Na~+/Ca~(2+) Exchange-mediated La~(3+) Entry in Human Lymphocytes

With extensive applications the rare earth elements to agriculture, medicine and animal husbandry, whether rare earth ions can cross cell membranes and participate in the metabolism of animals and plants is not clear until now. Otherwise, rare earth ions have different interaction fashions to different kinds of cells, therefore, in this study we determined whether La3+ enter human peripheral blood lymphocytes via Na+/Ca2+ exchanger (measured with fura-2).Relative sensitivity of fura-2 to Ca2+…     

Na+-Ca2+ exchanger modulates Ca2+ content in intracellular Ca2+ stores in rat osteoblasts

Na+-Ca2+ exchanger (NCX) transports Ca2+ coupled with Na+ across the plasma membrane in a bi-directional mode. Ca2+ flux via NCX mediates osteogenic processes, such as formation of extracellular matrix proteins and bone nodules. However, it is not clearly understood how the NCX regulates cellular Ca2+ movements in osteogenic processes. In this study, the role of NCX in modulating Ca2+ content of intracellular stores ([Ca2+]ER) was investigated by measuring intracellular Ca2+ activity in isolated rat osteoblasts. Removal of extracellular Na+ elicited a transient increase of intracellular Ca2+ concentration ([Ca2+]i). Pretreatment of antisense oligodeoxynucleotide (AS) against NCX depressed this transient Ca2+ rise and raised the basal level of [Ca2+]i. In AS-pretreated cells, the expression and activity of alkaline phosphatase (ALP), an osteogenic marker, were decreased. However, the cell viability was not affected by AS-pretreatment. Suppression of NCX activity by the AS-pretreatment decreased ATP-activated Ca2+ release from intracellular stores and significantly enhanced Ca2+ influx via store operated calcium influx (SOCI), compared to those of S-pretreated or control cells. These results strongly suggest that NCX has a regulatory role in cellular Ca2+ pathways in osteoblasts by modulating intracellular Ca2+ content.     

Effect of the ionic strength and prostaglandin E2 on the free Ca2+ concentration and the Ca2+ influx in human red blood cells

Human red blood cells (RBCs) were loaded with the Ca(2+)-sensitive fluorescent dye fura-2 to investigate the effects of media ionic strength and prostaglandin E2 (PGE2) on the intracellular free Ca2+ concentration ([Ca2+]i). [Ca2+]i of intact RBCs in a Ca(2+)-containing physiological (high) ionic strength (HIS) solution was 75.1 +/- 8.3 nM after 5 min incubation, increasing to 114.9 +/- 9.6 nM after 1 h. In Ca(2+)-containing low ionic strength (LIS) solutions, [Ca2+]i was significantly lower than in the Ca(2+)-containing HIS solution (p = 0.041 or 0.0385 for LIS solutions containing 200 or 250 mM sucrose, respectively), but, as in HIS solution, an increase of [Ca2+]i was seen after 1 h. In Ca(2+)-free (0 Ca2+ plus 15 microM EGTA) media, [Ca2+]i decreased (ranging from 15 to 21 nM), but were not significantly different in HIS or LIS, and did not change following 1 h incubation. The effect of the ionic strength and PGE2 on passive Ca2+ influx was investigated on ATP-depleted RBCs. Ca2+ influx was faster during the initial 10 min in comparison with the subsequent time period (10-45 min), both in HIS and LIS media, decreasing from 20.3 +/- 1.9 to 12.9 +/- 1.3 micromol/(lcells x h) in HIS, and from 36.7 +/- 5.3 to 8.6 +/- 1.2 micromol/(lcells x h) in LIS. Prostaglandin E2 (PGE2; 10(-7)-10(-11) M), dissolved in deionised water or in ethanol, did not affect [Ca2+]i in either normal or in ATP-depleted RBCs suspended in Ca(2+)-containing HIS medium. Finally, the addition of carbachol (100 microM) did not affect [Ca2+]i. The present findings suggest that stimulation of the Ca(2+)-activated K+ channel by PGE2, reported in [J. Biol. Chem. 271 (1996) 18651], cannot be mediated via increased [Ca2+]i.     

