laura A Colangelo
- Department of Preventive Medicine, Northwestern University, Chicago, IL
| | - Mary Frances Cotch
- Division of Epidemiology and Clinical Applications, NIH Intramural Research Program, National Eye Institute, National Institutes of Health, Bethesda, MD
| | - Tien Y Wong
- National University of Singapore and Singapore Eye Research Institute, Singapore National Eye Centre, Duke-NUS Graduate Medical School, National University of Singapore, Singapore
| | - Barbara E K Klein
- Department of Ophthalmology and Visual Sciences, School of Medicine and Public Health, University of Wisconsin, Madison, WS
| | | | - Steven J Shea
- Departments of Medicine and Epidemiology, Columbia University, New York, NY
| | - Kiang Liu
- Department of Preventive Medicine, Northwestern University, Chicago, IL
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Hein TW, Rosa RH, Ren Y, Xu W, Kuo L. VEGF Receptor-2-Linked PI3K/Calpain/SIRT1 Activation Mediates Retinal Arteriolar Dilations to VEGF and Shear Stress. Invest Ophthalmol Vis Sci 2015; 56:5381-9. [PMID: 26284543 DOI: 10.1167/iovs15-16950] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
PURPOSE Vasomotor responses of retinal arterioles to luminal flow/shear stress and VEGF have a critical role in governing retinal blood flow possibly via nitric oxide synthase (NOS) activation. However, the cellular mechanism for flow-sensitive vasomotor activity in relation to VEGF signaling in retinal arterioles has not been characterized. We used an isolated vessel approach to specifically address this issue. METHODS Porcine retinal arterioles were isolated, cannulated, and pressurized to 55 cm H2O luminal pressure by two independent reservoir systems. Luminal flow was increased stepwise by creating hydrostatic pressure gradients across two reservoirs. Diameter changes and associated signaling mechanisms corresponding to increased flow and VEGF receptor 2 (VEGFR2) activation were assessed using videomicroscopic, pharmacological, and molecular tools. RESULTS Retinal arterioles developed basal tone under zero-flow condition and dilated concentration-dependently to VEGF165. Stepwise increases in flow produced graded vasodilation. Vasodilations to VEGF165 and increased flow were abolished by endothelial removal, and inhibited by pharmacological blockade of VEGFR2, NOS, phosphoinositide 3-kinase (PI3K), calpains, or sirtuin-1 (SIRT1) deacetylase. A VEGF165 antibody blocked vasodilation to VEGF165 but not flow. Immunostaining indicated that VEGFR2 was expressed in the endothelial and smooth muscle layers of retinal arterioles. CONCLUSIONS Ligand-dependent and ligand-independent activation of VEGFR2 in the endothelium mediates NO-dependent dilations of porcine retinal arterioles in response to VEGF165 and luminal flow/shear stress, respectively. It appears that NOS stimulation via PI3K, calpain proteases, and SIRT1-dependent deacetylation downstream from VEGFR2 activation contributes to these vasodilator responses.
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Affiliation(s)
- Travis W Hein
- Department of Surgery Scott & White Eye Institute, College of Medicine, Texas A&M Health Science Center, Temple, Texas, United States 2Department of Ophthalmology, Scott & White Eye Institute, College of Medicine, Texas A&M Health Science Center, Temple
| | - Robert H Rosa
- Department of Surgery Scott & White Eye Institute, College of Medicine, Texas A&M Health Science Center, Temple, Texas, United States 2Department of Ophthalmology, Scott & White Eye Institute, College of Medicine, Texas A&M Health Science Center, Temple
| | - Yi Ren
- Department of Surgery Scott & White Eye Institute, College of Medicine, Texas A&M Health Science Center, Temple, Texas, United States
| | - Wenjuan Xu
- Department of Surgery Scott & White Eye Institute, College of Medicine, Texas A&M Health Science Center, Temple, Texas, United States
| | - Lih Kuo
- Department of Surgery Scott & White Eye Institute, College of Medicine, Texas A&M Health Science Center, Temple, Texas, United States 2Department of Ophthalmology, Scott & White Eye Institute, College of Medicine, Texas A&M Health Science Center, Temple
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Thengchaisri N, Hein TW, Ren Y, Kuo L. Endothelin-1 impairs coronary arteriolar dilation: Role of p38 kinase-mediated superoxide production from NADPH oxidase. J Mol Cell Cardiol 2015. [PMID: 26211713 DOI: 10.1016/j.yjmcc.2015.07.014] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Elevated levels of endothelin-1 (ET-1), a potent vasoactive peptide, are implicated as a risk factor for cardiovascular diseases by exerting vasoconstriction. The aim of this study was to address whether ET-1, at sub-vasomotor concentrations, elicits adverse effects on coronary microvascular function. Porcine coronary arterioles (50-100μm) were isolated, cannulated and pressurized without flow for in vitro study. Diameter changes were recorded using a videomicrometer. Arterioles developed basal tone (60±3μm) and dilated to the endothelium-dependent nitric oxide (NO)-mediated vasodilators serotonin (1nmol/L to 0.1μmol/L) and adenosine (1nmol/L to 10μmol/L). Treating the vessels with a clinically relevant sub-vasomotor concentration of ET-1 (10pmol/L, 60min) significantly attenuated arteriolar dilations to adenosine and serotonin but not to endothelium-independent vasodilator sodium nitroprusside. The arteriolar wall contains ETA receptors and the adverse effect of ET-1 was prevented by ETA receptor antagonist BQ123, the superoxide scavenger Tempol, the NADPH oxidase inhibitors apocynin and VAS2870, the NOX2-based NADPH oxidase inhibitor gp91 ds-tat, or the p38 kinase inhibitor SB203580. However, ETB receptor antagonist BQ788, H2O2 scavenger catalase, scrambled gp91 ds-tat, or inhibitors of xanthine oxidase (allopurinol), PKC (Gö 6983), Rho kinase (Y27632), and c-Jun N-terminal kinase (SP600125) did not protect the vessel. Immunohistochemical staining showed that ET-1 elicited Tempol-, apocynin- and SB203580-sensitive superoxide productions in the arteriolar wall. Our results indicate that exposure of coronary arterioles to a pathophysiological, sub-vasomotor concentration of ET-1 leads to vascular dysfunction by impairing endothelium-dependent NO-mediated dilation via p38 kinase-mediated production of superoxide from NADPH oxidase following ETA receptor activation.
