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Bastia E, Toris CB, Brambilla S, Galli C, Almirante N, Bergamini MVW, Masini E, Sgambellone S, Unser AM, Ahmed F, Torrejon KY, Navratil T, Impagnatiello F. NCX 667, a Novel Nitric Oxide Donor, Lowers Intraocular Pressure in Rabbits, Dogs, and Non-Human Primates and Enhances TGFβ2-Induced Outflow in HTM/HSC Constructs. Invest Ophthalmol Vis Sci 2021; 62:17. [PMID: 33704360 PMCID: PMC7960798 DOI: 10.1167/iovs.62.3.17] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
Purpose NCX 667, a novel nitric oxide (NO) donor with an isomannide core, was characterized for its IOP-lowering ability in animal models of ocular hypertension and glaucoma. Bioengineered human trabecular meshwork/Schlemm's canal (HTM/HSC) constructs were used to explore the mode of action. Methods Ocular normotensive New Zealand white (NZW) rabbits (ONT-rabbits), spontaneously ocular hypertensive pigmented Dutch-belted rabbits (sOHT-rabbits), hypertonic saline (5%)–induced transient ocular hypertensive NZW rabbits (tOHT-rabbits), ocular normotensive Beagle dogs (ONT-dogs), and laser-induced ocular hypertensive cynomolgus monkeys (OHT-monkeys) were used. NCX 667 or vehicle (30 µL) was instilled in a crossover, masked fashion and intraocular pressure (IOP) measured before dosing (baseline) and for several hours thereafter. The ONT-rabbits were used for cyclic guanosine monophosphate (cGMP) determination in ocular tissues after ocular dosing with NCX 667. Transforming growth factor-beta2 (TGFβ2) (2.5 ng/mL, six days)–treated HTM/HSC constructs were used to address changes in outflow facility. Results NCX 667 resulted in robust and dose-dependent IOP decrease in all models used. Maximal IOP-lowering efficacy at 1% was −4.1 ± 0.6, −12.2 ± 2.7, −10.5 ± 2.0, −5.3 ± 0.8, and −6.6 ± 1.9 mmHg, respectively, in ONT-dogs, sOHT-rabbits, tOHT-rabbits, ONT-rabbits, and OHT-monkeys. In ONT-rabbits NCX 667 (1%) increased cGMP in aqueous humor (AH) but not in retina and iris/ciliary body. NCX 667 concentration-dependently increased outflow facility in TGFβ2-treated HTM/HSC constructs (outflow facility, 0.10 ± 0.06 and 0.30 ± 0.10 µL/min/mmHg/mm2, respectively, in vehicle- and NCX 667–treated constructs). Conclusions NCX 667 leads to robust IOP lowering in several animal models. Evidence in HTM/HSC constructs indicate that the IOP reduction likely results from NO-mediated increase of the conventional outflow pathway. Other mechanisms including changes in AH production and episcleral vein pressure may not be excluded at this time.
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Affiliation(s)
| | - Carol B Toris
- University of Nebraska Medical Center, Omaha, Nebraska, United States
| | | | | | | | - Michael V W Bergamini
- North Texas Eye Research Institute, University of North Texas Health Science Center, Fort Worth, Texas, United States
| | - Emanuela Masini
- Department of NEUROFARBA, Section of Pharmacology, University of Florence, Florence, Italy
| | - Silvia Sgambellone
- Department of NEUROFARBA, Section of Pharmacology, University of Florence, Florence, Italy
| | - Andrea M Unser
- Glauconicx Biosciences Inc., Albany, New York, Unites States
| | - Feryan Ahmed
- Glauconicx Biosciences Inc., Albany, New York, Unites States
| | | | - Tomas Navratil
- Nicox Ophthalmics, Inc., Durham, North Carolina, United States
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Mao YJ, Wu JB, Yang ZQ, Zhang YH, Huang ZJ. Nitric oxide donating anti-glaucoma drugs: advances and prospects. Chin J Nat Med 2021; 18:275-283. [PMID: 32402405 DOI: 10.1016/s1875-5364(20)30035-2] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2020] [Indexed: 12/11/2022]
Abstract
Glaucoma is a disease that causes irreversible blindness. Reducing intraocular pressure (IOP) is the main treatment at present. Nitric oxide (NO), an endogenous gas signaling molecule, can increase aqueous humor outflow facility, inhibit aqueous humor production thereby reducing IOP, as well as regulate eye blood flow and protect the optic nerve. Therefore, NO donating anti-glaucoma drugs have broad research prospects. In this review, we summarize NO-mediated therapy for glaucoma, and the state of the art of some NO donating molecules, including latanoprostene bunod in market and some other candidate compounds, for the intervention of glaucoma, as well as prospects and challenges ahead in this field.