Development of intracellular calcium measurement by time-resolved photon-counting fluorescence

Calcium green I, a ratiometric probe based on fluorescence lifetime measurements, was used to monitor intracellular calcium activity ([Ca2+]i) in RINm5F cells using a time-resolved fluorescence confocal microscope. The probe affinity constant has been recalibrated in single cells using ionomycin as a calcium ionophore and ethylenebis(oxyethylenenitrilo)tetraacetic acid as a calcium buffer; Kd was found to equal 150 nmol/L. The kinetics of ionomycin equilibration showed that the calcium release from calcium stores occurs before equilibration with extracellular calcium. The response to the muscarinic agonist carbachol, measured on 17 cells receiving three consecutive applications was characterized both by a [Ca2+]i peak lasting 50 s without any trailing plateau and by desensitization with a 30% decrease in the response. The dose-dependent response was obtained for a carbachol concentration from 5 mumol/L to 0.5 mmol/L. The ability of our set-up to obtain a value every 10 ms enabled us to record asynchronous spikes of [Ca2+]i in the RINm5F cells. The spikes, lasting less than 1 s, are significantly bigger than the noise, and they are not observed in the colonic HT29 cells.     

Design, synthesis, and structure-activity relationships of 3,4-dihydropyridopyrimidin-2(1H)-one derivatives as a novel class of sodium/calcium exchanger inhibitor

Design, synthesis, and structure-activity relationships for 3,4-dihydropyridopyrimidin-2(1H)-one derivatives, which are aza-3,4-dihydro-2(1H)-quinazolinone derivatives, as the sodium/calcium (Na+/Ca2+) exchanger inhibitors are discussed. These studies based on 3,4-dihydro-2(1H)-quinazolinone derivatives led to the discovery of a structurally novel and potent Na+/Ca2+ exchanger inhibitor, 3,4-dihydropyridopyrimidin-2(1H)-one derivative (26), with an IC30 value of 0.02 microM. Compound 26 directly inhibited the Na+-dependent Ca2+ influx via the Na+/Ca2+ exchanger after Na+-free treatment in cardiomyocytes.     

Inhibition of superoxide generation and of increase in intracellular Ca2+ concentration by zinc in rat neutrophils stimulated with zymosan

The effect of Zn2+ on the O2- generation and change in intracellular Ca2+ concentration ([Ca2+]i) of rat peritoneal neutrophils was studied. Zymosan (serum-treated zymosan (STZ))-induced O2- generation was inhibited by Zn2+ at concentrations as low as 10 microM. A large amount of the inhibition was observed in the absence of extracellular Ca2+ but the inhibition could not be restored by increasing the extracellular Ca2+ concentration, indicating that Zn2+ does not necessarily inhibit the O2- generation competitively with extracellular Ca2+. In the absence of extracellular Ca2+, Zn2+ inhibited STZ-induced transient increase in [Ca2+]i in the concentration range that evoked a marked inhibition in the O2- generation. On the other hand, Zn2+ did not inhibit significantly STZ-induced uptake of 45Ca2+ from extracellular medium by the cells. From these results, it is suggested that Zn2+ inhibits STZ-induced release of Ca2+ from intracellular storage sites, resulting in the suppression of the activation mechanism of neutrophils.     

La3+ Transmembrane Research in Guinea Pig Ventricular Cells by Fura-2 Fluorescence

The safety of rare earth fertilizer was paid more attention now, Whether RE' (rare earthion)cross membrane or not is the key problem of rare earth element biological effect. Itwas not solved until now. Ventricular cells which have different type of ions channel andadrenoceptor played very important role in biological functionl. To our knowledge, transventricular cells membrane behavior of rare earth ions has not been researched byFura-2 fluorescent probe technique. Guinea pig ventricular cel…     

Decationization and dealumination of clinoptilolite tuff and ammonium exchange on acid-modified tuff

