香草素受体4型瞬时感受器电位通道及其抑制剂与相关呼吸系统疾病关系的研究进展

香草素受体4型瞬时感受器电位(TRPV4)通道是瞬时感受器电位通道家族成员之一,是一种对钙离子具有选择通透性的阳离子通道。该通道激活后可引起胞内钙离子浓度升高,进而参与调节机体多种生理或病理过程。近年来大量文献表明,TRPV4通道可能与多种呼吸系统疾病的发病机制有关,包括急性肺损伤、慢性阻塞性肺疾病、肺动脉高压、特发性肺纤维化和哮喘等,TRPV4抑制剂的应用可不同程度地缓解上述疾病进展。本文对TRPV4通道及其抑制剂与有关呼吸系统疾病关系的研究进展予以综述。     

缝隙连接及其连接蛋白对血管加压素诱导的失血性休克大鼠血管收缩的作用研究

摘要：目的 观察缝隙连接（GJ）及其组成亚单位连接蛋白（Cx）在血管加压素（AVP）诱导失血性休克大鼠血管收缩中的作用。方法 采用失血性休克大鼠模型和缺氧培养血管平滑肌细胞（VSMC）,观察GJ阻断剂CBX和octanol、以及各Cx亚型反义寡核苷酸（AODN）对AVP诱导的血管收缩反应的影响,随后进一步观察参与AVP作用的Cx37和Cx43对AVP调节休克血管钙敏感性和缺氧VSMC内钙离子浓度的影响。结果 GJ阻断剂CBX和octanol明显抑制了AVP诱导的休克血管的收缩反应。在所有血管中表达的连接蛋白中,Cx37AODN和Cx43AODN明显抑制了AVP的血管收缩作用。进一步结果显示,Cx43AODN、而不是Cx37AODN,可拮抗AVP升高休克血管钙敏感性的作用。此外, AVP处理和干扰Cx37及Cx43对缺氧VSMC内钙离子浓度无明显影响。结论 缝隙连接在休克后AVP介导的血管收缩调节中有重要作用,Cx37和Cx43参与了这一过程,其中Cx43可能通过影响AVP介导的血管钙敏感性调节途径来发挥作用,而Cx37可能通过其它机制来参与AVP的血管调节作用。     

丙戊酸钠对烧伤休克大鼠肺微血管内皮细胞活化和通透性的影响

目的观察组蛋白去乙酰化酶抑制剂丙戊酸钠（VPA）对大鼠50%TBSAⅢ度烧伤休克模型肺微血管内皮细胞（PMEC）活化和通透性的影响。方法雄性SD大鼠随机分为4组：假烫组,烫伤组（给予50%TBSAⅢ度烫伤）,烫伤＋VPA组及烫伤＋2M2P组（烫伤后即刻皮下注射VPA 300 mg/kg或对照药物2-甲基-2-戊烯酸,即2M2P300 mg/kg）。分别于烫伤后2 h、6 h及12 h,伊文斯蓝（EB）染色法检测肺血管通透性;采血检测红细胞压积（HCT）及脏器功能指标;HE染色观察肺组织病理变化,干湿重法检测肺组织含水率;免疫组化法检测肺组织血管内皮细胞生长因子（VEGF）、E-选择素（E-selectin）和细胞间黏附分子-1（ICAM-1）的表达;TUNEL法检测肺微血管内皮细胞（PMEC）凋亡率。结果与烫伤组比较,伤后2 h及6 h烫伤＋VPA组和烫伤＋2M2P组血HCT和肺组织含水率降低,肺血管通透性明显降低（P〈0.05）,肺水肿等病理改变减轻;烫伤＋VPA组PMEC凋亡率低于烫伤＋2M2P组（P〈0.05）。烫伤＋VPA组VEGF、E-selectin、ICAM-1阳性率均显著低于烫伤组和烫伤＋2M2P组（P〈0.05）。结论 VPA能抑制烧伤休克大鼠肺血管内皮细胞的活化以及凋亡,从而减少血管通透性增加引起的血容量丢失。     

