神经肽Y对大鼠血管平滑肌细胞内钙离子浓度的影响

目的 应用激光共聚焦显微镜动态观察神经肽Y(NPY)受体激动剂[Leu31, Pro34]-NPY干预大鼠血管平滑肌细胞(VSMC)产生的细胞内钙离子([Ca2 ]i)浓度变化,以确定NPY对大鼠VSMC[Ca2 ]i浓度的影响.方法 用分散细胞培养法培养VSMC.用10 μmol/L的Fluo-3孵育细胞.使其与细胞内的游离[Ca2 ]i相结合,从而能够在525 nm的激发光激发下产生荧光.分别用正常细胞外液、无钙细胞外液稀释的10-6 mol/L[Leu31, Pro34 ]-NPY、1 μmol/L硝苯地平、10-6 mol/L[Leu31, Pro34 ]-NPY 1 μmol/L硝苯地平灌流细胞,同时用激光共聚焦显微镜扫描、记录图像.用Leica图像分析系统分析图像,定量分析不同情况下的[Ca2 ]i荧光强度.结果 正常细胞外液灌流时[Ca2 ]i变化不明显,最高值为57.3±3.1,最低值为53.7±2.9,无明显差异(P＞0.05). [Leu31, Pro34]-NPY干预细胞时,[Ca2 ]i明显地升高,随后又开始下降.最高值为86.4±2.7,最低值为58.1±3.0,有非常显著差异(P＜0.01).无钙细胞外液 [Leu31, Pro34 ]-NPY灌流VSMC时[Ca2 ]i浓度变化不明显,最高值为52.5±3.5,最低值为48.0±1.2(P＞0.05);[Leu31, Pro34 ]-NPY 硝苯地平组[Ca2 ]i变化不明显,最高值为52.6±2.1,最低值为51.7±2.7,差异无统计学意义(P＞0.05).硝苯地平组[Ca2 ]i呈下降趋势,最高值为52.8±2.2,最低值为37.5±2.1,有非常显著差异(P＜0.01).结论 NPY能够通过NPY-Y1受体使细胞内的[Ca2 ]i浓度升高,这种升高是依赖于细胞外的[Ca2 ]i由L型[Ca2 ]i通道进入细胞的.     

神经肽Y对大鼠血管平滑肌细胞内钙离子浓度的影响

目的应用激光共聚焦显微镜动态观察神经肽Y(NPY)受体激动剂[Leu31,Pro34]-NPY干预大鼠血管平滑肌细胞(VSMC)产生的细胞内钙离子([Ca2 ]i)浓度变化,以确定NPY对大鼠VSMC[Ca2 ]i浓度的影响。方法用分散细胞培养法培养VSMC。用10μmol/L的Fluo-3孵育细胞。使其与细胞内的游离[Ca2 ]i相结合,从而能够在525nm的激发光激发下产生荧光。分别用正常细胞外液、无钙细胞外液稀释的10-6mol/L[Leu31,Pro34]-NPY、1μmol/L硝苯地平、10-6mol/L[Leu31,Pro34]-NPY 1μmol/L硝苯地平灌流细胞,同时用激光共聚焦显微镜扫描、记录图像。用Leica图像分析系统分析图像,定量分析不同情况下的[Ca2 ]i荧光强度。结果正常细胞外液灌流时[Ca2 ]i变化不明显,最高值为57.3±3.1,最低值为53.7±2.9,无明显差异(P>0.05)。[Leu31,Pro34]-NPY干预细胞时,[Ca2 ]i明显地升高,随后又开始下降。最高值为86.4±2.7,最低值为58.1±3.0,有非常显著差异(P<0.01)。无钙细胞外液 [Leu31,Pro34]-NPY灌流VSMC时[Ca2 ]i浓度变化不明显,最高值为52.5±3.5,最低值为48.0±1.2(P>0.05);[Leu31,Pro34]-NPY 硝苯地平组[Ca2 ]i变化不明显,最高值为52.6±2.1,最低值为51.7±2.7,差异无统计学意义(P>0.05)。硝苯地平组[Ca2 ]i呈下降趋势,最高值为52.8±2.2,最低值为37.5±2.1,有非常显著差异(P<0.01)。结论NPY能够通过NPY-Y1受体使细胞内的[Ca2 ]i浓度升高,这种升高是依赖于细胞外的[Ca2 ]i由L型[Ca2 ]i通道进入细胞的。     

