Extracellular Mg2+- and Ca2+-sensing in mouse distal convoluted tubule cells
Extracellular Mg2+- and Ca2+-sensing in mouse distal convoluted tubule cells
复制标题
DOI：
10.1046/j.1523-1755.1998.00790.x
复制
发表时间：
1998-03-01
影响因子：
19.6
通讯作者：
Quamme, GA
中科院分区：
文献类型：
--
作者：
Bapty, BW;Dai, LJ;Quamme, GA
永生化细胞系（命名为MDCT）已被广泛用于研究电解质在小鼠远曲小管内转运的细胞机制。小鼠远曲小管细胞具有体内远曲小管的许多功能特征。在本研究中，我们发现MDCT细胞也具有多价阳离子敏感机制，对细胞外镁和钙敏感。反转录-聚合酶链反应（RT-PCR）产物的Southern杂交、序列测定和Western分析表明，钙敏感受体（Casr）在MDCT细胞中表达。使用单个MDCT细胞的显微荧光来确定胞质Ca 2+信号传导，表明多价阳离子传感机制对在血浆中正常观察到的浓度范围内的细胞外镁浓度（[Mg 2 +]（o））和细胞外钙浓度（[Ca 2 +]（o））敏感。此外，[Mg 2 +]（o）和[Ca 2 +]（o）在分别存在高浓度[Ca 2 +]（o）和[Mg 2 +]（o）的情况下有效地产生细胞内Ca 2+瞬变。这些反应与甲状旁腺管型中观察到的反应不同。最后，用[Mg 2 +]（o）或[Ca 2 +]（o）激活聚阳离子敏感机制抑制甲状旁腺激素、降钙素、胰高血糖素和精氨酸加压素刺激的MDCT细胞中cAMP释放。这些研究表明，永生化MDCT细胞具有多价阳离子敏感机制，并强调了该机制在调节细胞内信号响应[Mg 2 +]（o）和[Ca 2 +]（o）变化中的重要作用。
An immortalized cell line (designated MDCT) has been extensively used to investigate the cellular mechanisms of electrolyte transport within the mouse distal convoluted tubule. Mouse distal convoluted tubule cells possess many of the functional characteristics of the in vivo distal convoluted tubule. In the present study, we show that MDCT cells also possess a polyvalent cation-sensing mechanism that is responsive to extracellular magnesium and calcium. Southern hybridization of reverse transcribed-polymerase chain reaction (RT-PCR) products, sequence determination and Western analysis indicated that the calcium-sensing receptor (Casr) is expressed in MDCT cells. Using microfluorescence of single MDCT cells to determine cytosolic Ca2+ signaling, it was shown that the polyvalent cation-sensing mechanism is sensitive to extracellular magnesium concentration ([Mg2+](o)) and extracellular calcium concentration ([Ca2+](o)) in concentration ranges normally observed in the plasma. Moreover, both [Mg2+](o) and [Ca2+](o) were effective in generating intracellular Ca2+ transients in the presence of large concentrations of [Ca2+](o) and [Mg2+](o), respectively. These responses are unlike those observed for the Cast in the parathyroid gland. Finally, activation of the polycation-sensitive mechanism with either [Mg2+](o) or [Ca2+](o) inhibited parathyroid hormone-, calcitonin-, glucagon-and arginine vasopressin-stimulated cAMP release in MDCT cells. These studies indicate that immortalized MDCT cells possess a polyvalent cation-sensing mechanism and emphasize the important role this mechanism plays in modulating intracellular signals in response to changes in [Mg2+](o) as well as in [Ca2+](o).