A nicardipine-sensitive Ca2+ entry contributes to the hypotonicity-induced increase in [Ca2+]i of principal cells in rat cortical collecting duct
A nicardipine-sensitive Ca2+ entry contributes to the hypotonicity-induced increase in [Ca2+]i of principal cells in rat cortical collecting duct
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DOI：
10.1016/j.ceca.2010.11.006
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发表时间：
2011-01-01
期刊：
影响因子：
4
通讯作者：
Kubokawa, Manabu
中科院分区：
文献类型：
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作者：
Komagiri, You;Nakamura, Kazuyoshi;Kubokawa, Manabu
我们使用Fura-2/AM荧光成像技术研究了新分离的大鼠皮质集管（CCD）主细胞中[Ca2+](i)对细胞外低渗的反应机制。细胞外渗透压从305（对照）降低到195 mosmol/kgH(2)O（低渗）引起大鼠ccd主细胞[Ca2+](i)的短暂增加。通过去除细胞外Ca2+， [Ca2+](i)的增加明显减弱。应用P-2嘌呤受体拮抗剂苏拉明未能抑制低张力诱导的[Ca2+](i)增加。[Ca2+](i)对细胞外低渗反应的增加不受Gd3+和钌红应用的影响。另一方面，电压门控Ca2+通道抑制剂尼卡地平显著降低了主细胞中[Ca2+](i)增加的峰值幅度。为了评估Ca2+在低渗刺激期间的进入，我们测量了Mn2+对Fura-2荧光强度的猝灭。低渗刺激增强了Mn2+对Fura-2荧光的猝灭，表明低渗刺激激活了Ca2+可渗透途径。尼卡地平可显著抑制低渗介导的Mn2+猝灭增强。这些结果强烈表明，尼卡地平敏感的Ca2+进入途径可能有助于大鼠CCD低张力诱导的[Ca2+](i)升高的机制。(C) 2010 Elsevier Ltd.版权所有。
We examined the mechanisms involved in the [Ca2+](i) response to the extracellular hypotonicity in the principal cells of freshly isolated rat cortical collecting duct (CCD), using Fura-2/AM fluorescence imaging.Reduction of extracellular osmolality from 305 (control) to 195 mosmol/kgH(2)O (hypotonic) evoked transient increase in [Ca2+](i) of principal cells of rat CCDs. The [Ca2+](i) increase was markedly attenuated by the removal of extracellular Ca2+. The application of a P-2 purinoceptor antagonist, suramin failed to inhibit the hypotonicity-induced [Ca2+](i) increase. The [Ca2+](i) increase in response to extracellular hypotonicity was not influenced by application of Gd3+ and ruthenium red. On the other hand, a voltage-gated Ca2+ channel inhibitor, nicardipine, significantly reduced the peak amplitude of [Ca2+](i) increase in the principal cells. In order to assess Ca2+ entry during the hypotonic stimulation, we measured the quenching of Fura-2 fluorescence intensity by Mn2+. The hypotonic stimulation enhanced quenching of Fura-2 fluorescence by Mn2+, indicating that a Ca2+-permeable pathway was activated by the hypotonicity. The hypotonicity-mediated enhancement of Mn2+ quenching was significantly inhibited by nicardipine.These results strongly suggested that a nicardipine-sensitive Ca2+ entry pathway would contribute to the mechanisms underlying the hypotonicity-induced [Ca2+](i) elevation of principal cells in rat CCD. (C) 2010 Elsevier Ltd. All rights reserved.