Törnquist K
Endocrine Research Laboratory, University of Helsinki, Minerva Foundation Institute for Medical Research, Finland.
Cell Calcium. 1993 May;14(5):411-7. doi: 10.1016/0143-4160(93)90045-8.
The aim of the present study was to investigate whether the Ca(2+)-ATPase inhibitor cyclopiazonic acid (CPA) could empty intracellular Ca2+ stores and activate Ca2+ influx in thyroid FRTL-5 cells. Addition of CPA to Fura-2 loaded cells rapidly increased intracellular free Ca2+ ([Ca2+]i) which then stabilized at a new elevated steady state level. The initial increase was mainly dependent on the release of sequestered Ca2+, but was decreased in Ca(2+)-free buffer and in depolarized cells. The plateau phase was totally dependent on extracellular Ca2+. Addition of Ca2+ to cells exposed to CPA in Ca(2+)-free buffer rapidly increased [Ca2+]i. This influx was decreased in depolarized cells and inhibited by SKF 96365. Addition of CPA to cells prior to stimulating the cells with ATP totally abolished the ATP-induced increase in [Ca2+]i. In Ca(2+)-free buffer, addition of ATP prior to CPA decreased the response in [Ca2+]i evoked by CPA. The results show that emptying intracellular Ca2+ stores with CPA rapidly activates influx of Ca2+ in FRTL-5 cells. Furthermore, ATP and CPA appear to release Ca2+, at least in part, from the same intracellular Ca2+ store in these cells.
本研究的目的是调查Ca(2+)-ATP酶抑制剂环匹阿尼酸（CPA）是否能够排空甲状腺FRTL-5细胞内的Ca2+储存并激活Ca2+内流。向负载Fura-2的细胞中添加CPA会迅速增加细胞内游离Ca2+（[Ca2+]i），然后稳定在一个新的升高的稳态水平。最初的增加主要依赖于被隔离的Ca2+的释放，但在无Ca(2+)缓冲液和去极化细胞中会降低。平台期完全依赖于细胞外Ca2+。向在无Ca(2+)缓冲液中暴露于CPA的细胞中添加Ca2+会迅速增加[Ca2+]i。这种内流在去极化细胞中会降低，并被SKF 96365抑制。在用ATP刺激细胞之前向细胞中添加CPA完全消除了ATP诱导的[Ca2+]i增加。在无Ca(2+)缓冲液中，在添加CPA之前添加ATP会降低CPA引起的[Ca2+]i反应。结果表明，用CPA排空细胞内Ca2+储存会迅速激活FRTL-5细胞中的Ca2+内流。此外，ATP和CPA似乎至少部分地从这些细胞中的同一细胞内Ca2+储存中释放Ca2+。
