粉防己碱对培养乳牛基底动脉平滑肌细胞内游离钙浓度的影响

目的：研究粉防己碱对培养乳牛基底动脉平滑肌细胞游离钙浓度（[Ca^2 ]i)的影响。方法：利用AR－CM－MIC阳离子测定系统,采用Fura 2-AM为指示剂,测量单个细胞内[Ca^2 ]i。结果：粉防己碱10－100μmol/L对培养乳牛基底动脉平滑肌细胞静息[Ca^2 ]i无明显影响。在细胞外钙为1．3mmol/L,粉防己碱可浓度依赖性地抑制KC1引起[Ca^2 ]i的升高。咖啡因10mmol/L可诱导一次[Ca^2 ]i瞬间快速升高,随后自发回复到静息水平,粉防己碱10和30μmol/L对咖啡因诱导的[Ca^2 ]i瞬间升高没有作用,但高浓度（100μmol/L）粉防己碱抑制了[Ca^2 ]i瞬间升高。在细胞外钙为1.3mmol/L,苯肾上腺素10μmol/L可引起双相[Ca^2 ]i变化,包括快速升高相和持续升高相。在细胞外钙为零,苯肾上腺素仅引起[Ca^2 ]i的快速升高相。粉防己碱可浓度依赖性地抑制苯肾上腺素引起[Ca^2 ]i快速升高相。结论：在培养乳牛基底动脉平滑肌细胞,粉防己碱可能通过影响电压依赖性和苯肾上腺素受体介导的钙通道而抑制钙内流。高浓度粉防己碱也可能影响肌浆网钙释放或钙摄取。     

Gua对培养的皮质神经元和成神经细胞瘤细胞钙超载的影响

目的：探讨Guattegaumerine（Gua）对H2O2、谷氨酸（glutamate，Glu）和缓激肽（bradykinin，BK）诱导的培养皮质神经元和成神经细胞瘤细胞内钙超载的影响。方法：采用钙荧光探针Furo-2／Am标记培养的细胞，荧光显微图象分析系统和双荧光波长分光光度计检测不同组细胞内钙荧光信号。结果：Gua能显抑制H2O2、谷氨酸引起的培养皮质神经[Ca^2＋]i升高（P〈0．05），亦明显抑制BK所诱导的培养人成神经细胞瘤细胞[Ca^2＋]i升高（P〈0．01）。结论：Gua具有一定的钙拮抗作用，其作用机制可能与其抑制外钙内流及抑制内质网钙释放有关。     

龙葵碱对HepG2细胞线粒体膜电位及细胞内[Ca^2＋]i的影响

目的：观察龙葵碱对HepG2细胞线粒体膜电位及细胞内[Ca^2＋]i的影响，揭示龙葵碱诱导细胞凋亡的机制。方法：采用AO／EB双染HepG2细胞，激光共聚焦扫描显微镜观察细胞形态学改变；TMRE单染HepG2细胞，激光共聚焦扫描显微镜观察细胞线粒体膜电位的改变；Fluo-3／AM单染HepG2细胞，激光共聚焦扫描显微镜观察细胞内[Ca^2＋]i的改变；TMRE和Fluo-3／AM双染HepG2细胞，激光共聚焦扫描显微镜同时观察细胞线粒体膜电位和细胞内[Ca^2＋]i的改变。结果：形态学实验表明0．0032μg／mL、0．016μg／mL龙葵碱使细胞外周呈微弱皱缩状改变，0．08、0．4、2μg／mL龙葵碱使HepG2细胞出现大量碎片及凋亡小体等典型的细胞凋亡形态，即龙葵碱能够诱导HepG2细胞凋亡；TMRE单染激光共聚焦测定表明龙葵碱能够降低HepG2细胞膜电位；Fluo-3／AM单染激光共聚焦测定表明龙葵碱能够升高肿瘤细胞内[Ca^2＋]。浓度；TMRE和Fluo-3／AM双染激光共聚焦观察表明龙葵碱在降低线粒体膜电位的同时能够升高细胞内[Ca^2＋]i浓度。结论：龙葵碱能够诱导HepG2细胞凋亡，其机制为降低HepG2细胞膜电位，开放细胞膜PT通道，使细胞内Ca^2＋顺浓度梯度转运，从而升高细胞内Ca^2＋浓度启动细胞凋亡机制。     