伽玛刀对正常大鼠皮层神经元胞浆内游离钙离子水平的影响

目的观察伽玛刀对正常大鼠皮层神经元胞浆内游离钙离子水平的影响。方法12只雄性Wistar大鼠随机分为假照射组和照射组,以大鼠左侧额叶为靶区进行伽玛刀照射,分别于照射后24h、30d、60d处死动物,急性分离皮层神经元并负载荧光染料fluo-3,激光共聚焦显微镜观察皮层神经元胞浆内游离钙离子浓度。结果24h组靶区皮层神经元胞浆内游离钙离子荧光强度与假照射组相比无显著性差异,30d组和60d组靶区皮层神经元胞浆内游离钙离子荧光强度与假照射组相比分别升高65.4%和57.8%,有显著性差异。结论伽玛刀可以引起靶区神经元胞浆内游离钙离子水平在较长时期内保持相对超载状态。     

硝酸甘油对人脐血管内皮细胞内钙离子浓度的影响

目的 探讨不同剂量硝酸甘油对体外培养人脐血管内皮细胞内钙离子浓度的影响。方法分离人脐静脉内皮细胞，体外原代培养，细胞经钙荧光探针Fluo-3-AM染色后，在激光共聚焦显微镜下观察培养液中分别加入三种浓度硝酸甘油后，细胞内游离钙离子浓度[Ca^2 ]i的动态变化情况。结果 低浓度和高浓度硝酸甘油作用后，[Ca^2 ]i呈现不同的变化曲线。10μg／ml NTG持续缓慢下降；30μg／mlNTG先明显下降，然后缓慢上升；1000／μg／mlNTC持续缓慢上升。结论 硝酸甘油的药理作用与内皮细胞有关，不同浓度的硝酸甘油可能通过不同的信号传导路径发挥不同的生理作用。     

葛根素对糖尿病大鼠心功能及心肌细胞内钙离子的影响

目的探讨葛根素对糖尿病大鼠心功能及心肌细胞内钙离子的影响。方法 40只SD大鼠随机分成空白对照组、糖尿病模型组、葛根素低剂量组和葛根素高剂量组,每组10只。测定大鼠心脏功能、心室重量指数、心脏重量指数和心肌细胞内钙离子瞬间变化。结果与糖尿病模型组比较,葛根素低剂量组和葛根素高剂量组心脏功能明显改善,心室重量指数、心脏重量指数及钙瞬变峰幅度下降,钙瞬变时程缩短,且高剂量组改善更加明显。结论葛根素可以改善糖尿病大鼠心功能、心室重量指数和心脏重量指数,其机制可能与调节心肌细胞内钙离子水平有关。     

槟榔碱促结肠平滑肌细胞收缩及对胞内钙离子浓度的影响

目的:观察氢溴酸槟榔碱(Ah)促进培养的结肠平滑肌细胞收缩作用及对胞内游离Ca2 浓度的影响．方法:培养大鼠结肠平滑肌细胞,分为4组:正常对照组、Ah刺激组、乙酰胆碱(Ach)刺激组、阿托品预处理组．应用特异性Ca2 荧光批示剂Fluo-3／AM负载细胞,激光共聚焦显微镜检测游离Ca2 浓度和细胞收缩率．结果:正常对照组细胞未发生自主性收缩,因指示剂的衰减,荧光强度(FI)有递减的趋势; Ah刺激组在加药后短时间内胞内钙离子浓度迅速升高,出现一个波峰,FI平均基础值与峰值有差异(P<0．05),而后胞内钙离子浓度再缓慢攀升,在484．0±47．6 s达到高峰,而后有一个较长时间的平台期,在1 400 s左右恢复至静息水平,FI基础值与峰值有显著差异 (P<0．01),细胞收缩百分数为20．70％±0．07％; Ach刺激组在加药后胞内钙离子浓度升高,形成一个小波峰,FI基础值和峰值差异有显著性(P<0．01)．随后胞内钙离子浓度缓慢攀升, 在600 s左右达到高峰,而后有一个较长时间的平台期．FI基础值与峰值差异有显著性 (P<0．001);经阿托品预孵育处理后的细胞,加入Ah后,其收缩效应被完全抑制．结论:Ah可引起结肠平滑肌细胞收缩,升高细胞内游离Ca2 浓度．其收缩效应可以被M受体阻断剂阿托品所抑制．     

