scholarly journals Activation of endothelial NADPH oxidase during normoxic lung ischemia is KATP channel dependent

2005 ◽  
Vol 289 (6) ◽  
pp. L954-L961 ◽  
Author(s):  
Qunwei Zhang ◽  
Ikuo Matsuzaki ◽  
Shampa Chatterjee ◽  
Aron B. Fisher
Keyword(s):  
Endothelial Cells ◽  
Membrane Potential ◽  
Endothelial Cell ◽  
Cell Membrane ◽  
Nadph Oxidase ◽  
Membrane Depolarization ◽  
Fluorescence Probes ◽  
Ros Generation ◽  
Wild Type ◽  
Channel Dependent

Previous studies have shown endothelial cell membrane depolarization and generation of reactive oxygen species (ROS) in endothelial cells with abrupt reduction in shear stress (ischemia). This study evaluated the role of ATP-sensitive potassium (KATP) channels and NADPH oxidase in the ischemic response by using Kir6.2−/− and gp91phox−/− mice. To evaluate ROS generation, we subjected isolated perfused mouse lungs labeled with 2′,7′-dichlorodihydrofluorescein (DCF), hydroethidine (HE), or diphenyl-1-pyrenylphosphine (DPPP) to control perfusion followed by global ischemia. In wild-type C57BL/6J mice, imaging of subpleural endothelial cells showed a time-dependent increase in intensity for all three fluorescence probes with ischemia, which was blocked by preperfusion with cromakalim (a KATP channel agonist) or diphenyleneiodonium (DPI, a flavoprotein inhibitor). Endothelial cell fluorescence with bis-oxonol, a membrane potential probe, increased during lung ischemia indicating cell membrane depolarization. The change in membrane potential with ischemia in lungs of gp91phox−/− mice was similar to wild type, but ROS generation did not occur. Lungs from Kir6.2−/− showed marked attenuation of the change in both membrane potential and ROS production. Thus membrane depolarization during lung ischemia requires the presence of a KATP channel and is required for activation of NADPH oxidase and endothelial ROS generation.

Membrane depolarization and NADPH oxidase activation in aortic endothelium during ischemia reflect altered mechanotransduction

2005 ◽  
Vol 288 (1) ◽  
pp. H336-H343 ◽  
Author(s):  
Ikuo Matsuzaki ◽  
Shampa Chatterjee ◽  
Kris DeBolt ◽  
Yefim Manevich ◽  
Qunwei Zhang ◽  
...  
Keyword(s):  
Endothelial Cells ◽  
Plasma Membrane ◽  
Membrane Potential ◽  
Nadph Oxidase ◽  
Membrane Depolarization ◽  
Ros Generation ◽  
Similar Response ◽  
Aortic Endothelial Cells ◽  
Aortic Endothelium ◽  
Aortic Endothelial

We previously showed that “ischemia” (abrupt cessation of flow) leads to rapid membrane depolarization and increased generation of reactive oxygen species (ROS) in lung microvascular endothelial cells. This response is not associated with anoxia but, rather, reflects loss of normal shear stress. This study evaluated whether a similar response occurs in aortic endothelium. Plasma membrane potential and production of ROS were determined by fluorescence microscopy and cytochrome c reduction in flow-adapted rat or mouse aorta or monolayer cultures of rat aortic endothelial cells. Within 30 s after flow cessation, endothelial cells that had been flow adapted showed plasma membrane depolarization that was inhibited by pretreatment with cromakalim, an ATP-sensitive K+ (KATP) channel agonist. Flow cessation also led to ROS generation, which was inhibited by cromakalim and the flavoprotein inhibitor diphenyleneiodonium. Aortic endothelium from mice with “knockout” of the KATP channel (KIR6.2) showed a markedly attenuated change in membrane potential and ROS generation with flow cessation. In aortic endothelium from mice with knockout of NADPH oxidase (gp91phox), membrane depolarization was similar to that in wild-type mice but ROS generation was absent. Thus rat and mouse aortic endothelial cells respond to abrupt flow cessation by KATP channel-mediated membrane depolarization followed by NADPH oxidase-mediated ROS generation, possibly representing a cell-signaling response to altered mechanotransduction.

