氧自由基在肝缺血再灌注损伤中的作用及川芎嗪的影响

目的：探讨氧自由基在肝缺血再灌注损伤（ＨＩＲＩ）中的作用及川芎嗪的防护作用。方法：应用ＨＩＲＩ家兔及肝癌手术患者,观察超氧化物歧化酶（ＳＯＤ）、谷胱甘肽过氧化物酶（ＧＳＨ－ＰＸ）,黄嘌呤氧化酶（ＸＯ）、谷丙转氨酶（ＡＬＴ）活性、丙二醛（ＭＤＡ）含量、肝细胞形态学变化及川芎嗪对上述指标的影响。结果：ＨＩＲＩ时ＳＯＤ、ＧＳＨ－ＰＸ活性显著下降（Ｐ〈０．０５和Ｐ〈０．０１）,ＸＯ、ＡＬＴ活性及ＭＤＡ含是     

SHRsp大鼠阻力血管平滑肌IKca对Ca~（2＋）i敏感性的改变

ＳＨＲｓｐ大鼠阻力血管平滑肌ＩＫｃａ对〔Ｃａ￣（２＋）〕ｉ敏感性的改变王国勇，郑永芳，屈金河，王晓芳（中国医学科学院基础医学研究所生理室，北京１００００５）细胞兴奋时胞内钙浓度升高可激活细胞膜上的钙激活钾通道（ＩＫｃａ），使胞内钾离子外流，细胞膜电位...     

雷蓊滕及铅,镉对小鼠睾丸间质细胞一氧化氮合酶活性的影响

目的 探讨雷公藤及铅、镉等重金属元素对丸间质细胞一氧化氮合酶（ＮＯＳ）活性的影响。方法 用ＮＡＤＰＨ－ｄ黄递酶组织化学方法，观察给于氧化镉、醋酸铅、雷公藤１、２、３、４周后，小鼠睾丸回质ＮＯＳ活性的变化。结果 正常组间质细胞呈ＮＯＳ强阳性反应，而曲精小管生精细胞均呈ＮＯＳ阴性反应。给予雷公藤２周内ＮＯＳ反应无变化，第３和第４周后，ＮＯＳ阳笥的睾丸间质数量无明显变化，但ＮＯＳ活性精降低，给予醋酸铅     

低氧缺血海马神经元内Ca~(2 )动态变化的LSCM测定

测定脑组织细胞内 Ｃａ~(2 )浓度是评价缺血引起神经元损伤的重要指标。本研究用激光扫描共聚焦显微镜（ＬＳＣＭ）和Ｆｌｕｏ－３／ＡＭ荧光探针标记技术,从单个活细胞水平检测缺血刺激诱发的海马神经元内Ｃａ２＋瞬间动态变化。结果显示低氧使胞内Ｃａ２＋浓度显著升高。谷氨酸引起Ｃａ２＋浓度升高缓慢但持续时间长。缺血对Ｃａ２＋浓度影响不显著。撤除葡萄糖则引起胞内Ｃａ２＋迅速降低。实验结果表明不同缺血刺激因素引起的钙振荡各异。用ＬＳＣＭ对活细胞内部非侵入光学断层扫描,能清晰记录到这些瞬态钙值变化。     

缺氧大鼠肺组织氧化／抗氧化平衡的变化及其与TXA_2／PGI_2平衡的关系

检测缺氧大鼠肺组织丙二醛（ＭＤＡ）、超氧化物歧化酶（ＳＯＤ）和过氧化氢酶（ＣＡＴ）含量以及血浆ＴＸＡ＿２和ＰＧＩ＿２浓度，以探讨氧自由基（ＯＦＲ）及ＴＸＡ＿－ＰＧＩ＿２在缺氧性肺动脉高压中的作用。结果表明：与对照组比较缺氧大鼠肺组织ＭＤＡ明显升高、ＳＯＤ、ＣＡＴ明显降低，ＶｉｔＥ可逆转ＭＤＡ和ＳＯＤ的变化；缺氧大鼠血浆ＴＸＢ＿２高于对照组，其浓度与肺组织ＭＤＡ含量呈正相关（ｒ＝０．６５．Ｐ＜０．０５）。以上结果提示，ＯＦＲ与ＴＸＡ＿２／ＰＲＩ＿２平衡失调相互作用，可能共同参与缺氧性肺动脉高压的发生。     