柚皮苷通过减轻氧化应激降低急性肺损伤小鼠内皮通透性的研究

目的 研究柚皮苷对脂多糖（LPS）诱导的小鼠急性肺损伤模型肺微血管内皮通透性及气道炎症的改善作用。方法 将66只C57BL/6雄性小鼠随机分为对照组、模型组、地塞米松组及柚皮苷40、80、120 mg/kg组,每组11只。对照组小鼠正常饲养;模型组和给药组小鼠麻醉后给予LPS滴鼻,每只小鼠滴鼻50 μL。柚皮苷40、80、120 mg/kg组和地塞米松5 mg/kg组在LPS滴鼻前分别ig相应剂量的柚皮苷和地塞米松,连续给药5 d,滴鼻后继续ig相应剂量的柚皮苷和地塞米松,连续给药2 d。对照组和模型组同时间ig 0.2 mL生理盐水。苏木精–伊红（HE）染色观察肺实质病理变化;血常规分析仪检测血液及肺泡灌洗液淋巴细胞、中性粒细胞、血细胞、血小板数量;ELISA检测肺泡灌洗液白细胞介素（IL）-1β、IL-6、肿瘤坏死因子-α（TNF-α）含量和血清内皮素-1（ET-1）水平;肺组织伊文思蓝成像分析肺泡–血管通透性,qPCR检测紧密连接蛋白紧密连接蛋白-1（ZO-1）、密封蛋白（OCLN）、血管内皮钙黏素（VE-cadherin）、β-连环蛋白（β-catenin）和水通道蛋白AQP1、AQP5的mRNA表达水平;化学分析法检测血清丙二醛（MDA）、超氧化物歧化酶（SOD）、一氧化氮（NO）水平。结果 与模型组相比,柚皮苷120 mg/kg组能够显著改善LPS诱导的急性肺损伤小鼠肺水肿及肺组织炎症浸润的病理状态,减少肺泡内炎症细胞数量、炎症因子和总蛋白含量,以及肺组织伊文思蓝渗入量;增强紧密连接蛋白和水通道蛋白表达;减缓血液炎症细胞流失,降低血管氧化应激水平（P＜0.05）。结论 柚皮苷能够减轻LPS诱导的气道炎症,并可能通过降低血管氧化应激水平减少对紧密链接蛋白和水通道蛋白的损害作用从而改善肺内皮高通透性。     

oxLDL对人脐静脉内皮细胞通透性影响及机制研究

目的探讨氧化低密度脂蛋白（ox LDL）对人脐静脉内皮细胞（HUVECs）通透性的影响及其可能机制。方法采用Transwell单层细胞模型系统和油红O染色,观察ox LDL对单层血管内皮细胞通透性的影响以及THP-1巨噬细胞内脂质的蓄积情况;采用蛋白质印迹法及免疫荧光技术检测ox LDL对HUVECs紧密连接occludin蛋白的表达及分布改变。结果 ox LDL增加单层内皮细胞对LDL的通透性和THP-1巨噬细胞脂质的蓄积;ox LDL降低occludin蛋白的表达,同时免疫荧光染色显示,ox LDL处理后,血管内皮细胞间隙增宽,occludin染色减少或脱失,而抑制氧化应激可以减弱ox LDL对内皮细胞的高通透性反应和occludin蛋白表达和形态学的影响。结论 ox LDL可能是通过occludin蛋白表达下降使内皮细胞构改变来介导内皮通透性增加,从而促进内皮下巨噬细胞内的脂质蓄积。     