在地昔帕明诱导胶质瘤C6细胞凋亡过程中caspase3基因表达和[Ca^2＋]i稳态^1

目的：研究抗抑郁药地昔帕明（Des)对胶质瘤C6细胞的凋亡诱导作用以及对凋亡关键效应分子caspase3和凋亡早期信号[Ca^2 ]i的调控作用。方法：采用流式细胞术（FCM）和凝胶电泳观察Des对C6细胞凋亡的DNA裂解作用,RT－PCR分析caspase3基因的表达以及激光扫描共聚焦显微镜测量单个活细胞[Ca^2 ]i浓度。结果：Des(10,20,40μmol/L)处理C6细胞24h后,FCM图的G1峰左侧出现凋亡特征性亚二倍体细胞峰,凋亡细胞百分率分别为5.2%,21.9%和41.9%。同时,凝胶电泳显示典型的DNA“梯带”.Des 20 μmol/L处理C6细胞24h可明显增强caspase 3基因的表达,而未经Des处理的C6细胞则检测不到caspase 3基因的表达。此外,Des 40μmol/L可使C6细胞[Ca^2 ]i迅速升高并维持超过28min,而钙螯合剂依他酸可显著降低C6细胞[Ca^2 ]i增高幅度,提示Des致C6细胞[Ca^2 ]i增高主要与细胞外钙内流有关。结论：Des诱导C6胶质瘤细胞凋亡可能与caspase 3基因表达的上调以及细胞内钙稳态的失衡有关。     

J—894对人体血小板激活时胞浆内游离钙浓度的影响

细胞内游离钙浓度在细胞反应的调节中作为第二信使起很重要的作用。本文实验采用荧光钙指示剂quin-2测定血小板胞浆内游离钙浓度[Ca^2 ]i的变化。结果表明在1mmol/L外钙的存在下，凝血酶（0.3U/ml）使血小板[Ca^2 ]i增高4－5倍。但在外钙缺乏的情况下，凝血酶使血小板[Ca^2 ]i增加较少，似科凝血酶增加[Ca^2 ]i，部分是通过释放内钙，但主要是通过钙内.J-894通过减少钙内流和释放明显抑制凝血酶引起的血小板[Ca^2 ]i的升高，剂量与效应相关。提示J－894可能是一种钙通道阻滞剂。     

维拉帕米、噻庚啶和山莨菪碱拮抗TNFα诱导单个内皮细胞胞内游离Ca^2＋浓度的增高

目的：研究肿瘤坏死因子（TNFα）对单个内皮细胞胞内游离Ca^2 浓度（[Ca^2 ]i)的影响及维拉帕米（Ver)、噻庚啶（Cyp)和山莨菪碱（Ani)对TNFα介导休克和Cyp、Ani的抗休克的机制。方法：人脐静脉内皮细胞株（ECV304）接种于35mm含有2mL DMEM培养基的组织培养盘中培养,Fluo-3/AM负载细胞,激光扫描共聚集显微技术测定单个内皮细胞[Ca^2 ]i。结果：TNFα使单个内皮细胞[Ca^2 ]i呈剂量依赖性升高,在60s内达到峰值,然后下降并保持在基础水平之上。共聚焦扫描图像显示细胞核区[Ca^2 ]i升高比胞浆区明显,下降比胞浆区慢。维拉帕米1和2,噻庚啶30和60或山莨菪碱20和40μmol/L均能显著抑制由TNFα 1.2nmol/L诱导的单个内皮细胞[Ca^2 ]i升高。结论：TNFα介导休克的重要机制;维拉帕米、噻庚啶和山莨菪碱对TNFα诱导的[Ca^2 ]i升高有拮抗作用,可能是噻庚啶和山莨菪碱抗休克作用的机制之一。     

羊栖菜多糖抗肿瘤作用及其作用机制的研究

目的观察羊栖菜多糖对6种不同组织肿瘤的抑瘤作用，并对其作用机制进行了讨论。方法通过对S180、H22荷瘤小鼠瘤重和生存时间的研究，观察了羊栖菜多糖的体内抗肿瘤作用，采用MTT法和集落形成实验法观察羊栖菜多糖的体外抗肿瘤作用。采用流式细胞仪观察羊栖菜多糖对肿瘤细胞周期及细胞凋亡的影响。结果羊栖菜多糖对人胃癌细胞SGC-7901和人直肠癌COLO-205有较好的疗效。羊栖菜多糖可阻滞SGC-7901人胃癌细胞内Go／G，期进入S期，升高细胞凋亡指数(APO％)。结论羊栖菜多糖对人胃癌细胞和直肠癌细胞效果较好，这一作用是通过诱导肿瘤细胞凋亡达到的。     