针刺对小鼠腹腔巨噬细胞的热休克蛋白、诱导性一氧化氮合酶及其基因表达的效应

目的研究针刺对小鼠腹腔巨噬细胞的热休克蛋白（ＨＳＰ）、诱导性一氧化氮合酶（ｉＮＯＳ）及其ｍＲ－ＮＡ表达的效应。方法将２４只昆明小鼠腹腔注射无菌石蜡油后,随机分为３组：电针（ＥＡ）组、对照１（Ｃ１）组和对照２（Ｃ２）组。将３组收集的腹腔巨噬细胞制备成玻片和硝酸纤维素膜（ＮＣＭ）两种标本,应用原位杂交、免疫细胞化学、细胞化学及斑点印迹技术检测ＨＳＰ７０、ｉＮＯＳ及ｉＮＯＳｍＲＮＡ。结果ＨＳＰ７０定位于巨噬细胞的胞质和胞核;ｉＮＯＳｍＲＮＡ及ｉＮＯＳ均定位于巨噬细胞的胞质;３组的ｉＮＯＳｍＲＮＡ、ｉＮＯＳ、ＨＳＰ７０的斑点印迹的扫描数值均为ＥＡ组＞Ｃ２组＞Ｃ１组（Ｐ＜０．０１）。结论电针可显著提高小鼠腹腔巨噬细胞的ＨＳＰ７０、ｉＮＯＳ及ｉＮＯＳｍＲ－ＮＡ表达。     

阿司匹林,卡托普利及二者合用对豚鼠心肌活性氧损伤的保护作用

用黄嘌呤黄嘌呤氧化酶系统产生活性氧，诱发豚鼠右室前乳头肌氧化损伤，通过动物实验观察了阿司匹林，卡托普利及Ａｓｐ＋Ｃａｐ对心肌活性氧损伤的保护作用。发现Ａｓｐ对Ｘ／ＸＯ诱导的心乳头肌收缩性，不应期，兴奋性和自律性的变化，以及心肌ＳＯＤ活性降低，ＭＤＡ含量升高，无显著抑制作用；     

心肌缺血／再灌注对球结膜微循环的影响以及一氧化氮的调节作用

对照观察兔急性心肌缺血／再灌注时球结膜微循环的变化，测定动物血浆中内皮舒张因子／一氧化氮（ＥＤＲＦ／ＮＯ）、血栓素Ｂ２（ＴＸＢ２）、６－酮－前列腺素Ｆ１α（６－Ｋｅｔｏ－ＰＧＦ１α）、超氧化物歧化酶（ＳＯＤ）、丙二醛（ＭＤＡ）的浓度变化，并用光镜和电镜对缺血／再灌注心肌组织作形态学观察。结果发现：（１）兔心肌缺血／再灌注后球结膜微循环异常；表现为Ａ３、Ａ４微动脉血管管径缩小，毛细血管交换距离增大。（２）血浆中ＥＤＲＦ／ＮＯ水平降低；（３）血浆ＴＸＢ２、ＭＤＡ水平升高，ＳＯＤ、６－Ｋｅｔｏ－ＰＧＦ１α下降；（４）光镜下：缺血区心肌组织细胞肿胀变性。电镜下：内皮细胞肿胀，部分毛细血管腔内有红细胞、白细胞附壁阻塞，线粒体肿胀，糖原颗粒减少。结果提示：心肌在较短时间缺血后再灌注（缺血３０ｍｉｎ再灌注３０ｍｉｎ）后就可产生组织损伤，这可能与血管内皮受损，ＥＤＲＦ／ＮＯ合成释放减少，缩血管物质ＴＸＡ２升高，血小板、白细胞粘附、聚集在血管内皮上，氧自由基产生过多等有关。上述因素共同作用导致缺血／再灌注心肌微循环功能障碍进而引起组织形态改变。     