急性低压缺氧复合梭曼中毒对大鼠肺微血管损伤作用

应用伊文思蓝标记白蛋白法，微量滴定法和紫外法观察了急性低压缺氧复合梭曼中毒肺组织伊文思蓝含量，磷脂酶Ａ２（ＰＬＡ２）活力以及支气管肺泡灌洗液（ＢＡＬＦ）中ＰＬＡ２活力，血管紧张素转换酶（ＡＣＥ）活性和蛋白含量的变化。结果表明，低压缺氧（模拟海拔４０００ｍ）６ｈ后，给大鼠梭曼７２μｇ·ｋｇ－１ｓｃ，继续减压可引起肺组织伊文思蓝含量增加，ＢＡＬＦ中ＡＣＥ活性和蛋白含量升高，同时伴有肺组织和ＢＡＬＦ中ＰＬＡ２活性明显升高，提示急性低压缺氧复合梭曼中毒导致的肺损伤可表现为肺微血管通透性（ＰＭＶＰ）增高，微血管内皮细胞损伤和ＰＬＡ２的作用是引起ＰＭＶＰ增高的主要原因。     

氟桂利嗪在神经科临床的应用

氟桂利嗪(flunarizine,FNZ)又名氟苯桂嗪、西比灵(sibelium),系新型选择性钙离子通道阻滞剂。本药已广泛用于治疗多种神经系统疾病,并取得一定疗效,兹将近几年FNZ 在神经科临床的应用情况作一简述。1 脑梗塞FNZ 可透过血脑屏障.其通过阻断钙离子进入细胞内使血管扩张、脑血管阻力减低、脑血流量增加,并能减轻脑细胞的缺血、缺氧性损伤,还能抑制血管内皮细胞收缩,降低其通透性,减轻组织水肿。动物实验资料表明,急性脑梗塞时,用FNZ 治疗的动物,其脑梗塞的范围较用赋形剂治疗的平均小31%。冯幼启等用两种不同剂量的FNZ(10mg 和7.5mg)治疗急性缺血性脑卒中患者67例,治疗90d 后,两组的显效率分别为80%和83%,头颅CT 梗塞影象缩小者分别为40%和     

下调间隙连接蛋白43表达对血管内皮细胞生物功能的影响

间隙连接蛋白43(Cx43)在伤口愈合过程中发挥重要作用。血管生成也是创伤修复的一个重要特征,但目前很少有关Cx43对血管内皮细胞功能影响的研究。本文采用小干扰RNA(si RNA)特异性减少Cx43在人脐静脉内皮细胞(HUVEC)的表达,研究Cx43的表达下调对HUVEC细胞间信号传递、活力、增殖、迁移以及血管生成活性的影响。结果表明,经si RNA处理后,HUVEC内Cx43的表达降低约80%(P<0.05),HUVEC细胞间信号传递功能减少约65%(P<0.05),细胞活力、增殖和迁移活性显著降低(P<0.05)、血管生成速度减缓。推测在创伤早期维持Cx43的低水平表达,抑制渗透性和炎性等异常血管的生成速度,是保证伤口愈合过程中各关键步骤协调进行的前提条件之一。     

N-乙酰半胱氨酸对急性肺损伤大鼠肺组织水通道蛋白表达的研究

目的:观察N-乙酰半胱氨酸(NAC)对急性肺损伤(ALI)肺组织水通道蛋白-1的表达,进一步探讨N-乙酰半胱氨酸对急性肺损伤(ALI)肺组织的保护作用。方法:应用脂多糖(LPS)诱导大鼠急性肺损伤(ALI)模型,然后应用N-乙酰半胱氨酸进行干预。实验设对照组、模型组、N-乙酰半胱氨酸组,在肺损伤模型成功后24 h处死大鼠,取左叶肺组织。采用免疫组化染色,检测N-乙酰半胱氨酸对急性肺损伤大鼠肺组织中水通道蛋白-1(AQP-1)的表达,利用HPIAS-2000图像分析系统测定水通道蛋白-1在以上各组中表达的平均光密度和平均阳性面积率。结果:实验对照组肺组织表达高水平AQP-1;模型组肺组织呈浅黄色染色,AQP-1表达较低;N-乙酰半胱氨酸组肺组织表达高水平AQP-1。经q检验,实验对照组与模型组之间,AQP-1的平均光密度及阳性面积率有显著性差异(P<0.01?,实验对照组与N-乙酰半胱氨酸组之间,AQP-1的平均光密度及阳性面积率差异无显著性(P>0.05)。结论:N-乙酰半胱氨酸能使急性肺损伤组织中AQP-1呈高表达,对急性肺损伤组织有重要的保护作用。     