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Affiliation(s)
- Naris Thengchaisri
- Department of Medical Physiology, Cardiovascular Research Institute, College of Medicine, Texas A&M Health Science Center, Temple, TX 76504, USA; Department of Companion Animal Clinical Sciences, Faculty of Veterinary Medicine, Kasetsart University, Bangkok 10900, Thailand
| | - Travis W Hein
- Department of Surgery, College of Medicine, Texas A&M Health Science Center, Temple, TX 76504, USA
| | - Yi Ren
- Department of Surgery, College of Medicine, Texas A&M Health Science Center, Temple, TX 76504, USA
| | - Lih Kuo
- Department of Medical Physiology, Cardiovascular Research Institute, College of Medicine, Texas A&M Health Science Center, Temple, TX 76504, USA; Department of Surgery, College of Medicine, Texas A&M Health Science Center, Temple, TX 76504, USA.
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Activation of the endothelin system mediates pathological angiogenesis during ischemic retinopathy. THE AMERICAN JOURNAL OF PATHOLOGY 2014; 184:3040-51. [PMID: 25203536 DOI: 10.1016/j.ajpath.2014.07.012] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/23/2014] [Revised: 07/10/2014] [Accepted: 07/15/2014] [Indexed: 02/08/2023]
Abstract
Retinopathy of prematurity adversely affects premature infants because of oxygen-induced damage of the immature retinal vasculature, resulting in pathological neovascularization (NV). Our pilot studies using the mouse model of oxygen-induced retinopathy (OIR) showed marked increases in angiogenic mediators, including endothelins and endothelin receptor (EDNR) A. We hypothesized that activation of the endothelin system via EDNRA plays a causal role in pathological angiogenesis and up-regulation of angiogenic mediators, including vascular endothelial growth factor A (VEGFA) in OIR. Mice were exposed to 75% oxygen from post-natal day P7 to P12, treated with either vehicle or EDNRA antagonist BQ-123 or EDNRB antagonist BQ-788 on P12, and kept at room air from P12 to P17 (ischemic phase). RT-PCR analysis revealed increased levels of EDN2 and EDNRA mRNA, and Western blot analysis revealed increased EDN2 expression during the ischemic phase. EDNRA inhibition significantly increased vessel sprouting, resulting in enhanced physiological angiogenesis and decreased pathological NV, whereas EDNRB inhibition modestly improved vascular repair. OIR triggered significant increases in VEGFA protein and mRNA for delta-like ligand 4, apelin, angiopoietin-2, and monocyte chemoattractant protein-1. BQ-123 treatment significantly reduced these alterations. EDN2 expression was localized to retinal glia and pathological NV tufts of the OIR retinas. EDN2 also induced VEGFA protein expression in cultured astrocytes. In conclusion, inhibition of the EDNRA during OIR suppresses pathological NV and promotes physiological angiogenesis.
