Martentoxin, a large-conductance Ca^(2+)-activated K^+ channel inhibitor, attenuated TNF-α-induced nitric oxide release by human umbilical vein endothelial cells

Martentoxin, a 4,046 Da polypeptide toxin purified from the venom of the scorpion Buthus martensii Karsch, has been demonstrated to block large-conductance Ca2＋-activated K＋ （BKca） channels; however, its biological roles are still largely unknown. In the present study, we investigated the pharmacological effects of martentoxin on regulating the production of nitric oxide induced by TNF-a in human umbilical vein endothelial cells （HU- VECs）. We found that, 1, 10 and 100 ~tmol/L martentoxin decreased nitric oxide production by HUVECs ex- posed to 10 ng/mL TNF for 6, 12 and 24 hours. We further demonstrated that martentoxin inhibited the activity of iNOS and retarded the down-regulation of eNOS mRNA induced by TNF-a. Therefore, martentoxin could be a potential therapeutic agent for vascular diseases.

Effect of IBD sera on expression of inducible and endothelial nitric oxide synthase in human umbilical vein endothelial cells

AIM： To study the expression of endothelial and inducible nitric oxide synthases （eNOS and iNOS） and their role in inflammatory bowel disease （IBD）. METHODS： We examined the effect of sera obtained from patients with active Crohn＇s disease （CD） and ulcerative colitis （UC） on the function and viability of human umbilical vein endothelial cells （HUVEC）. HUVECs were cultured for 0-48 h in the presence of a medium containing pooled serum of healthy controls, or serum from patients with active CD or UC. Expression of eNOS and iNOS was visualized by immunofluorescence, and quantified by the densitometry of Western blots. Proliferation activity was assessed by computerized image analyses of Ki-67 immunoreactive cells, and also tested in the presence of the NOS inhibitor, 10^-4 mol/L L-NAME. Apoptosis and necrosis was examined by the annexin-V-biotin method and by propidium iodide staining, respectively. RESULTS： In HUVEC immediately after exposure to UC, serum eNOS was markedly induced, reaching a peak at 12 h. In contrast, a decrease in eNOS was observed after incubation with CD sera and the eNOS level was minimal at 20 h compared to control （18%±16% vs 23%± 15% P〈0.01）. UC or CD serum caused a significant increase in iNOS compared to control （UC： 300%±21%; CD： 275% ± 27% vs 108% ± 14%, P〈0.01）. Apoptosis/necrosis characteristics did not differ significantly in either experiment. Increased proliferation activity was detected in the presence of CD serum or after treatment with L-NAME. Cultures showed tube-like formations after 24 h treatment with CD serum. CONCLUSION： IBD sera evoked changes in the ratio of eNOS/iNOS, whereas did not influence the viability of HUVEC. These involved down-regulation of eNOS and up-regulation of iNOS simultaneously, leading to increased proliferation activity and possibly a reduced antiinflammatory protection of endothelial cells.

Endothelial nitric oxide synthase deficiency influences normal cell cycle progression and apoptosis in trabecular meshwork cells

AIM： To clarify how the endothelial nitric oxide synthase （eNOS, NOS3） make effect on outflow facility through the trabecular meshwork （TM）. METHODS： Inhibition of NOS3 gene expression in human TM cells were conducted by three siRNAs. Then the mRNA and protein levels of NOS3 in siRNA-treated and negative control （NC） cells were determined, still were the collagen, type IV, alpha 1 （COL4A1） and fibronectin 1 by real-time PCR and Western blot analysis. In addition, NOS3 concentrations in culture supernatant fluids of TM cells were measured. Cell cycle and cell apoptosis analysis were performed using flow cytometry. RESULTS： The mRNA level of NOS3 was decreased by three different siRNA interference, similar results were obtained not only of the relative levels of NOS3 protein, but also the expression levels of COL4A1 and fibronectin 1. The number of cells in S phase was decreased, while contrary result was obtained in G2 phase. The number of apoptotic cells in siRNA-treated groups were significant increased compared to the NC samples. CONCLUSION： Abnormal NOS3 expression can make effects on the proteins levels of extracellular matrix component （e.g. fibronectin 1 and COL4A1）. Reduced NOS3 restrains the TM cell cycle progression at the G2/ M-phase transition and induced cell apoptosis.