黄芪总黄酮对心肌细胞内游离钙离子浓度的影响

目的研究黄芪总黄酮（Total flavonoids of Ast ragalus,TFA）对体外培养的乳鼠心肌细胞内游离钙离子浓度的作用。方法实验应用钙离子荧光指示剂Fluo-3AM负载原代培养的乳鼠心肌细胞,通过激光共聚焦扫描显微镜上机检测,记录其荧光强度变化,同时观察黄芪总黄酮对乳鼠心肌细胞及化学处理因素H2O2损伤大鼠心肌细胞的荧光强度的作用。结果①H2O2损伤的乳鼠心肌细胞游离钙离子[Ca^2＋]i平均荧光强度值为（1346．89±65．36）nmol／L,与对照组平均荧光强度值（743．15±34．78）nmol／L相比,差异有统计学意义（P〈0．01,n=7）;同时H2O2（0．3mmol／L）使予给TFA（20mg／kg）组乳鼠心肌细胞的[Ca^2＋]i平均荧光强度值由（668．29±41．15）nmol／L下降到（649．31±39．17）nmol／L,差异无统计学意义（P〉0．05,n=7）。结论H2O2可明显升高乳鼠心肌细胞游离钙离子浓度,黄芪总黄酮可对抗H2O2的这种作用。     

硝酸甘油对人脐血管内皮细胞内钙离子浓度的影响

目的探讨不同剂量硝酸甘油对体外培养人脐血管内皮细胞内钙离子浓度的影响.方法分离人脐静脉内皮细胞,体外原代培养,细胞经钙荧光探针Fluo-3-AM染色后,在激光共聚焦显微镜下观察培养液中分别加入三种浓度硝酸甘油后,细胞内游离钙离子浓度[Ca2+]i的动态变化情况.结果低浓度和高浓度硝酸甘油作用后,[Ca2+]i呈现不同的变化曲线.10 μg/ml NTG持续缓慢下降;30 μg/ml NTG先明显下降,然后缓慢上升;1000 μg/ml NTG持续缓慢上升.结论硝酸甘油的药理作用与内皮细胞有关,不同浓度的硝酸甘油可能通过不同的信号传导路径发挥不同的生理作用.     

脂欣康胶囊对大鼠血管平滑肌细胞源性泡沫细胞钙离子浓度的影响

目的观察脂欣康及洛伐他汀干预大鼠血管平滑肌细胞（VSMC）源性泡沫细胞产生的细胞内钙离子（[Ca^2＋]i）浓度变化，以探讨脂欣康对动脉粥样硬化（AS）泡沫化细胞形成的可能调控机制。方法用组织块培养法培养VSMC，以氧化低密度脂蛋白使其泡沫化，并以脂欣康、洛伐他汀分别干预。以10μmol／L的Fluo-3孵育细胞后，用激光共聚焦显微镜扫描、记录图像，并作分析。结果脂欣康与洛伐他汀均能降低VSMC[Ca^2＋]i浓度，与生理盐水组、空白对照组相比，脂欣康组和洛伐他汀组均有统计学意义（P〈0．01），但两组之间差异无统计学意义（P〉0．05）。结论脂欣康具有与洛伐他汀相似的降低VSMC[Ca^2＋]i浓度的作用，这可能是其抑制VSMC增殖和泡沫化细胞形成的机制之一。     