The paper presents results of investigation of exchange of the clinoptilolite tuff cations with hydrogen ions from HCl solution of concentration 0.1 mmol cm(-3) and ammonium ions solutions of concentrations 0.0071 to 2.6 mmol cm(-3). Molal concentrations, x (mmol g(-1)) of cations exchanged in acid solution and in ammonium ions solutions were compared with molal concentrations of cations obtained by determination of the cation-exchange capacity of clinoptilolite tuff. The obtained results show that at ammonium ion concentrations lower than 0.1 mmol cm(-3), with regard to exchange capacity for particular ions, best exchanged are Na+ ions, followed by Mg2+ and Ca2+ ions, while exchange of K+ ions is the poorest (Na+ > Mg2+ > Ca2+ > K+). At ammonium concentrations from 0.2 to 1 mmol cm(-3) the order is Na+ > Ca2+ > Mg2+ > K+. At concentrations higher than 1 mmol cm(-3) the order is Na+ > Ca2+ > K+ > Mg2+. The results are a consequence of the uptake of hydrogen ions by zeolite samples in ammonium ions solutions at concentrations lower than 1 mmol cm(-3) and indicate the importance of Mg2+ (besides Na+ ions) for the exchange between clinoptilolite cations and H+ ions, in contrast to K+ ions, whose participation in the reaction with H+ ions is the lowest. During decationization of the clinoptilolite in acid solution, best exchanged are Na+, Mg2+, and Ca2+ ions, while exchange of K+ ions is the poorest. Due to poor exchange of K+ and H+ ions and good exchange of Na+, Mg2+, and Ca2+ ions, it is to be assumed that preservation of stability of the clinoptilolite structure is caused by K+ ions present in the channel C. Clinoptilolite is dissolved in the clinoptilolite A and B channels where Na+, Mg2+, and Ca2+ ions are present. On the acid-modified clinoptilolite samples, exchange of ammonium ions is poorer than on natural zeolite. The longer the contact time of the zeolite and acid solution, the worse ammonium ions exchange. It can be assumed that H+ ions exchanged with zeolite cations are consumed for solution of aluminum in the clinoptilolite structure; therefore the concentration of H+ ions as exchangeable cations decreases. In the ammonium ion solution at a concentration of 0.0065 mmol cm(-3), from the acid-modified zeolite samples, Al3+ ions are exchanged best, followed by Na+, Mg2+, Ca2+, and K+ ions. Further to the results, it is to be assumed that exchangeable Al3+ ions available from clinoptilolite dissolution are best exchanged with H+ ions in acid solution.     

Doxorubicin-induced reactive oxygen species generation and intracellular Ca2+ increase are reciprocally modulated in rat cardiomyocytes

Doxorubicin (DOX) is one of the most potent anticancer drugs and induces acute cardiac arrhythmias and chronic cumulative cardiomyopathy. Though DOX-induced cardiotoxicity is known to be caused mainly by ROS generation, a disturbance of Ca2+ homeostasis is also implicated one of the cardiotoxic mechanisms. In this study, a molecular basis of DOX-induced modulation of intracellular Ca2+ concentration ([Ca2+]i) was investigated. Treatment of adult rat cardiomyocytes with DOX increased [Ca2+]i irrespectively of extracellular Ca2+, indicating DOX-mediated Ca2+ release from intracellular Ca2+ stores. The DOX-induced Ca2+ increase was slowly processed and sustained. The Ca2+ increase was inhibited by pretreatment with a sarcoplasmic reticulum (SR) Ca2+ channel blocker, ryanodine or dantrolene, and an antioxidant, alpha-lipoic acid or alpha-tocopherol. DOX-induced ROS generation was observed immediately after DOX treatment and increased in a time-dependent manner. The ROS production was significantly reduced by the pretreatment of the SR Ca2+ channel blockers and the antioxidants. Moreover, DOX-mediated activation of caspase-3 was significantly inhibited by the Ca2+ channel blockers and a-lipoic acid but not a-tocopherol. In addition, cotreatment of ryanodine with alpha-lipoic acid resulted in further inhibition of the casapse-3 activity. These results demonstrate that DOX-mediated ROS opens ryanodine receptor, resulting in an increase in [Ca2+]i and that the increased [Ca2+]i induces ROS production. These observations also suggest that DOX/ROS-induced increase of [Ca2+]i plays a critical role in damage of cardiomyocytes.     

Na^+／Ca^2+交换介导的Nd^3+跨淋巴细胞膜的行为研究

利用Fura-2荧光浓度指示剂法对Na^+／Ca^2+交换介导的Nd^3+跨入外赂血淋巴 细胞膜行为进行了一系列研究。结果表明：当细胞形成向外的Na^+梯度时Nd^3+能 跨膜进入细胞,电压依赖性L-型Ca^2+通道对Nd^3+进入无贡献,提出了Na^+／ Ca^2+交换系统是Nd^3+进入细胞的主要途径;在安全浓度范围内进入胞内的游 Nd^3+浓度成正比,计算表明进入胞内的最大游离Nd^3+浓度为（3.67±0.32）× 10^-14mol·L^-1;当胞外pH值降低时进入胞内的游离Nd^3+浓度减小,胞内游离 Ca^2+浓度减小时进入的游离Nd^3+浓度略微增大,胞外Nd^3+和Ca^2+竞争Na^+／ Ca^2+交换位点;结果进一步推测进入胞内的Nd^3+可被质膜钙泵泵出胞外,初步实 验表明进入胞浆中的Nd^3+会在内质网中进一步累积,而在线粒体中不累积。     

