Gorodeski G I, Hopfer U, Jin W
Department of Reproductive Biology, Case Western Reserve University School of Medicine, Cleveland, OH, USA.
Cell Biochem Biophys. 1998;29(3):281-306. doi: 10.1007/BF02737899.
In human cervical (CaSki) cells, extracellular adenosine triphosphate (ATP) induces an acute decrease in the resistance of the lateral intercellular space (RLIS), phase I response, followed by an increase in tight junctional resistance (RTJ), phase II response. ATP also stimulates release of calcium from intracellular stores, followed by augmented calcium influx, and both effects have similar sensitivities to ATP (EC50 of 6 microM). The objective of the study was to determine the degree to which the changes in [Ca2+]i mediate the responses to ATP. 1,2-bis (2-aminophenoxy) ethane-N,N,N1,N1-tetraacetic acid (BAPTA) abrogated calcium mobilization and phase I response; in contrast, nifedipine and verapamil inhibited calcium influx and attenuated phase II response. Barium, La3+, and Mn2+ attenuated phase I response and attenuated and shortened the ionomycin-induced phase I-like decrease in RLIS, suggesting that store depletion-activated calcium entry was inhibited. Barium and La3+ also inhibited the ATP-induced phase II response, but Mn2+ had no effect on phase II response, and in the presence of low extracellular calcium it partly restored the increase in RTJ. KCl-induced membrane depolarization stimulated an acute decrease in RLIS and a late increase in RTJ similar to ATP, but only the latter was inhibited by nifedipine. KCl also induced a nifedipine-sensitive calcium influx, suggesting that acute increases in [Ca2+]i, regardless of mobilization or influx, mediate phase I response. Phase II-like increases in RTJ could be induced by treatment with diC8, and were not affected by nifedipine. Biphasic, ATP-like changes in RTE could be induced by treating the cells with ionomycin plus diC8. We conclude that calcium mobilization mediates the early decrease in RLIS, and calcium influx via calcium channels activates protein kinase C and mediates the late increase in RTJ.
在人宫颈（CaSki）细胞中，细胞外三磷酸腺苷（ATP）可诱导细胞外侧细胞间隙电阻（RLIS）急性降低，即I期反应，随后紧密连接电阻（RTJ）增加，即II期反应。ATP还能刺激细胞内钙库释放钙，随后钙内流增加，这两种效应对ATP的敏感性相似（半数有效浓度为6微摩尔）。本研究的目的是确定细胞内钙离子浓度（[Ca2+]i）的变化在多大程度上介导了对ATP的反应。1,2-双（2-氨基苯氧基）乙烷-N,N,N1,N1-四乙酸（BAPTA）消除了钙动员和I期反应；相反，硝苯地平和维拉帕米抑制钙内流并减弱II期反应。钡离子、镧离子和锰离子减弱I期反应，并减弱和缩短离子霉素诱导的RLIS中类似I期的降低，表明储存耗竭激活的钙内流受到抑制。钡离子和镧离子也抑制ATP诱导的II期反应，但锰离子对II期反应无影响，且在细胞外钙浓度较低时，它部分恢复了RTJ的增加。氯化钾诱导的膜去极化刺激RLIS急性降低和RTJ后期增加，类似于ATP，但只有后者被硝苯地平抑制。氯化钾还诱导了硝苯地平敏感的钙内流，表明[Ca2+]i的急性增加，无论其动员或内流情况如何，均介导I期反应。用二辛酰甘油（diC8）处理可诱导RTJ出现类似II期的增加，且不受硝苯地平影响。用离子霉素加diC8处理细胞可诱导出类似ATP的RTE双相变化。我们得出结论，钙动员介导了RLIS的早期降低，通过钙通道的钙内流激活蛋白激酶C并介导RTJ的后期增加。