西兰花中葡萄糖异硫氰酸盐诱导肿瘤细胞凋亡作用及机理研究

目的：探讨西兰花中葡萄糖异硫氰酸盐体内、体外抗肿瘤作用，并初步探讨作用机理。结果：在体内研究中，实验以S180和H22小鼠为研究对象。实验结果表明，GS对S180／小鼠具有抑瘤作用，其中，以中、高剂量组效果最好，与阴性对照组相比具有显著性差异（P〈0.01），抑瘤率呈现一定量效关系（45.45％、57.58％、63.64％）；在生存时间方面，GS能延长H22小鼠的生存时间，其中以高剂量的生存时间延长显著（P〈0．05）。GS还能升高S180小鼠胸腺指数和脾指数，与阴性组比较有显著性差异（P〈0．05，P〈0.01），说明GS对荷瘤小鼠两大免疫器官具有良好的保护作用。在体内抗肿瘤研究中。GS可提高S180和H22小鼠红细胞中SOD、CAT和全血中GSH的活性，并降低全血中红细胞MDA含量。GS的抗肿瘤作用可能是通过提高SOD、CAT、GSH活性，和降低自由基水平来实现的。在体外研究中GS对SGC-7901和HepG2细胞的凋亡过程及其可能机理。从SRB实验结果可看出，1、10、100和1000μg／mL的GS作用于SGC-7901和HepG2细胞72h后，均可抑制肿瘤细胞的增殖，采用荧光倒置显微镜观察GS作用于SGC-7901和HepG2细胞18h后，细胞均出现早期凋亡细胞的形态；通过流式细胞仪检测得300、600、1200μg／mL的GS作用于SGC-7901和HepG2细胞18h后，SGC-7901细胞凋亡率分别为14．544％、10．110％、34．117％，对细胞周期作用显著；HepG2细胞凋亡率分别为2．159％、16．538％和54．455％。可见GS具有一定程度诱导肿瘤细胞凋亡的作用。在GS诱导肿瘤细胞凋亡机理实验中，300、600、1200％μg／mL的GS作用于SGC-7901和HepG2细胞18h后，肿瘤细胞内的Ca^2＋。浓度剂量升高，此作用可能是GS诱导肿瘤细胞凋亡的作用机理之一。线粒体是细胞凋亡的调控中心。所以，通过流式细胞仪检测300、600、1200μg／mL的GS作用于SGC-7901和HepG2细胞18h后，肿瘤细胞内活性氧均增加，线粒体跨膜电位均降低。GS诱导肿瘤细胞凋亡可能是Ca^2＋、活性氧和线粒体之间相互作用的结果，这也许是GS诱导肿瘤细胞凋亡的机理之一。结论：GS无论在体内还是在体外研究中均表现出良好的肿瘤抑制作用，具有一定的诱导肿瘤细胞凋亡的作用。     

川芎嗪甲酸对平滑肌细胞游离钙浓度的影响

研究川芎嗪代谢产物川芎嗪甲酸（CTPZ）对大鼠阴茎海绵体平滑肌细胞（PCSMC）胞质内游离钙离子浓度的影响。方法：用新型Ca^2＋荧光染色剂Fluo-3／AM负载大鼠PCSMC,细胞分为氯化钾（KCl）和去甲肾上腺素（NE）作用组,应用激光扫描共聚焦显微镜（LSCM）实时测定胞质内[Ca^2＋]的变化,分别观察不同浓度的CTPZ对高钾和NE诱导胞质内钙浓度升高的影响,并与母药川芎嗪作用相比。结果：静息状态下,CTPZ对大鼠PCSMC胞质内[Ca^2＋]无明显影响。1,10,100μmol·L^-1 CTPZ能显著抑制高钾诱发的细胞内的钙浓度升高的影响,抑制率分别为（39．84-4．3）％,（49．2±3．6）％,（58．2±3．9）％。也能抑制1μmol·L^-1 NE诱发钙库释放的细胞内[Ca^2＋]升高,抑制率分别为（20．8±3．9）％,（32．3±2．5）％,（43．7±3．2）％。结论：CTPZ对大鼠PCSMC电压依赖性钙通道和细胞内钙库释放的抑制作用,能降低PCSMC胞质内[Ca^2＋]水平,其作用效果比母药川芎嗪佳。     