野马追对急性油酸性肺损伤大鼠肺血管通透性的影响

目的探讨中药野马追对急性油酸性肺损伤大鼠肺血管通透性的影响。方法将72只Wistar大鼠随机均分为空白对照组,模型对照组,地塞米松组,野马追大剂量组、中剂量组和小剂量组,试验前2周各组大鼠灌服相应的药物,然后以油酸0.1mL/kg静脉注射复制急性肺损伤模型,光镜观察肺部组织形态学变化,称重法计算肺系数,紫外分光光度法检测肺组织微血管的渗透性和支气管-肺泡灌洗液（BALF）中蛋白含量并进行渗出细胞计数。结果野马追能明显降低BALF中渗出细胞数、蛋白含量、肺系数及肺含水量和肺血管通透性。结论中药野马追对急性肺损伤有防治作用,可能是通过降低急性肺损伤时肺血管通透性来实现的。     

Harvesting,identification and barrier function of human lung microvascular endothelial cells

Endothelial barrier dysfunction is an important contributor to the pathogenesis of acute lung injury (ALI) and acute respiratory distress syndrome (ARDS). Even though approaches that target the prevention and repair of endothelial barrier dysfunction are clearly needed, our understanding of the molecular regulation of pulmonary microvascular endothelial permeability remains incomplete. Cultured pulmonary microvascular endothelial cells represent an attractive paradigm for the study of barrier function. Here, we describe a method for the harvest, identification and culture of human lung microvascular endothelial cells (HLMVEC). HLMVEC thus obtained, grow as a monolayer, exhibit contact inhibition and have the typical cobblestone appearance. They express endothelial proteins, such as von Willebrand factor and endothelial nitric oxide synthase and take up an acetylated LDL. Furthermore, HLMVEC respond predictably and with superior sensitivity to the barrier disruptive effects of Gram positive and Gram negative bacterial products, thrombin, vascular endothelial growth factor and microtubule disrupting agents. These HLMVEC present an in-house-derived alternative to commercially available human cells for the study of mechanisms contributing to ALI and ARDS.     

Taxol alleviates 2-methoxyestradiol-induced endothelial permeability

We have previously shown that the anti-cancer agent 2-methoxyestradiol (2ME) induces hyperpermeability across endothelial monolayers. Here, we show that both microtubule disruptor, 2ME, and microtubule stabilizer, paclitaxel (taxol), increase vascular lung permeability in vitro and in vivo. Simultaneous application of 2ME and taxol alleviates 2ME-induced endothelial barrier dysfunction, which is evident by the decreased Evans Blue Dye accumulation in lung tissue and increased transendothelial resistance across monolayers. 2ME significantly increases the level of p38 and MLC phosphorylation in both endothelial monolayers and murine lungs; this increase is suppressed in the presence of taxol. Taxol treatment leads to an immediate and sustained increase in tubulin acetylation in human pulmonary artery endothelial cells (HPAEC). Surprisingly, 2ME treatment also increases tubulin acetylation; however, the onset of this process is delayed and coincides with the stage of a partial barrier restoration in HPAEC monolayer. Inhibition of histone deacetylase 6 (HDAC6) with tubacin increases tubulin acetylation level, suppresses 2ME-induced HSP27 and MLC phosphorylation, and decreases 2ME-induced barrier dysfunction, suggesting barrier-protective and/or barrier-restorative role for tubulin acetylation in vascular endothelium.     

