氯离子通道-3反义寡核苷酸对内皮素-1促增殖体外培养的牛角膜内皮细胞的抑制作用

目的 观察氯离子通道-3(chloride channel 3,CIC-3)反义寡核苷酸(antisense oligonucleotides,AS-ODN)对内皮素1(endothelin-1,ET-1)促增殖体外培养的牛角膜内皮细胞(bovine corneal endothelial cells,BCECs)的抑制作用.方法 BCECs细胞悬液接种培养12 h后,通过脂质体介导转染不同浓度的ClC-3寡核苷酸.体外培养BCECs 24 h后加入200 pmol·L-1 ET-1,继续培养48 h.通过倒置荧光显微镜观察BCECs寡核苷酸的摄取.采用逆转录聚合酶链反应、免疫印迹法检测ClC-3 mRNA和蛋白的表达.采用MTT法观察BCECs增殖状况,计算细胞存活率,同时应用流式细胞仪检测细胞周期时相的变化,计算细胞增殖指数.结果 寡核苷酸可被培养的BCECs摄取.ClC-3 mRNA与蛋白的表达变化呈平行关系.与不加时相比,ClC-3 AS-ODN浓度依赖性地减少BCECs ClC-3 mRNA和蛋白的表达,同样也浓度依赖性地降低BCECs MTT吸光度值(OD值)和细胞存活率.经100 mg·L-1ClC-3 ASODN处理后,与对照组相比,细胞G0/G1期细胞比例明显增高,S期及G2期细胞比例则明显降低,出现明显的凋亡峰,增殖指数明显下降.结论 ClC-3 AS-ODN可能通过减少ClC-3 mRNA和蛋白的表达,浓度依赖性抑制ET-1对体外培养BCECs的增殖作用,并使细胞周期停滞在G1期.     

乙酰唑胺对培养的牛角膜内皮细胞液体转运功能的影响

目的 研究乙酰唑胺对培养的牛角膜内皮细胞液体转运功能的影响．方法 观察并记录给予不同浓度乙酰唑胺（0．1μmol／L，1μmol／L，10μmol／L，100μmol／L）角膜内皮细胞在低渗溶液中的体积改变．并计算其渗透水通透性（osmoilc water permeability，Pf）的变化。结果 培养的正常牛角膜内皮细胞的Pf值为（0．0446±0．0089）cm／s，在0．1-100μmol／L乙酰唑胺孵育72h后，培养的牛角膜内皮细胞的渗透性水通透性逐渐减少，其Pf值分别为（0．0406±0．0014）cm／s，（0．0364±0．0015）cm／s，（0．0300±0．0022）cm／s，（0．0226±0．0019）cm／s。结论 乙酰唑胺呈剂量依赖性地减低角膜内皮渗透性水通透性．抑制角膜内皮细胞液体转运功能。     

水通道蛋白-1在培养的牛角膜内皮细胞中的表达研究

目的研究水通道蛋白-1在培养的牛角膜内皮细胞中的表达情况及意义。方法用免疫组织化学方法,检测水通道蛋白-1在培养的牛角膜内皮细胞中的表达。结果培养的牛角膜内皮细胞中有水通道蛋白-1的表达,且主要位于细胞膜上。结论牛角膜内皮细胞中的水通道蛋白-1在角膜内皮液体转运中起着重要作用,其表达改变可能导致角膜水肿和功能改变。     

培养牛角膜上皮细胞水通道蛋白功能的表达

目的 研究培养牛角膜上皮细胞水渗透力（ｗａｔｅｒ ｐｅｒｍｅａｂｉｌｉｔｙ,Ｐｆ）及水通道蛋白（ａｐｕａｐｏｒｉｎｓ,ＡＱＰｓ）的存在。方法 应用激光散射法（ｌａｓｅｒ ｌｉｇｈｔ ｓｃａｔｔｅｒｉｎｇ ｓｙｓｔｅｍ）,测定培养牛角膜上皮细胞自参状态快速转为低渗时体积的改变,并 计算Ｐｆ值：自该细胞提取ｍＲＮＡ注入爪蟾卵。测定卵细胞Ｐｆ值改变。结果 激光散射法测定培养牛角膜上皮细胞Ｐｆ值为７２ｕｍ     