三叶青黄酮诱导SGC-7901胃癌细胞凋亡的实验研究

目的：观察三叶青黄酮对SGC-7901人胃癌细胞凋亡的诱导作用，初步探讨其可能的机制。方法：体外培养SGC-7901人胃癌细胞，并用MTT法检测三叶青黄酮对肿瘤细胞生长的抑制作用，流式细胞仪分析细胞周期，光镜和电镜观察细胞形态改变，酶谱分析基质金属蛋白酶-2（MMP-2）蛋白的表达改变。结果：三叶青黄酮能显著地抑制SGC-7901细胞的生长，并且具有浓度依赖性，且细胞有明显的凋亡特征性改变，并能降低细胞上清液中MMP-2的含量。结论：三叶青黄酮具有抗肿瘤细胞增殖和诱导凋亡的作用，有潜在的抗肿瘤价值，值得进一步研究。     

白藜芦醇对人胃癌SGC-7901细胞形态、线粒体膜电位、活性氧及钙离子浓度的影响

目的研究白藜芦醇对人胃癌SGC-7901细胞的影响。方法 SGC-7901细胞体外培养48h,分为白藜芦醇低、中、高剂量组(44、88、176μmol/L),阳性对照组(5-FU153.8μmol/L);阴性对照组(不含药物同体积培养液),荧光显微镜观察不同浓度的白藜芦醇对SGC-7901细胞的形态学影响;流式细胞仪检测白藜芦醇对肿瘤细胞中线粒体膜电位、活性氧的的影响;激光共聚焦显微镜观察白藜芦醇对肿瘤细胞中钙离子浓度的影响。结果显微镜下可见肿瘤细胞染色程度加深,染色质聚集、断裂,产生大小不等的凋亡小体,且随着白藜芦醇浓度加大,现象越来越明显,表明细胞凋亡的比例不断增加;白藜芦醇能够明显降低肿瘤细胞中线粒体膜电位,随着白藜芦醇浓度不断增加,肿瘤细胞中活性氧也不断增加,说明白藜芦醇能够提高肿瘤细胞中的活性氧水平来诱导其凋亡;白藜芦醇对肿瘤细胞中钙离子的浓度有一定的作用,其中高剂量能够显著提高肿瘤细胞中钙离子的浓度,且呈现一定的剂量依赖关系。结论白藜芦醇通过影响SGC-7901肿瘤细胞线粒体膜电位、活性氧及钙离子浓度导致肿瘤细胞凋亡,且与剂量相关。     

苦马豆素诱导人胃癌细胞SGC-7901凋亡作用机制的实验研究

目的:探讨SW体外诱导人胃癌细胞株SGC7901凋亡的机制。方法:应用MTT法确定SW对体外培养的SGC7901细胞的作用剂量,通过流式细胞术及凋亡相关调控基因p53、cmyc、Bcl2的检测对细胞凋亡及细胞周期的测定,观察SW对胃癌细胞SGC7901增殖周期的影响以及抑制肿瘤细胞增殖的方式,同时利用激光共聚焦显微镜对细胞内Ca2 浓度的监测,研究SW与细胞内Ca2 超载的关系。结果:SW体外抗SGC7901细胞的完全致死剂量为6.2μg·ml-l,高于0.05μg·ml-l时抑制作用明显(P<0.05),其LC50为0.84μg·ml-l;经SW0.5～1.5μg·ml-l处理24h可引起凋亡抑制基因p53、Bcl2的明显下降、凋亡促进基因cmyc的明显升高以及肿瘤细胞内Ca2 超载,最终诱导SGC7901细胞凋亡。实验还证实SW主要作用于肿瘤细胞的S期,使瘤细胞主要积聚在S期。结论:SW通过多种途径诱导细胞凋亡可能是其发挥抗癌作用的重要机制。     

Mechanism of apoptosis induced by a polysaccharide, from the loach Misgurnus anguillicaudatus (MAP) in human hepatocellular carcinoma cells