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Veurink M, Mangioris G, Kaufmann B, Asmus L, Hennig M, Heiligenhaus A, Gurny R, Möller M, Pournaras CJ. Development of an Intravitreal Peptide (BQ123) Sustained Release System Based on Poly(2-Hydroxyoctanoic Acid) Aiming at a Retinal Vasodilator Response. J Ocul Pharmacol Ther 2014; 30:517-23. [DOI: 10.1089/jop.2013.0117] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Affiliation(s)
- Marieke Veurink
- School of Pharmaceutical Sciences, University of Geneva, University of Lausanne, Geneva, Switzerland
| | - Georgios Mangioris
- Department of Ophthalmology, Geneva University Hospitals, Geneva, Switzerland
| | - Béatrice Kaufmann
- School of Pharmaceutical Sciences, University of Geneva, University of Lausanne, Geneva, Switzerland
| | - Lutz Asmus
- School of Pharmaceutical Sciences, University of Geneva, University of Lausanne, Geneva, Switzerland
| | - Maren Hennig
- Department of Ophthalmology, St. Franziskus Hospital, Muenster, Germany
| | - Arnd Heiligenhaus
- Department of Ophthalmology, St. Franziskus Hospital, Muenster, Germany
| | - Robert Gurny
- School of Pharmaceutical Sciences, University of Geneva, University of Lausanne, Geneva, Switzerland
| | - Michael Möller
- School of Pharmaceutical Sciences, University of Geneva, University of Lausanne, Geneva, Switzerland
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Cannabinoid and lipid-mediated vasorelaxation in retinal microvasculature. Eur J Pharmacol 2014; 735:105-14. [DOI: 10.1016/j.ejphar.2014.03.055] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2013] [Revised: 03/07/2014] [Accepted: 03/19/2014] [Indexed: 11/21/2022]
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Kamiya T, Nagaoka T, Omae T, Yoshioka T, Ono S, Tanano I, Yoshida A. Role of Ca2+-dependent and Ca2+-sensitive mechanisms in sphingosine 1-phosphate-induced constriction of isolated porcine retinal arterioles in vitro. Exp Eye Res 2014; 121:94-101. [DOI: 10.1016/j.exer.2014.01.011] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2013] [Revised: 01/07/2014] [Accepted: 01/14/2014] [Indexed: 01/15/2023]
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Hein TW, Qamirani E, Ren Y, Xu X, Thengchaisri N, Kuo L. Selective Activation of Lectin-Like Oxidized Low-Density Lipoprotein Receptor-1 Mediates C-Reactive Protein–Evoked Endothelial Vasodilator Dysfunction in Coronary Arterioles. Circ Res 2014; 114:92-100. [DOI: 10.1161/circresaha.114.301763] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Rationale
:
Studies in cultured endothelium implicate that lectin-like oxidized low-density lipoprotein receptor-1 (LOX-1) or Fcγ receptor II (CD32) contributes to the proatherogenic effects of C-reactive protein (CRP). However, the identity of the receptors linking to deleterious actions of CRP in vasomotor regulation remains unknown.
Objective
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We tested the hypothesis that LOX-1 contributes to adverse effects of CRP on endothelium-dependent vasomotor function in resistance arterioles.
Methods and Results
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Porcine coronary arterioles were isolated for vasoreactivity study, dihydroethidium fluorescence staining of superoxide, immunohistochemical localization of receptors, immunoprecipitation of receptor/CRP interaction, and protein blot. Intraluminal treatment of pressurized arterioles with a pathophysiological level of CRP (7 µg/mL; 60 minutes) attenuated endothelium-dependent nitric oxide–mediated and prostacyclin-mediated dilations to serotonin and arachidonic acid, respectively. LOX-1 and CD32 were detected in the endothelium of arterioles. Blockade of LOX-1 with either pharmacological antagonist κ-carrageenan or anti–LOX-1 antibody prevented the detrimental effect of CRP on vasodilator function, whereas anti-CD32 antibody treatment was ineffective. Denudation of endothelium and blockade of LOX-1 but not CD32 prevented CRP-induced elevation of superoxide in the vessel wall. CRP was coimmunoprecipitated with LOX-1 and CD32 from CRP-treated arterioles. Similarly, LOX-1 and CD32 blockade prevented CRP-induced arteriolar expression of plasminogen activator inhibitor-1, a thrombogenic protein.
Conclusions
:
CRP elicits endothelium-dependent oxidative stress and compromises nitric oxide–mediated and prostacyclin-mediated vasomotor function via LOX-1 activation. In contrast, both LOX-1 and CD32 mediate plasminogen activator inhibitor-1 upregulation in arterioles by CRP. Thus, activation of LOX-1 and CD32 may contribute to vasomotor dysfunction and proatherogenic actions of CRP, respectively.
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Affiliation(s)
- Travis W. Hein
- From the Departments of Surgery (T.W.H., Y.R., L.K.) and Medical Physiology (E.Q., X.X., N.T., L.K.), College of Medicine, Texas A&M Health Science Center, Scott & White Healthcare, Temple; and Department of Companion Animal Clinical Sciences, Faculty of Veterinary Medicine, Kasetsart University, Bangkok, Thailand (N.T.)
| | - Erion Qamirani
- From the Departments of Surgery (T.W.H., Y.R., L.K.) and Medical Physiology (E.Q., X.X., N.T., L.K.), College of Medicine, Texas A&M Health Science Center, Scott & White Healthcare, Temple; and Department of Companion Animal Clinical Sciences, Faculty of Veterinary Medicine, Kasetsart University, Bangkok, Thailand (N.T.)
| | - Yi Ren
- From the Departments of Surgery (T.W.H., Y.R., L.K.) and Medical Physiology (E.Q., X.X., N.T., L.K.), College of Medicine, Texas A&M Health Science Center, Scott & White Healthcare, Temple; and Department of Companion Animal Clinical Sciences, Faculty of Veterinary Medicine, Kasetsart University, Bangkok, Thailand (N.T.)