虎杖甙对正常人血管平滑肌细胞内钙和膜电位的调节作用

目的和方法：观察虎杖甙（ＰＤ）对人脐带动脉平滑肌细胞（ＶＳＭＣ）内游离钙、细胞膜电位的变化,以探讨ＰＤ对血管平滑肌的调节机制。用Ｆｌｕｏ－３－ＡＭ、ＤｉＢＡＣ４（３）标记培养的ＶＳＭＣ,在激光共聚焦显微镜上测定细胞内游离钙和膜电位变化。结果：给ＰＤ（０５ｍｍｏｌ／Ｌ）１０ｍｉｎ后,ＶＳＭＣ内游离钙浓度升高５６％±５６％。当ＰＤ加入前用维拉帕米和ＥＧＴＡ预处理后,则游离钙不再升高;ＥＧＴＡ和肝素预处理也抑制ＰＤ的升钙作用,而ＥＧＴＡ和普鲁卡因预处理则使细胞内钙显著升高。ＰＤ还可使ＶＳＭＣ膜电位去极化,加入钠通道阻断剂河豚毒素（２５μｍｏｌ／Ｌ）可完全阻断ＰＤ的去极化作用：加甲氰咪胍、维拉帕米、优降糖和利及丁预处理不能阻断ＰＤ去极化作用。结论：：ＰＤ可通过细胞外钙内流来增加细胞内游离钙浓度,并促进细胞外钠离子内流而导致细胞去极化     

自发性高血压大鼠视网膜内含一氧化氮合酶神经元的研究

本实验用ＮＡＤＰＨ－黄递酶组织化学染色法观察了自发性高血压大鼠和京都种大鼠（ＷＫＹ，正常对照）视网膜内一氧化氮合酶（ＮＯＳ）的变化。结果显示，ＮＯＳ阳性神经元位于内核层和视网膜节细胞层。ＳＨＲ组视网膜ＮＯＳ阳性细胞属无长突细胞和移位无长突细胞。偶见最怀的节细胞。ＮＯＳ阳性无长突细胞和节细胞胸质显强阳性反应，可较长而清晰的突起，ＮＯＳ阳性神经元的分布密度长，且在视网膜中央区（视神经盘附近）的分布密度     

虎杖甙对心肌细胞钙的调节作用

目的:观察虎杖甙(polydatin,PD)对大鼠心肌细胞内游离钙浓度([Ca²⁺]i)的影响,以探讨PD增强心肌细胞收缩性的作用机制。方法:用荧光染料Fluo-3-AM标记细胞,在粘附式细胞仪上测定细胞[Ca²⁺]i的变化。结果:给予PD后心肌[Ca²⁺]i升高。但不同细胞群的[Ca²⁺]i升幅不一致。10min后有些细胞[Ca²⁺]i仅升至起始浓度的111.80%±2.22%,有些细胞内钙则急升到最初的224.00%±24.33%。当先用EGTA或维拉帕米分别预孵育10min后再加PD,细胞[Ca²⁺]i则呈持续下降趋势,10min后[Ca²⁺]i下降至起始浓度的53.00%±9.20%和52.00%±7.07%。给予TTX预处理后再加PD,[Ca²⁺]i也下降为起始值的72.67%±12.70%。与单纯PD作用相比都有显著差异。结论:PD可通过增加心肌[Ca²⁺]i而增强心肌收缩性,其作用可能与钙、钠通道开放有关。     

Oxidative injury induces influx-dependent changes in intracellular calcium homeostasis.

Understanding of the mechanisms of cell injury and cell death is fundamental to the understanding of both protection against and initiation of cell injury and cell death. We subjected primary cultures of proximal tubular epithelium (PTE) from adult rats to an exogenous oxidative stress, generated by xanthine/xanthine oxidase (X/XOD), and studied its effect on the concentration of cytosolic ionized calcium ([Ca2+]i) by means of digital imaging fluorescence microscopy (DIFM) using a cytosolic calcium probe, fura-2. Exposure to 25 mU/ml X/XOD caused notable increases in [Ca2+]i detectable within 15 sec and increasing to micromolar levels with time. Experiments with Ca(2+)-free medium containing ethylene glycol-bis(beta-aminoethyl ether)N,N,N',N'-tetraacetic acid (EGTA) showed that the increase of [Ca2+]i was due to influx from the extracellular space. Smaller and slower increases in [Ca2+]i were seen after exposure to lower concentrations of X/XOD (5 and 10 mU/ml). PTE injury and killing were assessed by measuring the release of cytosolic lactate dehydrogenase (LDH), exclusion of trypan blue, and observation of morphologic changes. Exposures to the 25 mU/ml concentration of X/XOD caused significant LDH release after 2 hr and correlated with trypan blue staining of exposed cells. Again, lesser concentrations of X/XOD resulted in a slower release of smaller amounts of LDH, and thus delayed trypan blue staining. Cytoplasmic bleb formation was seen by phase microscopy within minutes of exposure to 25 mU/ml, followed by cell rounding, retraction, and disintegration. Transmission electron microscopy revealed a progression of changes characteristic of lethal cell injury, beginning with dilatation of the endoplasmic reticulum, detachment of ribosomes, condensation of mitochondria, and chromatin clumping and terminating with mitochondrial swelling and formation of intramitochondrial flocculent densities. These studies clearly show that notable increases of [Ca2+]i precede both sub-lethal and lethal changes in rat PTE. These results indicate that interventions designed to minimize or to accelerate calcium entry could be of importance in cell preservation or cell killing, respectively, and therefore to therapeutic strategies for myocardial infarction, stroke, or shock in the former instance and for cancers in the latter.     