Caveolar Uptake and Endothelial-Protective Effects of Nanostructured Lipid Carriers in Acid Aspiration Murine Acute Lung Injury

Purpose

Nanostructured lipid carriers (NLC), nanosized phospholipids/triglyceride particles developed for drug delivery, are considered biologically inactive. We assessed the efficacy of unloaded NLC as experimental treatment for acute lung injury (ALI).

Methods

To induce ALI, C57Black/6 male mice received intratracheal injections of HCl or saline; A single dose of 16 mg/Kg NLC or saline was injected intravenously concomitantly with HCl challenge. NLC uptake mechanisms and effects on endothelial permeability and signaling were studied in cultured endothelial cells and neutrophils.

Results

NLC pre-treatment attenuated pulmonary microvascular protein leak, airspace inflammatory cells, thrombin proteolytic activity and histologic lung injury score 24 h post insult. Using fluorescence measurements and flow cytometry in mouse lung microvascular endothelial cell culture homogenates, we determined that NLC rendered fluorescent by curcumin labeling are taken up by endothelial cells from mice expressing caveolin-1, the coat protein of caveolar endocytic vesicles, but not from caveolin-1 gene-disrupted mice, which lack caveolae. In contrast, conventional emulsions (CE), consisting of larger particles, were not incorporated. In addition, NLC pre-treatment of cultured human lung microvascular endothelial cells abrogated thrombin-induced activation of p44/42, albumin permeability response, actin cytoskeletal remodeling and interleukin-6 production. Finally, NLC but not CE abrogated lipopolysaccharide-triggered interleukin-8 release.

Conclusions

NLC are engulfed by endothelial caveolae and possess endothelial-protective effects. These novel properties may be of potential utility in ALI.     

Inhibition of a store-operated Ca2+ entry pathway in human endothelial cells by the isoquinoline derivative LOE 908.

1. The novel cation channel blocker, LOE 908, was tested for its effects on Ca2+ entry and membrane currents activated by depletion of intracellular Ca2+ stores in human endothelial cells. 2. LOE 908 inhibited store-operated Ca2+ entry induced by direct depletion of Ca2+ stores with 100 nM thapsigargin or 100 nM ionomycin with an EC50 of 2 microM and 4 microM, respectively. 3. LOE 908 did not affect thapsigargin- or ionomycin-induced Ca2+ release from intracellular stores up to concentrations of 3 microM. 4. LOE 908 reversibly suppressed thapsigargin- as well as ionomycin-induced whole-cell membrane currents. 5. The LOE 908-sensitive membrane conductance corresponded to a cation permeability of 5.5 and 6.9 fold selectivity for Ca2+ over K+ in the presence of thapsigargin and ionomycin, respectively. 6. Our results suggest that the isoquinoline, LOE 908 is a novel, potent inhibitor of the store-operated (capacitive) Ca2+ entry pathway in endothelial cells.     

Endothelial pathomechanisms in acute lung injury

Acute lung injury (ALI) and its most severe extreme the acute respiratory distress syndrome (ARDS) refer to increased-permeability pulmonary edema caused by a variety of pulmonary or systemic insults. ALI and in particular ARDS, are usually accompanied by refractory hypoxemia and the need for mechanical ventilation. In most cases, an exaggerated inflammatory and pro-thrombotic reaction to an initial stimulus, such as systemic infection, elicits disruption of the alveolo-capillary membrane and vascular fluid leak. The pulmonary endothelium is a major metabolic organ promoting adequate pulmonary and systemic vascular homeostasis, and a main target of circulating cells and humoral mediators under injury; pulmonary endothelium is therefore critically involved in the pathogenesis of ALI. In this review we will discuss mechanisms of pulmonary endothelial dysfunction and edema generation in the lung with special emphasis on the interplay between the endothelium, the immune and hemostatic systems, and highlight how these principles apply in the context of defined disorders and specific insults implicated in ALI pathogenesis.     