Changes in Human Umbilical Vein Endothelial Cells Induced by Endothelial Nitric Oxide Synthase Traffic Inducer

This study investigated the changes in human umbilical vein endothelial cells （HUVECs） induced by overexpression of endothelial nitric oxide synthase traffic inducer （NOSTRIN） and its role in cellular injury. Recombinant NOSTRIN-expressing and empty vectors were transfected into cultured HUVECs, and factor Ⅷ-related antigen was examined by using immunohistochemical analysis. Growth curves were generated for both transfected and untransfected cells and these indicated that the prolifera- tive ability of cells overexpressing NOSTRIN was significantly decreased. The expression of NOSTRIN and eNOS proteins was detected by using Western blot analysis, endothelial NOS （eNOS） activity was assayed by using spectrophotometry, and NO2-/NO3- levels were measured usin~ nitrate reductase. Immunohistochemical analysis demonstrated that all groups expressed NOSTRIN in the plasma mem- brane and cytoplasm, and Western blot analysis confirmed that NOSTR1N levels were significantly higher in cells transfected with the NOSTR1N plasmid （P〈0.01）. The activity of eNOS and the levels of NO2-/NO3 were significantly decreased in NOSTRIN overexpressing cells as compared with empty vector and untransfected cells （P〈0.01 and P〈0.01, respectively）. Morphological and ultrastructural changes were observed under light and electron microscopy, and it was found that NOS- TRIN-overexpressing cells were elongated with deformities of the karyotheca, injury to the plasma membrane, increased lipids in the cytoplasm, and shortened microvilli. This study showed that overex- pression of NOSTRIN had a significant effect on eNOS activity in HUVECs and resulted in significant cellular damage.

Effects of rotational culture on morphology,nitric oxide production and cell cycle of endothelial cells

Devices for the rotational culture of cells and the study of biological reactions have been widely applied in tissue engineering.However,there are few reports exploring the effects of rotational culture on cell morphology,nitric oxide(NO)production,and cell cycle of the endothelial cells from human umbili-cal vein on the stent surface.This study focuses on these parameters after the cells are seeded on the stents.Results showed that covering of stents by endothelial cells was improved by rotational culture.NO produc-tion decreased within 24 h in both rotational and static culture groups.In addition,rotational culture signifi-cantly increased NO production by 37.9%at 36 h and 28.9%at 48 h compared with static culture.Flow cytometry showed that the cell cycle was not obviously influenced by rotational culture.Results indicate that rotational culture may be helpful for preparation of cell-seeded vascular grafts and intravascular stents,which are expected to be the most frequently implanted materials in the future.

Shear stress effect on endothelial nitric oxide synthase in cultured human umbilical vein endothelial cells

Background: Low shear stress caused by disturbed or turbulent flow at arterial branch points is known to associate with atherosclerosis. However, shear stress at the venous valve location and its association with deep vein thrombosis are less understood due to the complex and poorly understood bi-directional flow in the valve pocket region. We investigated how venous endothelial cells respond to flow shear stress around the venous valve region using a novel in vitro system that mimics venous flow. Results: Human umbilical vein EAhy. 926 cells were cultured on a flexible silastic membrane that mimicked venous tissue. Confluent cells were exposed to sinusoidal uni-and bi-directional pulsatile shear stress (0.1 to 1 dyne/cm2) for up to 6 h. Western-blot analyses indicated that endothelial nitric oxide (eNOS) expression levels decreased regardless of all tested flow patterns, stress magnitude, and shearing time. In contrast, the expression levels of inhibitor of κB (kappa B) and α (alpha)-tubulin were unaffected by the shear stress. Conclusions: Our results indicate that shear stress causes a decrease specifically in eNOS expression, suggesting that it may play a significant role in regulating inflammation related protein expression in endothelial cells.