地塞米松对谷氨酸升高海马神经元胞内[Ca~(2+)]i作用的影响

为了研究谷氨酸致痫和人工合成的糖皮质激素地塞米松抑痫作用的细胞内机制,本文在ＥＰＣ ９ 光电联合检测系统上用Ｆｕｒａ ２ 阳离子检测法观察了地塞米松对谷氨酸引起的培养乳鼠海马神经细胞内［Ｃａ２＋ ］ｉ 的影响。结果：（１）谷氨酸引起海马神经元内［Ｃａ２＋ ］ｉ 显著升高,ＥＧＴＡ（５ ｍ ｍ ｏｌ／Ｌ）耗竭细胞外钙后,谷氨酸升钙作用消失,给予氯化钙（１ ｍ ｍ ｏｌ／Ｌ）后其升钙作用恢复：Ｖｅｒａｐａｍ ｉｌ（１０ μｍ ｏｌ／Ｌ）对谷氨酸升钙作用无明显的影响,ＭＫ ８０１（１０ μｍ ｏｌ／Ｌ,ＮＭ ＤＡ 受体特异性非竞争性阻断剂）可明显阻断谷氨酸的升钙作用。（２）地塞米松（１００ μｍ ｏｌ／Ｌ）作用２ ｈ 明显抑制了谷氨酸（２００ μｍ ｏｌ／Ｌ）的升钙作用,地塞米松（１００ μｍ ｏｌ／Ｌ）＋ 放线菌酮（１０ μｍ ｏｌ／Ｌ,蛋白合成抑制剂）共同作用２ ｈ,再加入谷氨酸,则地塞米松的抑制作用消失,地塞米松（１００ μｍ ｏｌ／Ｌ）作用２ ｍ ｉｎ 对谷氨酸（２００ μｍ ｏｌ／Ｌ）的升钙作用无明显影响。本实验结果提示,谷氨酸通过ＮＭ ＤＡ 受体介导的外钙内流升高了海马神经元胞内［Ｃａ２＋ ］ｉ,地塞米松可能通过基因组机制抑制了谷氨酸的这种升     

超氧阴离子对缺氧大鼠肺内动脉乙酰胆碱舒张反应的影响

本文应用微量生物测定法观察超氧阴离子在慢性缺氧影响肺内动脉乙酰胆硷舒张反应中的作用。发现慢性缺氧可明显减弱大鼠肺内动脉的ACh内皮依赖性舒张,超氧化物歧化酶则可使此舒张反应恢复到正常水平。利用黄嘌呤—黄嘌呤氧化酶系统产生氧自由基(主要为O_2~((?))可削弱正常大鼠肺内动脉的ACh舒张反应,同样SOD可保护其免遭外源性氧自由基的损伤。结果表明慢性缺氧使肺血管氧自由基(尤其是O_2~((?))产生增多是大鼠肺内动脉ACh舒张反应受到损伤的原因之一。     