| | - Xin Xu
- From the Departments of Surgery (T.W.H., Y.R., L.K.) and Medical Physiology (E.Q., X.X., N.T., L.K.), College of Medicine, Texas A&M Health Science Center, Scott & White Healthcare, Temple; and Department of Companion Animal Clinical Sciences, Faculty of Veterinary Medicine, Kasetsart University, Bangkok, Thailand (N.T.)
| | - Naris Thengchaisri
- From the Departments of Surgery (T.W.H., Y.R., L.K.) and Medical Physiology (E.Q., X.X., N.T., L.K.), College of Medicine, Texas A&M Health Science Center, Scott & White Healthcare, Temple; and Department of Companion Animal Clinical Sciences, Faculty of Veterinary Medicine, Kasetsart University, Bangkok, Thailand (N.T.)
| | - Lih Kuo
- From the Departments of Surgery (T.W.H., Y.R., L.K.) and Medical Physiology (E.Q., X.X., N.T., L.K.), College of Medicine, Texas A&M Health Science Center, Scott & White Healthcare, Temple; and Department of Companion Animal Clinical Sciences, Faculty of Veterinary Medicine, Kasetsart University, Bangkok, Thailand (N.T.)
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Potts LB, Bradley PD, Xu W, Kuo L, Hein TW. Role of endothelium in vasomotor responses to endothelin system and protein kinase C activation in porcine retinal arterioles. Invest Ophthalmol Vis Sci 2013; 54:7587-94. [PMID: 24243985 DOI: 10.1167/iovs13-13178] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
PURPOSE Endothelial cells synthesize vasodilator nitric oxide (NO) and vasoconstrictor endothelin-1 (ET-1) from NO synthase (eNOS) and endothelin-converting enzyme-1 (ECE-1), respectively. Protein kinase C (PKC) and Rho kinase (ROCK) are major signaling molecules mediating vasoconstriction. Although endothelial cells express eNOS, ECE-1, endothelin B (ET(B)) receptors, PKC, and ROCK, their influences on ET-1-induced vasoconstriction remain elusive. We studied whether these endothelial signaling molecules modulate retinal arteriolar constriction to ET-1. METHODS Porcine retinal arterioles were isolated and pressurized for vasomotor study, under conditions with intact or denuded endothelium, using videomicroscopic techniques. RESULTS Retinal arterioles developed similar resting tone (≈45% of maximum diameter) with or without endothelium. Endothelial denudation attenuated vasoconstriction to ET-1 precursor, big ET-1, by almost equal to 50%, but did not affect vasoconstrictions to ET-1, ET(B) agonist sarafotoxin S6c, or PKC activator phorbol-12, 13-dibutyrate (PDBu). The ROCK inhibitor H-1152 caused vasodilation, and abolished vasoconstrictions to ET-1 and PDBu independent of endothelium. With L-type voltage-operated calcium channel (L-VOCC) blocker nifedipine, PDBu-induced vasoconstriction was abolished and converted to NO-mediated vasodilation in the presence of endothelium. The ET-1-induced vasoconstriction was unaffected by NO released from endothelium during flow elevation. CONCLUSIONS Endothelial and smooth muscle ECE-1 contribute equally to synthesis of vasoactive ET-1 in retinal arterioles, with nominal role of endothelial ETB receptors in vasoconstriction to ET-1. The PKC activation leads to endothelium-dependent NO-mediated vasodilation when smooth muscle contraction is ablated by L-VOCC blockade. Endothelial cells and NO appear to have modest roles in modulating ROCK-dependent vasoconstriction, and are insufficient to counteract smooth muscle contractions to ET-1 and PKC activation.
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Affiliation(s)
- Luke B Potts
- Department of Medical Physiology, Scott & White Healthcare, College of Medicine, Texas A&M Health Science Center, Temple, Texas
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Hein TW, Potts LB, Xu W, Yuen JZ, Kuo L. Temporal development of retinal arteriolar endothelial dysfunction in porcine type 1 diabetes. Invest Ophthalmol Vis Sci 2012; 53:7943-9. [PMID: 23139282 DOI: 10.1167/iovs.12-11005] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
PURPOSE Although hyperglycemia is implicated in retinal vascular dysfunction associated with the development of diabetic retinopathy, the temporal influence of hyperglycemia on retinal arteriolar reactivity remains unclear. Development of a large animal model of diabetes relevant to the human retina for evaluation of vascular function is also lacking. Herein, we examined nitric oxide (NO)-mediated dilation and endothelin-1 (ET-1)-induced constriction in retinal arterioles at various time periods in a porcine model of type 1 diabetes. METHODS Retinal arterioles were isolated from streptozocin-induced diabetic pigs (2, 6, and 12 weeks of hyperglycemia, 427 ± 23 mg/dL) and age-matched control pigs (73 ± 4 mg/dL), and then cannulated and pressurized for vasoreactivity study using videomicroscopic techniques. RESULTS Retinal arterioles isolated from control and diabetic pigs developed comparable levels of myogenic tone. The endothelium-dependent NO-mediated vasodilations to bradykinin and stepwise increases in luminal flow were significantly reduced within 2 weeks of hyperglycemia. The inhibitory effect was comparable following 6 and 12 weeks of hyperglycemia. However, the endothelium-independent vasodilation to sodium nitroprusside was unaffected. Constriction of retinal arterioles to ET-1 was unaltered at all time periods of hyperglycemia. CONCLUSIONS Our findings provide the first direct evidence for selective impairment of endothelium-dependent NO-mediated dilation of retinal arterioles within 2 weeks of hyperglycemia in a pig model of diabetes. By contrast, the ability of arteriolar smooth muscle to dilate to NO donor or contract to ET-1 was unaffected throughout the study period. This endothelial vasodilator dysfunction during early diabetes may contribute to development of retinopathy with chronic hyperglycemia.