压力对体外培养的牛角膜内皮细胞的影响

目的观察压力对体外培养的牛角膜内皮细胞形态结构及细胞活力的影响。方法对体外培养的牛眼角膜内皮细胞施以2.67kPa、5.33kPa及8.00kPa的压力各6、12、24、36、48h,以不加压组作为对照组。用倒置相差显微镜及电镜观察细胞形态结构,以台盼蓝染色观察比较48h时各组细胞活力的差别,用单因素方差分析比较不同压力下阳性细胞率。结果当作用于细胞的压力为2.67kPa(1kPa=7.5mmHg),作用时间为6、12、24、36、48h时,与对照组比较,细胞形态结构均无明显变化;48h时台盼蓝计数与对照组比较差异无统计学意义(P=0.776)。当压力为5.33kPa,作用时间为24h时,细胞形态结构出现轻度的损伤,在36、48h时加重;48h时台盼蓝计数与对照组比较,差异有统计学意义(P=0.00)。当压力为8.00kPa时,6h时即出现明显细胞形态结构损害,随着压力和作用时间的进一步增加,细胞的损伤程度也进一步加重;48h时台盼蓝计数与对照组比较差异有统计学意义(P=0.000)。结论牛角膜内皮细胞在加压48h时只能承受2.67kPa的压力,当压力为5.33kPa及8.00kPa,施压48h时,将造成细胞...     

水通道蛋白1在人角膜内皮细胞的表达

目的 研究水通道蛋白1(water channel protein1,AQP1)抗体在人角膜中的表达及水转运机制。方法 运用免疫组织化学法测定人角膜中AQP1的表达。结果 在角膜内皮细胞和基质细胞中有AQP1的表达，而角膜上皮细胞不表达AQP1。结论 本实验证实了AQP1在角膜内皮的表达，为角膜的水转运及角膜水肿机制的研究提供了分子生物学基础。     

角膜内皮细胞对丝裂原剌激的淋巴细胞活化和增殖的抑制作用

目的 观察角膜内皮细胞（ＣＥＣ）对淋巴细胞活化和增殖的抑制活性,并分析其机制。方法 通过植片技术分离大鼠和兔ＣＥＣ。在ＣＥＣ单层上,观察淋巴细胞对丝裂原刀豆蛋白Ａ（ＣｏｎＡ）和同种异体抗原剌激的增殖反应。另外,将ＣＥＣ培养上清直接转移到由ＣｏｎＡ剌激的淋巴细胞增殖系统以观察ＣＥＣ释放某些因子的抑制效应。结果 ＣＥＣ对ＣｏｎＡ或同种异体抗原剌激的淋巴细胞增殖反应可以施加有效的抑制效应。在这些检测系统     

神经生长因子对兔角膜内皮细胞增殖的影响

目的 探讨神经生长因子（NGF）对角膜内皮细胞增殖的影响。方法 在培养兔角膜内皮细胞的培养液中分别添加5U／ml,50U／ml和500u/ml的NGF,加药后第3,7天采用四甲基偶氮唑盐（MTT）法,在酶标仪上测定570nm波长处的吸光度值来观测细胞增殖情况。结果 与对照组比较,加药后第3,7天,3组的NGF对培养的兔角膜内皮细胞增殖均促进作用（P＜0．01）,且呈剂量依赖性。其中50U／ml组及500U／ml组作用强于5U／ml（P＜0．05）,而50U／ml组和500U／ml组比较作用无差异（P＞0．05）。结论 外源性NGF对培养的兔角膜内皮细胞增殖有明显的促进作用。     