CeO2-MOx（M=La^3＋,Ca^2＋）改性Pd/γ-Al2O3催化甲烷燃烧性能

采用沉积-沉淀法制备了固溶体CeO2-MOx=(M=La3+,Ca2+)改性的Pd/γ-Al2O3催化剂,利用XRD、Raman和XPS对催化剂进行了表征.结果表明,金属(M)离子进入CeO2的晶格,形成CeO2-MOx固溶体,Raman谱上463cm-1处对应于Ce-O键的F2g对称伸缩振动强度降低.其中,样品Pd/γ-Al2O3CeO2-CaO在615 cm-1处出现一小峰,样品Pd/γ-Al2O3-CeO2-La2O3在320cm-1处出现的肩峰,都表明固溶体CeO2-MOx的形成使O2-亚晶格结构对称性降低.XPS分析表明,固溶体改性的Pd/γ-Al2O3催化剂中Pd的3d5/2结合能比正常价态的PdO的结合能高出0.5-0.6 eV,形成了一种高度离子化的.与载体具有强相互作用的Pd物种.催化甲烷燃烧实验证明,固溶体CeO2-MOx(M=La3+,Ca2+)改性的Pd/γ-Al2O3催化剂的低温活性和稳定性均高于未经改性的Pd/γ-Al2O3催化剂和仅用CeO2改性的Pd/γAl2O3催化剂,在空速为50000 h-1时,可使1%CH4-99%空气(体积分数)混合气中甲烷的10%转化温度降至254℃,转化率100%时的转化温度降至340℃.     

CeO2-MOx (M=La3+, Ca2+)改性Pd/γ-Al2O3催化甲烷燃烧性能

采用沉积-沉淀法制备了固溶体CeO2-MOx(M=La3+, Ca2+)改性的Pd/γ-Al2O3催化剂, 利用XRD、Raman和XPS对催化剂进行了表征. 结果表明, 金属(M)离子进入CeO2的晶格, 形成CeO2-MOx固溶体, Raman谱上463 cm-1处对应于Ce—O键的F2g对称伸缩振动强度降低. 其中, 样品Pd/γ-Al2O3-CeO2-CaO在615 cm-1处出现一小峰, 样品Pd/γ-Al2O3-CeO2-La2O3在320 cm-1处出现的肩峰, 都表明固溶体CeO2-MOx的形成使O2-亚晶格结构对称性降低. XPS分析表明, 固溶体改性的Pd/γ-Al2O3催化剂中Pd 的3d5/2结合能比正常价态的PdO的结合能高出0.5-0.6 eV, 形成了一种高度离子化的, 与载体具有强相互作用的Pd物种. 催化甲烷燃烧实验证明, 固溶体CeO2-MOx(M=La3+, Ca2+)改性的Pd/γ-Al2O3催化剂的低温活性和稳定性均高于未经改性的Pd/γ-Al2O3催化剂和仅用CeO2改性的Pd/γ-Al2O3催化剂, 在空速为50000 h-1时, 可使1%CH4-99%空气(体积分数)混合气中甲烷的10%转化温度降至254 ℃, 转化率100%时的转化温度降至340 ℃.     

重稀碱金属Cs~+跨人红细胞膜行为的研究(英文)

采用原子吸收光谱法检测体外人红细胞摄取Cs+的含量,系统讨论了胞外Cs+浓度,温育时间、温育温度、介质pH值对人红细胞摄取Cs+过程的影响。选用不同离子通道或离子载体的特异性抑制剂进一步探讨Cs+的跨膜途径和机理。结果显示,各实验参数对人红细胞摄取Cs+均有一定的促进作用。Cs+主要借助Na+/K+-泵的主动运输方式跨膜;少量的Cs+能"漏入"细胞,微量的Cs+可以模拟Na+/Li+-反向协同运输的方式跨膜;在允许HCO3-存在的pH环境下,少量Cs+以Cl-/CsCO3-交换的形式通过膜上带3蛋白进入人红细胞;Ca2+通道对Cs+没有通透作用。     