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Affiliation(s)
- Travis W Hein
- Department of Surgery, Scott & White Memorial Hospital, College of Medicine, Texas A&M Health Science Center, Temple, Texas 76504, USA.
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Age-associated alterations in retinal arteriole reactivity to endothelin-1 differ between the sexes. Mech Ageing Dev 2012; 133:611-9. [DOI: 10.1016/j.mad.2012.08.001] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2012] [Revised: 07/26/2012] [Accepted: 08/04/2012] [Indexed: 12/13/2022]
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Stewart M, Needham M, Bankhead P, Gardiner TA, Scholfield CN, Curtis TM, McGeown JG. Feedback via Ca²⁺-activated ion channels modulates endothelin 1 signaling in retinal arteriolar smooth muscle. Invest Ophthalmol Vis Sci 2012; 53:3059-66. [PMID: 22427579 DOI: 10.1167/iovs.11-9192] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
PURPOSE To investigate the role of feedback by Ca²⁺-sensitive plasma-membrane ion channels in endothelin 1 (Et1) signaling in vitro and in vivo. Methods. Et1 responses were imaged from Fluo-4-loaded smooth muscle in isolated segments of rat retinal arteriole using two-dimensional (2-D) confocal laser microscopy. Vasoconstrictor responses to intravitreal injections of Et1 were recorded in the absence and presence of appropriate ion channel blockers using fluorescein angiograms imaged using a confocal scanning laser ophthalmoscope. Results. Et1 (10 nM) increased both basal [Ca²⁺](i) and the amplitude and frequency of Ca²⁺-waves in retinal arterioles. The Ca²⁺-activated Cl⁻-channel blockers DIDS and 9-anthracene carboxylic acid (9AC) blocked Et1-induced increases in wave frequency, and 9AC also inhibited the increase in amplitude. Iberiotoxin, an inhibitor of large conductance (BK) Ca²⁺-activated K⁺-channels, increased wave amplitude in the presence of Et1 but had no effect on frequency. None of these drugs affected basal [Ca²⁺](i). The voltage-operated Ca²⁺-channel inhibitor nimodipine inhibited wave frequency and amplitude and also lowered basal [Ca²⁺](i) in the presence of Et1. Intravitreal injection of Et1 caused retinal arteriolar vasoconstriction. This was inhibited by DIDS but not by iberiotoxin or penitrem A, another BK-channel inhibitor. Conclusions. Et1 evokes increases in the frequency of arteriolar Ca²⁺-waves in vitro, resulting in vasoconstriction in vivo. These responses, initiated by release of stored Ca²⁺, also require positive feedback via Ca²⁺-activated Cl⁻-channels and L-type Ca²⁺-channels.
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Affiliation(s)
- Michael Stewart
- Centre for Vision and Vascular Science, Queen's University of Belfast, Institute of Clinical Sciences, The Royal Victoria Hospital, Belfast, Northern Ireland
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Potts LB, Ren Y, Lu G, Kuo E, Ngo E, Kuo L, Hein TW. Constriction of retinal arterioles to endothelin-1: requisite role of rho kinase independent of protein kinase C and L-type calcium channels. Invest Ophthalmol Vis Sci 2012; 53:2904-12. [PMID: 22427601 DOI: 10.1167/iovs.12-9542] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
PURPOSE Although endothelin-1 (ET-1) is a potent vasoconstrictor peptide implicated in several retinal pathologies, the underlying mechanism of vasoconstriction is understood incompletely. We addressed this issue by assessing the contributions of extracellular calcium (Ca²⁺), L-type voltage-operated calcium channels (L-VOCCs), Rho kinase (ROCK), and protein kinase C (PKC) to ET-1-induced constriction of porcine retinal arterioles, all of which have been implicated commonly in vascular smooth muscle contraction. METHODS Porcine retinal arterioles (~50-100 μm) were isolated for vasomotor study and molecular assessment of ROCK isoforms. RESULTS Isolated arterioles developed stable basal tone at 55 cmH₂O luminal pressure and constricted to ET-1 (0.1 nM) with a 40 ± 6% reduction in resting diameter in 20 minutes. In the absence of extraluminal Ca²⁺, arterioles lost basal tone and failed to constrict to ET-1. Although L-VOCC inhibitor nifedipine reduced basal tone and blocked vasoconstriction to PKC activator PDBu, vasoconstriction to ET-1 was unaffected. The broad-spectrum PKC inhibitor Gö-6983 abolished vasoconstriction to PDBu, but did not alter ET-1-induced vasoconstriction or basal tone. Incubation of arterioles with ROCK inhibitor H-1152 abolished basal tone and vasoconstrictions to ET-1 and PDBu. Both ROCK1 and ROCK2 isoforms were expressed in the retinal arteriolar wall. CONCLUSIONS Extracellular Ca²⁺ entry via L-VOCCs and basal ROCK activity play important roles in the maintenance of basal tones of porcine retinal arterioles. ET-1-induced constriction is mediated by extracellular Ca²⁺ entry independent of L-VOCCs and by ROCK activation without the involvement of PKC. However, direct PKC activation can cause vasoconstriction via L-VOCC and ROCK signaling.