角膜内皮细胞培养方法的改进

介绍三种角膜内皮细胞的原代培养方法，这三种方法的特点是简便、易行、不需特殊的试剂和设备。应用这些方法，均获得良好的单层角膜内皮原代培养细胞。     

EDTA对兔角膜内皮细胞增殖的影响

目的 观察不同浓度的EDTA对免角膜内皮细胞(corneal endothelial cells,CECs)增殖的影响.方法 采取揭取角膜后弹力层联合酶消化法分离培养兔CECs;分别用0.5 mmol·L-1、2.5 mmol·L-1、5.0 mmol·L-1的EDTA作用于体外培养的免CECs 1h然后于24 h、48 h、72 h、96 h观察不同浓度的EDTA对免CECs的影响.采用CCK-8检测方法测定在450 nm处各吸光度(A值)来判断CECs的增殖状况采用流式细胞检测仪对各组细胞周期进行检测同时采用倒置显微镜观察细胞形态的变化.结果 揭取带内皮细胞的后弹力层联合酶消化法培养的兔CECs可很快贴壁、增殖,并在4～5 d融合为单层 CCK-8检测结果显示0.5 mmol·L-1、2.5 mmol·L-1、5.0 mmol·L-1的EDTA作用后各个时间点均能使CECs的吸光度发生改变,同一时间点0.5 mmol·L-1的EDTA对细胞增殖的作用最为显著,各摩尔浓度的EDTA对兔CECs作用后96h吸光度改变最明显(A值分别为:2.595 2±0.053 0、2.090 4±0.159 2、0.939 1±0.077 2).作用48 h后0.5mmol·L-1组兔CECs的S+C2/M期细胞所占比例(A值为1.292 5±0.018 3)与阴性对照组比较,差异有统计学意义,而2.5mmol·L-1、5.0 mmol·L-1组与阴性对照组(A值为0.921 2±0.084 8)比较,差异均无统计学意义.结论 0.5 mmol·L-1的EDTA作用于兔CECs 1 h后的不同时间均有明显的促进增殖的作用.     

Effect of bradykinin on cultured bovine corneal endothelial cells

PURPOSE: To clarify the effect of bradykinin on cytosolic free calcium mobilization and cell proliferation in cultured bovine corneal endothelial cells (BCEC). METHODS: The cytosolic free calcium concentration (Ca2+]i) was measured with the InCa(TM) Imaging System after the treatment of bradykinin (10(-11) to 10(-7) M) alone or with the pretreatments of EGTA, bradykinin receptor (Bk1 and Bk2) antagonists and an inhibition of phospholipase C (U-73122). Also, the effect of bradykinin on cell proliferation in BCEC was evaluated using cell counts. RESULTS: In BCEC, [Ca2+]i in the resting state was 87 +/- 9 nM. Bradykinin induced an increment of [Ca2+]i in a concentration-dependent manner and its 50% effective concentration was approximately 5 x 10(-11) M. A [Ca2+]i increment at 10(-8) M bradykinin was inhibited with the pretreatment of EGTA, an extracellular calcium chelator. U-73122 (5 x 10(-6) M) attenuated the bradykinin-induced [Ca2+]i increment. The pretreatment of HOE-140 (Bk2 antagonist) almost attenuated the bradykinin (10(-8) M)-induced [Ca2+]i increase, but des-Arg9-[Leu(8)]-bradykinin (Bk1 antagonist) did not suppress it. To investigate the physiological effect of bradykinin, the effect of bradykinin on cell proliferation was studied. 10(-8) M of bradykinin produced a significant increase in cell numbers. This mitogenic effect of bradykinin was inhibited by the Bk2 antagonist. CONCLUSIONS: Bradykinin-induced stimulation of the signal transduction pathway in BCEC is coupled with the Bk2 type receptor. Furthermore, bradykinin produces the mitogenic effect in BCEC.     