肥胖大鼠血脂和体脂肪变化及心室肌细胞内钙离子强度与心律失常发生的关系

目的 观察高脂饮食诱导肥胖(DIO)大鼠血脂和体脂肪变化,探讨心室肌细胞内钙离子强度与心律失常发生的关系.方法 健康雄性SD大鼠60只,体质量200～250 g.将大鼠按体质星随机分为对照组(15只)和高脂饮食组(45只),高脂饮食组采用高脂饮食诱导法建立肥胖大鼠模型.喂养12周后,在高脂饮食组筛选体质量增加明显的大鼠进入肥胖组(15只).两组各选8只大鼠舌下注射0.1 ms/kg BaCl2,诱导心律失常.应用标准Ⅱ导联心电图连续监测1 h,评价大鼠心律失常发生率及严重程度.采集两组大鼠腹主动脉血,分离血清,测血清总胆同醇,甘油三酯,低密度脂蛋白胆固醇和高密度脂蛋白胆固醇.分离大鼠肾周脂肪,睾周脂肪和肠系膜脂肪,称重,计算体脂比.酶解法分离大鼠单个心室肌细胞,应用激光共聚焦技术记录细胞内钙离子强度([Ca2+]i).结果 肥胖组大鼠体脂比[(7.71±0.74)%]明显高于对照组[(4.69±0.37)%],两组比较差异有统计学意义(t＝3.650,P＜0.05),血清总胆固醇,甘油三酯和低密度脂蛋白水平,肥胖组[(1.26±0.04),(0.58±0.10),(0.51±0.04)mmol/L]与对照组[(0.92±0.08),(0.29±0.03),(0.31±0.04)mmol/L]比较显著增高(t值分别为3.801,2.778,3.536,P＜0.05),肥胖组大鼠心律失常发生率高于对照组(X2＝5.333,P＜0.05),心律失常评分肥胖组(2.5±0.6)高于对照组(0),肥胖组大鼠心室肌细胞内钙离子强度(247.96±20.03)明显高于对照组(174.25±23.13),两组比较差异有统计学意义(t=2.409,P＜0.05).结论 肥胖大鼠心律失常发生率增加,血脂升高,心肌细胞内钙离子积聚是引发肥胖源性心律失常的主要机制之一.     

Effect of solanine on the membrane potential of mitochondria in HepG2 cells and [Ca^2＋]i in the cells

AIM: To observe the effect of solanine on the membrane potential of mitochondria in HepG2 cells and [Ca2 ]i in the cells, and to uncover the mechanism by which solanine induces apoptosis. METHODS: HepG2 cells were double stained with AO/EB, and morphological changes of the cells were observed using laser confocal scanning microscopy (LCSM). HepG2 cells were stained with TMRE, and change in the membrane potential of mitochondria in the cells were observed using LCSM. HepG2 cells were double stained with Fluo-3/AM, and change of [Ca2 ]i in the cells were observed using LCSM. HepG2 cells were double stained with TMRE and Fluo-3/AM, and both the change in membrane potential of mitochondria and that of [Ca2 ]i in the cells were observed using LCSM. RESULTS: Cells in treated groups showed typical signs of apoptosis. Staining with TMRE showed that solanine could lower membrane potential; staining with Fluo-3/AM showed that solanine could increase the concentration of Ca2 in tumor cells; and those of double staining with TMRE and Fluo-3/AM showed that solanine could increase the concentration of Ca2 in the cells at the same time as it lowered the membrane potential of mitochondria. CONCLUSION: Solanine opens up the PT channels in the membrane by lowering the membrane potential, leading to Ca2 being transported down its concentration gradient, which in turn leads to the rise of the concentration of Ca2 in the cell, turning on the mechanism for apoptosis.     

Effects of new intravascular contrast agents on [Ca2+]i transients and contraction in cultured ventricular myocytes