INSULIN INDUCES NITRIC OXIDE PRODUCTION IN BOVINE AORTIC ENDOTHELIAL CELLS

Objective To examine the effects of insulin on cell proliferation, nitric oxide (NO) release and nitric oxide synthase (NOS) gene expression in bovine aortic endothelial cells ( BAEC ) . Methods The mi togenesis was assessed by MTT method; the products of NO in the culture media, by Griess reaction; and the levels of NOS mRNA in BAEC , by RT/PCR tech nique. Results BAEC were not responsive to the growth-promoting effects of insulin. Stimulation with insulin resulted a dose-dependent rise of NO in the culture supernatants 2h later, with a maximum at 12～24h and a decline at 24h. This rise was inhibited by an inhibitor of NOS (L-NAME). NOS mRNA increased slightly in BAEC without statistical significance. Conelu sion The study suggested that the insulin-induced NO release might be caused directly by NOS activation.

Simvastatin Increases the Activity of Endothelial Nitric Oxide Synthase via Enhancing Phosphorylation

3-hydroxy-3-methylgulutaryl-coenzyme A （HMG-CoA） reductase inhibitors or statins are a kind of lipid-lowering agents and have been used for the prevention and treatment of Cardiovascular diseases. Recent studies suggested that statins, besides lowering cholesterol, may protect vessels by enhancing the activity of endothelial nitric oxide synthase （eNOS）. In the present study, we investigated if simvastatin increases eNOS activity through its phosphorylation in 293 cells （293-eNOS） with stable expression of eNOS. The results showed that incubation of 293-eNOS cells with simvastatin （10 μm/L） for 2 h significantly increased in the activity of eNOS as shown by the conversion of L-arginine to L-citrulline （2889.70±201.51 versus 5630.18＋218.75 pmol/min . mg proteins） （P〈0.01）. Western blotting revealed that simvastatin increased phosphorylation of eNOS at 1177 （ser） and also 495 （thr） but did not affect the overall expression of eNOS or inducible NOS. Further study found that simvastatin raised phosphorylation levels of Akt and AMPK, and such effect could be antagonized by Akt inhibitor or AMPK inhibitor. These results suggest that simvastatin could stimulate,the activity of eNOS via its phosphorylation by Akt and AMPK, which provides a new mechanism, other than lipid-lowering effect, for the cardiovascular protection of statins.

Prednisolone inhibits SaOS2 osteosarcoma cell proliferation by activating inducible nitric oxide synthase

AIM:To investigate the effect of prednisolone,a synthetic glucocorticoid used in inflammatory diseases,on the growth of cultured osteosarcoma cells.METHODS:Two osteosarcoma cell lines with different degree of differentiation were used.SaOS2 show a rather mature phenotype,while U2 OS are negative for almost all osteoblastic markers.The cells were exposed to different concentrations of prednisolone(1-9 μmol/L) with or without antioxidants or the inhibitor of inducible nitric oxide synthase(i NOS) l-N6-(iminoethyl)-lysine-HCl(L-NIL).Cell growth was assessed by counting viable cells.The production of nitric oxide(NO) was measured in the conditioned media by the Griess method.The production of reactive oxygen species was quantified using 2'-7'-dichlorofluorescein diacetate.Western blot with specific antibodies against NOSs was performed on cell extracts.RESULTS:Prednisolone inhibited SaOS2 cell growth in a dose dependent manner.No significant effects were observed in U2OS.The inhibition of SaOS2 growth is not due to oxidative stress,because antioxidants do not rescue cell proliferation.Since high concentrations of NO inhibit bone formation,we also measured NO and found it induced in SaOS2,but not in U2 OS,exposed to prednisolone,because of the upregulation of i NOS as detected by western blot.Therefore,we treated SaOS2 with prednisolone in the presence or in the absence of L-NIL.L-NIL prevented NO release induced by prednisolone at all the concentrations apart from 9 μmol/L.At the same concentrations,we found that L-NIL rescued SaOS2 growth after exposure to prednisolone.In U2 OS cells,prednisolone did not induce NO production nor affected cell growth.All together,these data indicate that a link exists between increased amounts of NO and growth inhibition in response to prednisolone in SaOS2.CONCLUSION:Prednisolone inhibited SaOS2 proliferation by increasing the release of NO through the upregulation of i NOS,while no effect was exerted on U2OS.