Swelling activated chloride channels in cultured bovine corneal endothelial cells

Swelling induced enhancement of anion permeability was investigated using the halide-sensitive fluorescent dye SPQ in cultured bovine corneal endothelial cells (BCEC). Rates of anion influx were quantified in terms of the rate of change of SPQ fluorescence during exposure to short duration pulses of Cl-, I-or NO3-while the cells were being perfused with I-, NO3-or Cl-Ringer, respectively. Since SPQ fluorescence is quenched to different extents by these anions, their influx or efflux causes significant changes in fluorescence. The ratio of the maximum rate of change of fluorescence during the pulse period under hyposmotic conditions to that under isosmotic conditions, referred to as the enhancement ratio (ER), was calculated as a measure of the increase in anion permeability. When cells were perfused with NO3-Ringer, exposure to I-pulses yielded an ER=9.0+/-2.6 for 110+/-5 mosmhyposmotic shock. This was higher than with Cl-/I-(6.4+/-0.7) or NO3-/Cl-(3.2+/-0.8) anion-pairs for the same level of shocks. In all cases, the enhancement occurred within approximately 100 seconds after swelling but decreased with continued progress of regulatory volume decrease (RVD). ER returned to approximately 1 within 4 minutes after returning to isosmotic conditions. The membrane potential (Em) depolarized immediately after hyposmotic shock. When cells were depolarized prior to the shocks by high [K+], changes in Emwere relatively small. ER, for the NO3-/I-anion-pair, was significantly reduced by DIDS (100% at 500 microm), NPPB ( approximately 80% at 100 microm) and tamoxifen (approximately 85% at 12 microm). Tamoxifen and NPPB also inhibited swelling induced depolarization. Increasing cationic conductance with Gramicidin D at approximately 2 minutes following hyposmotic shock induced NPPB-inhibitable secondary swelling or accelerated RVD under normal or low Na+conditions, respectively. These results demonstrate that BCEC express swelling activated Cl-channels, which facilitate RVD by enhancing anionic permeability and also by providing a favorable electrical gradient for K+efflux.     

Effect of hypotonic media on the membrane voltage of cultured bovine corneal endothelial cells

The effects of hypotonicity on cultured bovine corneal endothelial cells were investigated using standard microelectrode and superfusion techniques. Confluent monolayers of cells were superfused with an isotonic (305 +/- 5 mosm/kg) control solution until a stable membrane voltage (V) was obtained, then with a hypotonic (240 +/- 5 mosm/kg) solution. Under control conditions, V was - 51.4 +/- 0.8 mV (means +/- SEM, n = 154). Decreasing solution osmolality resulted in an immediate depolarization: mean maximal delta V = 18.7 +/- 0.9 mV at 2.6 +/- 0.2 minutes with a gradual recovery to a new but still depolarized steady-state V (delta v = 11.1 +/- 0.9 mV at 8.2 +/- 0.3 minutes, n = 25). The depolarizing response to hypotonicity persisted in the presence of amiloride (10(-3)M), DIDS (10(-3)M), bumetanide (10(-4)M) or ouabain (10(-4)M) as well as in the absence of extracellular Cl-, Na+, HCO3- or Ca2+. Relative K+ conductance was estimated by the effect on V of increased extracellular [K+] - this was significantly reduced at 5, 10 and 20 mM K+ under hypotonic conditions. The depolarization induced by 1mM Ba2+ was also reduced from 19.6 +/- 0.5 mV (n = 8) under isotonic conditions to 15.4 +/- 0.4 mV (n = 6) under hypotonic conditions (p less than 0.001). The conductive HCO3- pathway - as judged by the hyperpolarization of V induced by increasing extracellular [HCO3-] from 28 to 60 mM, was also reduced under hypotonic conditions (delta V = 17.2 +/- 0.8 mV, n = 13 (isotonic) compared to delta V = 9.5 +/- 0.3 mV, n = 15 (hypotonic].(ABSTRACT TRUNCATED AT 250 WORDS)     