Summary We examined the effects of four kinds of intravascular contrast agents (amidtrizoic acid, iohexol, iopamidol, and ioxaglic acid) on [Ca²⁺]_i transients (indo-1 fluorescence) and cell contraction (video motion analyzer), using cultured chick embryo ventricular myocytes. Exposure of ventricular myocytes to amidtrizoic acid (a conventional contrast agent) reduced the [Ca²⁺]_i transients and the sensitivity of the contractile elements to [Ca²⁺]_i. Ioxaglic acid (a low osmotic contrast agent) also reduced the [Ca²⁺]_i transients, but did not significantly change the sensitivity of the contractile elements to [Ca²⁺]_i. Neither iohexol nor iopamidol (nonionic contrast agents) reduced the [Ca²⁺]_i transients, but both significantly decreased the sensitivity of the contractile elements to [Ca²⁺]_i. A marked negative inotropic effect of amidtrizoic acid was caused by both calcium binding and hypertonicity. The less marked depression of contractility produced by ioxaglic acid is possibly the result of calcium binding, but is not caused by hypertonicity. The negative inotropism produced by nonionic contrast agents (iohexol and iopamidol) was due to hypertonicity, but not due to alterations in the [Ca²⁺]_i transients.Exposure of ventricular myocytes to nonionic contrast agents (iohexol and iopamidol) slowed decay in the [Ca²⁺]_i transients with increased end-diastolic [Ca²⁺]_i. After washing out the nonionic contrast agents, these parameters returned to control levels. On the other hand, exposure to amidtrizoic acid decreased end-diastolic [Ca²⁺]_i without changing decay time in the [Ca²⁺]_i transients. After washing out amidtrizoic acid, there was a prolongation of half decay time in [Ca²⁺]_i transients with a significant increase in end-diastolic [Ca²⁺]_i and cell position. Diastolic dysfunction just after washout of amidtrizoic acid was possibly caused by an increase in [Na⁺]_i due to sodium influx during exposure to the contrast agent.     

同型半胱氨酸对单个人脐静脉内皮细胞胞内游离钙的影响

目的 :观察同型半胱氨酸 (HCY)对单个血管内皮细胞 (EC)胞内游离钙〔Ca2 + 〕i的影响。方法 :进行人脐静脉内皮细胞 (HUVECs)原代培养 ,用激光扫描共聚焦显微镜观察。结果 :不同浓度HCY均可引起HU VECs单个EC〔Ca2 + 〕i升高。尼莫地平抑制这种〔Ca2 + 〕i浓度升高。结论 :HCY引起血管EC〔Ca2 + 〕i升高可能是HCY致血管病变的机制之一。     

3,5,3'-Triiodothyronine deprivation affects phenotype and intracellular [Ca2+]i of human cardiomyocytes in culture

OBJECTIVE: A decrease in plasma T3 concentration is a frequent finding in patients with heart failure. However, the role of this 'low T3 syndrome' on disease evolution has never been clarified. As phenotypic and functional cardiomyocyte impairments are alterations that correlate with the failing myocardium, we studied the long-term effects of T3 deprivation on human cardiomyocyte structure and calcium handling. METHODS: Atrial cardiomyocytes and myocardial tissue were cultured with or without 3 nM T3. Microscopical examination of structural features was followed by analysis of alpha-sarcomeric actinin and sarcoplasmic reticulum calcium ATP-ase (SERCA-2) content. Calcium handling was studied by [Ca2+](i) imaging. RESULTS: When stimulated with cyclopiazonic acid, a SERCA-2 inhibitor, T3-deprived cardiomyocytes showed significantly faster (P=0.03) and more transient (P=0.04) increases in [Ca(2+)](i) than T3-supplemented cells. Moreover, in the T3-free cultures a significantly lower number of cells (P=0.003) responded to caffeine, a typical activator of sarcoplasmic reticulum Ca(2+)-release channel. T3-deprived cardiomyocytes also presented altered morphology with larger dimensions than T3-supplemented cells (P < 0.0001). Additionally, in T3-deprived samples alpha-sarcomeric actinin and SERCA-2 protein levels were reduced to 65.6 +/- 3% (P < 0.0001) and 74.1 +/- 4% (P=0.005), respectively, when compared with the T3-supplemented group. CONCLUSIONS: Our data show that human cardiomyocyte calcium handling and phenotype are strongly influenced by T3 suggesting important implications of the 'low T3 syndrome' on the progression of heart failure.     

Progress and problems in measuring the [Ca2+]i

Since Ca(2+) has been recognized as an important intracellular second messenger for many signal transduction pathways, several methods to measure the intracellular Ca(2+) concentration ( [Ca(2+)](i) ) have been invented, including Ca(2+) microelectrodes, Ca(2+) sensitive dyes, and artificial Ca(2+) sensitive proteins. These techniques have been further evolving in combination with progression of computer technology, while true [Ca(2+)](i) is not still measurable.     