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Affiliation(s)
- Yu-Jie Mao
- State Key Laboratory of Natural Medicines, Jiangsu Key Laboratory of Drug Discovery for Metabolic Diseases, Center of Drug Discovery, China Pharmaceutical University, Nanjing 210009, China
| | - Jian-Bing Wu
- State Key Laboratory of Natural Medicines, Jiangsu Key Laboratory of Drug Discovery for Metabolic Diseases, Center of Drug Discovery, China Pharmaceutical University, Nanjing 210009, China
| | - Ze-Qiu Yang
- State Key Laboratory of Natural Medicines, Jiangsu Key Laboratory of Drug Discovery for Metabolic Diseases, Center of Drug Discovery, China Pharmaceutical University, Nanjing 210009, China
| | - Yi-Hua Zhang
- State Key Laboratory of Natural Medicines, Jiangsu Key Laboratory of Drug Discovery for Metabolic Diseases, Center of Drug Discovery, China Pharmaceutical University, Nanjing 210009, China
| | - Zhang-Jian Huang
- State Key Laboratory of Natural Medicines, Jiangsu Key Laboratory of Drug Discovery for Metabolic Diseases, Center of Drug Discovery, China Pharmaceutical University, Nanjing 210009, China.
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Andrés-Guerrero V, García-Feijoo J. Nitric oxide-donating compounds for IOP lowering in glaucoma. ARCHIVOS DE LA SOCIEDAD ESPANOLA DE OFTALMOLOGIA 2018; 93:290-299. [PMID: 29580758 DOI: 10.1016/j.oftal.2018.02.004] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/07/2017] [Revised: 02/01/2018] [Accepted: 02/02/2018] [Indexed: 06/08/2023]
Abstract
INTRODUCTION An elevated intraocular pressure (IOP) remains the main risk factor for progression of glaucoma upon which we can efficiently act. Pharmacological strategies to reduce IOP are directed towards the reduction of aqueous humour (AH) production and/or the increase in AH drainage through the uveoscleral pathway. However, there are no drugs currently available as first-line treatment to increase AH outflow primarily via the conventional route. Ocular nitric oxide (NO) production takes place in AH outflow pathways and in the ciliary muscle, modulating the cellular response to elevated IOP. METHODS This review describes the mechanism of action of endogenous NO and NO-donating compounds that are under research. It includes information regarding pre-clinical and clinical studies previously conducted with these compounds, discussing their role and therapeutic potential in the pharmacological treatment of ocular hypertension in glaucoma. RESULTS The topical ocular administration of NO-donating compounds significantly lowered IOP and maintained it in animal models of glaucoma and subjects with ocular hypertension. CONCLUSIONS The mechanism of action of these compounds is novel and scientific evidence that shows promising results. However, there is a need for more comprehensive studies to assess long-term safety and tolerability in order to properly evaluate their use in chronic therapies.
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Affiliation(s)
- V Andrés-Guerrero
- Servicio de Oftalmología, Instituto de Investigación Sanitaria San Carlos (IdISSC), Hospital Clínico San Carlos. Red de Enfermedades Oculares OftaRed, Instituto de Salud Carlos III, Madrid, España.