Arachidonic acid metabolism by cultured bovine corneal endothelial cells

Pathways of arachidonic acid metabolism were identified in freshly prepared and in cultured bovine corneal endothelial cells. The principal pathway of arachidonic acid metabolism in the bovine corneal endothelial cells appears to be the cyclooxygenase pathway with the resultant synthesis of PGI2, PGF2 alpha and PGE2. At least two of these products, PGI2 and PGF2 alpha, are formed by the enzymatic conversion of the substrate, PGH2. Measurements of endogenous prostaglandin production by radioimmunoassay demonstrated that PGE2 was the major arachidonic acid metabolite released, with smaller amounts of PGF2 alpha and the stable hydrolysis product of PGI2, 6-keto PGF1 alpha. The release of all three prostanoids was significantly increased by the addition of the calcium ionophore (A23187), human thrombin, bradykinin and histamine. Basal and stimulated release of prostaglandins by the corneal endothelium may contribute to the regulation of intraocular pressure and also in the modulation of the corneal response to injury.     

Ion transport mechanisms in cultured bovine corneal endothelial cells

Intracellular potential measurements of confluent monolayers of cultured bovine corneal endothelial cells were used to define passive ion transport processes in these cells. Previous studies (Jentsch et al., J. Membr. Biol. 78:103 (1984); Jentsch et al., J. Membr. Biol. 81:189 (1984] have provided the experimental basis for a cellular model, in which bicarbonate entry across the basolateral membrane is indirectly driven by a Na+/H+-exchanger, which is inhibitable by amiloride (1mM). Bicarbonate and sodium should leave the cell via an electrogenic bicarbonate sodium cotransport, which is inhibitable by the disulfonic stilbene derivates SITS or DIDS. This model is also consistent with results from transendothelial studies. In this paper, we briefly review the evidence we have obtained for this model and demonstrate, that the electrical response to sodium (depolarization upon Na+-removal) is neither due to an inhibition of Na+/K+-ATPase nor explainable in terms of changes in K+-conductance. This is concluded from the observation of these responses in the presence of ouabain (10(-4)M) or barium (1mM).     

ATP-dependent paracrine intercellular communication in cultured bovine corneal endothelial cells

PURPOSE: Intercellular communication (IC) in nonexcitable cells is mediated through gap junctions and/or through the release of paracrine mediators. This study was conducted to investigate adenosine-5' triphosphate (ATP)-dependent paracrine IC in the propagation of Ca2+ waves in confluent monolayers of cultured bovine corneal endothelial cells (BCECs). METHODS: A Ca2+ wave was induced by point mechanical stimulation (PMS) of a single cell by indentation with a glass micropipette (approximately 1 microm tip) for <1 second. Dynamic changes in [Ca2+]i in the mechanically stimulated (MS) cell and in the neighboring (NB) cells were visualized with a confocal microscope, using a fluorescent dye. Normalized fluorescence (NF), calculated as the ratio of the average fluorescence of a cell to the average under resting conditions, was used as a measure of [Ca2+]i. Expression of P2Y receptors and ecto-adenosine triphosphatases (ATPases) was investigated by RT-PCR. ATP release in response to PMS was measured by luciferin-luciferase (LL) bioluminescence. RESULTS: BCECs subjected to PMS showed a transient [Ca2+]i increase. Under control conditions, the maximum NF in the MS cell occurred within 600 ms, and the fluorescence returned to baseline within 170 seconds. NB cells also presented a [Ca2+]i increase with a transient characterized by decreasing maximum NF and increasing latency as a function of the distance from the MS cell. These transients propagated as an intercellular Ca2+ wave to a distance of five or six NB cells away from the MS cell, covering areas (called active areas, AAs) up to 77,000 +/- 3,200 microm2 (N=21). The percentage of responsive cells (defined as cells showing maximum NF >1.1) decreased with increasing distance from the MS cell. The Ca2+ wave crossed cell-free lanes. Pretreatment of cells with the nonselective purinergic receptor antagonist suramin (200 microM), exogenous apyrases, which break down nucleotides (10 U/mL), or the PLC inhibitor U-73122 (10 microM) reduced the wave propagation, whereas the ecto-ATPase inhibitor ARL-67156 (100 microM) significantly enhanced it. ATP-dependent LL bioluminescence increased after PMS. RT-PCR showed mRNAs for P2Y1 and P2Y2 receptors and ecto-ATPases in BCECs. CONCLUSIONS: PMS of BCECs induces release of ATP and a concomitant intercellular Ca2+ wave, even in the absence of direct cell-cell contacts. The AA of the wave is modulated by agents that affect P2Y receptor activity. Thus, PMS-induced intercellular Ca2+ wave propagation in BCECs involves ATP-dependent paracrine IC.     