The biological activities of the polysaccharide have attracted more and more attention in the biochemical and medical areas due to their anti-cancer effects. To estimate the anti-tumor mechanism of MAP, a novel polysaccharide from the loach, Misgurnus anguillicaudatus, the apoptosis effects of the polysaccharide on the human hepatocellular carcinoma cells (SMMC-7721 cells) were studied. The present studies showed that MAP could induce cell apoptosis which was closely accompanied with an increase of intracellular-free calcium concentration ([Ca2+]i), the enhancement of reactive oxygen species (ROS) level, dissipation of mitochondria membrane potential (MMP), up-regulation of p53 mRNA, increase expression of Bax mRNA, and decrease expression of Bcl-2 mRNA. These results suggested that cell apoptosis induced by MAP mainly was mediated by mitochondrial pathways, not involved death receptors (DRs) pathways. The mechanism possibly is that MAP acts on mitochondria and boosts ROS, ROS mediates a release of Ca2+ from the intracellular Ca2+ pool, increasing [Ca2+]i targets the cells a start-up of the apoptosis program. However, further research on the molecular mechanisms of MAP effecting on the cells' mitochondria is necessary.     

Rise in intracellular calcium concentration elicited by isradipine in Gin-1 cells.

We performed experiments to examine whether isradipine (Isr), a calcium antagonist, would raise the intracellular calcium concentration ([Ca2+]i) in Gin-1 cells and, if so, to elucidate the mechanism of the [Ca2+]i rise. Gin-1 cells, which are human normal gingival fibroblasts were used as the material. The [Ca2+]i was measured with the Ca2+-sensitive fluorescent dye fura-2/AM. Changes in the fluorescence intensity of fura-2 in the cells were recorded with a video-imaging analysis system. Isr concentration-dependently raised the [Ca2+]i. A Ca2+-free saline significantly inhibited the Isr-induced [Ca2+]i rise. Whereas Isr in Ca2+-containing solution weakly raised the [Ca2+]i by pretreatment with thapsigargin, an inhibitor of Ca2+ release from Ca2+ stores, the Ca2+-free saline plus thapsigargin completely depressed the Isr-induced [Ca2+]i rise. The same response was observed in the case of pretreatment with cyclopiazonic acid (1 microM), another inhibitor of Ca2+ release from the Ca2+ stores. Isr raises the [Ca2+]i in Gin-1 cells and that the Isr-induced [Ca2+]i rise is ascribable to both the Ca2+ influx through the plasma membrane and Ca2+ release from the intracellular Ca2+ store.     

D-氨基葡糖盐酸盐对胃癌细胞SGC-7901细胞周期及相关蛋白表达的影响

目的 研究D-氨基葡萄糖盐酸盐诱导人胃癌细胞SGC-7901的凋亡作用,并探讨其作用机制.方法 分别采用SRB法测定D-氨基葡萄糖盐酸盐对SGC-7901细胞的生长抑制作用,流式细胞仪观察对细胞周期及细胞色素C表达的影响,激光共聚焦显微镜检测细胞内Ca2+浓度的变化,Western Blot法测定周期蛋白B1、钙调神经磷酸酶表达的变化.结果 D-氨基葡萄糖盐酸盐能够引起SGC-7901细胞周期产生S期阻滞,细胞内Ca2+浓度增加,周期蛋白B1表达下降、钙调神经磷酸酶及细胞色素C的表达升高.结论 D-氨基葡萄糖盐酸盐使SGC-7901细胞周期发生阻滞并诱导细胞凋亡.     

Anandamide-induced Ca2+ elevation leading to p38 MAPK phosphorylation and subsequent cell death via apoptosis in human osteosarcoma cells

The effect of anandamide on human osteoblasts is unclear. This study examined the effect of anandamide on viability, apoptosis, mitogen-activated protein kinases (MAPKs) and Ca2+ levels in MG63 osteosarcoma cells. Anandamide at 50-200 microM decreased cell viability via apoptosis as demonstrated by propidium iodide staining and activation of caspase-3. Immunoblotting suggested that anandamide induced expression of ERK, JNK and p38 MAPK. Anandamide-induced cell death and apoptosis were reversed by SB203580, but not by PD98059 and SP600125, suggesting that anandamide's action was via p38 MAPK, but not via ERK and JNK. Anandamide at 1-100 microM induced [Ca2+]i increases. Removal of extracellular Ca2+ decreased the anandamide response, indicating that anandamide induced Ca2+ influx and Ca2+ release. Chelation of intracellular Ca2+ with BAPTA reversed anandamide-induced cell death and p38 MAPK phosphorylation. Collectively, in MG63 cells, anandamide induced [Ca2+]i increases which evoked p38 MAPK phosphorylation. This p38 MAPK phosphorylation subsequently activated caspase-3 leading to apoptosis.     