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Affiliation(s)
- Luke B Potts
- Department of Systems Biology and Translational Medicine, College of Medicine, Texas A&M Health Science Center, Temple, Texas, USA
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Wang Z, Yadav AS, Leskova W, Harris NR. Inhibition of 20-HETE attenuates diabetes-induced decreases in retinal hemodynamics. Exp Eye Res 2011; 93:108-13. [PMID: 21658386 DOI: 10.1016/j.exer.2011.05.011] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2010] [Revised: 05/16/2011] [Accepted: 05/23/2011] [Indexed: 11/19/2022]
Abstract
The mechanisms of early diabetes-induced decreases in retinal blood flow have yet to be fully determined. The aim of this study was to explore the hypothesis that 20-hydroxyeicosatetraenoic acid (20-HETE) plays a role in the early decrease of retinal hemodynamics in diabetic mice. 20-HETE has been implicated previously in the diabetes-enhanced vasoconstriction of mesenteric and renal vessels; however, its role in the diabetic retinal microcirculation has not been investigated. Diabetes was induced by multiple low-dose injections of streptozotocin (STZ; 50 mg/kg for 5 consecutive days), then ∼2 weeks later the mice were administered daily intraperitoneal injections with or without the 20-HETE inhibitor HET0016 (2.5 mg/kg/day) for the following 2 weeks. Non-diabetic age-matched mice were included as controls. Intravital microscopy was used to obtain measurements of retinal vascular diameters and red blood cell (RBC) velocities for the feed arterioles and draining venules extending out of and into the optic disk. From these values, wall shear rates and blood flow rates were calculated. Diabetes induced approximately 30-40% decreases in RBC velocity, wall shear rate, and blood flow rate. These decreases were attenuated to 5-10% in the mice given HET0016. In summary, the 20-HETE inhibitor HET0016 is able to attenuate the retinal hemodynamic changes induced by diabetes.
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Affiliation(s)
- Zhongli Wang
- Department of Molecular & Cellular Physiology, Louisiana State University Health Sciences Center, Shreveport, LA 71130, USA
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Konieczka K, Meyer P, Schoetzau A, Neutzner A, Mozaffarieh M, Flammer J. Effect of avosentan (SPP-301) in porcine ciliary arteries. Curr Eye Res 2011; 36:118-24. [PMID: 21281066 DOI: 10.3109/02713683.2010.529982] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
PURPOSE To investigate the vasoactive effect of ET(A)-endothelin receptor antagonists avosentan (SPP-301) and BQ-123 in isolated porcine ciliary arteries with and without endothelium. To investigate the effect of avosentan on the endothelin-1 induced contractions in comparison with BQ-123 and BQ-788 (ET(B)-endothelin receptor antagonist) in isolated porcine ciliary arteries with and without endothelium. METHODS Vessels were placed in a myograph system to measure isometric forces. In a first set of experiments, quiescent vessels were exposed, cumulatively, to increasing concentrations of avosentan and BQ-123 (10(-9) M-3 × 10(-6) M). In a second set of experiments, quiescent vessels were first incubated with avosentan (10(-6) M and 10(-8) M), BQ-123 (10(-6) M), and BQ-788 (10(-6) M), respectively. Then the vessels were exposed, cumulatively, to increasing concentrations of endothelin-1 (10(-12) M-3 × 10(-8) M). Each set of experiments was conducted in the vessels with and without endothelium. RESULTS Cumulative concentrations of avosentan and BQ-123 had no vasoactive effect in quiescent vessels. Avosentan had a strong inhibitory effect on the endothelin-1-induced contractions. The inhibitory effect of 10(-6) M avosentan was significantly stronger than the effect of 10(-8) M avosentan. The effect of avosentan (10(-6) M) tended to be stronger than the effect of BQ-123 (10(-6) M). To a lesser extent, BQ-788 also had an inhibitory effect on the endothelin-1-induced contractions. CONCLUSIONS Avosentan has a strong inhibitory effect on the endothelin-1-induced contractions. Blockade of ET receptors is potentially an attractive target in many eye diseases including glaucoma. Further studies are needed to evaluate the usefulness of endothelin blockers in ophthalmology.