钙离子体外微渗透的时间延迟

目的检验微渗透（MD）系统回收时间（RT）延迟的存在性。方法建立一个用于钙离子（ca2＋）检测的特定MD体外系统。灌注液为生理盐水（NS）,灌注速度为2．0μl／min。析出液经过同步稀释,每10分钟采样1次至80min。样本中的Ca2＋用原子吸收光谱仪检测,计算MD系统的Ca2＋回收率。用Ns和Ca2＋标准液间的切换模拟待测液目标分子浓度变化,记录不同时间点的ca。’浓度和MD系统用于caz＋检测的RT。结果MD系统的ca。’回收率为16％,析出液钙离子浓度自10min[（57±17）μmol／L]开始上升,20min达到峰值,持续至50min[（159＋26）Ixmol／L]开始下降,稳态峰值浓度约200I~mol／L。基线值时间点组（0、60、70、80min）与峰值时间点组（20、30、40min）间Ca2’浓度差异有统计学意义[0min：（3＋4）μmol／L,60min：（7±8）μmo]／L,70min：（7＋7）μmol／L,80min：（5＋9）μmol／L比20min：（197±29）μmol／L,30min：（194＋21）μmol／L,40min：（192＋11）μmol／L,均P〈0．05]。析出液中ca2＋浓度上升和下降变化均较待测液显著延迟,对于该MD系统而言,用于caz＋检测的RT应为20min。结论在10min的采样间隔下,MD系统的caz＋检测RT延迟存在,并且不能事先准确预估。信号切换方法用于RT延迟的校正是可行的。     

低氧与缺血诱导培养海马和皮质神经元钙应答反应的比较

目的：钙作为重要信使参与多种生理和病理代谢过程,而且在缺血性神经元损伤机制中起着重要的作用。本实验模拟脑缺血的病理生化改变,用激光扫描共聚焦显微镜（LSCM）和Fluo-3荧光探针标记技术,观察低氧缺血状态下体外培养的海马,皮质神经元内钙浓度的变化。方法：用100μmol/L氰化钠造成细胞低氧;100μmol/L氰化钠和3.5mmol/L碘醋酸盐模拟在体完全性脑缺血;1mmol/LL-谷氨酸模拟在体脑缺血时兴奋性氨基酸大量释放;无葡萄糖介质剥夺细胞能量代谢的底物。结果：低氧使海马神经元[Ca^2 ]i显著升高,但有两种不同的钙振荡现象,谷氨酸引起海马神经元[Ca^2 ]i持续升高,但峰值低于低氧组,缺血组未见[Ca^2 ]i大幅升高,葡萄糖缺如不引起[Ca^2 ]i升高,结论：低氧和谷氨酸引起的神经元损害是能量依赖性的,轻度酸中毒可阻止胞内Ca^ 升高,糖对神经元具有保护作用,但单纯无糖引起的神经元损害与Ca^2 超载机制无关。     

耳蜗外毛细胞两种胞内钙库的初步探讨

为探讨毛细胞胞内钙库的种类 ,本文观察了在无钠、无钙和含镧液体中 ,在不受胞外 Ca2 +内流和质膜上 Ca2 +转运机制影响的条件下 ,和在三磷酸肌醇敏感钙库的工具药 thapsigargin和 ryanodine敏感钙库的工具药 caffeine作用下 ,毛细胞胞内游离钙([Ca2 + ] i)的变化过程。分离的豚鼠耳蜗外毛细胞经钙敏荧光染料 5μmol/L fluo-3染色后 ,用激光扫描共聚焦显微镜监测 ,以 fluo-3荧光相对值指示毛细胞 [Ca2 + ] i的高低。 3 0 nmol/L thapsigargin使外毛细胞 [Ca2 + ] i由静态值 1.0增至 1.64± 0 .76,再加入 10mmol/L caffeine后更增至 2 .45± 1.5 9(x± s,n=11,F=7.90 ,P<0 .0 1)。Q值检验示两种试剂引起外毛细胞 [Ca2 + ] i增高程度的差别有极显著意义 (P<0 .0 1) ,表明毛细胞内有对三磷酸肌醇敏感和对 ryanodine敏感的两种钙库参与了胞内 Ca2 + 释放机制     

Protection by deferoxamine from endothelial injury: a possible link with inhibition of intracellular xanthine oxidase