| | - J García-Feijoo
- Servicio de Oftalmología, Instituto de Investigación Sanitaria San Carlos (IdISSC), Hospital Clínico San Carlos. Red de Enfermedades Oculares OftaRed, Instituto de Salud Carlos III, Madrid, España; Departamento de Oftalmología y ORL, Instituto de Investigaciones Oftalmológicas Ramón Castroviejo, Facultad de Medicina, Universidad Complutense de Madrid, Madrid, España
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Wareham LK, Buys ES, Sappington RM. The nitric oxide-guanylate cyclase pathway and glaucoma. Nitric Oxide 2018; 77:75-87. [PMID: 29723581 DOI: 10.1016/j.niox.2018.04.010] [Citation(s) in RCA: 43] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2018] [Revised: 04/18/2018] [Accepted: 04/23/2018] [Indexed: 01/12/2023]
Abstract
Glaucoma is a prevalent optic neuropathy characterized by the progressive dysfunction and loss of retinal ganglion cells (RGCs) and their optic nerve axons, which leads to irreversible visual field loss. Multiple risk factors for the disease have been identified, but elevated intraocular pressure (IOP) remains the primary risk factor amenable to treatment. Reducing IOP however does not always prevent glaucomatous neurodegeneration, and many patients progress with the disease despite having IOP in the normal range. There is increasing evidence that nitric oxide (NO) is a direct regulator of IOP and that dysfunction of the NO-Guanylate Cyclase (GC) pathway is associated with glaucoma incidence. NO has shown promise as a novel therapeutic with targeted effects that: 1) lower IOP; 2) increase ocular blood flow; and 3) confer neuroprotection. The various effects of NO in the eye appear to be mediated through the activation of the GC- guanosine 3:5'-cyclic monophosphate (cGMP) pathway and its effect on downstream targets, such as protein kinases and Ca2+ channels. Although NO-donor compounds are promising as therapeutics for IOP regulation, they may not be ideal to harness the neuroprotective potential of NO signaling. Here we review evidence that supports direct targeting of GC as a novel pleiotrophic treatment for the disease, without the need for direct NO application. The identification and targeting of other factors that contribute to glaucoma would be beneficial to patients, particularly those that do not respond well to IOP-dependent interventions.
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Affiliation(s)
- Lauren K Wareham
- Vanderbilt Eye Institute, Vanderbilt University Medical Center, Nashville, TN 37232, USA
| | | | - Rebecca M Sappington
- Department of Ophthalmology and Visual Sciences, Vanderbilt University School of Medicine, Nashville, TN 37232, USA; Vanderbilt Eye Institute, Vanderbilt University Medical Center, Nashville, TN 37232, USA; Department of Pharmacology, Vanderbilt University, Nashville, TN 37232, USA.
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Muenster S, Lieb WS, Fabry G, Allen KN, Kamat SS, Guy AH, Dordea AC, Teixeira L, Tainsh RE, Yu B, Zhu W, Ashpole NE, Malhotra R, Brouckaert P, Bloch DB, Scherrer-Crosbie M, Stamer WD, Kuehn MH, Pasquale LR, Buys ES. The Ability of Nitric Oxide to Lower Intraocular Pressure Is Dependent on Guanylyl Cyclase. Invest Ophthalmol Vis Sci 2017; 58:4826-4835. [PMID: 28973329 PMCID: PMC5624778 DOI: 10.1167/iovs.17-22168] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Purpose While nitric oxide (NO) donors are emerging as treatments for glaucoma, the mechanism by which NO lowers intraocular pressure (IOP) is unclear. NO activates the enzyme guanylyl cyclase (GC) to produce cyclic guanosine monophosphate. We studied the ocular effects of inhaled and topically applied NO gas in mice and lambs, respectively. Methods IOP and aqueous humor (AqH) outflow were measured in WT and GC-1α subunit null (GC-1−/−) mice. Mice breathed 40 parts per million (ppm) NO in O2 or control gas (N2/O2). We also studied the effect of ocular NO gas exposure (80, 250, 500, and 1000 ppm) on IOP in anesthetized lambs. NO metabolites were measured in AqH and plasma. Results In awake WT mice, breathing NO for 40 minutes lowered IOP from 14.4 ± 1.9 mm Hg to 10.9 ± 1.0 mm Hg (n = 11, P < 0.001). Comparable results were obtained in anesthetized WT mice (n = 10, P < 0.001). In awake or anesthetized GC-1−/− mice, IOP did not change under similar experimental conditions (P ≥ 0.08, n = 20). Breathing NO increased in vivo outflow facility in WT but not GC-1−/− mice (+13.7 ± 14.6% vs. −12.1 ± 9.4%, n = 4 each, P < 0.05). In lambs, ocular exposure to NO lowered IOP in a dose-dependent manner (−0.43 mm Hg/ppm NO; n = 5 with 40 total measurements; P = 0.04) without producing corneal pathology or altering pulmonary and systemic hemodynamics. After ocular NO exposure, NO metabolites were increased in AqH (n = 8, P < 0.001) but not in plasma. Conclusions Breathing NO reduced IOP and increased outflow facility in a GC-dependent manner in mice. Exposure of ovine eyes to NO lowers IOP.