scholarly journals NADPH Oxidase Mediates Antiphospholipid Antibody-Induced Endothelial Cell Activation

Blood ◽  
2014 ◽  
Vol 124 (21) ◽  
pp. 1447-1447
Author(s):  
Meifang Wu ◽  
Keith R. McCrae
Keyword(s):  
Endothelial Cells ◽  
Endothelial Cell ◽  
Nadph Oxidase ◽  
Conditioned Medium ◽  
Cell Activation ◽  
Fluorescent Dyes ◽  
Ros Generation ◽  
Antiphospholipid Antibody ◽  
Dependent Manner ◽  
Endothelial Cell Activation

Abstract Introduction: Antiphospholipid Syndrome (APS) is characterized by thrombosis and/or recurrent fetal loss in the presence of persistently elevated antiphospholipid antibodies (APLA). The majority of pathologic APLA are directed against β2-glycoprotein I (β2GPI), an abundant plasma phospholipid binding protein. APLA/anti-β2GPI antibodies activate endothelial cells in a β2GPI-dependent manner, though the underlying mechanisms are not well defined. Objective: To define the role of NOX1 in the generation of ROS and activation of endothelial cells by anti-β2GPI antibodies. Methods: Endothelial cells were incubated with β2GPI and either control or affinity-purified anti-β2GPI antibodies in the absence or presence of diphenyleneiodonium (DPI), an NADPH oxidase (NOX) inhibitor. Generation of reactive oxygen species (ROS) in treated cells and conditioned medium were measured by using fluorescent dyes (CM-H2DCFDA and CellROX Deep Red) or luminescent substrate. NOX mRNA and protein expression were assessed using quantitative PCR and immunoblot. Endothelial cell activation was measured by increased expression of E-selectin. Results: Incubation of endothelial cells with β2GPI and anti-β2GPI antibodies stimulated ROS generation in endothelial cells, as well as the release of ROS into conditioned medium. The expression of NOX1 mRNA and protein levels were significantly increased in endothelial cells exposed to anti-β2GPI antibodies, but not control IgG (Figure 1). The ability of β2GPI and anti-β2GPI antibodies to induce endothelial cell E-selectin mRNA expression was blocked by pretreatment of cells with DPI (Figure 2), suggesting that ROS is required for downstream events underlying endothelial cell activation. Conclusions: Endothelial cells exposed to β2GPI and anti-β2GPI antibodies generate ROS, which is subsequently released into the conditioned medium. NOX1 appears to be essential for ROS generation. The impairment of endothelial cell activation by DPI suggests that NOX is also essential for endothelial cell activation by anti-β2GPI antibodies. We hypothesize that production of ROS by NOX plays a central role in APLA-induced endothelial dysfunction. Acknowledgment: This work was supported by an ASH Bridge Grant Figure 1 Figure 1. Disclosures No relevant conflicts of interest to declare.

Endothelial cell hyperpolarization increases [Ca2+]i and venular microvessel permeability

1994 ◽  
Vol 76 (6) ◽  
pp. 2288-2297 ◽  
Author(s):  
P. He ◽  
F. E. Curry
Keyword(s):  
Endothelial Cells ◽  
Membrane Potential ◽  
Endothelial Cell ◽  
Cell Membrane ◽  
Ringer Solution ◽  
Experimental Conditions ◽  
Vasoactive Substances ◽  
Microvessel Permeability ◽  
Low K ◽  
Microvessel Wall