Dexamethasone, tetrahydrobiopterin and uncoupling of endothelial nitric oxide synthase

Objective To find out whether dexamethasone induces an uncoupling of the endothelial nitric oxide synthase （eNOS）. Methods ＆ Results A major cause of eNOS uncoupling is a deficiency of its cofactor tetrahydrobiopterin （BH4）. Treatment of human EA.hy 926 endothelial cells with dexamethasone decreased mRNA and protein expression of both BH4-synthesizing enzymes： GTP cyclobydrolase I and dihydrofolate reductase. Consistently, a concentration- and time-dependent reduction of BH4, dihydrobiopterin （BH2） as well as BH4：BH2 ratio was observed in dexamethasone-treated cells. Surprisingly, no evidence for eNOS uncoupling was found. We then analyzed the expression and phosphorylation of the eNOS enzyme. Dexamethasone treatment led to a down-regulation of eNOS protein and a reduction of eNOS phosphorylation at serine 1177. A reduction of eNOS expression may lead to a relatively normal BH4： eNOS molar ratio in dexamethasone-treated cells. Because the BH4-eNOS stoichiometry rather than the absolute BH4 amount is the key determinant of eNOS functionality （i.e., coupled or uncoupled）, the down-regulation of eNOS may represent an explanation for the absence of eNOS uncoupling. Phosphorylation of eNOS at serine 1177 is needed for both the NO-producing activity of the coupled eNOS and the superoxide-producing activity of the uncoupled eNOS. Thus, a reduction of serine 1177 phosphorylation may render a potentially uncoupled eNOS hardly detectable. Conclusions Although dexamethasone reduces BH4 levels in endothelial cells, eNOS uncoupling is not evident. The reduction of NO production in dexamethasone-treated endothelial cells is mainly attributable to reduced eNOS expression and decreased eNOS phosphorylation at serine 1177.

Protective effects of icariin on human umbilical vein endothelial cell injured by angiotensin Ⅱ

To investigate the effects of icariin （ICA） on angiotensin Ⅱ（Ang Ⅱ）-induced injury in human umbilical vein endothelial cells line （ECV-304）. The ECV-304 cells were cultured in vitro. After 24 h incubating with icariin, the model of AngⅡ-induced injury in ECV-304 was established. The cell viability （MTT method）, Lactate dehydrogenase （LDH） release and Nitric oxide （NO） production in the medium, the capacity of scavenging superoxide anion radicals （O2^-） and hydroxyl radicals （.OH） were measured. The activities of superoxide dismutase （SOD）, total nitric oxide synthase （T-NOS）, inducible nitric oxide synthase （iNOS） and constitutive nitric oxide synthase （cNOS） in the cells were determined. Compared with the Ang Ⅱ-treated group, ICA can significantly raise the viability of EC, increase the activities of SOD, T-NOS and cNOS, increase the production of NO, enhance the capacity of scavenging superoxide anion radicals （ O2^- ） and hydroxyl radicals（.OH）, and lower LDH leakage and iNOS activity. The results suggest that ICA can protect endothelial cells （ECV-304） from Ang II-induced injury.

Angiotensin Ⅱ promotes NO production, inhibits apoptosis and enhances adhesion potential of bone marrow-derived endothelial progenitor cells

Endothelial progenitor cells （EPCs） participate in the processes of postnatal neovascularization and re-endothelialization in response to tissue ischemia and endothelial injury. The level of EPCs present has been found to be directly associated with the outcome of cardiovascular diseases, and could be regulated by stimulatory or inhibitory factors. Given the close relationship between angiotensin Ⅱ （AngⅡ） and the cardiovascular＇ system, we investigated the effect of AngⅡ on the activities of bone marrow （BM）-derived EPCs. Cells were isolated from BM of rats by density gradient centrifugation. Administration of AngⅡ significantly promoted nitric oxide （NO） release, inhibited EPC apoptosis and enhanced EPC adhesion potential. All of these AngⅡ-mediated effects on EPCs were attenuated by pretreatment with valsartan or L-NAME. Moreover, both LY294002 and wortmannin abolished the anti-apoptotic effect of AngⅡ. Western blot analyses indicated that endothelial NO synthase （eNOS） protein and phosphorylated Akt increased with the treatment of AngⅡ in EPCs. Thus, AngⅡ improved several activities of EPCs through AngⅡ type 1 receptor （AT1R）, which may represent a possible mechanism linking AnglI and ATIR with angiogenesis. Additionally, AngⅡ-induced NO synthesis through eNOS in EPCs regulates apoptosis and adhesion, and the PI3-kinase/Akt pathway has an essential role in AngⅡ-induced antiapoptosis signaling.