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de Beer VJ, Bender SB, Taverne YJ, Gao F, Duncker DJ, Laughlin MH, Merkus D. Exercise limits the production of endothelin in the coronary vasculature. Am J Physiol Heart Circ Physiol 2011; 300:H1950-9. [PMID: 21317308 DOI: 10.1152/ajpheart.00954.2010] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
We previously demonstrated that endothelin (ET)-mediated coronary vasoconstriction wanes with increasing exercise intensity via a nitric oxide- and prostacyclin-dependent mechanism (Ref. 23). Therefore, we hypothesized that the waning of ET coronary vasoconstriction during exercise is the result of decreased production of ET and/or decreased ET receptor sensitivity. We investigated coronary ET receptor sensitivity using intravenous infusion of ET and coronary ET production using intravenous infusion of the ET precursor Big ET, at rest and during continuous treadmill exercise at 3 km/h in 16 chronically instrumented swine. In the systemic vasculature, Big ET and ET induced similar changes in hemodynamic parameters at rest and during continuous exercise at 3 km/h, indicating that exercise does not alter ET production or receptor sensitivity in the systemic vasculature. In the coronary vasculature, infusion of ET resulted in similar dose-dependent decreases in coronary blood flow and coronary venous oxygen tension and saturation at rest and during exercise. In contrast, administration of Big ET resulted in dose-dependent decreases in coronary blood flow, as well as coronary venous oxygen tension and saturation at rest. These effects of Big ET were significantly reduced during exercise. Altogether, our data indicate that continuous exercise at 3 km/h attenuates ET-mediated coronary vasoconstriction through reduced production of ET from Big ET rather than through reduced ET sensitivity of the coronary vasculature. The decreased ET production during exercise likely contributes to metabolic coronary vasodilation.
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Affiliation(s)
- Vincent J de Beer
- Division of Experimental Cardiology, Department of Cardiology, Thoraxcenter, he Netherlands.
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Fernández-Musoles R, López-Díez JJ, Torregrosa G, Vallés S, Alborch E, Manzanares P, Salom JB. Lactoferricin B-derived peptides with inhibitory effects on ECE-dependent vasoconstriction. Peptides 2010; 31:1926-33. [PMID: 20600419 DOI: 10.1016/j.peptides.2010.06.024] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/10/2010] [Revised: 06/21/2010] [Accepted: 06/21/2010] [Indexed: 12/22/2022]
Abstract
Endothelin-converting enzyme (ECE), a key peptidase in the endothelin (ET) system, cleaves inactive big ET-1 to produce active ET-1, which binds to ET(A) receptors to exert its vasoconstrictor and pressor effects. ECE inhibition could be beneficial in the treatment of hypertension. In this study, a set of eight lactoferricin B (LfcinB)-derived peptides, previously characterized in our laboratory as angiotensin-converting enzyme (ACE) inhibitory peptides, was examined for their inhibitory effects on ECE. In vitro inhibitory effects on ECE activity were assessed using both the synthetic fluorogenic peptide substrate V (FPS V) and the natural substrate big ET-1. To study vasoactive effects, an ex vivo functional assay was developed using isolated rabbit carotid artery segments. With FPS V, only four LfcinB-derived peptides induced inhibition of ECE activity, whereas the eight peptides showed ECE inhibitory effects with big ET-1 as substrate. Regarding the ex vivo assays, six LfcinB-derived peptides showed inhibition of big ET-1-induced, ECE-dependent vasoconstriction. A positive correlation between the inhibitory effects of LfcinB-derived peptides on ECE activity when using big ET-1 and the inhibitory effects on ECE-dependent vasoconstriction was shown. ECE-independent vasoconstriction induced by ET-1 was not affected, thus discarding effects of LfcinB-derived peptides on ET(A) receptors or intracellular signal transduction mechanisms. In conclusion, a combined in vitro and ex vivo method to assess the effects of potentially antihypertensive peptides on the ET system has been developed and applied to show the inhibitory effects on ECE-dependent vasoconstriction of six LfcinB-derived peptides, five of which were dual vasopeptidase (ACE/ECE) inhibitors.