We tested the hypothesis that Ca2+ influx into endothelial cells forming the walls of intact venular microvessels was increased when the cell membranes were hyperpolarized. Cytoplasmic free Ca2+ concentration ([Ca2+]i) was measured after the endothelial cells forming the microvessel wall were loaded with fura 2, endothelial cell membrane potential was measured with the membrane potential dye bis-oxonol, and hydraulic conductivity (Lp) of the vessels was measured by the modified Landis technique to follow changes in microvessel permeability. When microvessels were exposed to low-K+ (0.1 mM) Ringer solution, the membrane of the endothelial cells was hyperpolarized approximately 27 mV and [Ca2+]i increased from 47 nM to a peak value of 151 +/- 28 nM. Under the same experimental conditions, Lp increased to a peak 6.3 times control. In the presence of ionomycin (5 microM), the initial peak [Ca2+]i measured with low-K+ Ringer solution was 347 +/- 58 nM compared with 252 +/- 58 nM with ionophore and normal Ringer solution. The corresponding initial increases in Lp were 28 times control and 10 times control, respectively. The results conform to the hypothesis that vasoactive substances that hyperpolarize the endothelial cell membrane may initiate and/or potentiate the inflammatory response in venular microvessels.

scholarly journals Membrane depolarization is the trigger for PI3K/Akt activation and leads to the generation of ROS

2012 ◽  
Vol 302 (1) ◽  
pp. H105-H114 ◽  
Author(s):  
Shampa Chatterjee ◽  
Elizabeth A. Browning ◽  
NanKang Hong ◽  
Kris DeBolt ◽  
Elena M. Sorokina ◽  
...  
Keyword(s):  
Endothelial Cells ◽  
Cell Membrane ◽  
Fluid Shear Stress ◽  
Membrane Depolarization ◽  
Microvascular Endothelial Cells ◽  
Ros Generation ◽  
Ros Production ◽  
Akt Activation ◽  
Pulmonary Microvascular Endothelial Cells ◽  
Microvascular Endothelial

Loss of fluid shear stress (ischemia) to the lung endothelium causes endothelial plasma membrane depolarization via ATP-sensitive K+(KATP) channel closure, initiating a signaling cascade that leads to NADPH oxidase (NOX2) activation and ROS production. Since wortmannin treatment significantly reduces ROS production with ischemia, we investigated the role of phosphoinositide 3-kinase (PI3K) in shear-associated signaling. Pulmonary microvascular endothelial cells in perfused lungs subjected to abrupt stop of flow showed membrane depolarization and ROS generation. Stop of flow in flow-adapted mouse pulmonary microvascular endothelial cells in vitro resulted in the activation of PI3K and Akt as well as ROS generation. ROS generation in the lungs in situ was almost abolished by the PI3K inhibitor wortmannin and the PKC inhibitor H7. The combination of the two (wortmannin and H7) did not have a greater effect. Activation of NOX2 was greatly diminished by wortmannin, knockout of Akt1, or dominant negative PI3K, whereas membrane depolarization was unaffected. Ischemia-induced Akt activation (phosphorylation) was not observed with KATPchannel-null cells, which showed minimal changes in membrane potential with ischemia. Activation of Akt was similar to wild-type cells in NOX2-null cells, which do not generate ROS with ischemia. Cromakalim, a KATPchannel agonist, prevented both membrane depolarization and Akt phosphorylation with ischemia. Thus, Akt1 phosphorylation follows cell membrane depolarization and precedes the activation of NOX2. These results indicate that PI3K/Akt and PKC serve as mediators between endothelial cell membrane depolarization and NOX2 assembly.

Abstract 3640: Mitochondrial Uncoupling Protein 2 Facilitates Endothelial Cell Growth and Angiogenesis via Reduction of Mitochondrial Superoxide

Circulation ◽  
2008 ◽  
Vol 118 (suppl_18) ◽  
Author(s):  
Yukio Shimasaki ◽  
Kai Chen ◽  
John F Keaney
Keyword(s):  
Endothelial Cells ◽  
Endothelial Cell ◽  
Cell Growth ◽  
Mitochondrial Function ◽  
Endothelial Cell Proliferation ◽  
Wild Type ◽  
Sprouting Angiogenesis ◽  
Mitochondrial Superoxide ◽  
Endothelial Cell Growth ◽  
Aortic Explants