Hydroxyl radical scavengers and xanthine oxidase inhibitors protect cultured bovine pulmonary endothelial cells (BPAEC) from lytic injury by the endotoxin lipopolysaccharide (LPS). We hypothesized that exposure of BPAEC to cytotoxic concentrations of LPS activated intracellular xanthine oxidase, and that intracellular iron-dependent hydroxyl radical formation (a Fenton reaction) ensued, resulting in cell lysis. To test this, the protective effects of deferoxamine against H2O2 and LPS-induced cytotoxicity to BPAEC was assessed by 51Cr release. Preincubation with 0.4 mM deferoxamine conferred 67 +/- 15% (mean +/- SE) protection from LPS-induced cytotoxicity but 48 h of preincubation were required to induce significant protection. Significant protection form a classical Fenton reaction model, injury by 50 microM H2O2, could be induced by a 1-h preincubation with a 0.4 mM deferoxamine. The dissociated time course suggested that deferoxamine might work by different mechanisms in these models. The effects of LPS and deferoxamine on BPAEC-associated xanthine oxidase (XO) and xanthine dehydrogenase (XD) activity were assessed using a spectrofluorophotometric measurement of the conversion of pterin to isoxanthopterin. BPAEC had 106 +/- 7 microU/mg XD+XO activity; XO activity constituted 48 +/- 1% of total XO+XD activity. LPS at a cytotoxic concentration did not alter XO, XD, or percent XO. Deferoxamine had striking proportional inhibitory effects on XO and XD in intact cells. XO+XD activity fell to 6 +/- 1% of control levels during a 48-h exposure of BPAEC to deferoxamine. Deferoxamine did not inhibit XO+XD ex vivo.(ABSTRACT TRUNCATED AT 250 WORDS)     

促甲状腺素及白细胞介素-6对大鼠甲状腺细胞钙离子的作用

本文利用激光扫描共聚焦显微镜（LSCM）对促甲状腺素（TSH）及白细胞介素-6（IL6）诱导的FRTL－5细胞内Ca2 变化进行了研究。方法：培养的FRTL－5细胞以FLuo－3染色,用LSCM在488nm扫描并加入不同浓度的TSH及IL－6检测细胞内Ca2 的变化。结果：TSH（1－5U／L）可使细胞内Ca2 的水平上升,且与TSH的浓度有一定关系。IL－6（1～100μg／L）对FRTL－5细胞内基础Ca 浓度无直接作用。     

Cyclosporin-A-induced effects on the free Ca2+ concentration in LLC-PK1-cells and their mechanisms

Here we have examined the effects of Cyclosporin A (CyA) on the free intracellular Ca2+ concentration ([Ca2+]i) of LLC-PK1/PKE20 cells to evaluate mechanisms of CyA nephrotoxicity using Fura-2 microspectrofluorometry or digital fluorescence video imaging. The CyA-associated changes were compared to the effects of tacrolimus (Tac), a structurally unrelated immunosuppressant with similar cellular pathways which also causes nephrotoxicity. CyA (EC50(: 1 nmol/l, n=16) and Tac (EC50: 1 nmol/l, n=5) caused a concentration-dependent increase of [Ca2+]i which was substantially attenuated by reducing the external Ca2+ concentration (10(-6) mol/l). Similarly Cyclosporin H, a non-immunosuppressive analogue of CyA, stimulated a Ca2+ influx. Nicardipine (10(-6) mol/l) reduced the CyA- and the Tac-induced Ca2+ influx to 52+/-16% (n=10) and 13+/-10% (n=13) of control respectively. Diltiazem and verapamil (10(-6) mol/l) were also effective, but flufenamate (10(-4) mol/l), Gd3+ (10(-5) mol/l) and La3+ (10(-5) mol/l) were not. In the absence of extracellular Ca2+ CyA led to a small but significant [Ca2+]i increase, indicating additional release from internal stores. Depletion of inositol-1,4,5-trisphosphate-(InsP3-) sensitive Ca2+ stores by extracellular ATP (10(4) mol/l) in low-Ca2+ solution completely suppressed the CyA-induced [Ca2+]i rise. CyA had no effect on the cellular InsP3 concentration. Furthermore, inhibition of phospholipase-Cbeta (PLCbeta) by U73122 (2x10(-5) mol/l) did not alter the CyA-stimulated [Ca2+]i rise. A direct effect of CyA on InsP3-sensitive Ca2+ stores, the InsP3 receptor, the Ca2+ content of the stores or involvement of additional stores is assumed. Incubation with CyA for 1, 12 and 24 h enhanced the rise in [Ca2+]i peak induced by ATP, arginine vasopressin (AVP) and angiotensin II. In summary, CyA stimulated a [Ca2+]i increase in LLC-PK1 cells through Ca2+ release from InsP3-sensitive stores and Ca2+ influx via a nicardipine-sensitive pathway. The CyA-mediated [Ca2+]i increase is independent of PLCbeta activity and InsP3 metabolism. CyA caused long-term enhancement of the agonist-induced rise in [Ca2+]i. The effects of CyA on Ca2+ signaling appear to be independent of its immunosuppressive action.