Modulation of intracellular Ca2+ by glucose in MDCK cells: role of endoplasmic reticulum Ca(2+)-ATPase.
Modulation of intracellular Ca2+ by glucose in MDCK cells: role of endoplasmic reticulum Ca(2+)-ATPase.
复制标题
MDCK 细胞中葡萄糖对细胞内 Ca2+ 的调节：内质网 Ca(2)-ATP 酶的作用。
DOI：
10.1152/ajprenal.1995.268.4.f671
复制
发表时间：
1995
期刊：
影响因子：
--
通讯作者：
Martinez-Zaguilan,R
中科院分区：
文献类型：
--
作者：
Lien,YH;Wang,X;Gillies,RJ;Martinez-Zaguilan,R
细胞内游离钙离子（[Ca ~（2+）]i）在肾上皮细胞中具有多种功能，包括介导配体和容积激活的K ~+和Cl ~-通道，调节顶端膜对Na ~+的通透性，以及调节肾小管-肾小球反馈。我们研究了葡萄糖对Madin-Darby犬肾（MDCK）细胞内pH值（pHi）和[Ca 2 +]i的影响，分别使用荧光探针SNARF-1和Fura 2。葡萄糖的加入以剂量依赖性方式降低pHi和[Ca 2 +]i。内质网Ca（2+）-ATP酶（Ca（2+）-ATPase）抑制剂毒胡萝卜素（TG）和环匹阿尼酸（CPA）可阻断葡萄糖引起的[Ca（2+）]i降低。在没有葡萄糖的情况下，1 μ M TG诱导[Ca 2 +]i持续升高，随着葡萄糖的加入进一步增加，而15 μ M CPA诱导[Ca 2 +]i短暂增加，不受进一步加入葡萄糖的影响。TG引起的[Ca ~（2+）]i持续升高依赖于细胞外Ca ~（2+）。TG诱导的[Ca 2 +]i增加受葡萄糖调节，即，在较高的葡萄糖浓度下，TG诱导[Ca 2 +]i更大和更快的上升。我们得出结论，葡萄糖对[Ca 2 +]i的调节具有双重作用。葡萄糖单独通过激活ER型Ca（2+）-ATP酶降低[Ca 2 +]i，因为这种现象是TG和CPA敏感的。在TG存在下，葡萄糖可能通过增加Ca 2+内流来增加[Ca 2 +]i。我们的数据表明，TG激活的ER Ca 2+池耗尽的电容性Ca 2+进入的模型。葡萄糖通过进一步增强容量性Ca 2+内流增加TG诱导的[Ca 2 +]i升高。
Intracellular free calcium ([Ca2+]i) has multiple functional roles in renal epithelia, including mediating ligand- and volume-activated K+ and Cl- channels, modulating the permeability of apical membrane to Na+, and regulating tubuloglomerular feedback. We investigated glucose effects on intracellular pH (pHi) and [Ca2+]i in Madin-Darby canine kidney (MDCK) cells using fluorescent probes, SNARF-1 and fura 2, respectively. The addition of glucose decreased both pHi and [Ca2+]i in a dose-dependent fashion. Thapsigargin (TG) and cyclopiazonic acid (CPA), well-known endoplasmic reticulum (ER) Ca(2+)-adenosinetriphosphatase (Ca(2+)-ATPase) inhibitors, abolished the glucose-induced [Ca2+]i decrease. Without glucose, 1 microM TG induced a sustained elevation in [Ca2+]i, which increased further with glucose addition, whereas 15 microM CPA induced a transient increase in [Ca2+]i that was not affected by further addition of glucose. The sustained elevation in [Ca2+]i induced by TG was dependent on extracellular Ca2+. TG-induced [Ca2+]i increase was modulated by glucose, i.e., at higher glucose concentrations, TG induced a larger and more rapid rise in [Ca2+]i. We conclude that glucose has dual effects on [Ca2+]i regulation. Glucose alone reduces [Ca2+]i by activating ER-type Ca(2+)-ATPase, since this phenomenon is TG and CPA sensitive. In the presence of TG, glucose increases [Ca2+]i probably by increasing Ca2+ entry. Our data suggest a model in which TG activates capacitative Ca2+ entry by depletion of the ER Ca2+ pool. Glucose increases TG-induced [Ca2+]i elevation by further enhancing capacitative Ca2+ entry.