Background: Growing evidence suggests that mitochondrial function contributes to cell phenotype. One important component of mitochondrial function is the membrane potential that is controlled, in part, by uncoupling proteins (UCPs). Based on our previous data, the UCP2 is predominantly expressed in cultured endothelial cells. Therefore, we sought to examine the role of UCP2 in endothelial cell growth and angiogenesis. Methods and Results: Murine lung endothelial cells (MLECs) were isolated from UCP2-null and wild-type mice. UCP2-null cells were found less proliferative than wild-type cells (P<0.02, UCP2-null cells vs. wild-type cells, n=4). This defect of UCP2-null cells was rescued by UCP2 adenovirus transfection (19% increase, p<0.02 vs. LacZ adenovirus treated cells, n=3), and also rescued by transfection with manganese superoxide dismutase (MnSOD) adenovirus (53% increase, P<0.002 vs. LacZ adenovirus treated cells, n=3). We found a reciprocal relation such as no UCP2 expression and higher mitochondrial superoxide level in the MLECs (P<0.005, UCP2-null cells vs. wild-type cells, n=3), suggesting that mitochondrial superoxide may regulate endothelial cell growth. Then, we prepared murine aortic rings from UCP2-null and wild-type mice and embedded in rat tail collagen gel. The sprouting angiogenesis of UCP2-null explants was significantly less than wild-type explants (P<0.02, UCP2-null explants vs. wild-type explants, n=3– 4). Furthermore, MLECs from MnSOD-heterozygous mice showed less proliferation with lower expression of UCP2 protein and higher mitochondrial superoxide level compared to the MLECs from wild-type littermates (P<0.02, MnSOD-heterozygous cells vs. wild-type cells, n=4 – 8). We also observed less sprouting angiogenesis in MnSOD-heterozygous aortic explants than wild-type aortic explants (P<0.05, MnSOD-heterozygous explants vs. wild-type explants, n=3– 6). Conclusions: These data indicate that mitochondrial superoxide controls endothelial cell proliferation and angiogenesis, suggesting that mitochondrial metabolism modulates the endothelial cell growth and angiogenesis.

Possible usefulness of apocynin, an NADPH oxidase inhibitor, for nitrate tolerance: prevention of NO donor-induced endothelial cell abnormalities

2007 ◽  
Vol 293 (1) ◽  
pp. H790-H797 ◽  
Author(s):  
Akiko Fukatsu ◽  
Toshio Hayashi ◽  
Asaka Miyazaki-Akita ◽  
Hisako Matsui-Hirai ◽  
Yukie Furutate ◽  
...  
Keyword(s):  
Nitric Oxide ◽  
Endothelial Cells ◽  
Endothelial Cell ◽  
Nadph Oxidase ◽  
Oxidase Inhibitor ◽  
Nitrate Tolerance ◽  
Tolerance Development ◽  
No Donor ◽  
Nadph Oxidase Inhibitor ◽  
Free Interval

The long-term benefits of nitroglycerin therapy are limited by tolerance development. Understanding the precise nature of mechanisms underlying nitroglycerin-induced endothelial cell dysfunction may provide new strategies to prevent tolerance development. In this line, we tested interventions to prevent endothelial dysfunction in the setting of nitrate tolerance. When bovine aortic endothelial cells (BAECs) were continuously treated with nitric oxide (NO) donors, including nitroglycerin, over 2–3 days, basal production of nitrite and nitrate (NOx) was diminished. The diminished basal NOx levels were mitigated by intermittent treatment allowing an 8-h daily nitrate-free interval during the 2- to 3-day treatment period. Addition of the nicotinamide adenine dinucleotide phosphate (NADPH) oxidase inhibitor apocynin restored the basal levels of NOx that were decreased by continuous nitroglycerin treatment of BAECs. Apocynin caused significant improvement of increased mRNA and protein levels of endothelial nitric oxide synthase (eNOS) in BAECs given nitroglycerin continuously over the treatment period. Apocynin also reduced endothelial production of reactive oxygen species (ROS) after continuous nitroglycerin treatment. These results showed an essential similarity to the effects of a nitrate-free interval. Application of the NOS inhibitor Nω-nitro- l-arginine methyl ester caused a recovery effect on basal NOx and eNOS expression but was without effect on ROS levels in continuously NO donor-treated BAECs. In conclusion, the present study characterized abnormal features and functions of endothelial cells following continuous NO donor application. We suggest that inhibition of NADPH oxidase, by preventing NO donor-induced endothelial dysfunction, may represent a potential therapeutic strategy that confers protection from nitrate tolerance development.