A confocal study of mechanism of 5-hydroxytryptamino induced intracellular calcium dynamics in cultured rat stomach fundus smooth muscle cells with a new Ca~(2+) indicator STDIn-AM

A new fluorescent Ca2+ indicator STDIn-AM for detecting [Ca2+]i transients in cultured smooth muscle cells is presented. By making a comparison, the difference between STDIn and fluo-3 is discussed in detail. Using the new Ca2+ indicator, the mechanism of 5-hydroxytryptamino (5-HT) induced intracellular calcium dynamics in stomach fundus smooth muscle cells (SFSMC) of rats is investigated. It is shown that in contrast with fluo-3, STDIn is uniformly distributed in the cytosolic compartment but excluded from the nucleus, when it is transfected into cells. This feature makes it a real cytosol Ca2+ indicator and can reflect changes of cytosol [Ca2+] more accurately than that of fluo-3. In addition, STDIn responds to the [Ca2+]i transients more sensitive and faster than fluo-3. The results also show that, the L-type Ca2+channel inhibitor Mn9202 and the PLC inhibitor Compound 48/80 can significantly inhibit the [Ca2+]i elevation induced by 5-HT, while the PKC inhibitor D-Sphingosine can enhance the effect of     

On the formation of iron(III) hydroxo acetate complexes

The formation of hydroxo acetate complexes of iron (III) ion has been studied at 25 degrees C in 3 M (Na)ClO4 ionic medium by measuring with a glass electrode the hydrogen ion concentration in Fe(ClO4)3-HClO4-NaAc mixtures (Ac = acetate ion). The acetate/metal ratio ranged from 0 to 6, the metal concentration varied from 0.005 to 0.06 M, whereas [H+] was stepwise decreased from 0.1 M to initial precipitation of hydroxo-acetates. This occurred, depending on the acetate/metal ratio, in the -log[H+] range 1.85-2.7. The potentiometric data are consistent with the presence of Fe3(OH)3Ac3(3+), Fe2(OH)2(4+), Fe3(OH)4(5+), Fe3(OH)5(4+) and, as minor species, of Fe3(OH)2Ac6+, FeAc2+, FeAc2+, FeOH2+ and Fe(OH)2+. Previously published EMF measurements with redox and glass half-cells were recalculated to refine the stability constants of FeAc2+, FeAc2+ and Fe3(OH)2Ac6+. Formation constants *beta pqr for pFe(3+)+(q-r)H2O + rHAc reversible Fep(OH)(q-r)(Ac)r3p-q + qH+ (in parenthesis the infinite dilution value): log*beta 111 = -1.85 +/- 0.02 (-0.67 +/- 0.15), log*beta 122 = -3.43 +/- 0.02 (-1.45 +/- 0.15); log*beta 363 = -5.66 +/- 0.03 (-2.85 +/- 0.40), log*beta 386 = -8.016 +/- 0.006 (-4.06 +/- 0.15), log*beta 220 = -2.88 +/- 0.02 (-2.84 +/- 0.05), log*beta 340 = -6.14 +/- 0.18 (-6.9 +/- 0.4), log*beta 350 = -8.44 +/- 0.09 (-7.65 +/- 0.15).     

Cation exchange selectivity of some fission products on strongly acidic cation exchanger of sulfonic acid type-nitric acid system

Distribution coefficients of fission products in nitric acid for strongly acidic cation exchanger of sulfonic acid type with different cross-linking and structure were measured by a column method. Uptake of cationic fission products increases with resin cross-linking and decreases of nitric acid concentration. The distribution coefficient of the ion, [Kd_Mn+]^*, in a given system is expressed as log [Kd_Mn+]^*=B·log[Kd_Mn+]+A where [Kd_Mn+] is the distribution coefficient of the ion at 1M nitric acid for 10% crosslinked gel type cation exchanger, while A and B constants. Deviation from the above relation were observed for Y³⁺ and complex ions of ruthenium upward for macroporous type cation exchanger and downward for highly porous type cation exchanger. Upward deviation of Y³⁺ for 10% cross-linked gel type cation exchanger increased with concentration of nitric acid. Consequently, elution sequence varied from Y³⁺–Eu³⁺–Pm³⁺–Ce³⁺⁺ at 1M nitric acid to Eu³⁺–Pm³⁺–Y³⁺–Ce³⁺ for the same cation exchanger at 2M nitric acid. The same elution sequence, Eu³⁺–Pm³⁺–Y³⁺–Ce³⁺, was observed for 8% cross-linked gel type cation exchanger and 10% cross-linking macroporous type cation exchanger at 1M nitric acid.     