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Affiliation(s)
- Stefan Muenster
- Anesthesia Center for Critical Care Research, Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital Research Institute and Harvard Medical School, Boston, Massachusetts, United States.,Department of Anesthesiology and Critical Care Medicine, University Hospital Bonn, Bonn, Germany
| | - Wolfgang S Lieb
- Anesthesia Center for Critical Care Research, Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital Research Institute and Harvard Medical School, Boston, Massachusetts, United States.,Institute of Cell Biology and Immunology, University of Stuttgart, Stuttgart, Germany
| | - Gregor Fabry
- Anesthesia Center for Critical Care Research, Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital Research Institute and Harvard Medical School, Boston, Massachusetts, United States
| | - Kaitlin N Allen
- Anesthesia Center for Critical Care Research, Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital Research Institute and Harvard Medical School, Boston, Massachusetts, United States
| | - Shivani S Kamat
- Massachusetts Eye and Ear Infirmary, Department of Ophthalmology, Harvard Medical School, Boston, Massachusetts, United States
| | - Ann H Guy
- Massachusetts Eye and Ear Infirmary, Department of Ophthalmology, Harvard Medical School, Boston, Massachusetts, United States
| | - Ana C Dordea
- Anesthesia Center for Critical Care Research, Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital Research Institute and Harvard Medical School, Boston, Massachusetts, United States
| | - Leandro Teixeira
- Department of Pathological Science, School of Veterinary Medicine, University of Wisconsin, Wisconsin, United States
| | - Robert E Tainsh
- Anesthesia Center for Critical Care Research, Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital Research Institute and Harvard Medical School, Boston, Massachusetts, United States
| | - Binglan Yu
- Anesthesia Center for Critical Care Research, Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital Research Institute and Harvard Medical School, Boston, Massachusetts, United States
| | - Wei Zhu
- Department of Ophthalmology and Visual Sciences, University of Iowa, Iowa City, Iowa, United States
| | - Nicole E Ashpole
- Department of Ophthalmology, Duke University, Durham, North Carolina, United States.,Department of Biomedical Engineering, Duke University, Durham, North Carolina, United States
| | - Rajeev Malhotra
- Cardiovascular Research Center and Cardiology Division of the Department of Medicine, Massachusetts General Hospital Research Institute and Harvard Medical School, Boston, Massachusetts, United States
| | - Peter Brouckaert
- Department of Biomedical Molecular Biology, Ghent University, Ghent, Belgium Department of Molecular Biomedical Research, VIB, Ghent, Belgium
| | - Donald B Bloch
- Anesthesia Center for Critical Care Research, Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital Research Institute and Harvard Medical School, Boston, Massachusetts, United States.,The Center for Immunology and Inflammatory Diseases and the Division of Rheumatology, Allergy and Immunology, Department of Medicine, Massachusetts General Hospital Research Institute and Harvard Medical School, Boston, Massachusetts, United States
| | - Marielle Scherrer-Crosbie
- Anesthesia Center for Critical Care Research, Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital Research Institute and Harvard Medical School, Boston, Massachusetts, United States.,Cardiac Ultrasound Laboratory and Division of Cardiology, Massachusetts General Hospital Research Institute and Harvard Medical School, Boston, Massachusetts, United States
| | - W Daniel Stamer
- Department of Ophthalmology, Duke University, Durham, North Carolina, United States.,Department of Biomedical Engineering, Duke University, Durham, North Carolina, United States
| | - Markus H Kuehn
- Department of Ophthalmology and Visual Sciences, University of Iowa, Iowa City, Iowa, United States
| | - Louis R Pasquale
- Massachusetts Eye and Ear Infirmary, Department of Ophthalmology, Harvard Medical School, Boston, Massachusetts, United States.,Channing Division of Network Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts, United States
| | - Emmanuel S Buys
- Anesthesia Center for Critical Care Research, Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital Research Institute and Harvard Medical School, Boston, Massachusetts, United States