Identification of an octamer element required for in vivo expression of the TIE1 gene in endothelial cells

2001 ◽  
Vol 360 (1) ◽  
pp. 23-29 ◽  
Author(s):  
Stephane C. BOUTET ◽  
Thomas QUERTERMOUS ◽  
Bahaa M. FADEL
Keyword(s):  
Endothelial Cells ◽  
Endothelial Cell ◽  
Molecular Mechanisms ◽  
Vascular Development ◽  
Common Mechanism ◽  
Tyrosine Kinase Receptor ◽  
Wild Type ◽  
Binding Studies ◽  
In Vivo Expression

TIE1, an endothelial-cell-specific tyrosine kinase receptor, is required for the survival and growth of microvascular endothelial cells during the capillary sprouting phase of vascular development. To investigate the molecular mechanisms that regulate the expression of TIE1 in the endothelium, we analysed transgenic mouse embryos carrying wild-type or mutant TIE1 promoter/LacZ constructs. Our data indicate that an upstream DNA octamer element (5′-ATGCAAAT-3′) is required for the in vivo expression of TIE1 in embryonic endothelial cells. Transgenic embryos carrying the wild-type TIE1 promoter (−466 to +78bp) fused to LacZ and spanning the octamer element demonstrate endothelial-cell-specific expression of the reporter transgene. Point mutations introduced within the octamer element result in a significant decrease of endothelial LacZ expression, suggesting that the octamer site functions as a positive regulator for TIE1 gene expression in endothelial cells. DNA–protein binding studies show that the octamer element exhibits an endothelial-cell-specific pattern of binding via interaction with endothelial-cell-restricted factor(s). Our findings suggest an important role for the octamer element in regulating the expression of the TIE1 receptor in the embryonic endothelium and suggest a common mechanism for the regulation of the angiogenic and cell-specific TIE1 and TIE2 genes during vascular development.

Epigallocatechin Gallate Reduces Homocysteine-Caused Oxidative Damages through Modulation SIRT1/AMPK Pathway in Endothelial Cells

2020 ◽  
pp. 1-17
Author(s):  
Pei-Ying Pai ◽  
Wan-Ching Chou ◽  
Shih-Hung Chan ◽  
Shu-Yih Wu ◽  
Hsiu-I Chen ◽  
...  
Keyword(s):  
Endothelial Cells ◽  
Endothelial Cell ◽  
Protein Kinase ◽  
Cell Apoptosis ◽  
Pathological Condition ◽  
Nicotinamide Adenine Dinucleotide Phosphate ◽  
Epigallocatechin Gallate ◽  
Sirtuin 1 ◽  
Ros Generation ◽  
Endothelial Cell Apoptosis

Elevated plasma concentration of total homocysteine is a pathological condition that causes vascular endothelial injury and subsequently leads to the progression of endothelial apoptosis in atherosclerosis. Epigallocatechin gallate (EGCG), a well-known anti-oxidant in green tea, has been reported with benefits on metabolic and cardiovascular diseases. This study aimed to explore that EGCG ameliorates homocysteine-induced endothelial cell apoptosis through enhancing the sirtuin 1 (SIRT1)/AMP-activated protein kinase (AMPK) survival signaling pathway. Human umbilical endothelial cells were treated with homocysteine in the presence or absence of EGCG. We found that EGCG significantly increased the activities of SIRT1 and AMPK. EGCG diminished homocysteine-mediated nicotinamide adenine dinucleotide phosphate (NADPH) oxidase activation by inhibiting protein kinase C activation as well as reactive oxygen species (ROS) generation and recovered the activity of the endogenous antioxidant enzyme, superoxidase dismutase (SOD). Besides, EGCG also restores homocysteine-mediated dephosphorylation of Akt and decreases endothelial NO synthase (eNOS) expression. Furthermore, EGCG ameliorates homocysteine-activated pro-apoptotic events. The present study shows that EGCG prevents homocysteine-induced endothelial cell apoptosis via enhancing SIRT1/AMPK as well as Akt/eNOS signaling pathways. Results from this study indicated that EGCG might have some benefits for hyperhomocysteinemia.