Decreased endothelin binding and [Ca2+]i signaling in microvessels of DOCA-salt hypertensive rats

OBJECTIVES AND DESIGN: The deoxycorticosterone acetate (DOCA)-salt model of hypertension is characterized by elevated vascular endothelin-1 (ET-1) and by reduced contraction to ET-1 in isolated mesenteric small arteries. The decreased contraction to ET-1 may be a compensatory mechanism caused by elevations in ET-1 and arterial pressure. The present study was designed to determine whether down-regulation of endothelin receptors or altered Ca2+ signaling contribute to the decreased contraction to ET-1. METHODS AND RESULTS: Contraction to ET-1 (10 to 10 mol/l) was significantly reduced in isolated mesenteric small arteries (87-286 microm intraluminal diameter) from DOCA-salt rats compared with placebo rats. Membrane protein was obtained for measurement of [125I]ET-1 receptor binding and ET receptor expression. Maximum binding was significantly reduced in vascular membranes from DOCA-salt rats (670 +/- 71 fmol/mg protein) compared with placebo rats (1165 +/- 75 fmol/mg protein), but binding affinity was unchanged. Conversely, ETA receptor protein was increased in DOCA-salt rat vessels. To assess Ca2+ signaling, freshly dissociated mesenteric small artery smooth muscle cells were loaded with fura-2 for measurement of the average myoplasmic free Ca2+ concentration ([Ca2+ ] ). The ET-1 (10 mol/l) induced increase in [Ca2+ ] was significantly less in cells from DOCA-salt rats compared with from placebo rats. This effect was not due to a loss of L-type Ca2+ channels since expression was increased in membrane protein from DOCA-salt rats compared with placebo rats, as measured by Western blot analysis. CONCLUSIONS: These findings indicate that decreases in receptor binding and Ca2+ signaling contribute to the impaired contraction to ET-1 in DOCA-salt hypertensive rats. However, these changes are not due to reduced expression of ETA receptors or L-type Ca2+ channels.     

Neuropeptide Y rapidly enhances [Ca2+]i transients and Ca2+ sparks in adult rat ventricular myocytes through Y1 receptor and PLC activation

Neuropeptide Y (NPY) is the most abundant peptide in the mammalian heart, but its cardiac actions are not fully understood. Here we investigate the effect of NPY in intracellular Ca2+ release, using isolated rat cardiac myocytes and confocal microscopy. Cardiac myocytes were field-stimulated at 1 Hz. The evoked [Ca2+]i transient was of higher amplitude and of faster decay in the presence of 100 nM NPY. Cell contraction was also increased by NPY. We analyzed the occurrence of Ca2+ sparks and their characteristics after NPY application. NPY significantly increased Ca2+ sparks frequency in quiescent cells. The Ca2+ spark amplitude was enhanced by NPY but the other characteristics of Ca2+ sparks were not significantly altered. Because cardiac myocytes express both Y1 and Y2 NPY receptors, we repeated the experiments in the presence of the receptor blockers, BIBP3226 and BIIE0246. We found that Y1 NPY receptor blockade completely inhibited NPY effects on [Ca2+]i transient. PTX-sensitive G-proteins and/or phospholypase C (PLC) have been invoked to mediate NPY effects in other cell types. We tested these two hypotheses. In PTX-treated myocytes NPY was still effective, which suggests that the observed NPY actions are not mediated by PTX-sensitive G-proteins. In contrast, the increase in [Ca2+]i transient by NPY was completely inhibited by the PLC inhibitor U73122. In conclusion, we find that NPY has a positive inotropic effect in isolated rat cardiac myocytes, which involves increase in Ca2+ release after activation of Y1 NPY receptor and subsequent stimulation of PLC.     