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Alario AF, Strong TD, Pizzirani S. Medical Treatment of Primary Canine Glaucoma. Vet Clin North Am Small Anim Pract 2015; 45:1235-59, vi. [DOI: 10.1016/j.cvsm.2015.06.004] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
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Shahidullah M, Mandal A, Wei G, Delamere NA. Nitric oxide regulation of Na, K-ATPase activity in ocular ciliary epithelium involves Src family kinase. J Cell Physiol 2014; 229:343-52. [PMID: 24037816 DOI: 10.1002/jcp.24454] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2013] [Accepted: 08/16/2013] [Indexed: 01/22/2023]
Abstract
The nitric oxide (NO) donor sodium nitroprusside (SNP) is known to reduce aqueous humor (AH) secretion in the isolated porcine eye. Previously, SNP was found to inhibit Na,K-ATPase activity in nonpigmented ciliary epithelium (NPE), AH-secreting cells, through a cGMP/protein kinase G (PKG)-mediated pathway. Here we show Src family kinase (SFK) activation in the Na,K-ATPase activity response to SNP. Ouabain-sensitive (86) Rb uptake was reduced by >35% in cultured NPE cells exposed to SNP (100 µM) or exogenously added cGMP (8-Br-cGMP) (100 µM) and the SFK inhibitor PP2 (10 µM) prevented the response. Ouabain-sensitive ATP hydrolysis was reduced by ~40% in samples detected in material obtained from SNP- and 8-Br-cGMP-treated cells following homogenization, pointing to an intrinsic change of Na,K-ATPase activity. Tyrosine-10 phosphorylation of Na,K-ATPase α1 subunit was detected in SNP and L-arginine-treated cells and the response prevented by PP2. SNP elicited an increase in cell cGMP. Cells exposed to 8-Br-cGMP displayed SFK activation (phosphorylation) and inhibition of both ouabain-sensitive (86) Rb uptake and Na,K-ATPase activity that was prevented by PP2. SFK activation, which also occurred in SNP-treated cells, was suppressed by inhibitors of soluble guanylate cyclase (ODQ; 10 µM) and PKG (KT5823; 1 µM). SNP and 8-Br-cGMP also increased phosphorylation of ERK1/2 and p38 MAPK and the response prevented by PP2. However, U0126 did not prevent SNP or 8-Br-cGMP-induced inhibition of Na,K-ATPase activity. Taken together, the results suggest that NO activates guanylate cyclase to cause a rise in cGMP and subsequent PKG-dependent SFK activation. Inhibition of Na,K-ATPase activity depends on SFK activation.
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Russell-Randall KR, Dortch-Carnes J. Kappa opioid receptor localization and coupling to nitric oxide production in cells of the anterior chamber. Invest Ophthalmol Vis Sci 2011; 52:5233-9. [PMID: 21666232 DOI: 10.1167/iovs.10-6613] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
PURPOSE The present study was designed to determine whether kappa opioid receptors (KORs) are localized to cells of the inflow and outflow pathways of the eye and if activation of these receptors has an effect on nitric oxide (NO) production, because these effects could play a role in KOR agonist-mediated reduction of IOP. METHODS Human nonpigmented ciliary epithelial (NPCE) and trabecular meshwork (HTM-3) cells were treated with spiradoline (SPR), a selective KOR agonist, or estradiol, for 24 hours. Some cells were pretreated with the selective KOR antagonist norbinaltorphimine (norBNI) or the nonselective NO synthase inhibitor Nω-nitro-L-arginine methyl ester (L-NAME) for 30 minutes, followed by the addition of SPR. Immunofluorescent localization of KORs was determined in isolated rabbit iris-ciliary bodies (ICBs) and NPCE and HTM-3 cells. RESULTS Immunohistochemical data show the localization of KORs to the rabbit ICB and more specifically to the ciliary epithelial layer. KORs were also found on cell membranes of NPCE and HTM-3 cells. Treatment of both these cell types with spiradoline caused concentration-dependent increases in the release of NO. Spiradoline-induced release of NO from both cell types was inhibited by pretreatment with norBNI and L-NAME. CONCLUSIONS Results from this study show the presence of KORs on rabbit ICBs and also on NPCE and HTM cells. Activation of these KORs on both cell types resulted in KOR-mediated increases in NO production. These findings provide evidence that previously demonstrated KOR-mediated reduction in IOP could be caused, in part, by NO production in both the ciliary body and the trabecular meshwork.