Endothelial pathomechanisms in acute lung injury

Acute lung injury (ALI) and its most severe extreme the acute respiratory distress syndrome (ARDS) refer to increased-permeability pulmonary edema caused by a variety of pulmonary or systemic insults. ALI and in particular ARDS, are usually accompanied by refractory hypoxemia and the need for mechanical ventilation. In most cases, an exaggerated inflammatory and pro-thrombotic reaction to an initial stimulus, such as systemic infection, elicits disruption of the alveolo-capillary membrane and vascular fluid leak. The pulmonary endothelium is a major metabolic organ promoting adequate pulmonary and systemic vascular homeostasis, and a main target of circulating cells and humoral mediators under injury; pulmonary endothelium is therefore critically involved in the pathogenesis of ALI. In this review we will discuss mechanisms of pulmonary endothelial dysfunction and edema generation in the lung with special emphasis on the interplay between the endothelium, the immune and hemostatic systems, and highlight how these principles apply in the context of defined disorders and specific insults implicated in ALI pathogenesis.     

Sevoflurane and bradykinin-induced calcium mobilization in pulmonary arterial valvular endothelial cells in situ: sevoflurane stimulates plasmalemmal calcium influx into endothelial cells

Kinins locally synthesized in the cardiovascular tissue are believed to contribute to the regulation of cardiovascular homeostasis by stimulating the endothelial cells to release nitric oxide, prostacyclin, or a hyperpolarizing factor via autocrine-paracrine mechanisms. This study was designed to investigate the action of sevoflurane on bradykinin-induced Ca2+ mobilization in endothelial cells in situ. Utilizing fura-2-loaded rat pulmonary arterial valve leaflets, the effects of sevoflurane were examined on bradykinin-induced increases in intracellular Ca2+ concentration ([Ca2+]i) in endothelial cells in situ. In the presence of extracellular Ca2+ (1.5 mM), bradykinin (3-30 microM) produced an initial phasic and a subsequent tonic increase in [Ca2+]i in a concentration-dependent manner. However, it produced only the phasic increase in [Ca2+]i in the absence of extracellular Ca2+. Sevoflurane (5%, 0.67 mM) inhibited both the phasic and tonic responses to bradykinin. In these experiments, sevoflurane (3-5%) generated sustained increases (approximately 20-40% of the bradykinin-induced maximal increase in [Ca2+]i) in the resting [Ca2+]i level. Sevoflurane still increased [Ca2+]i after depletion of the intracellular Ca stores with ionomycin (0.1 microM ). However, the sevoflurane-induced increase in [Ca2+]i was eliminated by removal of the extracellular Ca and attenuated by NiCl (1-3 mM). In conclusion, in the pulmonary arterial valvular endothelial cells, sevoflurane inhibits both bradykinin-induced Ca2+ release from the intracellular stores and bradykinin-induced plasmalemmal Ca2+ influx. In addition, sevoflurane appears to stimulate the plasmalemmal Ca2+ influx and thereby increase the endothelial [Ca2+]i level. Sevoflurane might influence the pulmonary vascular tone through its direct action on the pulmonary arterial valvular endothelial cells.     

Angiotensin peptide regulation of bovine brain microvessel endothelial cell monolayer permeability.

The passage of fluid-phase endocytosis markers--Lucifer yellow and a fluorescein isothiocyanate-conjugated dextran--across confluent primary cultures of bovine brain microvessel endothelial cell (BMEC) monolayers was characterized in the presence of angiotensin II (Ang II) peptides. Exposure to nanomolar concentrations of saralasin, an Ang II agonist, attenuated the passage of the fluorophores across the monolayers by 50-75%. In contrast, exposure to sarathrin, an Ang II antagonist, had no effect on passage of the fluorophores across the BMEC monolayers. Sarathrin, however, did inhibit the saralasin-induced reduction in transendothelial monolayer permeability and suggested specific Ang II binding site mediation. Other experiments performed suggest that saralasin-induced changes in BMEC monolayer permeability can be blocked by pretreatment with inhibitors of prostaglandin synthesis and that substantial saralasin-induced changes in BMEC monolayer permeability occurred only following exposure on the apical side of the endothelial cells. Results were consistent with previous studies demonstrating the existence of specific Ang II binding sites on BMECs and Ang II regulation of fluid-phase endocytosis. In addition, these studies support the role of angiotensin peptides in modulating permeability properties of the blood-brain barrier.     