Binding and processing of trypsin by cultured bovine corneal endothelial cells

Bovine corneal endothelial cells in culture bind internalize and degrade [125I]-trypsin. Binding involves the active site of trypsin and increases as a function of [125I]-trypsin concentration. Saturation is observed at a concentration of 0.5-1.0 micrograms ml-1. The cell surface binding of [125I]-trypsin is specific: a seven-fold excess of unlabeled trypsin abolishes about 60% of the total cell surface-associated radioactivity. In addition, thrombin competes poorly with [125I]-trypsin cell surface binding and only 20% of the specific cell surface binding of [125I]-trypsin is subjected to competition with thrombin. This fraction of the cell surface-bound [125I]-trypsin which is accessible to competition with thrombin appears in a covalent complex of [125I]-trypsin X protease-nexin with a molecular weight of 64000 daltons. The cells, when incubated at 37 degrees C, appear to internalize the cell surface-bound [125I]-trypsin at a rate of 0.15-0.25 ng (10(6) cells)-1 min-1. Both the non-covalently cell surface-bound and the protease-nexin (PN) mediated-bound [125I]-trypsin are internalized by the cells, but the [125I]-trypsin X PN complexes contribute about 75% of the total amount of [125I]-trypsin internalized by the cells. The internalized [125I]-trypsin is degraded by the cultures at a rate of about 0.05 ng (10(6) cells)-1 min-1 and the degradation products are released by the cells into the incubation medium as a trichloroacetic acid non-precipitable material. Chloroquine inhibits about 60% of the internalization of [125I]-trypsin by the cells, and inhibits more than 80% of the degradation process of [125I]-trypsin, which indicates that the degradation of the ligand is taking place in lysosomes. Bovine corneal endothelial cells in culture have demonstrated the binding and metabolism of the serine protease trypsin. This described process may indicate the ability of corneal endothelial cells to control the activity of serine proteases in their microenvironment.     

Tight junctions and paracellular permeability in cultured bovine corneal endothelial cells

Intramembrane specializations of cultured bovine corneal endothelial cells were studied with thin section and freeze-fracture electron microscopy and related to the paracellular permeability and the transendothelial resistance (R^t) of the monolayers. The following intercellular junctions were found: single and discontinuous networks of tight junctions (TJ) which girdle the apico-lateral cell perimeter incompletely, gap junctions, and membrane undulations suggesting intermediate junctions. The macromolecular tracer ruthenium red penetrated into the lateral intercellular space beyond the level of the incomplete belt of TJ. R^t of these monolayers was 20.9±1.0 º · cm² Protamine induced a reversible increase of R^t to 118±5 % of its control value. We conclude that incomplete belts of TJ may be the morphological counterpart of the high paracellular permeability of this monolayer and functionally and morphologically resemble those of their native endothelium. Cultured corneal endothelial cells are an excellent model for studying the influence of incomplete belts of TJ on paracellular permeability of cells.The results reported here were presented in part at the 91st Congress of the German Ophthalmological Society, Mannheim, 19–22 September 1993 and published in abstract form [22].