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Affiliation(s)
- Karen R Russell-Randall
- Department of Pharmacology and Toxicology, Morehouse School of Medicine, Atlanta, Georgia 30310-1495, USA.
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Shahidullah M, Mandal A, Delamere NA. Responses of sodium-hydrogen exchange to nitric oxide in porcine cultured nonpigmented ciliary epithelium. Invest Ophthalmol Vis Sci 2009; 50:5851-8. [PMID: 19608532 DOI: 10.1167/iovs.09-3453] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
PURPOSE To better understand how nitric oxide (NO) alters the function of the nonpigmented ciliary epithelium (NPE), studies were performed to determine the influence of NO on sodium-hydrogen exchanger (NHE) activity. METHODS Cytoplasmic pH (pH(i)) was measured in cultured porcine NPE loaded with BCECF (2',7'-bis(2-carboxyl)-5(6)-carboxyfluorescein-acetoxyethyl ester). Na-H exchanger (NHE) was examined by immunolocalization. RESULTS In cells acidified by 5 minutes of exposure to 20 mM ammonium chloride, pH(i) recovery was partially inhibited by sodium nitroprusside (SNP), an NO donor, and l-arginine, the endogenous substrate for NO synthase. SNP and dimethyl amiloride (DMA), an NHE inhibitor, inhibited pH(i) recovery to a similar degree. In bicarbonate-free buffer SNP+DMA elicited no additional change in pH(i) recovery beyond that elicited by DMA alone. This suggests that SNP causes NHE inhibition. the SNP's effect on pH(i) recovery was mimicked by 8-pCPT-cGMP but suppressed by ODQ and H-8. Ouabain alone reduced pH(i) recovery, but SNP+ouabain caused significant further reduction. Immunolocalization studies revealed NHE1 and -4 in native and cultured NPE. CONCLUSIONS NHE1 and -4 are expressed at the NPE basolateral margin. The findings suggest the NHE is inhibited by NO which acts via a cGMP and protein kinase G signaling pathway. The NHE response does not appear to be the consequence of NO-induced Na,K-ATPase inhibition. Because NO synthases are expressed in porcine NPE, NO could act as an autocrine regulator of NHE activity. Although NHE inhibitors are known to lower intraocular pressure (IOP), further studies are needed to understand whether changes in NHE activity contribute to the IOP-lowering effect of NO donors.
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Shahidullah M, Delamere NA. NO donors inhibit Na,K-ATPase activity by a protein kinase G-dependent mechanism in the nonpigmented ciliary epithelium of the porcine eye. Br J Pharmacol 2006; 148:871-80. [PMID: 16770322 PMCID: PMC1617073 DOI: 10.1038/sj.bjp.0706795] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
1. We developed a novel method to isolate nonpigmented epithelial (NPE) cells from porcine eyes in order to examine Na,K-ATPase responses to nitric oxide (NO) donors specifically in the epithelium. 2. Cells were treated with NO donors and other test compounds for 20 min prior to Na,K-ATPase activity measurement. 3. NO donors, sodium nitroprusside (SNP, 1 microM-1 mM), sodium azide (100 nM-1 microM) and S-nitroso-N-acetylpenicillamine (1 microM-1 mM) caused significant concentration-dependent inhibition of Na,K-ATPase activity. Detection of nitrite in the medium of L-arginine and SNP-treated NPE confirmed NO generation. 4. Concentration-dependent inhibition of Na,K-ATPase was also obtained by L-arginine (1-3 mM), a physiological precursor of NO and 8p-CPT-cGMP (1-100 microM), a cell permeable analog of cGMP. The L-arginine effect was abolished when the NO synthesizing enzyme, NO-synthase, was inhibited by L-NAME (100 microM). 5. The inhibitory effect of SNP or sodium azide on Na,K-ATPase activity was suppressed by soluble guanylate cyclase (sGC) inhibitors, ODQ (10 microM) or methylene blue (10 microM). 6. The inhibitory effect of 8p-CPT-cGMP on Na,K-ATPase was abolished by protein kinase G (PKG) inhibitors, H-8 (1 microM) and H-9 (20 microM), but not by the protein kinase A (PKA) inhibitor H-89 (100 nM). H-8 and H-9 partially suppressed the inhibitory effect of SNP on Na,K-ATPase. 7. Taken together the results indicate that Na,K-ATPase inhibition response to NO donors involves activation of sGC, generation of cGMP and activation of PKG. These findings suggest that Na,K-ATPase inhibition in NPE may contribute to the ability of NO donors to reduce aqueous humor secretion.