Role of changes in [Ca2+]i in energy deprivation contracture

Mechanisms of energy deprivation contracture were investigated in cultured chick embryo ventricular cells. In the presence of zero-extracellular-Na+, (choline chloride substitution)-nominal-zero-Ca2+ [( Ca2+] approximately 5 microM), exposure of ventricular cells to 1 mM cyanide (CN) and 20 mM 2-deoxyglucose (2-DG)-zero-glucose solution resulted in the development of a contracture (video motion detector) in 5.9 +/- 0.5 minutes. Early after contracture development, the resupply of extracellular Na+, in the continued presence of CN + 2-DG, resulted in a rapid partial relaxation (t1/2 = 1.9 +/- 0.3 seconds), associated with an increase in 45Ca efflux, presumably due to transsarcolemmal Ca2+ extrusion due to Na+-Ca2+ exchange. Resupply of glucose and removal of CN + 2-DG, in the continued absence of Na+, resulted in an initially slower (t1/2 = 11.6 +/- 2.5 seconds), but more complete relaxation of contracture, which was not associated with increased Ca2+ efflux. Pretreatment with 20 mM caffeine delayed the onset of contracture (9.2 +/- 1.1 minutes) and resulted in a contracture that could not be relaxed by resupply of external Na+ only. Studies using the fluorescent Ca2+ probe indo 1 demonstrated that in zero-Na+-zero-Ca2+ solutions, contracture due to CN + 2-DG was associated with an initial rise in [Ca2+]i but that this did not account for all of contracture force development. In cells exposed to CN + 2-DG in the presence of normal extracellular Na+ and Ca2+ concentrations, a small rise in [Ca2+]i was associated with initial contracture development, consistently preceding the development of a larger accelerated contracture presumably due to ATP depletion.(ABSTRACT TRUNCATED AT 250 WORDS)     

Influence of varied [Ca2+]0 and [Na+]0 on electrical activity of clusters of cultured cardiac cells from neonatal rats.

The effects of sodium and calcium concentration on the action potential of cell clusters derived from rat ventricle were studied. The maximum rate of rise ($\text{V}\text{̇}{}_{\mathrm{<mtext>max</mtext>}}$) decreased in low sodium (50 mm) medium, but the overshoot did not change. The $\text{V}\text{̇}{}_{\mathrm{<mtext>max</mtext>}}$ did not vary with [Ca²⁺]_o within the range of 0.4 to 5.0 mm, but the size of the overshoot increased with increasing [Ca²⁺]_o. A change of 8.8 mV/decade of change of [Ca²⁺]_o was observed. These results indicate that both calcium and sodium ions carry the inward current responsible for the upstroke. The insensitivity of $\text{V}\text{̇}{}_{\mathrm{<mtext>max</mtext>}}$ to changes in [Ca²⁺]_o can be explained if high calcium shifts the inactivation characteristic of the slow current (f_∞) towards more negative potentials. The slope of the diastolic depolarization decreased in low sodium and in low calcium media, and increased in 5 mm [Ca²⁺]_o. These findings, together with the different sensitivity of the upstroke and the diastolic depolarization to TTX [15] lead us to postulate that although calcium and sodium carry the current(s) involved in electrogenesis and automaticity, these phenomena may be mediated by two distinct types of ionic channels having different kinetics.     

硝苯地平控释片改善稳定性心绞痛患者一氧化氮对淋巴细胞[Ca2+]i的调节作用

目的观察硝苯地平控释片(商品名拜新同)对稳定性心绞痛患者的疗效及对外周淋巴细胞[Ca2+]i的影响.方法对61例稳定性心绞痛患者进行为期8周的随机单盲平行对照试验.硝苯地平控释片组系在对照组常规治疗的基础上加服硝苯地平控释片30mg/d.治疗前后测两组患者外周淋巴细胞[Ca2+]i和一氧化氮(NO).结果(1)两组心绞痛发作次数及硝酸甘油耗量均明显下降(P＜0.01),硝苯地平控释片组优于对照组(P＜0.05);(2)经过8周治疗后硝苯地平控释片组较对照组外周血淋巴细胞内源性NO明显增加(P＜0.01);同时也较对照组淋巴细胞[Ca2+]i降低(P＜0.01);(3)治疗后淋巴细胞[Ca2+]i随着NO升高而下降,二者呈显著负相关(r=-0.6283,P＜0.001).结论硝苯地平控释片明显改善稳定性心绞痛患者症状,逆转细胞内钙超负荷.