Role of p38 MAPK in lipopolysaccharide-induced iNOS expression by endothelial cells

Objective:To examine the role of p38 mitogen-activated protein kinase (MAPK) in NO production and Inos expression in human endothelial cells stimulated by lipopolysaccharide (LPS). Methods: The NO level in the supernatant of the cell culture media was measured with Griess method, expressions of Inos protein and Mrna in vitro cultured endothelial cell line ECV304 were detected with immunofluorescence analysis and reverse transcriptase-PCR respectively. Immunokinase assay was employed to measure P38mapk activity. Results: Compared with the basal level of Inos expression and NO production, the NO level and the expressions of Inos Mrna and protein in the cells were increased after LPS stimulation. P38mapk activity in ECV304 cells exhibited a marked increase at 15 min after LPS stimulation, lasting for about 45 min before gradually decline. The Inos protein and Mrna expressions induced by LPS stimulation was significantly inhibited by SB203580 [4-(4-fluorophenyl)-2-(4- methylsulfinylphenyl)-5-(4-pyridyl) imidazole], a highly specific inhibitor of p38 MAPK. Conclusion: p38 MAPK plays an important role in iNOS expression and NO production in ECV304 cells, and the inhibition of the signal transduction pathway can be effective to reduce the production of iNOS and other cytokines, and therefore constitutes a useful strategy for treating septic shock or inflammation.

A Decreased Responsiveness of Platelet to Nitric Oxide in Cholesterol-Fed Rabbits

Objective:To determine whether endothelial dysfunction leads to an abnormal responsiveness of platelet to nitric oxide(NO)during the development of atherosclerosis. Methods:Rabbits were fed a 1% cholesterol chow for 12 weeks to induce atherosclerosis.Serum NOx levels and the responsiveness of platelet to NO donor SNP were determined every 4 weeks during maintaining on a chow containing 1% cholesterol.The measurement of serum lipids and the examination of morphological feature and endothelial-dependent relaxation of aorta were performed after 12 weeks of cholesterol diet. Results:Cholesterol diet significantly increased serum levels of cholesterol and LDL,caused a remarkable platelet hyperaggregability,and produced an evident endothelial dysfunction as indicated by the diminished vasorelaxation induced by acetylcholine and endothelial cell lesion as exhibited by scanning electron microscope examination.The percentage of inhibition of ADP-induced platelet aggregation by NO donor SNP was significantly smaller in cholesterol chow group than that in normal chow group although no significant difference in serum NOx levels between normal and cholesterol chow group was observed throughout the development of atherosclerosis. Conclusion:The present study suggests that the endothelial dysfunction caused by enhanced serum cholesterol and LDL levels induces a decreased responsiveness of platelet to NO.

Effects of laminar shear stress versus resveratrol on the citrulline-NO cycle in endothelial cells