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Affiliation(s)
- Mohammad Shahidullah
- Department of Ophthalmology and Visual Sciences, University of Louisville, Louisville, Kentucky 40202, USA.
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Shahidullah M, Yap M, To CH. Cyclic GMP, sodium nitroprusside and sodium azide reduce aqueous humour formation in the isolated arterially perfused pig eye. Br J Pharmacol 2005; 145:84-92. [PMID: 15711584 PMCID: PMC1576120 DOI: 10.1038/sj.bjp.0706156] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
The effect of nitric oxide (NO) on aqueous humour formation (AHF) and intraocular pressure (IOP) was studied using NO donors, sodium azide (AZ) and sodium nitroprusside (SNP). Using the porcine arterially perfused eye preparation, drug effects on AHF and IOP were measured by fluorescein dilution and manometry, respectively. Perfusion pressure of the ocular vasculature was also monitored using digital pressure transducer and pen recorder. L-Arginine (1.0 mM), a precursor of NO, but not D-arginine (1.0 mM), the inactive analogue, produced a significant reduction in AHF (28.5%) and IOP (21.1%). L-NAME (L-nitro-L-arginine) (10-100 microM), an NO synthase inhibitor, had no effect on AHF and IOP. However, L-NAME (100 microM) completely reversed L-arginine's effect. AZ and SNP reduced the AHF and IOP dose-dependently. AZ at 100 nM, 1 and 10 microM reduced AHF by 26.0, 39.7 and 51.7% and IOP by 10.8, 17.3 and 24.0%, respectively. SNP at 1, 10 and 100 microM reduced the AHF by 6.0, 24.2 and 35.4% and IOP by 3.5, 9.5 and 15.5%, respectively. 8-pCPT-cGMP (8-para-chlorophenyl-thioguanosine-3',5'-cyclic guanosine monophosphate, 10 microM), a cGMP analogue, also reduced the AHF (34.9%) and IOP (15.9%). The effects of AZ and SNP on the AHF and IOP were blocked by a soluble guanylate cyclase inhibitor ODQ (10 microM), whereas ODQ alone or combined with 8-pCPT-cGMP had no effect on the AHF and IOP. None of the drugs had any significant effect on ocular vasculature. The reduction of the AHF and IOP in the arterially perfused pig eye by nitrovasodilators is likely to involve the NO-cGMP pathway.