Silica increases cytosolic free calcium ion concentration of alveolar macrophages in vitro.

Rat alveolar macrophages were exposed to silica dust (quartz) suspended in culture medium (SiO2, dry particle size less than 5 microns in diameter) and fluctuation in their cytosolic free calcium content ([Ca2+]i) was detected in cell monolayers with a fluorescent calcium probe (Indo-1AM). Cytosolic free calcium content was correlated with lactate dehydrogenase (LDH) release, an index of cell damage. SiO2 induced a concentration- and time-dependent increase of cytosolic free Ca2+ ion concentration and LDH release. [Ca2+]i was increased about fivefold when cells were exposed to 200 micrograms of SiO2 per milliliter (3 ml per dish) for 2 hr. [Ca2+]i changed within 15 min of SiO2 treatment, whereas LDH release was measurably increased only after 30 min. Chelation of extracellular Ca2+ by 2 mM ethylene glycol bis(beta-aminoethyl ether) N,N'-tetraacetate did not prevent SiO2-induced fluctuation of macrophage [Ca2+]i, but did partially prevent the SiO2-induced increase in LDH release (p less than 0.01). We conclude that a very early event in SiO2-induced damage of alveolar macrophages involves mobilization of intracellular calcium pools to increase [Ca2+]i. These results suggest that SiO2-induced macrophage damage, a key event in the development of silicosis, may involve perturbation of intracellular calcium homeostasis.     

(-)-Epigallocatechin gallate attenuates glutamate-induced cytotoxicity via intracellular Ca modulation in PC12 cells

1. The effects of (-)-epigallocatechin gallate (EGCG), a green tea polyphenol, on glutamate-induced increases in intracellular Ca2+ concentrations ([Ca2+]i) and cytotoxicity in PC12 cells were investigated. 2. Changes in [Ca2+]i were measured using Fura-2/AM calcium indicator dye and cellular viabilities were determined by a viable cell count and a 3-(4,4-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide reduction assay. 3. Glutamate increased [Ca2+]i in PC12 cells in a dose-dependent manner. (-)-Epigallocatechin gallate attenuated this glutamate (30 mmol/L)-induced [Ca2+]i increase and EGCG (50 micromol/L) increased the viability of PC12 cells against glutamate-induced cytotoxicity. The EGCG effect was also found to be independent of its general anti-oxidant mechanism. In contrast, EGCG directly suppressed both N-methyl-D-aspartate (50 mmol/L)- and kainate (20 mmol/L)-mediated Ca2+ influx, but not metabotropic receptor-mediated Ca2+ release. 4. These results suggest that EGCG reduces the glutamate-induced [Ca2+]i increase by attenuating ionotropic Ca2+ influx and that this promotes the viability of PC12 cells.     

Imaging of Ca2+ release by caffeine and 9-methyl-7-bromoeudistomin D and the associated activation of large conductance Ca2+-dependent K+ channels in urinary bladder smooth muscle cells of the guinea pig

Ca2+ release by caffeine and 9-methyl-7-bromoeudistomin D (MBED) and the concomitant activation of large conductance Ca2+-dependent K+ (BK) channels were analyzed using confocal Ca2+ imaging and whole cell voltage-clamp methods in guinea pig urinary bladder smooth muscle cells. Puff application of 3 or 10 mM caffeine for several seconds (2 - 5 s) elicited a large increase in intracellular Ca2+ concentration ([Ca2+]i) and induced a phasic outward current at a holding potential of -40 mV. The phasic outward current was the summation of spontaneous transient outward currents (STOCs) due to marked activation of BK channels and was followed by a short cessation of STOCs. Although the increase in superficial [Ca2+]i by caffeine was faster than that in global [Ca2+]i, the peak [Ca2+]i was identical in these areas. Puff application of 100 microM MBED also markedly enhanced STOCs for a few seconds. This response to MBED was not observed when stored Ca2+ was depleted by caffeine. The increase in [Ca2+]i by MBED occurred mainly in superficial areas. Longer application of 100 microM MBED for 2 min did not induce significant global [Ca2+]i increase but decreased the amount of Ca2+ release and cell shortening during the subsequent application of 10 mM caffeine. These results indicate that short application of MBED releases Ca2+ preferentially from superficial storage sites, presumably due to its slow approach to deeper sites. MBED may be a good pharmacological tool to manipulate selectively the superficial Ca2+ stores related to STOCs.