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Affiliation(s)
- Ricardo Fernández-Musoles
- Departamento de Biotecnología de Alimentos, Instituto de Agroquímica y Tecnología de Alimentos, Consejo Superior de Investigaciones Científicas, Burjassot, Valencia, Spain
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Wang Z, Yadav AS, Leskova W, Harris NR. Attenuation of streptozotocin-induced microvascular changes in the mouse retina with the endothelin receptor A antagonist atrasentan. Exp Eye Res 2010; 91:670-5. [PMID: 20727883 DOI: 10.1016/j.exer.2010.08.008] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2010] [Revised: 08/05/2010] [Accepted: 08/09/2010] [Indexed: 10/19/2022]
Abstract
Hyperglycemia mediates endothelial cell dysfunction through a number of potential mechanisms that could result in the decrease of retinal blood flow early in diabetes. The aim of this study was to explore the role of endothelin receptor A (ET(A)) in the early decrease of retinal blood flow in diabetic mice. Diabetes was induced by streptozotocin, then ∼1 wk later the mice were administered drinking water with or without the ET(A) receptor antagonist atrasentan (7.5mg/kg/day) for the following 3 weeks. Non-diabetic age-matched mice with or without atrasentan were included as controls. For each mouse, measurements of retinal vascular diameters and red blood cell (RBC) velocities were obtained via intravital microscopy for the 5-7 feed arterioles (and draining venules) extending out of (and into) the optic disk, and from these values, flow rates and wall shear rates were calculated. Additionally, the number of retinal capillaries was counted by fluorescent immunostaining of platelet-endothelial cell adhesion molecule-1 (PECAM-1). Diabetes induced statistically significant decreases in RBC velocity, flow rate, and wall shear rate, with these alterations partially inhibited by atrasentan. No changes were observed in PECAM-1 expression among groups. The changes induced by diabetes, and the attenuation provided by atrasentan, were greater in the smaller retinal arterioles. In summary, ET(A) appears to play a role in the early decreases in retinal blood flow in a mouse model of diabetes.
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Affiliation(s)
- Zhongli Wang
- Department of Molecular & Cellular Physiology, Louisiana State University Health Sciences Center, Shreveport, LA 71130, USA
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Abstract
IMPORTANCE OF THE FIELD Glaucoma is the second leading cause of blindness worldwide. To date, treatment of glaucoma has focused on lowering intraocular pressure (IOP) though there are other mechanisms that might damage the optic nerve, leading to characteristic visual field loss. Endothelin, a potent vasoconstrictor, is believed to play a role in the pathogenesis of glaucomatous optic neuropathy. AREAS COVERED IN THIS REVIEW We review the evidence from the last 20 years exploring the action of endothelin in the eye, its association with the pathophysiology of glaucoma, as well as the potential therapeutic role of targeting the endothelin pathway to affect disease progression in glaucomatous eyes. WHAT THE READER WILL GAIN The goal of this paper is to inform readers about endothelin structure, actions, and role in ocular pathology, pharmacology, and potential areas of future research. TAKE HOME MESSAGE Overall, we believe that the body of evidence supports the following conclusions; i) endothelin is a potent vasoconstrictor that plays a role in ocular physiology, ii) endothelin may play a role in the pathophysiology of glaucoma and iii) modulation of the endothelin system with newly discovered potent antagonists holds promise in treating glaucoma through both pressure-dependent and pressure-independent pathways.
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Affiliation(s)
- Travis J Good
- University of Colorado, Denver School of Medicine, Rocky Mountain Lions Eye Institute, Department of Ophthalmology, 1675 Aurora Court, PO Box 6510 Mail Stop F-731, Aurora, CO 80045, USA
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Hein TW, Rosa RH, Yuan Z, Roberts E, Kuo L. Divergent roles of nitric oxide and rho kinase in vasomotor regulation of human retinal arterioles. Invest Ophthalmol Vis Sci 2009; 51:1583-90. [PMID: 19850828 DOI: 10.1167/iovs.09-4391] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
PURPOSE Although the arteriolar segment contributes to flow regulation, there is sparse information at the single microvessel level on how vasomotor function is regulated in the human retina. The authors have previously reported vasoreactivity and its underlying mechanisms in isolated porcine retinal arterioles. Herein, they studied human retinal arterioles for comparison. METHODS Retinal tissues were obtained from seven patients undergoing enucleation. Human and porcine retinal arterioles were isolated and pressurized to 55 cm H(2)O luminal pressure for vasoreactivity study using videomicroscopic techniques. RESULTS Isolated human and porcine retinal arterioles developed myogenic tone and dilated dose dependently to bradykinin, adenosine, and sodium nitroprusside. Stepwise increases in luminal flow produced graded dilation with approximately 60% dilation at the highest flow tested. Nitric oxide (NO) synthase inhibitor L-NAME nearly abolished dilations to bradykinin and flow and attenuated the adenosine-induced dilation without altering the response to nitroprusside. Endothelin-1 caused dose-dependent constriction. Rho kinase (ROCK) inhibitor H-1152 blocked both myogenic tone and endothelin-1-induced constriction. Responses of retinal arterioles to all agonists and increased flow were similar between pigs and humans. CONCLUSIONS Isolated human retinal arterioles dilate to bradykinin and increased flow in an NO-dependent manner. NO contributes, in part, to adenosine-induced vasodilation. Conversely, ROCK activation mediates myogenic tone and endothelin-1-induced vasoconstriction. Similarities in these vasoactive responses and the underlying mechanisms between human and porcine retinal arterioles support the latter as a viable experimental model of the human retinal microcirculation.
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Affiliation(s)
- Travis W Hein
- Department of Ophthalmology, Scott and White Eye Institute, Temple, Texas 76504, USA.
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