白藜芦醇对脂多糖诱导小鼠急性肺损伤的保护作用

目的研究白藜芦醇对脂多糖(LPS)致小鼠急性肺损伤(ALI)的保护作用,探讨其可能的作用机制。方法以小鼠气道滴注LPS制备急性肺损伤模型,检测气道吸气阻力(Ri)、气道呼气阻力(Re)和动态肺顺应性(Cdyn)的变化,测定支气管肺泡灌洗液(BALF)中白细胞介素-1β(IL-1β)、白细胞介素-6(IL-6)和肿瘤坏死因子-α(TNF-α)的含量,检测肺湿/干比值和毛细血管通透性,观察组织病理学变化。结果白藜芦醇能明显抑制Ri、Re增长和Cdyn降低,降低BALF中IL-1βI、L-6、TNF-α的含量,降低肺湿/干比值和渗透性,减轻肺组织病理学的损伤。结论白藜芦醇对LPS诱导的ALI具有保护作用,作用机制可能与抑制炎症因子的合成与释放有关。     

Role of Ca2+ signaling in the regulation of endothelial permeability

The vascular endothelial cell forms a semipermeable barrier between blood and interstitium. Inflammatory mediators such as thrombin and histamine induce vascular leakage defined as increased endothelial permeability to plasma proteins and other solutes. Increased endothelial permeability is the hallmark of inflammatory vascular edema. Inflammatory mediators that bind to heptahelical G protein-coupled receptors (GPCR) trigger increased endothelial permeability by increasing the intracellular Ca(2+) concentration ([Ca(2+)](i)). The rise in [Ca(2+)](i) activates key signaling pathways, which mediate cytoskeletal reorganization (through myosin light chain (MLC)-dependent contraction) and disassembly of VE-cadherin at the adherens junctions. The Ca(2+)-dependent protein kinase C (PKC) isoform, PKC-alpha, plays a critical role in initiating endothelial cell contraction and disassembly of VE-cadherin junctions. The increase in [Ca(2+)](i) induced by a variety of agonists is achieved by the generation of inositol 1,4,5-trisphosphate (IP3), activation of IP3 receptors (IP3R), release of stored intracellular Ca(2+), and Ca(2+) entry through plasma membrane channels. Recent findings demonstrate that IP3-sensitive Ca(2+) store depletion activates plasma membrane cation channels (i.e., store-operated cation channels (SOC) or Ca(2+) release activated channels) to cause Ca(2+) influx in endothelial cells. This mode of Ca(2+) influx is also known as capacitative Ca(2+) entry (CCE). Store-operated Ca(2+) influx signals increase in permeability and nitric oxide (NO) production and provokes changes in gene expression in endothelial cells. Recent studies have established that the Drosophila transient receptor potential (TRP) gene family of channels expressed in endothelial cells can function as SOC. Deletion of one of the TRP homologues, TRPC4, in mouse caused impairment in store-operated Ca(2+) current and Ca(2+) store release activated Ca(2+) influx in aortic and lung endothelial cells (LEC). In TRPC4 knockout (TRPC4(-/-)) mice, acetylcholine-induced endothelium-dependent smooth muscle relaxation was drastically reduced. In addition, TRPC4(-/-) mice LEC exhibited lack of actin stress fiber formation and cell retraction in response to thrombin activation of proteinase-activated receptor-1 (PAR-1) in endothelial cells. The increase in lung microvascular permeability in response to thrombin receptor activation was inhibited in TRPC4(-/-) mice. These results indicate that endothelial TRP channels such as TRPC1 and TRPC4 play an important role in signaling the increase in endothelial permeability.