Laminar shear stress (LSS) due to pulsatile blood flow enhances endothelial function by multiple mechanisms including NO production. Red wine and its constituent, resveratrol, have also been postulated to provide vascular protective effects. The aim of the present study was to compare the effects of mechanical LSS and pharmacological resveratrol treatments on the endothelial citrulline-NO cycle. Human umbilical vein endothelial cells (HUVECs) were treated with LSS (12 dyn·cm-2) or resveratrol (25 - 100 μM). The expressions of argininosuccinate synthetase 1 (ASS1), argininosuccinate lyase (ASL), nitric oxide synthase 3 (NOS3) and cationic amino acid transporter 1 (CAT1), and the production of NO were determined. The expressions of Kruppel-like factor (KLF) 2 and KLF4 as upstream regulators of ASS1 and NOS3 were also analyzed. LSS strongly increased the mRNA levels of ASS1 (8.3 fold) and NOS3 (5.4 fold) without significant effects on ASL and CAT1 mRNAs. Resveratrol increased the ASS1 mRNA level in a dose-dependent manner up to 3.8 fold at 100 μM. The effects of resveratrol on the expressions of KLF2 and KLF4 mRNAs were smaller than those of LSS. Protein levels of ASS1 and NOS3, and NO production were markedly increased by LSS but resveratrol (50 μM) increased only ASS1 protein level. The results of the current study showed that LSS had greater effects on the citrulline-NO cycle activity leading to NO production, compared to resveratrol. Because resveratrol was not so effective at stimulating the endothelial citrulline-NO cycle, further studies are needed to find more potent drugs that increase the expression of ASS1 and NOS3 genes.

基于NOD样受体3炎性小体通路对利拉鲁肽在氧化低密度脂蛋白诱导内皮细胞损伤的作用机制研究

背景动脉粥样硬化是世界范围内引起心脑血管疾病最主要的原因,炎症是目前研究热点,其中NOD样受体3(NLRP3)是研究最为深入的炎症小体。胰高糖素样肽1(GLP-1)受体激动剂有抗动脉粥样硬化作用,具体机制尚不明确。目的研究利拉鲁肽通过拮抗氧化低密度脂蛋白(ox-LDL)诱导的内皮细胞损伤的作用机制。方法2022-03-25—05-19培养人脐静脉内皮细胞(HUVEC),取HUVEC加空白血清作为对照组,100μg/mL的ox-LDL干预HUVEC 48 h作为模型组,100μg/mL的ox-LDL干预HUVEC 24 h后分别加入100、200、400 nmol/L利拉鲁肽处理24 h作为利拉鲁肽低浓度组、利拉鲁肽中浓度组、利拉鲁肽高浓度组。CCK-8法计算细胞增殖率。通过扫描电镜观察焦亡细胞形态。检测乳酸脱氢酶(LDH)活力。酶联免疫吸附试验(ELISA)检测白介素(IL)-1β、IL-18表达水平。蛋白质免疫印迹试验(Western blot)检测NLRP3、接头蛋白凋亡相关斑点样蛋白(ASC)、天冬氨酸蛋白水解酶1(Caspase-1)、焦亡执行蛋白(GSDMD)、N端结构域的焦亡执行蛋白(N-GSDMD)表达水平。结果模型组、利拉鲁肽低浓度组和利拉鲁肽中浓度组细胞增殖率低于对照组,利拉鲁肽低浓度组、利拉鲁肽中浓度组、利拉鲁肽高浓度组细胞增殖率高于模型组(P<0.05)。细胞扫描电镜结果示模型组细胞焦亡明显,利拉鲁肽低浓度组、利拉鲁肽中浓度组、利拉鲁肽高浓度组细胞焦亡情况明显改善。模型组、利拉鲁肽低浓度组LDH活力高于对照组,利拉鲁肽低浓度组、利拉鲁肽中浓度组、利拉鲁肽高浓度组低于模型组(P<0.05)。模型组、利拉鲁肽低浓度组IL-1β表达水平高于对照组,利拉鲁肽中浓度组、利拉鲁肽高浓度组IL-1β表达水平低于模型组(P<0.05);模型组IL-18表达水平高于对照组,利拉鲁肽低浓度组、利拉鲁肽中浓度组、利拉鲁肽高浓度组IL-18表达水平低于模型组(P<0.05)。模型组NLRP3、ASC、Caspase-1、GSDMD、N-GSDMD表达水平高于对照组,利拉鲁肽低浓度组ASC、Caspase-1表达水平高于对照组,利拉鲁肽中浓度组NLRP3、ASC表达水平低于模型组,利拉鲁肽高浓度组NLRP3、ASC、Caspase-1表达水平低于模型组(P<0.05)。结论利拉鲁肽显著抑制ox-LDL诱导的内皮细胞NLRP3炎性小体活化,并且能够抑制内皮细胞的焦亡,具有抗动脉粥样硬化作用。