Theoretical analysis on ratiometric fluorescent indicators caused biased estimates of intracellular free calcium concentrations

Ratiometric fluorescent calcium indicator dyes have been widely used for the study of the role of Ca2+ in cell physiopathology. Although these ratiometric dyes offer several advantages over others, they suffer some drawbacks which cause serious errors in measurement of intracellular Ca2+ concentration, [Ca2+]i. The present study systematically analyzes theoretical reasons and technical sources of discrepancies occurring in the measurement of the characteristics of the agonists-induced cells [Ca2+]i. In order to avoid the errors and achieve the accurate determination of [Ca2+]i, this study proposes solutions and suggests some critical measures in both theoretical and technical aspects. Therefore, this analysis can be a valuable tool in clarifying proper usages of fluorescent dyes for [Ca2+]i measurements.     

硫酸浸渍La_2O_3掺杂TiO_2光催化剂对甲基橙废水化学耗氧量的影响

采用不同浓度的硫酸溶液浸渍处理La2O3掺杂TiO2,随后经焙烧制得一系列SO24-/TiO2-La2O3光催化剂;考察了SO24-/TiO2-La2O3光催化剂对甲基橙废水溶液化学耗氧量的影响.结果表明,SO24-/TiO2-La2O3的光催化活性比TiO2-La2O3的高;H2SO4浸渍液浓度对SO24-/TiO2-La2O3的光催化活性有一定的影响,H2SO4溶液的最佳浓度为0.5mol/L.同时,催化剂的焙烧温度对其光催化活性也有一定的影响,最佳焙烧温度为500℃;而复合催化剂中La2O3的最佳掺杂量为0.3%.     

La3+-catalyzed methanolysis of O,O-diethyl S-(p-nitrophenyl) phosphorothioate and O,O-diethyl S-phenyl phosphorothioate. Millions-fold acceleration of the destruction of V-agent simulants

The La3+-catalyzed methanolysis of two phosphorothioate derivatives, O,O-diethyl S-(p-nitrophenyl) phosphorothioate (4a) and O,O-diethyl S-phenyl phosphorothioate (4b) were studied as a function of [La3+] and pH in methanol solvent. In both cases the kinetics of catalyzed methanolysis maximize at pH 9.1 and a detailed analysis indicates that the dominant species responsible for catalysis are dimers formulated as La3+(2)(-OCH3)2 and La3+(2)(-OCH3)4. The catalysis is compared with that seen for the corresponding phosphate esters, namely paraoxon (3a) and O,O-diethyl phenyl phosphate (3b) for which La3+ catalysis is slightly better and markedly worse than for 4a and 4b respectively. Overall, at s(s)pH 9.1, a 2 mmol dm-3 solution of La(OTf)3 with equimolar NaOCH3 provides accelerations of 2.2x10(8)-fold, 9.7x10(6)-fold and 9.3x10(6)-fold for methanolysis of 3a, 4a and 4b, relative to the background reaction of methoxide reacting with the three substrates. In each case, the P-containing product of the reactions is exclusively diethyl methyl phosphate. Turnover experiments with 6-fold and 100-fold excesses of 4a and 4b respectively, methanolyzed in the presence of approximately 10 mmol dm-3 La3+ and equimolar NaOCH3, indicate that the reactions are essentially complete within 103 s and 70 min respectively. The latter turnover experiment with 4b corresponded to 100 turnovers in 70 min and an overall reaction t1/2 of 8 min. A common mechanism of reaction is postulated for each of the substrates which involves Lewis acid coordination of one of the La3+ to the P=O unit, followed by nucleophilic attack by the second La3+-(-)OCH3.     

Fura-2荧光探针法检测细胞内La~(3+)

使用Fura - 2荧光探针技术 ,检测细胞内的镧离子浓度 [La3+]i 变化 ,研究其跨膜行为。结果显示 ,细胞外镧 [La3+]o(0 .1mmol/L)可使细胞内镧离子浓度增加 ,说明镧离子能够跨越小鼠心肌细胞膜 ,讨论了跨膜机理。