Effect of membrane potential on cytosolic calcium of bovine aortic endothelial cells

1989 ◽  
Vol 257 (3) ◽  
pp. H778-H784 ◽  
Author(s):  
W. P. Schilling
Keyword(s):  
Endothelial Cells ◽  
Membrane Potential ◽  
Cytosolic Calcium ◽  
Membrane Depolarization ◽  
K Channel ◽  
Membrane Hyperpolarization ◽  
Aortic Endothelial Cells ◽  
Bovine Aortic Endothelial Cells ◽  
K Concentration ◽  
Aortic Endothelial

The effect of bradykinin on membrane potential of cultured bovine aortic endothelial cells (BAECs) was estimated by measuring the uptake of the lipophilic cation, tetra[3H]phenylphosphonium ([3H]TPP+). Uptake of [3H]TPP+ was found to be 1) a function of extracellular K+ concentration, 2) sensitive to valinomycin, and 3) decreased by the K+ channel inhibitor, Ba2+, suggesting that the uptake of [3H]TPP+ responds to changes in membrane potential of the BAEC. Bradykinin (50 nM) produced an increase in [3H]TPP+ uptake in low K+ buffer consistent with a bradykinin-induced membrane hyperpolarization. The effect of membrane depolarization with high K+ buffer on the bradykinin-stimulated changes in cytosolic Ca2+ was determined using the fluorescent Ca2+ indicator, fura-2. The results of these experiments demonstrated that both basal cytosolic Ca2+ and bradykinin-stimulated release of Ca2+ from internal stores were not affected by membrane depolarization. However, bradykinin-stimulated influx of Ca2+ from the extracellular space decreased with membrane depolarization in a manner consistent with the movement of Ca2+ through a channel.

scholarly journals Downregulation of Endogenous Hydrogen Sulfide Pathway Is Involved in Mitochondrion-Related Endothelial Cell Apoptosis Induced by High Salt

2015 ◽  
Vol 2015 ◽  
pp. 1-11 ◽  
Author(s):  
Yanfang Zong ◽  
Yaqian Huang ◽  
Siyao Chen ◽  
Mingzhu Zhu ◽  
Qinghua Chen ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Endothelial Cells ◽  
Membrane Potential ◽  
Endothelial Cell ◽  
Cell Apoptosis ◽  
Superoxide Anion ◽  
Mitochondrial Membrane ◽  
Caspase 3 ◽  
High Salt ◽  
Caspase 9

Background. The study aimed to investigate whether endogenous H2S pathway was involved in high-salt-stimulated mitochondria-related vascular endothelial cell (VEC) apoptosis.Methods. Cultured human umbilical vein endothelial cells (HUVECs) were used in the study. H2S content in the supernatant was detected. Western blot was used to detect expression of cystathionine gamma-lyase (CSE), cleaved-caspase-3, and mitochondrial and cytosolic cytochrome c (cytc). Fluorescent probes were used to quantitatively detect superoxide anion generation and measure thein situsuperoxide anion generation in HUVEC. Mitochondrial membrane pore opening, mitochondrial membrane potential, and caspase-9 activities were measured. The cell apoptosis was detected by cell death ELISA and TdT-mediated dUTP nick end labeling (TUNEL) methods.Results. High-salt treatment downregulated the endogenous VEC H2S/CSE pathway, in association with increased generation of oxygen free radicals, decreased mitochondrial membrane potential, enhanced the opening of mitochondrial membrane permeability transition pore and leakage of mitochondrial cytc, activated cytoplasmic caspase-9 and caspase-3 and subsequently induced VEC apoptosis. However, supplementation of H2S donor markedly inhibited VEC oxidative stress and mitochondria-related VEC apoptosis induced by high salt.Conclusion. H2S/CSE pathway is an important endogenous defensive system in endothelial cells antagonizing high-salt insult. The protective mechanisms for VEC damage might involve inhibiting oxidative stress and protecting mitochondrial injury.

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