Role of PERK/eIF2α/CHOP Endoplasmic Reticulum Stress Pathway in Oxidized Low-density Lipoprotein Mediated Induction of Endothelial Apoptosis

Objective PERK/elF2/CHOP is a major signaling pathway mediating endoplasmic reticulum （ER） stress related with atherosclerosis. Oxidized LDL （ox-LDL） also induces endothelial apoptosis and plays a vital role in the initiation and progression of atherosclerosis. The present study was conducted to explore the regulatory effect of ox-LDL on PERK/elF2a/CHOP signaling pathway in vascular endothelial cells. Methods The effects of ox-LDL on PERK and p-elF2a protein expression of primary human umbilical vein endothelial cells （HUVECs） were investigated by Western blot analysis. PERK gene silencing and selective elF2a phosphatase inhibitor, salubrinal were used to inhibit the process of ox-LDL induced endothelial cell apoptosis, caspase-3 activity, and CHOP mRNA level. Results Ox-LDL treatment significantly increased the expression of PERK, PERK-mediated inactivation of elF2a phosphorylation, and the expression of CHOP, as well as the caspase-3 activity and apoptosis. The effects of ox-LDL were markedly decreased by knocking down PERK with stable transduction of lentiviral shRNA or by selective elF2a phosphatase inhibitor, salubrinal. Conclusion This study provides the first evidence that ox-LDL induces apoptosis in vascular endothelial cells mediated largely via the PERK/elF2a/CHOP ER-stress pathway. It adds new insights into the molecular mechanisms underlying the pathogenesis and progression of atherosclerosis.

The hepatic sinusoidal endothelial lining and colorectal liver metastases

Colorectal cancer (CRC) is a common malignant disease and the severe nature of cases in men and women who develop colorectal cancer makes this an important socio-economic health issue. Major challenges such as understanding and modeling colorectal cancer pathways rely on our understanding of simple models such as outlined in this paper. We discuss that the development of novel standardized approaches of multidimensional (correlative) biomolecular microscopy methods facilitates the collection of (sub) cellular tissue information in the early onset of colorectal liver metastasis and that this approach will be crucial in designing new effective strategies for CRC treatment. The application of X-ray micro-computed tomography and its potential in correlative imaging of the liver vasculature will be discussed.

INHIBITION OF NITRIC OXIDE SYNTHESIS INCREASES THE SECRETION OF ENDOTHELIN-1 IN VIVO AND IN CULTURED ENDOTHELIAL CELLS

The aim of this study is to investigate the effects of nitric oxide, formed from L-arginine, on the production of endothelin?1 in vivo and in cultured endothelial cells. In mechanically ventilated anesthetized dogs (n = 5), mean pulmonary arterial pressure (PAPm) and pulmonary vascular resistance (PVR) during hypoxic ventilation (FIO2 = 0.10) was 25 ?3.1 kPa and 68.7 ?10.2 kPa.s / L respectively. IG-nitro-L-arginine methylester (L-NAME), an inhibitor of nitric oxide synthase, increased the peak value of PAPm and PVR during hypoxic ventilation to 36.6 ?4.7 kPa and 158.4 ?25 kPa.s / L and its effect lasted for 2-3 hours. Meanwhile, plasma endothelin? level in the femoral artery increased by 20.9+ 7.1, 25.6?7.7, 28.6?7.9 pg / ml at the 60 th, 120th, 180th minute after the injection of L-NAME respectively (P<0.05 vs hypoxic control before the injection). In cultured endothelial cells from umbilical veins, endothelin-1 level of culture medium in control group was 35.1 ?.9 pg / 105 cells /ml (n=9). L-NAME increased endothelin-1 level to 42.8 ?4.9pg / 105 cells / ml (n = 9, P < 0.05) in case of 10-11 mol / L and to 43.0+ 4.7 pg / 105 cells / ml in case of 10 -7 mol/L (n=9, F<0.05). These findings indicate that endogenous nitric oxide is an inhibitory modulator of hypoxic pulmonary vasoconstriction and that nitric oxide inhibits the production of endothelin? in vivo and in cultured vascular endothelial cells.