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Affiliation(s)
- Mohammad Shahidullah
- The Laboratory of Experimental Optometry, Department of Optometry and Radiography, The Hong Kong Polytechnic University, Kowloon, Hong Kong SAR, China
- Author for correspondence:
| | - Maurice Yap
- The Laboratory of Experimental Optometry, Department of Optometry and Radiography, The Hong Kong Polytechnic University, Kowloon, Hong Kong SAR, China
| | - Chi-ho To
- The Laboratory of Experimental Optometry, Department of Optometry and Radiography, The Hong Kong Polytechnic University, Kowloon, Hong Kong SAR, China
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Shahidullah M, Chan HHL, Yap MK, Liu Q, To CH. Multifocal electroretinography in isolated arterially perfused bovine eye. Ophthalmic Physiol Opt 2005; 25:27-34. [PMID: 15649180 DOI: 10.1111/j.1475-1313.2004.00241.x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
AIM To develop an isolated arterially perfused bovine eye as an in vitro model for studying retinal electrophysiology using multifocal electroretinography (mfERG). METHODS Fresh bovine eyes were cannulated through the ophthalmic artery and perfused with oxygenated Krebs' solution at 37 degrees C within 15 min postmortem. Multifocal ERG was recorded using the veris 1.0 (Visual Evoked Response Imaging System). RESULTS The mfERG waveform of in vitro bovine eyes had a typical trough (negative wave, N1) and peak (positive wave, P1) similar to those of human mfERG. The implicit times (peak latencies) for N1 and P1 were 20 and 42 ms respectively, and the average response amplitude (N1P1) was 55 nV. The implicit times of N1 and P1 were maintained for more than 4 h. The mfERG responses were affected proportionately by the stimulus intensity. Without a neutral density filter, the mean response amplitude was about 55 nV, which was diminished to 26, 18 and 10 nV under neutral density filters of 0.4, 1.0 and 1.4, respectively. Partial occlusion of the pupil completely abolished mfERG responses from the corresponding part of the retina. CONCLUSIONS Isolated arterially perfused bovine eye may be used as an experimental model to study retinal electrophysiology using mfERG. The in vitro eye may offer a convenient and easily obtainable alternative to live animals, particularly for drug screening and invasive studies.
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Affiliation(s)
- Mohammad Shahidullah
- Department of Optometry and Radiography, The Hong Kong Polytechnic University, Kowloon, Hong Kong
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Millar JC. Real-time direct measurement of nitric oxide in bovine perfused eye trabecular meshwork using a clark-type electrode. J Ocul Pharmacol Ther 2003; 19:299-313. [PMID: 12964955 DOI: 10.1089/108076803322279363] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
NO was detected in bovine trabecular meshwork (TM). Bovine eyes were perfused (posterior ciliary artery). In some eyes (operated eyes) a NO electrode was inserted adjacent to the TM (scleral flap). Vascular perfusion/intraocular pressures (VPP/IOP) were recorded. In operated eyes, epinephrine (1 nM-100 microM) increased NO (maximally 979.9 +/- 117.6 nM, mean +/- SDM). Timolol (1 mM) shifted the epinephrine-NO concentration-response curve rightward (2.94 log units) without significantly changing the maximal response (903.0 +/- 67.7 nM, mean +/- SDM). The non-selective NO synthase (NOS) inhibitor L-NMMA (100 microM) virtually abolished the NO response to epinephrine. L-NMMA alone (1 microM-100 microM) significantly reduced tonic NO generation (maximally 109.5 +/- 24.9 nM, mean +/- SDM), whereas timolol alone (1 microM-1 mM) had no effect. In unoperated eyes, epinephrine (1 nM-100 microM) reduced IOP (maximally 2.56 +/- 0.64 mmHg, mean +/- SDM). Epinephrine (100 microM) mildly increased VPP (4.6 +/- 1.3 mmHg, mean +/- SDM). Baseline aqueous humor formation rate (11.5 +/- 3.2 microl/min, mean +/- SDM) was unaffected. Effluent perfusate (effusate) total NO(2)(-) was determined by enzymatically reducing all NO(3)(-) to NO(2)(-), then assessing resultant NO(2)(-) (Griess assay). Epinephrine (1 nM-1 microM) increased effusate NO(2)(-) (maximally 15.8 +/- 4.9 microM, mean +/- SDM). Timolol (1 mM) reduced, and L-NMMA (100 microM) virtually abolished effusate NO(2)(-) response to epinephrine. L-NMMA alone (1 microM-100 microM) reduced tonic effusate NO(2)(-) (maximally from 5.8 +/- 1.6 microM to 1.1 +/- 0.9 microM, mean +/- SDM), whereas timolol alone (1 microM-1 mM) had no effect. NO is generated tonically in bovine TM and increases in response to epinephrine.
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Affiliation(s)
- J C Millar
- Department of Biology & Health Science, Faculty of Science, Technology & Design, University of Luton, Park Square Campus, Luton, England.
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